rf100

February, 2005 1 - 1RF100a(c) 2005 Scott Baxter v2.0

Wireless CDMA RF Engineering: Week 1Wireless CDMA RF

Engineering: Week 1

Course RF100


Integrated RF/CDMA/Performance Training

•Wireless Industry Intro.•Modulation Techniques•Mult. Access Methods•Wireless system Architectures•RF Propagation

•Physics•Mechanisms•Models•Link Budgets•Margins•Pred. Tools•Meas. Tools

•Wireless Antennas•Intro: Principles•Families/Types•Choosing the right antenna•Selecting ants. •Other devices•Tests/Problems

•Traffic Engineering•Units, principles•Traffic tables•Wireless appls.

•Introduction to CDMA•Spread Sp. Principles•CDMA’s Codes•Fwd & Rev Channels•System Architecture•Power Control•Phone Architecture•Handoff Process

•Ec/Io, Eb/No•phone’s limitations

•Call Processing•CDMA Messages

•CDMA Flow Examples•Critical CDMA Issues

•Interference control•Managing Soft HO%•Capacity constraints

•Forward big picture•Reverse big picture

•Sys Architecture details•Lucent•Nortel•Motorola

•System Growth Mgt.•Stopgap measures•Longterm strategies•Multiple carriers•Intercarrier Handoff

•Intro to Optimization•Perspectives

•Bottom-up: mobile•Top-down: OMs

•Survey of Tools•Performance Goals•Design Implications

Monday Tuesday Wednesday Thursday Friday

Course RF100: RF Introduction, CDMA Principles, Understanding System Design & Performance Issues

Course RF200: Optimization Principles, Tools, Techniques, and Real-Life Examples/Exercises

•Optimization Overview•RF100 Fast Review•General Q&A•Meet the CDMA performance indicators•Signatures of CDMA transmission problems•The classic CDMA death scenario•Introduction to Performance Data•System-side tools and their implications

•Intro to Mobile Tools•Collection Tools

•Grayson, LCC, HP•PN Scanners

•HP, Grayson, Berkeley

•Post-processing•Analyzer, DeskCat

•Drive-test Demo files•Grayson•LCC

•Intro to Post-Processing•Analyzer, DeskCat

•Handsets as test tools•Drive-Test Demo Lab

•RSAT/Collect 2000!•Grayson Inspector

•Data Analysis and Post-Processing

•Analyzer, DeskCat•what events did you see?•Identifying root causes•Parameter & configuration changes

•Operators’ Corporate RF Benchmarking Overview•PN Scanner Lab

•HP, Grayson, Berkeley•Gathering data, interpreting problems

•Applied Optimization•common scenarios

Day 1 Day 2 Day 3 Day 4


Wireless Systems:How did we get here? What’s it all about?

Wireless Systems:How did we get here? What’s it all about?

RF100 Chapter 1

MTS, IMTS


Radio Hasn’t Been Around Long!

Days before radio.....• 1680 Newton first suggested

concept of spectrum, but for visible light only

• 1831 Faraday demonstrated that light, electricity, and magnetism are related

• 1864 Maxwell’s Equations: spectrum includes more than light

• 1890’s First successful demos of radio transmission

UN S

LF HF VHF UHF MW IR UV XRAY


First Wired Communication: TelegraphySamuel F.B. Morse had the idea of the telegraph on a sea cruise in the 1833. He studied physics for two years, and In 1835 demonstrated a working prototype, which he patented in 1837.Derivatives of Morse’ binary code are still in use today The US Congress funded a demonstration line from Washington to Baltimore, completed in 1844.1844: the first commercial telegraph circuits were coming into use. The railroads soon were using them for train dispatching, and the Western Union company resold idle time on railroad circuits for public telegrams, nationwide1857: first trans-Atlantic submarine cable was installed

Samuel F. B. Morseat the peak of his career

Field Telegraphyduring the US Civil War, 1860’s

Submarine Cable Installationnews sketch from the 1850’s


Wired Communication for Everyone: Telephony

By the 1870’s, the telegraph was in use all over the world and largely taken for granted by the public, government, and business. In 1876, Alexander Graham Bell patented his telephone, a device for carrying actual voices over wires. Initial telephone demonstrations sparked intense public interest and by the late 1890’s, telephone service was available in most towns and cities across the USA

Telephone Line Installation Crew1880’s

Alexander Graham Bell and his phonefrom 1876 demonstration


Radio Milestones1888: Heinrich Hertz, German physicist, gives lab demo of existance of electromagnetic waves at radio frequencies1895: Guglielmo Marconi demonstrates a wireless radio telegraph over a 3-km path near his home it Italy1897: the British fund Marconi’s development of reliable radio telegraphy over ranges of 100 kM1902: Marconi’s successful trans-Atlantic demonstration 1902: Nathan Stubblefield demonstrates voice over radio1906: Lee De Forest invents “audion”, triode vacuum tube

• feasible now to make steady carriers, and to amplify signals1914: Radio became valuable military tool in World War I1920s: Radio used for commercial broadcasting1940s: first application of RADAR - English detection of incoming German planes during WW II1950s: first public marriage of radio and telephony -MTS, Mobile Telephone System1961: transistor developed: portable radio now practical1961: IMTS - Improved Mobile Telephone Service1970s: Integrated circuit progress: MSI, LSI, VLSI, ASICs1979, 1983: AMPS cellular demo, commercial systems

Guglielmo Marconiradio pioneer, 1895

Lee De Forestvacuum tube inventor

MTS, IMTS


Overview of the Radio SpectrumFrequencies Used by Wireless Systems

3 4 5 6 7 8 9 10 12 14 16 18 20 22 24 26 28 30 GHz30,000,000,000 i.e., 3x1010 Hz

Broadcasting Land-Mobile Aeronautical Mobile TelephonyTerrestrial Microwave Satellite

0.3 0.4 0.5 0/6 0.7 0.8 0.9 1.0 1.2 1.4 1.6 1.8 2.0 2.4 3.0 GHz3,000,000,000 i.e., 3x109 Hz

UHF TV 14-69UHF GPSDCS, PCSCellular

0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 1.2 1.4 1.6 1.8 2.0 2.4 3.0 MHz3,000,000 i.e., 3x106 Hz

AM LORAN Marine

3 4 5 6 7 8 9 10 12 14 16 18 20 22 24 26 28 30 MHz30,000,000 i.e., 3x107 Hz

Short Wave -- International Broadcast -- Amateur CB

30 40 50 60 70 80 90 100 120 140 160 180 200 240 300 MHz300,000,000 i.e., 3x108 Hz

FM VHF TV 7-13VHF LOW Band VHFVHF TV 2-6


In the late 1970’s, the FCC (USA Federal Communications Commission) allocated 40 MHz. of spectrum in the 800 MHz. range for public mobile telephony. FCC adopted Bell Lab’s AMPS (Advanced

Mobile Phone System) standard, creating cellular as we know it today

• The USA was divided into 333 MSAs(Metropolitan Service Areas) and over

300 RSAs (Rural Service Areas)In 1987, FCC allocated an additional 10 MHz. of “expanded spectrum”By 1990, all MSAs and RSAs had competing licenses granted and at least one system operating. In the 1990’s, additional technologies were developed for cellular

• TDMA (IS-54,55,56, IS-136) (also, GSM in Europe/worldwide)• CDMA (IS-95)

US Operators did not pay for their spectrum, although processing fees (typically $10,000’s) were charged to cover license administrative cost

Development of North American Cellular

333 MSAs300+ RSAs


North American Cellular Spectrum

In each MSA and RSA, eligibility for ownership was restricted• “A” licenses awarded to non-telephone-company applicants only• “B” licenses awareded to existing telephone companies only • subsequent sales are unrestricted after system in actual operation

Downlink Frequencies(“Forward Path”)

Uplink Frequencies(“Reverse Path”)

824 835 845 870 880 894

869

849

846.5825

890

891.5

Frequency, MHz

Paging, ESMR, etc.A B A B

Ownership andLicensing

Frequencies used by “A” Cellular OperatorInitial ownership by Non-Wireline companies

Frequencies used by “B” Cellular OperatorInitial ownership by Wireline companies


Development of North America PCS

51 MTAs493 BTAs

A D B E F C unlic.data

unlic.voice A D B E F C

1850 MHz.

1910 MHz.

1990 MHz.

1930 MHz.

15 15 155 5 5 15 15 155 5 5

PCS SPECTRUM ALLOCATIONS IN NORTH AMERICA

By 1994, US cellular systems were seriously overloaded and looking for capacity relief

• The FCC allocated 120 MHz. of spectrum around 1900 MHz. for new wireless telephony known as PCS (Personal Communications Systems), and 20 MHz. for unlicensed services

• allocation was divided into 6 blocks; 10-year licenses were auctioned to highest bidders

PCS Licensing and Auction Details• A & B spectrum blocks licensed in 51 MTAs (Major Trading Areas )

• Revenue from auction: $7.2 billion (1995) • C, D, E, F blocks were licensed in 493 BTAs (Basic Trading Areas)

• C-block auction revenue: $10.2 B, D-E-F block auction: $2+ B (1996)• Auction winners are free to choose any desired technology• About half the C-block winners were unable to pay for their licenses. They

wrangled in and out of court, with final disposition in 2005.


Major PCS Auction WinnersThe Largest Players, Areas, and Technologies

Sprint PCS• Began as partnership of Sprint, TCI, Cox Cable• Bid & won in 2/3 of US markets A or B blocks• Sprint won D and/or E blocks in remaining markets• CDMA: Mix of Nortel, Lucent, Motorola

AT&T Wireless Systems• Bid & won a majority of markets in A&B Blocks• will combine and integrate service between its new

PCS 1900 systems and its former McCaw cellular 800 MHz. properties

• IS-136: mix of Lucent and Ericsson equipmentOther CDMA Operators

• Primeco: partnership of various operators• GTE, others

GSM Operators• Western Wireless, OmniPoint, BellSouth, GTE,

Powertel, Pacific Bell• Mix of Ericsson, Nokia, and Nortel networks

For auction details, check www.fcc.gov

Sprint PCSCDMA

AT&T WirelessIS-136

PrimecoCDMA

Western Wireless

Pacific Bell

PowertelBellSouth

OmniPoint

Aerial

GSM


Progress in Radio Technology Development

Systems, Signals, & Devices

RADAR

Spark Vacuum Tubes

Discrete Transistors

MSILSI

VLSI, ASICS

DevicesModulation CW AM FMFSK PM PSK QAM DQPSK GMSK

Radio Communication SystemsMobile Telephony30-50MHz

150MHz450MHz800MHz

1900MHzAM Bcst1MHz FM Bcst100MHzVHF-TV Bcst

UHF-TV Bcst

HFAmateurMarine

Military

VHFLand Mobile

MicrowavePoint-to-Point

MicrowaveSatellite

1910 1920 1930 1940 1950 1960 1970 1980 1990 2000Time


Evolution of Wireless Telephony

Standards, Technologies, & Capacity

1960 1990

Standards EvolutionMTS150MHz IMTS150MHz

450MHz

AMPS800MHz N_AMPSD-AMPS

CDMA

PCS1900MHz GSMCDMAAMPS, etc

ESMR800MHz

System Capacity Evolution - UsersDozens Hundreds 100,000’s 1,000,000’s

Technology EvolutionAnalog AM, FM Digital Modulation

DQPSKGMSK

Access StrategiesFDMATDMACDMA

Vacuum Tubes Discrete Transistors MSI LSI VLSI, ASICs

AMPS = Advanced Mobile Phone System N_AMPS = Narrowband AMPS (Motorola)D-AMPS = Digital AMPS (IS-54 TDMA)

ESMR = Enhanced Specialized Mobile Radio

PCS-1900 = Personal Communication SystemsFDMA = Frequency Division Multiple AccessTDMA = Time Division Multiple AccessCDMA = Code Division Multiple Access


Trends in Radio Communications

Time

Cost per Subscriber

System Complexity

System Capacity

Radio Frequencies Used

Analog Digital

Centralized Distributed

Technology:

System Organization:

Summary: Wireless Economics and Logistics

February, 2005 2 - 1RF100 v2.0 (c) 2005 Scott Baxter

Wireless Systems:Modulation Schemes and Bandwidth

Wireless Systems:Modulation Schemes and Bandwidth

RF100 Chapter 2

fc

fc

Upper Sideband

Lower Sideband

fc

fc

I axis

Q axis

a

b

φc

QPSK

I axis

Q axis

c

a

φ

b

p

r

vπ/4 shifted DQPSK

1 0 1 0

1 0 1 0

1 0 1 0


Characteristics of a Radio Signal

The purpose of telecommunications is to send information from one place to anotherOur civilization exploits the transmissible nature of radio signals, using them in a sense as our “carrier pigeons”To convey information, some characteristic of the radio signal must be altered (I.e., ‘modulated’) to represent the informationThe sender and receiver must have a consistent understanding of what the variations mean to each other

• “one if by land, two if by sea”Three commonly-used RF signal characteristics which can be varied for information transmission:

• Amplitude• Frequency• Phase

SIGNAL CHARACTERISTICS

S (t) = A cos [ ωc t + ϕ ]

The complete, time-varying radio signal

Amplitude (strength) of the signal

Natural Frequencyof the signal

Phase of the signal

Compare these Signals:

Different Amplitudes

Different Frequencies

Different Phases


AM: Our First “Toehold” for Transmission

The early radio pioneers could only turn their crude transmitters on and off. They could form the dots and dashes of Morse code. Thefirst successful radio experiments happened during the mid-1890’s by experimenters in Italy, England, Kentucky, and elsewhere.By 1910, vacuum tubes gave experimenters better control over RF power generation. RF power could now be linearly modulated in step with sound vibrations. Voices and music could now be transmitted!! Still, nobody anticipated FM, PM, or digital signals. Commercial public AM broadcasting began in the early 1920’s. Despite its disadvantages and antiquity, AM is still alive:

• AM broadcasting continues today in 540-1600 KHz.• AM modulation remains the international civil aviation standard,

used by all commercial aircraft (108-132 MHz. band).• AM modulation is used for the visual portion of commercial

television signals (sound portion carried by FM modulation)• Citizens Band (“CB”) radios use AM modulation• Special variations of AM featuring single or independent

sidebands, with carrier suppressed or attenuated, are used for marine, commercial, military, and amateur communicationsSSB

LSB USB


Amplitude Modulation (“AM”) DetailsTIME-DOMAIN VIEWof AM MODULATOR

x(t) = [1 + amn(t)]cos ωc twhere:

a = modulation index (0 < a <= 1)mn(t) = modulating waveform

ωc = 2π fc, the radian carrier freq.

Σa

1

+

+

x(t)

cos ωc

mn(t)

AM is “linear modulation” -- the spectrum of the baseband signal translates directly into sidebands on both sides of the carrier frequencyDespite its simplicity, AM has definite drawbacks which complicate its use for wireless systems:

• Only part of an AM signal’s energy actually carries information (sidebands); the rest is the carrier

• The two identical sidebands waste bandwidth

• AM signals can be faithfully amplified only by linear amplifiers

• AM is highly vulnerable to external noise during transmission

• AM requires a very high C/I (~30 to 40 dB); otherwise, interference is objectionable

FREQUENCY-DOMAIN VIEW

Volta

ge

Frequency0 fc

mn(t)BASEBAND

x(t)

UPPERSIDEBAND

LOWERSIDEBAND

CARRIER


Circuits to Generate & Detect AM Signals

AM modulation can be simply accomplished in a saturated amplifier

• superimpose the modulating waveform on the supply voltage of the saturated amplifier

AM de-modulation (detection) can be easily performed using a simple envelope detector

• example: half-wave rectifier• this “non-coherent” detection

works well if S/N >10 dB.AM demodulation can also be performed by coherent detectors

• incoming signal is mixed (multiplied) with a locally generated carrier

• enhances performance when S/N ratio is poor (<10 dB.)

TIME-DOMAIN VIEW:AM MODULATOR

x(t)∼

∼

cos ωc

mn(t)

[1 + amn(t)]

Sat.

Lin.

TIME-DOMAIN VIEW:AM DETECTOR(non-coherent)

x(t)∼

mn(t)

information

RF carrier

Modulated signal


Better Quality: Frequency Modulation (“FM”)Frequency Modulation (FM) is a type of angle modulation

• in FM, the instantaneous frequency of the signal is varied by the modulating waveform

Advantages of FM• the amplitude is constant

– simple saturated amplifiers can be used

– the signal is relatively immune to external noise

– the signal is relatively robust; required C/I values are typically 17-18 dB. in wireless applications

Disadvantages of FM• relatively complex detectors are

required• a large number of sidebands are

produced, requiring even larger bandwidth than AM

TIME-DOMAIN VIEW

sFM(t) =A cos [ωc t + mω m(x)dx+ϕ0 ]t

t0where:

A = signal amplitude (constant)ωc = radian carrier frequency

mω = frequency deviation indexm(x) = modulating signal

ϕ0 = initial phase


Volta

ge

Frequency0 fc

SFM(t)UPPERSIDEBANDS

LOWERSIDEBANDS


Circuits to Generate and Detect FM Signals

One way to build an FM signal is a voltage-controlled oscillator

• the modulating signal varies a reactance (varactor, etc.) or otherwise changes the frequency of the oscillator

• the modulation may be performed at a low intermediate frequency, then heterodyned to a desired communications frequency

FM de-modulation (detection) can be performed by any of several types of detectors

• Phase-locked loop (PLL)• Pulse shaper and integrator• Ratio Detector

TIME-DOMAIN VIEW:FM MODULATOR

sFM(t)m(x) ~VCO

x

LO

HPA

TIME-DOMAIN VIEW:FM DETECTOR

x

LO

LNA PLLsFM(t) m(x)

information

FM modulated signal


The Inventor of FMMajor Edwin H. Armstrong was one of the most famous

inventors in the early history of radio. In 1918, he invented the superheterodyne circuit -- and implemented the basic mixing principle of heterodyne frequency conversion used in virtually all modern radio receivers. Others got the credit.

In 1933, he invented wide-band frequency modulation. Armstrong’s primary motivation was to improve the audio quality of broadcast transmission, which had suffered from noise and static because it used AM modulation.

Promotion and commercial development of FM placed Armstrong in competition with David Sarnoff and Radio Corporation of America. Sarnoff and RCA were promoting television, and worried Armstrong’s FM would compete with TV and slow its public acceptance.

Mainly due to RCA influence, the US FCC decided to change the frequencies allocated for FM broadcasting, obsoletinghundreds of FM transmitters and 500,000+ home receivers Armstrong had helped finance as an FM demonstration.

In 1954, despondent over these setbacks, Armstrong took his life. But today, the technology he started is used not only in broadcasting and the sound portion of TV, but also in land mobile and first-generation analog cellular systems.

Edwin Howard Armstrong1890 - 1954


Sister of FM: Phase Modulation (“PM”)Phase Modulation (PM) is a type of anglemodulation, closely related to FM

• the instantaneous phase of the signal is varied according to the modulating waveform

Advantages of PM: very similar to FM• the amplitude is constant

– simple saturated amplifiers can be used

– the signal is relatively immune to external noise

– the signal is relatively robust; required C/I values are typically 17-18 dB. in wireless applications

Disadvantages of PM• relatively complex detectors are

required, just like FM• a large number of sidebands are

produced, just like FM, requiring even larger bandwidth than AM

TIME-DOMAIN VIEW

sPM(t) =A cos [ωc t + mω m(x) +ϕ0 ]

where:A = signal amplitude (constant)ωc = radian carrier frequencymω = phase deviation index

m(x) = modulating signalϕ0 = initial phase


Volta

ge

Frequency0 fc

SFM(t)UPPERSIDEBANDS

LOWERSIDEBANDS

information

Phase-modulated signal


Circuits to Generate and Detect PM SignalsPM and FM signals are identical with only one exception: in FM, the analog modulating signal is inherently de-emphasized by 1/FConsequences of this realization:

• the same types of circuitry can be used to generate and detect both analog PM or FM, determined by filtering the modulating signal at baseband

• FM has poorer signal-to-noise ratio than PM at high modulating frequencies. Therefore, pre-emphasis and de-emphasis are often used in FM systems

TIME-DOMAIN VIEW:FM DETECTOR FOR PM

x

LO

LNA PLLsFM(t) m(x)

The phase of an FM signal is proportional to the integral of the

amplitude of the modulating signal.

The phase of a PM signal is proportional to the amplitude of the modulating

signal.

TIME-DOMAIN VIEW:PHASE MODULATOR

sFM(t)m(x)

~ Phase Shifter

x

LO

HPA

information

Phase-modulated signal


How Much Bandwidth do Signals Occupy?

The bandwidth occupied by a signal depends on:

• input information bandwidth• modulation method

Information to be transmitted, called “input” or “baseband”

• bandwidth usually is small, much lower than frequency of carrier

Unmodulated carrier• the carrier itself has Zero bandwidth!!

AM-modulated carrier• Notice the upper & lower sidebands• total bandwidth = 2 x baseband

FM-modulated carrier• Many sidebands! bandwidth is a

complex Bessel function• Carson’s Rule approximation 2(F+D)

PM-modulated carrier• Many sidebands! bandwidth is a

complex Bessel function

Voltage

Time

Time-Domain(as viewed on an

Oscilloscope)

Frequency-Domain(as viewed on a

Spectrum Analyzer)Voltage

Frequency0

fc

fc

Upper Sideband

Lower Sideband

fc

fc


Claude Shannon: The Einstein of Information Theory

The core idea that makes CDMA possible was first explained by Claude Shannon, a Bell Labs research mathematicianShannon's work relates amount of information carried, channel bandwidth, signal-to-noise-ratio, and detection error probability

• It shows the theoretical upper limit attainable

In 1948 Claude Shannon published his landmark paper on information theory, A Mathematical Theory of Communication. He observed that "the fundamental problem of communication is that of reproducing at one point either exactly or approximately a message selected at another point." His paper so clearly established the foundations of information theory that his framework and terminology are standard today.Shannon died Feb. 24, 2001, at age 84.

SHANNON’S CAPACITY EQUATION

C = Bω log2 [ 1 + ]S N

Bω = bandwidth in HertzC = channel capacity in bits/secondS = signal powerN = noise power


Digital Sampling and VocodingDigital Sampling and Vocoding


Introduction to Digital Modulation

The modulating signals shown in previous slides were all analog. It is also possible to quantize modulating signals, restricting them to discrete values, and use such signals to perform digital modulation. Digital modulation has several advantages over analog modulation:Digital signals can be more easily regenerated than analog

• in analog systems, the effects of noise and distortion are cumulative: each demodulation and remodulationintroduces new noise and distortion, added to the noise and distortion from previous demodulations/remodulations.

• in digital systems, each demodulation and remodulation produces a cleanoutput signal free of past noise and distortion

Digital bit streams are ideally suited to multiplexing - carrying multiple streams of information intermixed using time-sharing

transmission

demodulation-remodulation

transmission


transmission



Theory of Digital Modulation: SamplingVoice and other analog signals first must be converted to digital form (“sampled”) before they can be transmitted digitallyThe sampling theorem gives the requirements for successful sampling

• The signal must be sampled at least twice during each cycle of fM , its highest frequency. 2 x fM is called the Nyquist Rate.

• to prevent “aliasing”, the analog signal is low-pass filtered so it contains no frequencies above fM

Required Bandwidth for Samples, p(t)• If each sample p(t) is expressed as

an n-bit binary number, the bandwidth required to convey p(t) as a digital signal is at least N*2* fM

• this follows Shannon’s Theorem: at least one Hertz of bandwidth is required to convey one bit per second of data

• Notice: lots of bandwidth required!

The Sampling Theorem: Two Parts•If the signal contains no frequency higher than fM Hz., it is completely described by specifying its samples taken at instants of time spaced 1/2 fM s.•The signal can be completely recovered from its samples taken at the rate of 2 fMsamples per second or higher.

m(t)

Sampling

Recoverym(t)

p(t)


The Mother of All Telephone Signals: DS-0

Telephony has adopted a world-wide PCM standard digital signal, using a 64 kb/s stream derived from sampled voice dataVoice waveforms are band-limited (see curve)

• upper cutoff beyond 3500-4000 Hz. to avoid aliasing

• rolloff below 300 Hz. For less sensitivity to “hum” picked up from AC power mains

Voice waveforms sampled 8000 times/second• A>D conversion has 1 byte (8 bit)

resolution; thus 256 voltage levels possible • 8000 samples x 1 byte = 64,000 bits/second• Levels are defined logarithmically rather

than linearly, to handle a wider range of audio levels with minimum distortion

– µ-law companding is used in North America & Japan

– A-law companding is used in most other countries

-10dB

-20dB

-30dB

-40dB

0 dB

100 300 1000 3000 10000Frequency, Hz

C-Message Weighting

t

012345687910111213141516

4

16

13

15

8

3 48

A-LAWy= sgn(x) A|x|

ln(1+ A) for 0 ≤ x≤ 1A

(where A = 87.6)

y= sgn(x) ln(1+ A|x)|ln(1+ A) for 1

A < x ≤1

µ-Lawy = sgn(x) ln(1+ µ|x|)

ln(1 + µ)(whereµ = 255)

Companding

Band-Limiting

x = analog audio voltagey = quantized level (digital)


Was Digital Supposed to Give More Capacity!?

A DS-0 telephone signal, carrying one person talking, is a 64,000 bits/second data stream.Shannon’s theorem tells us we’ll need at least 64,000 Hz. of bandwidth to carry this signal, even with the most advanced modulation techniques (QPSK, etc.)But regular analog cellular signals are only 30,000 Hz. wide! So does a digital signal require more bandwidth than analog?!!YES -- unless we do something fancy, like compression.We DO use compression, to reduce the number of bits being transmitted, thereby keeping the bandwidth as small as we canThe compressing device is called a Vocoder (voice coder). It both compresses the signal being sent, and expands the signal being receivedEvery digital mobile phone technology uses some type of Vocoder

• There are many types, with many different characteristics


Vocoders: Compression vs. Distortion

Objective: to significantly reduce the number of bits which must be transmitted, but without creating objectionable levels of distortionWe are concerned mainly with telephone applications, with voice signal already band-limited to 4 kHz. max. and sampled at 8 kHz.The objective is toll-quality voice reproductionGeneral Categories of Speech Coders

• Waveform Coders– attempt to re-create the input waveform– good speech quality but at relatively high bit rates

• Vocoders– attempt to re-create the sound as perceived by humans– quantize and mimic speech-parameter-defined properties– lower bit rates but at some penalty in speech quality

• Hybrid Coders– mixed approach, using elements of Waveform Coders &

Vocoders– use vector quantization against a codebook reference– low bit rates and good quality speech


Meet some Families of Speech Coders

Waveform Coders

PCM (pulse-code modulation), APCM (adaptive PCM)DPCM (differential PCM), ADPCM (adaptive DPCM)DM (delta modulation), ADM (adaptive DM)CVSD (continuously variable-slope DM)APC (adaptive predictive coding)RELP (residual-excited linear prediction)SBC (subband coding)ATC (adaptive transform coding)

Hybrid CodersMPLP (multipulse-excited linear prediction)RPE (regular pulse-excited linear prediction)VSELP (vector-sum excited linear prediction)CELP (code-excited linear prediction)

VocodersChannel, Formant, Phase, Cepstral, or HomomorphicLPC (linear predictive coding)STC (sinusoidal transform coding)MBE (multiband excitation), IMBE (improved MBE)

Objective: to significantly reduce the number of bits which must be transmitted, but without creating objectionable levels of distortionWe are concerned mainly with telephone applications, with voice signal already band-limited to 4 kHz. max. and sampled at 8 kHz.The objective is toll-quality voice reproductionA few different strategies and algorithms used in voice compression:


Speech Coders Used Mobile Technologies:Vocoders are usually described by their output rate (8 kilobits/sec, etc.) and the type of algorithm they use. Here’s a list of the vocoders used in currently popular wireless technologies:

bits/sec64k32k32k16k

13/7/4/2 v13k9.6k

8k6.7k6.4k

8/4/2/1 v8/4/2/1 v

4.8k2.4k

Algorithmlog PCMADPCM

LD-CELPAPC

QCELPRPE-LTP

MPLP

VSELPVSELPIMBE

QCELPQCELPCELP

LPC-10

Standard (Year)CCITT G.711 (1972)CCITT G.721 (1984)CCITT G.728 (1992)Inmarsat-B (1985)CTIA, IS-54/J-Std008 (1995) CDMAPan-European DMR, GSM (1991)BTI Skyphone (1990)

CTIA IS-54 (1993) TDMAJapanese DMR (1993)Inmarsat-M (1993)Enhanced Vocoder, 1997 CDMACTIA, IS-95 (1993) CDMAUS, FS-1016 (1991)US, FS-1015 (1977)

MOS4.34.14.0

n/availn/avail

3.53.4

3.53.43.4

n/avail3.43.22.3

8k EFRC IS-136 (1997) TDMA enhanced n/avail


The Latest Vocoder Technology, 2005

CDMA Family:• SMV (selective multirate vocoder)

ETSI GSM/WCDMA Family• AMR (adaptive multirate vocoder)


Digital ModulationDigital Modulation


Modulation by Digital Inputs

For example, modulate a signal with this digital waveform. No more continuous analog variations, now we’re “shifting”between discrete levels. We call this “shift keying”.

• The user gets to decide what levels mean “0” and “1” -- there are no inherent values

Steady Carrier without modulationAmplitude Shift Keying

ASK applications: digital microwaveFrequency Shift Keying

FSK applications: control messages in AMPS cellular; TDMA cellular

Phase Shift KeyingPSK applications: TDMA cellular,

GSM & PCS-1900

Our previous modulation examples used continuously-variable analog inputs. If we quantize the inputs, restricting them to digital values, we will produce digital modulation.

Voltage

Time1 0 1 0

1 0 1 0

1 0 1 0

1 0 1 0


Digital Modulation SchemesThere are many different schemes for digital modulation, each a compromise between complexity, immunity to errors in transmission, required channel bandwidth, and possible requirement for linear amplifiersLinear Modulation Techniques

• BPSK Binary Phase Shift Keying• DPSK Differential Phase Shift Keying• QPSK Quadrature Phase Shift Keying IS-95 CDMA forward link

– Offset QPSK IS-95 CDMA reverse link– Pi/4 DQPSK IS-54, IS-136 control and traffic channels

Constant Envelope Modulation Schemes• BFSK Binary Frequency Shift Keying AMPS control channels• MSK Minimum Shift Keying• GMSK Gaussian Minimum Shift Keying GSM systems, CDPD

Hybrid Combinations of Linear and Constant Envelope Modulation• MPSK M-ary Phase Shift Keying• QAM M-ary Quadrature Amplitude Modulation• MFSK M-ary Frequency Shift Keying FLEX paging protocol

Spread Spectrum Multiple Access Techniques• DSSS Direct-Sequence Spread Spectrum IS-95 CDMA• FHSS Frequency-Hopping Spread Spectrum


Modulation used in CDMA Systems

CDMA mobiles use offset QPSK modulation

• the Q-sequence is delayed half a chip, so that I and Q never change simultaneously and the mobile TX never passes through (0,0)

CDMA base stations use QPSK modulation

• every signal (voice, pilot, sync, paging) has its own amplitude, so the transmitter is unavoidably going through (0,0) sometimes; no reason to include 1/2 chip delay

Base Stations: QPSKQ Axis

I Axis

ShortPN Q

Σ

cos ωt

sin ωt

User’schips

ShortPN I

Mobiles: OQPSKQ Axis

I Axis

ShortPN Q

Σ

cos ωt

sin ωt

User’schips

1/2 chip

ShortPN I


CDMA Base Station Modulation Views

The view at top right shows the actual measured QPSK phase constellation of a CDMA base station in normal serviceThe view at bottom right shows the measured power in the code domain for each walsh code on a CDMA BTS in actual service

• Notice that not all walsh codes are active

• Pilot, Sync, Paging, and certain traffic channels are in use


Wireless Systems:Multiple Access Technologies & Standards

Wireless Systems:Multiple Access Technologies & Standards

Chapter 3


Multiple Access Technologies

FDMA (example: AMPS)Frequency Division Multiple Access• each user has a private frequency (at

least in their own neighborhood)

TDMA (examples: IS-54/136, GSM)Time Division Multiple Access• each user has a private time on a private

frequency (at least in their own neighborhood)

CDMA (examples: IS-95, J-Std. 008)Code Division Multiple Access• users co-mingle in time and frequency

but each user has a private code (at least in their own neighborhood)

FrequencyTime

Power

FrequencyTime

Power

FrequencyTime

Power

FDMA

TDMA

CDMA


Conventional Technologies:Recovering the Signal / Avoiding Interference

In ordinary radio technologies, the desired signal must be stronger than all interference by at least a certain margin called C/I (carrier-to-interference ratio)

• the type of signal modulation determines the amount of interference which can be tolerated, and thus the required C/I

In conventional systems, the C/I is controlled mainly by the distance between co-channel cells

• frequency usage is planned so that co-channel users don’t have interference worse than C/I

• any undesired interference we face is coming from the nearest co-channel cells, far away

• if the signal is delicate, then we need a big C/I and the co-channel cells must be very far away

• if the signal is more rugged, we can tolerate more interference (smaller C/I) allowing the co-channel cells a bit closer without bad effects

2

3

4

5 6

7

4

6

47 2

7

2

5

35

36

1

1

1

1

1

1

1

AMPS-TDMA-GSM

Figure of Merit: C/I(carrier/interference ratio)

AMPS: +17 dBTDMA: +14 to 17 dB

GSM: +7 to 9 dB.


Handoffs and C/I

One purpose of handoff is to keep the call from dropping as the mobile moves out of range of individual cellsAnother purpose of handoff is to ensure the mobile is using the cell with the best signal strength and best C/I at all timesNotice in the signal graphs at lower right how the mobile’s C/I is maintained at a usable level as it goes from cell to cell

A B

RSSI, dBm

-120

-50

C DSites

C/I

AB

CD

AMPS

Tech-nology

NAMPSTDMAGSM

CDMA

Analog FM

ModulationType

Analog FMDPQSKGMSK

QPSK/OQPSK

30 kHz.

Channel Bandwidth

10 kHz.30 kHz.

200 kHz.1,250 kHz.

C/I ≅ 17 dB

Quality Indicator

C/I ≅ 17 dBC/I ≅ 17 dBC/I ≅ 17 dBEb/No ≅ 6dB


CDMA: Using A New Dimension

All CDMA users occupy the same frequency at the same time! Frequency and time are not used as discriminatorsCDMA operates by using a new dimension, CODING, to discriminate between users

• In CDMA, we do not try to immediately recover the pulses of energy from each user. Instead, we watch long groups of the totals of everybody’s pulses, and detect little patterns which are the “signature” of the user we wish to decode

In CDMA, the interference originates mainly from nearby users in the same general areaEach user is a small voice in a roaring crowd -- but with a uniquely recoverable code

CDMA

Figure of Merit: C/IAMPS: +17 dB

TDMA: +14 to +17 dBGSM: +7 to 9 dB.

CDMA: -10 to -17 dB.Although the CDMA C/I is negative, the decoding process recovers the user’s energy while discarding others’energy. The final net result is Eb/No, typically about +6 db.We’ll study this in detail later.


The CDMA Migration Path to 3G

1xEV-DORev. A

IS-856

1250 kHz.59 active

users

Higher data rates on data-

only CDMA carrier

3.1 Mb/sDL

1.8 Mb/sUL

RL FLSpectrum

1xEV-DORev. 0IS-856

1250 kHz.59 active

users

High data rates on data-only

CDMA carrier

2.4 Mb/sDL

153 Kb/sUL

CDMAone CDMA2000 / IS-2000

Technology

Generation

SignalBandwidth,

#Users

Features:Incremental

Progress

1G

AMPS

DataCapabilities

30 kHz.1

First System,Capacity

&Handoffs

None,2.4K by modem

2G

IS-95A/J-Std008

1250 kHz.20-35

First CDMA,

Capacity,Quality

14.4K

2G

IS-95B

1250 kHz.25-40

•Improved Access•Smarter Handoffs

64K

2.5G? 3G

IS-2000:1xRTT

1250 kHz.50-80 voice

and data

•Enhanced Access

•Channel Structure

153K307K230K

3G

1xEV-DV1xTreme

1250 kHz.Many packet

users

High data rates on

Data-Voice shared CDMA carrier

5 Mb/s

3G

IS-2000:3xRTT

F: 3x 1250kR: 3687k

120-210 per 3 carriers

Faster data rates on shared 3-carrier bundle

1.0 Mb/s

RL FLRL FLRL FLRL FLRL FLRL FLRL FL


Modulation Techniques of 1xEV Technologies

1xEV, “1x Evolution”, is a family of alternative fast-data schemes that can be implemented on a 1x CDMA carrier.1xEV DO means “1x Evolution, Data Only”, originally proposed by Qualcomm as “High Data Rates” (HDR).

• Up to 2.4576 Mbps forward, 153.6 kbps reverse

• A 1xEV DO carrier holds only packet data, and does not support circuit-switched voice

• Commercially available in 20031xEV DV means “1x Evolution, Data and Voice”.

• Max throughput of 5 Mbps forward, 307.2k reverse

• Backward compatible with IS-95/1xRTT voice calls on the same carrier as the data

• Not yet commercially available; work continues

All versions of 1xEV use advanced modulation techniques to achieve high throughputs.

QPSKCDMA IS-95,

IS-2000 1xRTT,and lower ratesof 1xEV-DO, DV

16QAM1xEV-DOat highest

rates

64QAM1xEV-DVat highest

rates


GSM Technology Migration Path to 3G

Integrated voice/data(Future rates to 12 MBPS using adv.

modulation?)

Technology

Generation

SignalBandwidth,

#Users


Progress

1G

variousanalog

DataCapabilities

various

various

various

2G

GSM

200 kHz.7.5 avg.

Europe’sfirst Digitalwireless

none

2.5G or 3?

GPRS

200 kHz.Many

Pkt. users

•Packet IP access

•Multiple attached

users

9-160 Kb/s(conditionsdetermine)

3G

EDGE

200 kHz.fast data

many users

8PSK for 3x Faster data rates

than GPRS

384 Kb/smobile user

3GUMTSUTRA

WCDMA3.84 MHz.up to 200+voice users

and data

2Mb/sstatic user


TDMA IS-136 Technology Migration Path to 3G

2G

CDPD

30 kHz.Many

Pkt Usrs

19.2kbps

US PacketDataSvc.

Technology

Generation

SignalBandwidth,

#Users


Progress

DataCapabilities

2GTDMAIS-54

IS-136

30 kHz.3 users

USA’sfirst

Digitalwireless

none

2.5G or 3?

GPRS

200 kHz.Many

Pkt. users

•Packet IP access

•Multiple attached

users

9-160 Kb/s(conditionsdetermine)

3G

EDGE

200 kHz.fast data

many users

8PSK for 3x Faster data rates

than GPRS

384 Kb/smobile user

3GUMTSUTRA

WCDMA3.84 MHz.up to 200+voice users

and data

Integrated voice/data(Future rates to 12 MBPS using adv.

modulation?)

1G

AMPS

30 kHz.1


&Handoffs

None,2.4K by modem

2Mb/sstatic user

2G

GSM

200 kHz.7.5 avg.

Europe’sfirst

Digitalwireless

none

the familiar GSM path!


Not BWA; for comparison only

802.16

BPSK to256QAMOFDM

54 Mb/s

TDD, FDDvarious

2-11 GHz10-66 GHz

802.20Mobile BWA

4G: Broadband Wireless Access Technologies

Technology

ModulationType

Max RawData Rate

AccessMethod

FrequencyBand

InfraredIRDA

various

4 Mb/s

Single User perOptical Carrier

Optical

802.11b

CCK

11 Mb/s

DSSS

2.4 GHz

802.11a

BPSK, QPSK,16QAM, or

64QAM

54 Mb/s

DSSS

5 GHz

HIPERLANType 1

FSK orGMSK

23.5 Mb/s

OFDM

5 GHz

HIPERLANType 2

BPSK, QPSK,16QAM, or

64QAM

54 Mb/s

various.

5 GHz

Bluetooth

GFSKFH

1 Mb/s

various

2.4 GHz

BLUETOOTH

802.11A, B, WIFI, WILAN

Infrared IRDA

High Hopes!


Hig

h-Ti

er $

$$Lo

w-T

ier $

1G: AMPS

4G – Evolution or Revolution?

There’s a revolution going on!• New 2.5G services arriving now, new 3G arriving 2002 through 2005• A groundswell of commercial (and even free!) WILAN deployment

3G networks and 4G networks have their own unique advantagesUltimately 3G and 4G will be integrated by wireless operators!

Technology Environment Service Provider/Infrastructure Owner

PSTN IP/VPNs

2G: TDMA, GSM, IS95 CDMA, IDEN

2.5G: GPRS, EDGE3G: IS2000 1xRTT, 1xEV DO, 1xEV DVUMTS WCDMA4G: Wireless LAN802.11b “Wi-Fi”802.11a, gHIPERLAN Type 1HIPERLAN Type 2BluetoothInfrared freenetworks.org

Near-Universal Macro-Coverage

Hotspots


Global and US Wireless Snapshot 4Q 2003

Total Worldwide Wireless customers surpassed total worldwide landline customers at year-end 2002, with 1,00,080,000 of each.2/3 of worldwide wireless customers use the GSM technologyCDMA is second-most-prevalent with 17.0%In the US, CDMA is the most prevalent technology at 45.7%Both CDMA and GSM are growing in the US

• most IS-136 TDMA systems are converting to GSM + GPRS + EDGE

Worldwide USATotal Wireless Users

GSM usersCDMA usersTDMA usersIDEN users

Analog users

1,320,000,000 100%870,000,000 65.9%224,000,000 17.0%124,000,000 9.4%68,000,000 5.2%34,000,000 2.6%

141,000,000 100%33,732,506 23.9%64,503,287 45.7%26,375,232 18.6%11,978,382 8.5%4,510,594 3.2%


Other Misc.

A Quick Survey of Wireless Data Technologies

This summary is a work-in-progress, tracking latest experiences and reports from all the high-tier (provider-network-oriented) 2G and 3G wireless data technologiesHave actual experiences to share, latest announced details, or corrections to the above? Email to [email protected]. Thanks for your comments!

PAGINGETSI / GSMUS CDMA

IS-136

ANALOGAMPS Cellular

9.6 – 4.8 kb/sw/modem

IS-136 TDMA19.2 – 9.6 kb/s

GSM CSD9.6 – 4.8 kb/s

GSM HSCSD32 – 19.2 kb/s

IDEN19.2 – 19.2 kb/s

IS-9514.4 – 9.6 kb/s

IS-95B64 -32 kb/s

CDPD19.2 – 4.8 kb/sdiscontinued

GPRS40 – 30 kb/s DL

15 kb/s UL

EDGE200 - 90 kb/s DL

45 kb/s UL

1xRTT RC3153.6 – 80 kb/s

1xRTT RC4307.2 – 160 kb/s

1xEV-DO2400 – 600 DL153.6 – 76 UL

1xEV-DO A3100 – 800 DL1800 – 600 UL

1xEV-DV5000 - 1200 DL307 - 153 UL

WCDMA 0384 – 250 kb/s

WCDMA 12000 - 800 kb/s

WCDMA HSPDA12000 – 6000 kb/s

Flarion OFDM1500 – 900 kb/s

TD-SCDMAIn Development

Mobitex9.6 – 4.8 kb/s

obsolete


Wireless System CapacityEach wireless technology (AMPS,

NAMPS, D-AMPS, GSM, CDMA) uses a specific modulation type with its own unique signal characteristicsSignal Bandwidth determines how many RF signals will “fit” in the operator’s licensed spectrumRobustness of RF signal determines tolerable level of interference and necessary physical separation of cochannelcellsNumber of users per RF signal directly affects capacityIn the following page, we will develop the number of users and traffic in erlangs per site for each of the popular wireless technologies

AMPS, D-AMPS, N-AMPS

CDMA

30 30 10 kHz Bandwidth

200 kHz

1250 kHz

1 3 1 Users

8 Users

22 Users1

1

11

11

11

111

111

1 23

4

43

2

56 17

Typical Frequency Reuse N=7



Vulnerability:C/I ≅ 17 dB

Vulnerability:C/I ≅ 6.5-9 dB

Vulnerability:EbNo ≅ 6 dB


Comparison of Wireless System Capacities

Fwd/Rev Spectrum kHz. 12,500 12,500 12,500 15,000 15,000 15,000 5,000 5,000 5,000 Technology AMPS TDMA CDMA TDMA GSM CDMA TDMA GSM CDMAReq'd C/I or Eb/No, db 17 17 6 17 12 6 17 12 6Freq Reuse Factor, N 7 7 1 7 4 1 7 4 1RF Signal BW, kHz 30 30 1250 30 200 1250 30 200 1250Total # RF Carriers 416 416 9 500 75 11 166 25 3RF Sigs. per cell @N 59 59 9 71 18 11 23 6 3# Sectors per cell 3 3 3 3 3 3 3 3 3#CCH per sector 1 1 0 1 0 0 1 0 0RF Signals per sector 18 18 9 22 6 11 6 2 3Voicepaths/RF signal 1 3 22 3 8 22 3 8 22SH average links used 1 1 1.66 1 1 1.66 1 1 1.66Unique Voicepaths/carrier 1 3 13.253 3 8 13.253 3 8 13.253Voicepaths/Sector 18 54 198 66 48 242 18 16 66Unique Voicepaths/Sector 18 54 119 66 48 145 18 16 39P.02 Erlangs per sector 11.5 44 105.5 55.3 38.4 130.9 11.5 9.83 30.1P.02 Erlangs per site 34.5 132 316.5 165.9 115.2 392.7 34.5 29.49 90.3Capacity vs. AMPS800 1 3.8 9.2 4.8 3.3 11.4 1.0 0.9 2.6

800 Cellular (A,B) 1900 PCS (A, B, C) 1900 PCS (D, E, F)


Capacity of Multicarrier CDMA Systems

Fwd/Rev Spectrum kHz. 12,500 1,800 3,050 4,300 5,550 6,800 8,050 9,300 10,550 11,800 13,050 14,300 Technology AMPS CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA CDMA

Req'd C/I or Eb/No, db 17 6 6 6 6 6 6 6 6 6 6 6Freq Reuse Factor, N 7 1 1 1 1 1 1 1 1 1 1 1

RF Signal BW, kHz 30 1250 1250 1250 1250 1250 1250 1250 1250 1250 1250 1250Total # RF Carriers 416 1 2 3 4 5 6 7 8 9 10 11

RF Sigs. per cell @N 59 1 2 3 4 5 6 7 8 9 10 11# Sectors per cell 3 3 3 3 3 3 3 3 3 3 3 3#CCH per sector 1 0 0 0 0 0 0 0 0 0 0 0

RF Signals per sector 18 1 2 3 4 5 6 7 8 9 10 11Voicepaths/RF signal 1 22 22 22 22 22 22 22 22 22 22 22

SH average links used 1 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66 1.66Unique Voicepaths/carrier 1 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3 13.3

Voicepaths/Sector 18 22 44 66 88 110 132 154 176 198 220 242Unique Voicepaths/Sector 18 13 26 39 53 66 79 92 106 119 132 145

P.02 Erlangs per sector 11.5 7.4 18.4 30.1 43.1 55.3 67.7 80.2 93.8 105.5 119.1 130.9P.02 Erlangs per site 34.5 22.2 55.2 90.3 129.3 165.9 203.1 240.6 281.4 316.5 357.3 392.7

Capacity vs. AMPS800 1 0.64 1.60 2.6 3.7 4.8 5.9 7.0 8.2 9.2 10.4 11.4

f

1 2 3 4 5 6 7 8 9 1011

CDMA Carrier Frequencies


Physical Principles of Propagation

Physical Principles of Propagation

Chapter 4 Section A


Introduction to Propagation

Propagation is the heart of every radio link. During propagation, many processes act on the radio signal.

• attenuation– the signal amplitude is reduced by various natural mechanisms. If there

is too much attenuation, the signal will fall below the reliable detection threshold at the receiver. Attenuation is the most important single factor in propagation.

• multipath and group delay distortions– the signal diffracts and reflects off irregularly shaped objects, producing a

host of components which arrive in random timings and random RF phases at the receiver. This blurs pulses and also produces intermittent signal cancellation and reinforcement. These effects are overcome through a variety of special techniques

• time variability - signal strength and quality varies with time, often dramatically• space variability - signal strength and quality varies with location and distance• frequency variability - signal strength and quality differs on different

frequenciesTo master propagation and effectively design wireless systems, you must know:

• Physics: understand the basic propagation processes • Measurement: obtain data on propagation behavior in area of interest• Statistics: analyze known data, extrapolate to predict the unknown• Modelmaking: formalize all the above into useful models


Frequency and Wavelength: Implications

Radio signals in the atmosphere propagate at almost speed of light

λ = wavelengthC = distance propagated in 1 secondF = frequency, Hertz

The wavelength of a radio signal determines many of its propagation characteristics

• Antenna elements size are typically in the order of 1/4 to 1/2 wavelength

• Objects bigger than a wavelength can reflect or obstruct RF energy

• RF energy can penetrate into a building or vehicle if they have apertures a wavelength in size, or larger

λ/2

λ = C / Ffor AMPS: F= 870 MHz

λ = 0.345 m = 13.6 inches

for PCS-1900: F = 1960 MHzλ = 0.153 m = 6.0 inches


Propagation Effects of Earth’s Atmosphere

Earth’s unique atmosphere supports life (ours included) and also introduces many propagation effects -- some useful, some troublesomeSkywave Propagation: reflection from Ionized Layers

• LF and HF frequencies (below roughly 50 MHz.) are routinely reflected off layers of the upper atmosphere which become ionized by the sun

• this phenomena produces intermittent world-wide propagation and occasional total outages

• this phenomena is strongly correlated with frequency, day/night cycles, variations in earth’s magnetic field, 11-year sunspot cycle

• these effects are negligible for wireless systems at their much-higher frequencies


More Atmospheric Propagation Effects

Attenuation at Microwave Frequencies• rain droplets can substantially attenuate RF

signals whose wavelengths are comparable to, or smaller than, droplet size

• rain attenuations of 20 dB. or more per km. are possible

• troublesome mainly above 10 GHz., and in tropical areas

• must be considered in reliability calculations during path design

• not major factor in wireless systems propagationDiffraction, Wave Bending, Ducting

• signals 50-2000 MHz. can be bent or reflected at boundaries of different air density or humidity

• phenomena: very sporadic unexpected long-distance propagation beyond the horizon. May last minutes or hours

• can occur in wireless systems

Refraction by air layers

Ducting by air layers

>100 mi.

“Rain Fades” onMIcrowave Links


Dominant Mechanisms of Mobile PropagationMost propagation in the mobile

environment is dominated by these three mechanisms:Free space

• No reflections, no obstructions– first Fresnel Zone clear

• Signal spreading is only mechanism• Signal decays 20 dB/decade

Reflection• Reflected wave 180°out of phase• Reflected wave not attenuated much• Signal decays 30-40 dB/decade

Knife-edge diffraction• Direct path is blocked by obstruction• Additional loss is introduced• Formulae available for simple cases

We’ll explore each of these further...

Knife-edge Diffraction

Reflection with partial cancellation

BA

d

D

Free Space


Free-Space PropagationThe simplest propagation mode• Antenna radiates energy which spreads in space• Path Loss, db (between two isotropic antennas)

= 36.58 +20*Log10(FMHZ)+20Log10(DistMILES )• Path Loss, db (between two dipole antennas)

= 32.26 +20*Log10(FMHZ)+20Log10(DistMILES )• Notice the rate of signal decay:• 6 db per octave of distance change, which is

20 db per decade of distance changeFree-Space propagation is applicable if:• there is only one signal path (no reflections)• the path is unobstructed (i.e., first Fresnel zone

is not penetrated by obstacles)

First Fresnel Zone =Points P where AP + PB - AB < λ/2 Fresnel Zone radius d = 1/2 (λD)^(1/2)

1st Fresnel Zone

BA

d

D

Free Space “Spreading” Lossenergy intercepted by receiving antenna is proportional to 1/r2

r


Reflection With Partial Cancellation

Mobile environment characteristics:• Small angles of incidence and reflection• Reflection is unattenuated (reflection coefficient =1)• Reflection causes phase shift of 180 degrees

Analysis• Physics of the reflection cancellation predicts signal

decay of 40 dB per decade of distance

Heights Exaggerated for Clarity

HTFT

HTFT

DMILES

Comparison of Free-Space and Reflection Propagation ModesAssumptions: Flat earth, TX ERP = 50 dBm, @ 1950 MHz. Base Ht = 200 ft, Mobile Ht = 5 ft.

Received Signal in Free Space, DBMReceived Signal inReflection Mode

DistanceMILES

-52.4-69.0

1-58.4-79.2

2-64.4-89.5

4-67.9-95.4

6-70.4-99.7

8-72.4-103.0

10-75.9-109.0

15-78.4-113.2

20

Path Loss [dB ]= 172 + 34 x Log (DMiles )- 20 x Log (Base Ant. HtFeet)

- 10 x Log (Mobile Ant. HtFeet)

SCALE PERSPECTIVE


Signal Decay Rates in Various Environments

We’ve seen how the signal decays with distance in two basic modes of propagation:Free-Space

• 20 dB per decade of distance• 6 db per octave of distance

Reflection Cancellation• 40 dB per decade of distance• 12 db per octave of distance

Real-life wireless propagation decay rates are typically somewhere between 30 and 40 dB per decade of distance

Signal Level vs. Distance

-40

-30

-20

-10

0

Distance, Miles1 3.16 102 5 7 86

One Octaveof distance (2x)

One Decadeof distance (10x)


Knife-Edge DiffractionSometimes a single well-defined obstruction blocks the path, introducing additional loss. This calculation is fairly easy and can be used as a manual tool to estimate the effects of individual obstructions.First calculate the diffraction parameter ν from the geometry of the pathNext consult the table to obtain the obstruction loss in dbAdd this loss to the otherwise-determined path loss to obtain the total path loss.Other losses such as free space and reflection cancellation still apply, but computed independently for the path as if the obstruction did not exist

H

R1 R2

ν

attendB

0-5

-10-15-20-25

-4 -3 -2 -1 0 1 2 3-5

( + )ν = -H2λ

1 1R1 R2


Local Variability: Multipath Effects

The free-space, reflection, and diffraction mechanisms described earlier explain signal level variations on a large scale, but other mechanisms introduce small-scale local fadingSlow Fading occurs as the user moves over hundreds of wavelengths due to shadowing by local obstructionsRapid Fading occurs as signals received from many paths drift into and out of phase

• the fades are roughly λ/2 apart in space:7 inches apart at 800 MHz., 3 inches

apart at 1900 MHz• fades also appear in the frequency

domain and time domain• fades are typically 10-15 db deep,

occasionally deeper• Rayleigh distribution is a good model

for these fadesthese fades are often called “Rayleigh fades”

Multi-path Propagation

A

d

10-15 dBλ/2

Rayleigh Fading


Combating Rayleigh Fading: Space Diversity

Fortunately, Rayleigh fades are very short and last a small percentage of the timeTwo antennas separated by several wavelengths will not generally experience fades at the same time“Space Diversity” can be obtained by using two receiving antennas and switching instant-by-instant to whichever is bestRequired separation D for good decorrelation is 10-20λ

• 12-24 ft. @ 800 MHz.• 5-10 ft. @ 1900 MHz.

Signal received by Antenna 1


Combined Signal

D


Space Diversity Application Limitations

Space Diversity can be applied only on the receiving end of a link. Transmitting on two antennas would:

• fail to produce diversity, since the two signals combine to produce only one value of signal level at a given point -- no diversity results.

• produce objectionable nulls in the radiation at some angles

Therefore, space diversity is applied only on the “uplink”, i.e.., reverse path

• there isn’t room for two sufficiently separated antennas on a mobile or handheld



Combined Signal

D


Using Polarization DiversityWhere Space Diversity Isn’t Convenient

Sometimes zoning considerations or aesthetics preclude using separate diversity receive antennas Dual-polarized antenna pairs within a single radome are becoming popular

• Environmental clutter scatters RF energy into all possible polarizations

• Differently polarized antennas receive signals which fade independently

• In urban environments, this is almost as good as separate space diversity

Antenna pair within one radome can be V-H polarized, or diagonally polarized

• Each individual array has its own independent feedline

• Feedlines connected to BTS diversity inputs in the conventional way; TX duplexing OK

Antenna AAntenna BCombined

A B A B

V+Hor\+/


The Reciprocity PrincipleDoes it apply to Wireless?

Between two antennas, on the same exact frequency, path loss is the same in both directionsBut things aren’t exactly the same in cellular --

• transmit and receive 45 MHz. apart• antenna: gain/frequency slope?• different Rayleigh fades

up/downlink• often, different TX & RX antennas• RX diversity

Notice also the noise/interference environment may be substantially different at the two endsSo, reciprocity holds only in a general sense for cellular

-148.21 db@ 835.03 MHz

-151.86 db@ 870.03 MHz

-148.21 db@ 870.03 MHz


Propagation ModelsPropagation Models

Chapter 4 Section B


Types Of Propagation Models And Their Uses

Simple Analytical models • Used for understanding and

predicting individual paths and specific obstruction cases

General Area models• Primary drivers: statistical• Used for early system

dimensioning (cell counts, etc.)Point-to-Point models

• Primary drivers: analytical• Used for detailed coverage

analysis and cell planningLocal Variability models

• Primary drivers: statistical• Characterizes microscopic level

fluctuations in a given locale, confidence-of-service probability

Simple Analytical• Free space (Friis formula)• Reflection cancellation• Knife-edge diffraction

Area• Okumura-Hata• Euro/Cost-231• Walfisch-Betroni/Ikegami

Point-to-Point• Ray Tracing

- Lee’s Method, others• Tech-Note 101• Longley-Rice, Biby-C

Local Variability• Rayleigh Distribution• Normal Distribution• Joint Probability Techniques

Examples of various model types


General Principles Of Area Models

Area models mimic an averagepath in a defined areaThey’re based on measured data alone, with no consideration of individual path features or physical mechanismsTypical inputs used by model:

• Frequency• Distance from transmitter to

receiver• Actual or effective base

station & mobile heights• Average terrain elevation • Morphology correction loss

(Urban, Suburban, Rural, etc.)Results may be quite different than observed on individual paths in the area

RSSI, dBm

-120

-110

-100

-90

-80

-70

-60

-50

0 3 6 9 12 15 18 21 24 27 30 33

Distance from Cell Site, km

FieldStrength,dBµV/m

+90

+80

+70

+60

+50

+40

+30

+20

Green Trace shows actual measured signal strengths on a drive test radial, as determined by real-world physics.Red Trace shows the Okumura-Hata prediction for the same radial. The smooth curve is a good “fit” for real data. However, the signal strength at a specific location on the radial may be much higher or much lower than the simple prediction.


The Okumura Model: General Concept

The Okumura model is based on detailed analysis of exhaustive drive-test measurements made in Tokyo and its suburbs during the late 1960’s and early 1970’s. The collected date included measurements on numerous VHF, UHF, and microwave signal sources, both horizontally and vertically polarized, at a wide range of heights.

The measurements were statistically processed and analyzed with respect to almost every imaginable variable. This analysis was distilled into the curves above, showing a median attenuation relative to free space loss Amu (f,d) and correlation factor Garea (f,area), for BS antenna height ht = 200 m and MS antenna height hr = 3 m.

Okumura has served as the basis for high-level design of many existing wireless systems, and has spawned a number of newer models adapted from its basic concepts and numerical parameters.

Med

ian

Atte

nuat

ion

A(f,

d), d

B

1

2

5

40

70

80

100

100 3000500Frequency f, MHz

10

50

70 Urban Area

d, k

m

30

850

26

35

100 200 300 500 700 1000 2000 3000Frequency f, (MHz)

5

10

15

20

25

30

Cor

rect

ion

fact

or, G

area

(dB

)

9 dB

850 MHz

Open area

Quasi open area

Suburban area


Structure of the Okumura Model

The Okumura Model uses a combination of terms from basic physical mechanisms and arbitrary factors to fit 1960-1970 Tokyo drive test dataLater researchers (HATA, COST231, others) have expressed Okumura’s curves as formulas and automated the computation

Path Loss [dB] = LFS + Amu(f,d) - G(Hb) - G(Hm) - Garea

Free-Space Path Loss Base Station

Height Gain= 20 x Log (Hb/200)

Mobile StationHeight Gain

= 10 x Log (Hm/3)

Amu(f,d) Additional Median Lossfrom Okumura’s Curves

Med

ian

Atte

nuat

ion

A(f,d

), dB

1

2

5

40

70

80

100

100 3000500

Frequency f, MHz10

50

70 Urban Area

d, k

m

30

850

26

Morphology Gain0 dense urban5 urban10 suburban17 rural

35

100 200 300 500 700 1000 2000 3000Frequency f, (MHz)

5

10

15

20

25

30

Cor

rect

ion

fact

or, G

area

(dB

)

850 MHz

Open area

Quasi open area

Suburban area


The Hata Model: General Concept

The Hata model is an empirical formula for propagation loss derived from Okumura’s model, to facilitate automatic calculation.The propagation loss in an urban area is presented in a simple general format A + B x log R, where A and B are functions of frequency and antenna height, R is distance between BS and MS antennasThe model is applicable to frequencies 100 MHz-1500 MHz, distances 1-20 km, BS antenna heights 30-200 m, MS antenna heights 1-10 mThe model is simplified due to following limitations:

• Isotropic antennas • Quasi-smooth (not irregular) terrain • Urban area propagation loss is presented as the standard formula• Correction equations are used for other areas

Although Hata model does not imply path-specific corrections, it has significant practical value and provide predictions which are very closely comparable with Okumura’s model


Hata Model General Concept and Formulas

Formulas for median path loss are:(1) - Standard formula for urban areas(2) - For suburban areas(3) - For rural areas

Formulas for MS antenna ht. gain correction factor A(hm)(4) - For a small to medium sizes cities(5) and (6) - For large cities

f - carrier frequency, MHzhb and hm - BS and MS

antenna heights, md - distance between BS

and MS antennas, km

(1) LHATA (urban) [dB] =69.55 + 26.16 x log ( f ) + [ 44.9 - 6.55 x log ( hb ) ] x log ( d ) -13.82 x log ( hb ) - A ( hm )

(2) LHATA (suburban) [dB] = LHATA (urban) - 2 x [ log ( f/28 ) ]2 - 5.4

(3) LHATA (rural) [dB] =LHATA (urban) - 4.78 x [ log ( f ) ]2 - 18.33 x log ( f ) -40.98

(4) A ( hm ) [dB] = [ 11 x log ( f ) - 0.7 ] x hm - [ 1.56 x log ( f ) - 0.8 ]

(5) A ( hm ) [dB] = 8.29 x [ log ( 1.54 x hm ) ]2 - 1.1 (for f<= 300 MHz.)

(6) A ( hm ) [dB] = 3.2 x [ log ( 1175 x hm ) ]2 - 4.97 (for f > 300 MHz.)

Environmental Factor C0 dense urban-5 urban-10 suburban-17 rural


The COST-231 model was developed by European COoperative for Scientific and Technical Research committee. It extends the HATA model to the 1.8-2 GHz. band in anticipation of PCS use.COST-231 is applicable for frequencies 1500-2000 MHz, distances 1-20 km, BS antenna heights 30-200 m, MS antenna heights 1-10 mParameters and variables:

• f is carrier frequency , in MHz• hb and hm are BS and MS antenna heights (m)• d is BS and MS separation, in km• A(hm) is MS antenna height correction factor

(same as in Hata model)• Cm is city size correction factor: Cm=0 dB for

suburbs and Cm=3 dB for metropolitan centers

The EURO COST-231 Model

LCOST (urban) [dB] = 46.3 + 33.9 x log ( f ) + [ 44.9 - 6.55 x log ( hb ) ] x log ( d ) + Cm -13.82 x log ( hb ) - A ( hm )

EnvironmentalFactor C1900-2 dense urban-5 urban

-10 suburban-26 rural


Examples of Morphological ZonesSuburban: Mix of residential and business communities. Structures include 1-2 story houses 50 feet apart and 2-5 story shops and offices.Urban: Urban residential and office areas (Typical structures are 5-10 story buildings, hotels, hospitals, etc.)Dense Urban: Dense business districts with skyscrapers (10-20 stories and above) and high-rise apartments

Suburban SuburbanSuburban

UrbanUrbanUrban

Dense Urban Dense UrbanDense Urban

Although zone definitions are arbitrary, the examples and definitions illustrated above are typical of practice in North American PCS designs.


Example Morphological Zones

Rural - Highway: Highways near open farm land, large open spaces, and sparsely populated residential areas. Typical structures are 1-2 story houses, barns, etc.Rural - In-town: Open farm land, large open spaces, and sparsely populated residential areas. Typical structures are 1-2 story houses, barns, etc.SuburbanSuburban

RuralRural

Suburban

Rural

Rural Rural -- HighwayHighwayRural - Highway

Notice how different zones may abruptly adjoin one another. In the case immediately above, farm land (rural) adjoins built-up subdivisions (suburban) -- same terrain, but different land use, penetration requirements, and anticipated traffic densities.


The MSI Planet General Model

Pr - received power (dBm)Pt - transmit ERP (dBm)Hb - base station effective antenna heightHm - mobile station effective antenna heightDL - diffraction loss (dB) K1 - intercept K2 - slopeK3 - correction factor for base station antenna height gainK4 - correction factor for diffraction loss (accounts for clutter heights)K5 - Okumura-Hata correction factor for antenna height and distanceK6 - correction factor for mobile station antenna height gainKc - correction factor due to clutter at mobile station locationKo - correction factor for street orientation

Pr = Pt + K1 + k2 log(d) + k3 log(Hb) + K4 DL + K5 log(Hb) log(d)+ K6 log (Hm) + Kc + Ko

This is the general model format used in MSI’s popular PlaNET propagation prediction software for wireless systems. It includes terms similar to Okumura-Hata and COST-231 models, along with additional terms to include effects of specific obstructions and clutter on specific paths in the mobile environment.


Typical Model Results Including Environmental Correction

-2-5

-10-26

TowerHeight,

mEIRP

(watts)C,dB

Range,kmf =1900 MHz.

Dense UrbanUrban

SuburbanRural

30303050

200200200200

2.523.504.810.3

COST-231/Hata

f = 870 MHz.Okumura/Hata

0-5

-10-17

TowerHeight,

mEIRP

(watts)C,dB

Range,km

Dense UrbanUrban

SuburbanRural

30303050

200200200200

4.04.96.7

26.8


Propagation at 1900 MHz. vs. 800 MHz.

Propagation at 1900 MHz. is similar to 800 MHz., but all effects are more pronounced.

• Reflections are more effective• Shadows from obstructions are deeper• Foliage absorption is more attenuative• Penetration into buildings through openings is more effective,

but absorbing materials within buildings and their walls attenuate the signal more severely than at 800 MHz.

The net result of all these effects is to increase the “contrast” of hot and cold signal areas throughout a 1900 MHz. system, compared to what would have been obtained at 800 MHz.Overall, coverage radius of a 1900 MHz. BTS is approximately two-thirds the distance which would be obtained with the same ERP, same antenna height, at 800 MHz.


Walfisch-Betroni/Walfisch-Ikegami Models

Ordinary Okumura-type models do work in this environment, but the Walfisch models attempt to improve accuracy by exploiting the actual propagation mechanisms involved

Path Loss = LFS + LRT + LMS

LFS = free space path loss (Friis formula)LRT = rooftop diffraction lossLMS = multiscreen reflection loss

Propagation in built-up portions of cities is dominated by ray diffraction over the tops of buildings and by ray “channeling” through multiple reflections down the street canyons

-20 dBm-30 dBm-40 dBm-50 dBm-60 dBm-70 dBm-80 dBm-90 dBm

-100 dBm-110 dBm-120 dBm

Signal Level

Legend

Area View


Statistical TechniquesDistribution Statistics Concept

An area model predicts signal strength Vs. distance over an area

• This is the “median” or most probable signal strength at every distance from the cell

• The actual signal strength at any real location is determined by local physical effects, and will be higher or lower

• It is feasible to measure the observed median signal strength M and standard deviation σ

• M and σ can be applied to find probability of receiving an arbitrary signal level at a given distance

Median Signal Strength

σ,dB

Occurrences

RSSI

Normal Distribution

RSSI,dBm

Distance

Model is tweaked to produce “Best-Fit” curve

Signal Strength Predicted Vs. Observed

Observed Signal Strength

50% of observeddata is above curve

50% of observeddata is below curve


Statistical TechniquesPractical Application Of Distribution Statistics

General Approach:• Use favorite model to predict Signal

Strength• Analyze measured data, obtain:

– median signal strength M(build histogram of observed

vs. measured data)– standard deviation of error, σ

(determine from histogram) • add an extra allowance into model

– drop curve so a desired % of observations are above model predictions

Median Signal Strength

σ,dB

Occurrences

RSSI

Normal Distribution

RSSI,dBm

Distance

25% of locations exceed blue curve

50% exceed red

75% exceed black

SIGNAL STRENGTH vs DISTANCE

Min signal req’d for operation

Cell radius for 75% reliability

at edge

Cell radius for 25% reliability

at edgeCell radius for 50% reliability

at edge


Cell Edge Area Availability And Probability Of Service

Overall probability of service is best close to the BTS, and decreases with increasing distance away from BTSFor overall 90% location probability within cell coverage area, probability will be 75% at cell edge

• Result derived theoretically, confirmed in modeling with propagation tools, and observed from measurements

• True if path loss variations are log-normally distributed around predicted median values, as in mobile environment

• 90%/75% is a commonly-used wireless numerical coverage objective

• Recent publications by Nortel’s Dr. Pete Bernardin describe the relationship between area and edge reliability, and the field measurement techniques necessary to demonstrate an arbitrary degree of coverage reliability

Statistical View ofCell Coverage

Area Availability:90% overall within area

75%at edge of area

90%

75%


Application Of Distribution Statistics: ExampleLet’s design a cell to deliver at least -95 dBm to at least 75% of the locations at the cell edge (This will provide coverage to 90% of total locations within the cell)Assume that measurements you have made show a 10 dB standarddeviation σOn the chart:

• To serve 75% of locations at the cell edge , we must deliver a median signal strength which is.675 times σ stronger than -95 dBm

• Calculate:- 95 dBm + ( .675 x 10 dB ) = - 88 dBm

• So, design for a median signal strength of -88 dBm!

Standard Deviations from Median (Average) Signal Strength

Cumulative Normal Distribution

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

75%

0.675σ


Statistical Techniques:Normal Distribution Graph & Table For Convenient Reference

Cumulative Normal Distribution

Standard Deviation from Mean Signal Strength

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

CumulativeProbability

0.1%1%5%10%

StandardDeviation

-3.09-2.32-1.65-1.28-0.84 20%-0.52 30%

0.675 75%

0 50%0.52 70%

0.84 80%1.28 90%1.65 95%2.35 99%3.09 99.9%3.72 99.99%4.27 99.999%


Building PenetrationStatistical Characterization

Statistical techniques are effective against situations that are difficult to characterize analytically

• Many analytical parameters, all highly variable and complex

Building coverage is modeled using existing outdoor path loss plus an additional “building penetration loss”

• Median value estimated/sampled • Statistical distribution determined• Standard deviation estimated or

measured• Additional margin allowed in link

budget to offset assumed lossTypical values are shown at left

Building penetration

Typical Penetration Losses, dBcompared to outdoor street level

EnvironmentType

(“morphology”)

MedianLoss,

dB

Std.Dev.σ, dB

Urban Bldg. 15 8Suburban Bldg. 10 8

Rural Bldg. 10 88 4Typical Vehicle

Dense Urban Bldg. 20 8

Vehicle penetration


Composite Probability Of ServiceAdding Multiple Attenuating Mechanisms

For an in-building user, the actual signal level includes regular outdoor path attenuation plus building penetration lossBoth outdoor and penetration losses have their own variabilitieswith their own standard deviationsThe user’s overall composite probability of service must include composite median and standard deviation factors

σCOMPOSITE = ((σOUTDOOR)2+(σPENETRATION)2)1/2

LOSSCOMPOSITE = LOSSOUTDOOR+LOSSPENETRATION

Building

Outdoor Loss + Penetration Loss


Composite Probability of ServiceCalculating Fade Margin For Link Budget

Example Case: Outdoor attenuation σ is 8 dB., and penetration loss σ is 8 dB. Desired probability of service is 75% at the cell edgeWhat is the composite σ? How much fade margin is required?

Composite Probability of ServiceCalculating Required Fade Margin

EnvironmentType

(“morphology”)MedianLoss,

dB

Std.Dev.σ, dB

Urban Bldg. 15 8Suburban Bldg. 10 8

Rural Bldg. 10 88 4Typical Vehicle

Dense Urban Bldg. 20 8

BuildingPenetration

Out-DoorStd.Dev.σ, dB

8888

8

CompositeTotal

AreaAvailabilityTarget, %

90%/75% @edge90%/75% @edge90%/75% @edge90%/75% @edge

90%/75% @edge

FadeMargin

dB

7.67.67.66.0

7.6

σCOMPOSITE = ((σOUTDOOR)2+(σPENETRATION)2)1/2

= ((8)2+(8)2)1/2 =(64+64)1/2 =(128)1/2 = 11.31 dBOn cumulative normal distribution curve, 75%

probability is 0.675 σ above median. Fade Margin required =

(11.31) • (0.675) = 7.63 dB.Cumulative Normal Distribution

Standard Deviations from Median (Average) Signal Strength

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

-3 -2.5 -2 -1.5 -1 -0.5 0 0.5 1 1.5 2 2.5 3

75%

.675


CommercialPropagation Prediction

Software

CommercialPropagation Prediction

Software

Chapter 4 Section C


Point-To-Point Path-Driven Prediction Models

Use of models based on deterministic methods• Use of terrain data for construction of path profile• Path analysis (ray tracing) for obstruction, reflection analysis• Appropriate algorithms applied for best emulation of underlying

physics• May include some statistical techniques• Automated point-to-point analysis for enough points to appear

to provide large “area” coverage on raster or radial gridCommonly-used Resources

• Terrain databases• Morphological/Clutter Databases• Databases of existing and proposed sites• Antenna characteristics databases• Unique user-defined propagation models


Path-Driven Propagation Prediction Tools Data Structure

Geographic “Overlay” Format:Output Map(s) on screen or plotter

• Coverage– field strengths @ probability– probabilities @ field strength

• Best-Server• C/I (Adjacent Channel & Co-

Channel)Cell locations, cell gridTerrain elevation data

• USGS & Commercial databases• Satellite or aerial photography

Clutter data• Roads, rivers, railroads, etc.• State, county, MTA, BTA

boundariesTraffic density overlayLand use overlay


The World as “seen” by a Propagation Prediction Tool

Propagation tools use a terrain database, clutter data for land use, and vectors to represent features and traffic levels. The figure at right is a 3-D view of such databases in the area of this demonstration. Notice the granularity of the data and the very mild terrain undulations in the area, exaggerated 8 times in this view.


Survey Of Commercially Available Tools

A wide variety of software tools are available for propagation prediction and system design Some tools are implemented on PC/DOS/Windows platforms, others on more powerful UNIX platformCapabilities and user interfaces vary greatlySeveral of the better-known tools for cellular RF engineering are shown in the table at right

RF Prediction Software Tools•Qualcomm

•QEDesign CDMA Tool(Unix)

•MSI•PlaNet (Unix)

•LCC•CellCad (Unix)•ANet (DOS PC)

•CNET•Wings (Unix)•Solutions (mainframe)

•ComSearch•IQSignum (Unix)

•AT&T•PACE (DOS PC)

•Motorola•proprietary (Unix)

•TEC Cellular: Wizard (DOS)•Elebra: CONDOR, CELTEC•Virginia Tech MPRG

•SMT-Plus Indoor Site Planning Tool


Composite Coverage PlotA composite coverage plot shows the overall coverage produced by each sector in the field of view The color of each pixel corresponds to the signal level of the strongest server at that pointSuch plots are useful for identifying coverage holes and overall coverage extent


Equal Power Handoff Boundaries Plot

A Best Server Plot or in CDMA terms, an Equal Power Handoff Boundaries plot paints each pixel with a unique color to identify the best-serving sector at that point

• the boundaries shown are the equal-power points between cells

This type of plot is extremely useful in creating initial neighbor lists and identifying areas of no dominant serverSome tools (MSI Planet) can generate automatic neighbor lists from such a plot


Qualcomm’s QEDesign

Qualcomm’s commercial tool QEDesign offers a number of features targeted at CDMA system design and analysis. The figures above show the output of its microcell propagation analysis tool in the Washington, DC area, and a three-dimensional view of an antenna pattern. Other features of this package include live cursor mode in which the user can drag the cursor about and see in near-real-time the line-of-sight area visible from the selected location, or a coverage footprint calculated from that location.


General Survey Of Tool Features

Universal Basic Features of Most Tools

Automatically calculates signal strength at many points over a geographic area

• Use databases of terrain data, environmental conditions, land use, building “clutter”, estimated geographic traffic distribution, etc.

• User-definable 3-dimensional antenna patterns

• Automatically analyzes paths, selects appropriate algorithms based on path geometry

• Produces plots of coverage, C/I, etc.Used for analysis of sites, interference, frequency planning, C/I evaluation, etc.Drawback: requires significant computation power, time and RF staff special training

-20 dBm-30 dBm-40 dBm-50 dBm-60 dBm-70 dBm-80 dBm-90 dBm-100 dBm-110 dBm-120 dBm

Signal Level

Legend

C/ILegend

>20 dB<20 dB<17 dB<14 dB


General Survey Of Tool Features, Continued

Popular Features of Advanced Tools

Accepts measurement input, can automatically generate predicted-vs-measured statistics and map displaysAutomatic hexagon-manipulation grid utilityMaintains cell sites in relational database

• Easy manipulation, import, exportFlexible user interface allows multitaskingAllows multiple user-defined propagation modelsThree dimensional terrain viewRoads, boundaries, coastline easily overlaid onto any display

A

A

AA

A A

AA

A AA

A A

A

A

Pred. MeasMean -76 -72Std. Dv 9 12Samples 545 545

Area Name: DALLAS

Site Name

Subs: 100,000

Site # LatitudeLongitudeType Capacity

Number of Sites5 Total Capacity (Erlangs)221

SITE - 1SITE - 2SITE - 3SITE - 4SITE - 5

A1A2A3A4A5

33/17/4633/20/0833/16/5033/10/2833/25/21

96/08/3396/11/4996/12/1496/11/5196/03/53

S322S211S332S1101

77379188

Date: Initial Service

7

8

9

1

3

2

1

3

24

5

6

7

8

9

7

8

9

1

3

2

6

4

6

10

11



More Popular Advanced Features

Produces plots of server boundaries, C/I plots, handoff boundaries, etc.Allows interactive change of antenna number, type, orientation, power and tiltUsing growth-scaleable traffic input mask, can predict traffic carried by each site, # channels required

• Can automatically highlight cells not meeting specified grade of service

Algorithms for automatic frequency planning and optimizationUser can define or “mask” cells to be changed or unchanged during automatic optimization

43

2

56

1743

2

56

17

CELL ERL Channels14 8.3 1722 2.1 526X 1.7 426Y 23 3126Z 14 20



More Popular Advanced Features

Identification of server and interferer signal levels in live cursor mode upon graphical coverage displayGenerates bin C/I & coverage statistics for system evaluationPredicted handoff analysis

• Statistical analysis of most likely handoff candidates

• Automatic generation of neighbor cell lists

• Percentage probability of handover

Runs on powerful workstations to minimize computation time

Cell 51 -82 dBmCell 76 -97 dBmC/I +15 dB

Cell 18Cell 24 48%Cell 16 22%Cell 17 18%Cell 05 8%Cell 22 4%

C/I Pct. of Area>20 dB 93.0%<20 dB 7.0%<17 dB 2.2%


Resolution Of Terrain Databases

Elevation data in terrain databases can be stored in any of several formats:

• Contour vectors: lines of constant elevation in vector segment form, digitized from topographic maps

• Elevation sample points on rectangular grids with fixed spacing

• Elevation sample points on latitude-longitude grids with spacing of a fixed number of arc-seconds

• Data can be converted from one format to another

10m

10m

3 arc-seconds

3 arc-seconds


Resolution Of Terrain Databases, Continued

It is useful to know the horizontal spacing in feet between sample points in a terrain database using arc-seconds, i.e., latitude-longitude spacingNorth-South spacing is constant, everywhere on the planet

• 1 arc-second = 101.34 feet• 1 degree = 69.096 miles

East-West sample spacing varies with the cosine of the North Latitude

• = 101.34 feet/arcsecond at the Equator

• = 0 feet/arcsecond at Poles• = 101.34 ft. * Cos (N Lat)

per arcsecond, everywhere

N30º

N60º

(North Pole) N90º

(Equator) 0º

S30º

S60º

(South Pole) S90º

Latitude

0º Greenwich, UK

W 30º

W 60º

W 90º

W 120º

Longitude

1sec.101.34 ft

101.34 ft * Cos (N Latº )


CommercialMeasurement Tools

CommercialMeasurement Tools

Chapter 4 Section D


Propagation Data Collection Philosophy

RF testing of sites is usually performed for one of two reasons:Drive Testing for model calibration

• Prior to cell design of a wireless system, accurate models of propagation in the area must be developed for use by the prediction software. A significant number of typical sites are evaluated using the test transmitter and receiver to determine signal decay rates and to get a fairly accurate understanding of the effects of typical clutter in the area.

• Tests are also conducted to evaluate the additional attenuation which the signal suffers during penetration of typical buildings and vehicles.

• The focus is on developing models generally applicable to the area, not on the performance of specific individual sites.

Drive Testing for site evaluation• Although propagation models for an area already have been refined,

coverage of a particular site is so critical, or its environment so variable due to urban clutter, that it is essential to actually measure the coverage and interference it will produce. The focus is on this specific site.


CW or Modulated Test Signals?Can measurements of unmodulated RF carriers provide adequate propagation data for system design, or is it advisable to use amodulated RF signal similar to the type which will be radiated by actual BTS in the contemplated system?

• CW (continuous wave, i.e., unmodulated carriers) transmitters are moderately priced ($10K-$25K). CW-only receivers are priced from $5K to over $20K.

• Technology-specific GSM or CDMA modulated test transmitter-receiver systems are available, at costs in the $100,000-$275,000 range per TX-RX system.

Multiple Sites Simultaneously

Multipath Characteristics

Modulated Systems CW Systems

FER, BER statistics

Too expensive!

Delay Spread

Yes

Yes

Usually Not. However, DSP post-processing can yield some multipath data using various transforms. (Not

commercially available yet.)

NoPropagation Loss Mapping Yes Yes


Summary of Commercial Data Collection Tools

Measurement data can be collected manually, but it is simply too tedious to obtain statistically useful quantities by handThere are many commercial data collection systems available to automate the collection processMany modern propagation prediction software packages have the capability to import measurement data, compare it with predicted values, and generate statistical outputs (mean error, standard deviation, etc.).

Commercial Measurement Systems•Agilent (formerly HP)

•Digital receiver with spectrum analyzer and PN scanner capabilities; handset data collection capabilities

•Andrew (formerly Grayson):•Invex device and collection software•Interpreter post-processing tool

•COMARCO•configurable multi-device tool with scanners, receivers, handset data capture

•Ericsson TEMS tool•handset capture

•Qualcomm•CAIT tool (Common Air Interface Tester)

•Willtech•Bluerose tool with handset, PN scanner, and receiver functions)

•ZKSAM•collection tool and postprocessingmodule


Elements of Typical Measurement Systems

WirelessReceiver

PC or Collector

GPSReceiver

DeadReckoning

Main FeaturesField strength measurement

• Accurate collection in real-time• Multi-channel, averaging

capabilityLocation Data Collection Methods:

• Global Positioning System (GPS)• Dead reckoning on digitized map

database using on-board compass and wheel revolutions sensor

• A combination of both methods is recommended for the best results

Ideally, a system should be calibrated in absolute units, not just raw received power level indications

• Record normalized antenna gain, measured line loss


Typical Test Transmitter Operations

Typical Characteristics• portable, low power needs• weatherproof or weather resistant• regulated power output• frequency-agile: synthesized

Operational Concerns• spectrum coordination and proper

authorization to radiate test signal• antenna unobstructed• stable AC power• SAFETY:

– people/equipment falling due to wind, or tripping on obstacles

– electric shock– damage to rooftop


Example of Mobile Receiver: Andrew’s Invex3G Tool

100 MB ethernet connection to PCthe eight card slots can hold receivers or dual-phone cardsthere’s also room for two internal PN scannersMultiple Invex units can be cascaded for multi-phone load-test applicationsCards are field-swappable - Users can reconfigure the unit in the field for different tasks without factory assistanceReceivers and decoders are installed only for the appropriate technologies and frequency bandsInternal GPS or external GPS may be used, with or without dead-reckoning capabilities


Selecting and Tuning Propagation Models

Parameters of propagation models must be adjusted for best fit to actual drive-test measured data in the area where the model is appliedThe figure at right shows drive-test signal strengths obtained using a test transmitter at an actual test site Tools automate the process of comparing the measured data with its own predictions, and deriving error statisticsPrediction model parameters then can be “tuned” to minimize observed error


Measured Data vs. Model Predictions

Is the propagation model approximately correct?• Is the data scatter small enough to justify use of a model?• correct slope to match data• correct position up/down on Y-axis?


Analysis of Measured vs. Predicted

Several tools produce histograms showing the distribution of thedifferences between measured and predicted valuesThe mean of the difference between predicted and measured is a very important quantity. It should be small (on order of a few dB).The standard deviation of the difference also should be small. If it is substantially larger than 8 dB., then either:

• the environment is very diverse (perhaps it should be broken into pieces with separate models for better fit) or

• the slope of the model is significantly different than the observed slope of the measurements (review the Sig. vs. Dist. graph)


Displaying Error Distribution by Location

Suppose a major hill blocked the signal in one direction, or the antenna pattern had an unexpected minimum in that directionThis would cause the data in the shadowed region to differ substantially from data in all remaining directionsSome tools can display the error values on a map like the one at right, to provide quick visual evidence for recognizing this type of problem


Radiating Systems for Wireless Networks

Radiating Systems for Wireless Networks

Chapter 5

Dipole

Typical WirelessOmni Antenna

Isotropic


Antennas for WirelessAntennas for Wireless

Chapter 5 Section A


Understanding Antenna RadiationThe Principle Of Current Moments

An antenna is just a passive conductor carrying RF current

• RF power causes the current flow

• Current flowing radiates electromagnetic fields

• Electromagnetic fields cause current in receiving antennas

The effect of the total antenna is the sum of what every tiny “slice” of the antenna is doing

• Radiation of a tiny “slice” is proportional to its length times the current in it

• remember, the current has a magnitude and a phase!

TX RX

Width of banddenotes current

magnitude

Zero currentat each end

Maximum currentat the middle

Current induced inreceiving antennais vector sum of

contribution of everytiny “slice” of

radiating antenna

each tiny imaginary “slice”of the antennadoes its share

of radiating


Different Radiation In Different DirectionsEach “slice” of the antenna produces a definite amount of radiation at a specific phase angleStrength of signal received varies, depending on direction of departure from radiating antenna

• In some directions, the components add up in phase to a strong signal level

• In other directions, due to the different distances the various components must travel to reach the receiver, they are out of phase and cancel, leaving a much weaker signal

An antenna’s directivity is the same for transmission & reception

TXMaximumRadiation:contributions

in phase, reinforce

MinimumRadiation:contributionsout of phase,

cancel

MinimumRadiation:contributionsout of phase,

cancel


Antenna Polarization

To intercept significant energy, a receiving antenna must be oriented parallel to the transmitting antenna

• A receiving antenna oriented at right angles to the transmitting antenna is “cross-polarized”; will have very little current induced

• Vertical polarization is the default convention in wireless telephony• In the cluttered urban environment, energy becomes scattered and

“de-polarized” during propagation, so polarization is not as critical• Handset users hold the antennas at seemingly random angles…..

TX

ElectromagneticField

current almostno

current

Antenna 1VerticallyPolarized

Antenna 2Horizontally

Polarized

RX

RF current in a conductor causes electromagnetic fields that seek to induce current flowing in the samedirection in other conductors.

The orientation of the antenna is called its polarization.

Coupling between two antennas is proportional to the cosine of the angle of their relative orientation


Antenna Gain

Antennas are passive devices: they do not produce power

• Can only receive power in one form and pass it on in another, minus incidental losses

• Cannot generate power or “amplify”However, an antenna can appear to have “gain”compared against another antenna or condition. This gain can be expressed in dB or as a power ratio. It applies both to radiating and receivingA directional antenna, in its direction of maximum radiation, appears to have “gain” compared against a non-directional antennaGain in one direction comes at the expense of less radiation in other directionsAntenna Gain is RELATIVE, not ABSOLUTE

• When describing antenna “gain”, the comparison condition must be stated or implied

Omni-directionalAntenna

DirectionalAntenna


Reference Antennas

Isotropic Radiator• Truly non-directional -- in 3 dimensions• Difficult to build or approximate physically,

but mathematically very simple to describe• A popular reference: 1000 MHz and above

– PCS, microwave, etc.Dipole Antenna

• Non-directional in 2-dimensional plane only• Can be easily constructed, physically

practical• A popular reference: below 1000 MHz

– 800 MHz. cellular, land mobile, TV & FM

IsotropicAntenna

(watts or dBm) ERP Effective Radiated Power Vs. DipoleEffective Radiated Power Vs. Isotropic

Gain above Dipole referenceGain above Isotropic radiator

(watts or dBm) EIRP dBddBi

Quantity Units Dipole Antenna

Notice that a dipolehas 2.15 dB gaincompared to an isotropic antenna.


Effective Radiated Power

An antenna radiates all power fed to it from the transmitter, minus any incidental losses. Every direction gets some amount of powerEffective Radiated Power (ERP) is the apparentpower in a particular direction

• Equal to actual transmitter power times antenna gain in that direction

Effective Radiated Power is expressed in comparison to a standard radiator

• ERP: compared with dipole antenna• EIRP: compared with Isotropic antenna

AB

ERP B A (ref)

100w275w

ReferenceAntenna

TX100 W

A

DirectionalAntenna TX

100 W

B

Example: Antennas A and B each radiate 100 watts fromtheir own transmitters. Antenna A is our reference, ithappens to be isotropic.Antenna B is directional. In its maximum direction, itssignal seems 2.75 stronger than the signal from antennaA. Antenna B’s EIRP in this case is 275 watts.


Antenna Gain And ERPExamples

Many wireless systems at 1900 & 800 MHz use omni antennas like the one shown in this figureThese patterns are drawn to scale in E-field radiation units, based on equal power to each antennaNotice the typical wireless omni antenna concentrates most of its radiation toward the horizon, where users are, at the expense of sending less radiation sharply upward or downwardThe wireless antenna’s maximum radiation is 12.1 dB stronger than the isotropic (thus 12.1 dBi gain), and10 dB stronger than the dipole (so 10 dBd gain).

IsotropicDipoleOmni

12.1 dBi10dBd

Gain Comparison

Isotropic

Dipole

Typical WirelessOmni Antenna

Gain 12.1 dBi or 10 dBd


Radiation PatternsKey Features And Terminology

An antenna’s directivity is expressed as a series of patternsThe Horizontal Plane Pattern graphs the radiation as a function of azimuth (i.e..,direction N-E-S-W)The Vertical Plane Pattern graphs the radiation as a function of elevation (i.e.., up, down, horizontal)Antennas are often compared by noting specific landmark points on their patterns:

• -3 dB (“HPBW”), -6 dB, -10 dB points

• Front-to-back ratio• Angles of nulls, minor lobes, etc.

Typical ExampleHorizontal Plane Pattern

0 (N)

90(E)

180 (S)

270(W)

0 -10

-20

-30 dB

Notice -3 dB points

Front-to-back Ratio

10 dBpoints

MainLobe

a MinorLobe

nulls orminima


In phase

Out of phase

How Antennas Achieve Their Gain

Quasi-Optical Techniques (reflection, focusing)• Reflectors can be used to concentrate

radiation– technique works best at microwave frequencies,

where reflectors are small• Examples:

– corner reflector used at cellular or higher frequencies

– parabolic reflector used at microwave frequencies

– grid or single pipe reflector for cellular

Array techniques (discrete elements)• Power is fed or coupled to multiple

antenna elements; each element radiates• Elements’ radiation in phase in some

directions• In other directions, a phase delay for each

element creates pattern lobes and nulls


Types Of Arrays

Collinear vertical arrays• Essentially omnidirectional in

horizontal plane• Power gain approximately

equal to the number of elements

• Nulls exist in vertical pattern, unless deliberately filled

Arrays in horizontal plane• Directional in horizontal

plane: useful for sectorization• Yagi

– one driven element, parasitic coupling to others

• Log-periodic– all elements driven– wide bandwidth

All of these types of antennas are used in wireless

RF power

RF power

CollinearVerticalArray

Yagi

Log-Periodic


Omni AntennasCollinear Vertical Arrays

The family of omni-directional wireless antennas:Number of elements determines

• Physical size• Gain• Beamwidth, first null angle

Models with many elements have very narrow beamwidths

• Require stable mounting and careful alignment

• Watch out: be sure nulls do not fall in important coverage areas

Rod and grid reflectors are sometimes added for mild directivity

Examples: 800 MHz.: dB803, PD10017, BCR-10O, Kathrein 740-198

1900 MHz.: dB-910, ASPP2933

beamwidth

Angleof

firstnull

θ

-3 dB

Vertical Plane Pattern

Number ofElements

PowerGain

Gain,dB

Angleθ

0.00 n/a3.01 26.57°4.77 18.43°6.02 14.04°6.99 11.31°7.78 9.46°8.45 8.13°9.03 7.13°9.54 6.34°10.00 5.71°10.41 5.19°10.79 4.76°11.14 4.40°

1234567891011121314

1234567891011121314 11.46 4.09°

Typical Collinear Arrays


Sector AntennasReflectors And Vertical Arrays

Typical commercial sector antennas are vertical combinations of dipoles, yagis, or log-periodic elements with reflector (panel or grid) backing

• Vertical plane pattern is determined by number of vertically-separated elements

– varies from 1 to 8, affecting mainly gain and vertical plane beamwidth

• Horizontal plane pattern is determined by:

– number of horizontally-spaced elements

– shape of reflectors (is reflector folded?)

Vertical Plane PatternUp

Down

Horizontal Plane PatternN

E

S

W


Example Of Antenna Catalog Specifications

Frequency Range, MHz.Gain - dBd/dBiVSWRBeamwidth (3 dB from maximum)PolarizationMaximum power input - WattsInput Impedance - OhmsLightning ProtectionTermination - StandardJumper Cable

Electrical DataAntenna Model ASPP2933 ASPP2936 dB910C-M

1850-1990 1850-1990 1850-19703/5.1

<1.5:132°

Vertical400

50Direct Ground

N-FemaleOrder Sep.

6/8.1<1.5:1

15°Vertical

40050

Direct GroundN-Female

Order Sep.

10/12.1<1.5:1

5°Vertical

40050

Direct GroundN-Female

Order Sep.

Mechanical DataAntenna ModelOverall length - in (mm)Radome OD - in (mm)Wind area - ft2 (m2)Wind load @ 125 mph/201 kph lb-f (n)Maximum wind speed - mph (kph)Weight - lbs (kg)Shipping Weight - lbs (kg)Clamps (steel)

ASPP293324 (610)

1.1 (25.4).17 (.0155)

4 (17)140 (225)

4 (1.8)11 (4.9)

ASPA320

ASPP293636 (915)

1.0 (25.4).25 (.0233)

6 (26)140 (225)

6 (2.7)13 (5.9)

ASPA320

dB910C-M77 (1955)

1.5 (38).54 (.05)

14 (61)125 (201)

5.2 (2.4)9 (4.1)

Integral


Example Of Antenna Catalog Radiation Pattern

Vertical Plane Pattern • E-Plane (elevation plane)• Gain: 10 dBd• Dipole pattern is superimposed at

scale for comparison (not often shown in commercial catalogs)

• Frequency is shown• Pattern values shown in dBd• Note 1-degree indices through

region of main lobe for most accurate reading

• Notice minor lobe and null detail!


Other RF ElementsOther RF Elements

Chapter 5 Section B


Antenna Systems

Antenna systems include more than just antennasTransmission Lines

• Necessary to connect transmitting and receiving equipmentOther Components necessary to achieve desired system function

• Filters, Combiners, Duplexers - to achieve desired connections• Directional Couplers, wattmeters - for measurement of performance

Manufacturer’s system may include some or all of these items• Remaining items are added individually as needed by system operator

F R

Duplexer

Combiner

BPF

TX

RX

TXTransmission LineJumper

Jumpers

DirectionalCoupler

Antenna


Characteristics Of Transmission Lines

Physical CharacteristicsType of line

• Coaxial, stripline, open-wire

• Balanced, unbalancedPhysical configuration

• Dielectric:– air– foam

• Outside surface– unjacketed– jacketed

Size (nominal outer diameter)• 1/4”,1/2”, 7/8”, 1-1/4”,

1-5/8”, 2-1/4”, 3”Foam

DielectricAir

Dielectric

Typical coaxial cablesUsed as feeders in wireless applications


Transmission LinesSome Practical Considerations

Transmission lines practical considerations• Periodicity of inner conductor

supporting structure can cause VSWR peaks at some frequencies, so specify the frequency band when ordering

• Air dielectric lines– lower loss than foam-dielectric; dry air

is excellent insulator – shipped pressurized; do not accept

delivery if pressure leak• Foam dielectric lines

– simple, low maintenance; despite slightly higher loss

– small pinholes and leaks can allow water penetration and gradual attenuation increases

FoamDielectric

AirDielectric


Characteristics Of Transmission Lines, Continued

Electrical CharacteristicsAttenuation

• Varies with frequency, size, dielectric characteristics of insulation

• Usually specified in dB/100 ft and/or dB/100 m

Characteristic impedance Z0 (50 ohms is the usual standard; 75 ohms is sometimes used)

• Value set by inner/outer diameter ratio and dielectric characteristics of insulation

• Connectors must preserve constant impedance (see figure at right)

Velocity factor• Determined by dielectric characteristics

of insulation. Power-handling capability

• Varies with size, conductor materials, dielectric characteristics

dD

Characteristic Impedanceof a Coaxial Line

Zo = ( 138 / ( ε 1/2 ) ) Log10 ( D / d )ε = Dielectric Constant

= 1 for vacuum or dry air


Transmission LinesSpecial Electrical Properties

Transmission lines have impedance-transforming properties

• When terminated with same impedance as Zo, input to line appears as impedance Zo

• When terminated with impedance different from Zo, input to line is a complex function of frequency and line length. Use Smith Chart or formulae to compute

Special case of interest: Line section one-quarter wavelength long has convenient properties useful in matching networks

• ZIN = (Zo2)/(ZLOAD)

Zo=50Ω ZLOAD=50Ω

ZIN = 50Ω

Matched condition

Zo=50ΩZLOAD=

83-j22Ω

ZIN = ?Mismatched condition

Zo=50ΩZLOAD=100ΩZIN=25Ω

λ/4

ZIN= ZO2

/ ZLOAD

Deliberate mismatchfor impedance transformation


Transmission LinesImportant Installation Practices

Respect specified minimum bending radius!

• Inner conductor must remain concentric, otherwise Zo changes

• Dents, kinks in outer conductor change Zo

Don’t bend large, stiff lines (1-5/8” or larger) to make direct connection with antennas Use appropriate jumpers, weatherproofed properly.Secure jumpers against wind vibration.

ObserveMinimumBendingRadius!


Transmission LinesImportant Installation Practices, Continued

During hoisting• Allow line to support its own

weight only for distances approved by manufacturer

• Deformation and stretching may result, changing the Zo

• Use hoisting grips, messenger cable

After mounting• Support the line with proper

mounting clamps at manufacturer’s recommended spacing intervals

• Strong winds will set up damaging metal-fatigue-inducing vibrations

200 ft~60 mMax.

3-6 ft


RF FiltersBasic Characteristics And Specifications

Types of Filters• Single-pole:

– pass

– reject (notch)• Multi-pole:

– band-pass– band-reject

Key electrical characteristics• Insertion loss• Passband ripple• Passband width

– upper, lower cutoff frequencies

• Attenuation slope at band edge• Ultimate out-of-band attenuation

Typical bandpass filters have insertion loss of 1-3 dB. andpassband ripple of 2-6 dB.

Bandwidth is typically 1-20% of center frequency, depending on application. Attenuation slope and out-of-band attenuation depend on # of poles & design

Typical RF bandpass filter0

Atte

nuat

ion,

dB

Frequency, megaHertz

passband rippleinsertion loss

-3 dB passbandwidth


RF FiltersTypes And Applications

Filters are the basic building blocks of duplexers and more complex devicesMost manufacturers’ network equipment includes internal bandpass filters at receiver input and transmitter outputFilters are also available for special applications Number of poles (filter elements) and other design variables determine filter’s electrical characteristics

• Bandwidth rejection• Insertion loss• Slopes• Ripple, etc.

Notice construction: RF input excites one quarter-wave element and electromagnet fields propagate from element to element, finally exciting the last element which is directly coupled to the output.

Each element is individually set and forms a pole in the filter’s overall response curve.

Typical RF Bandpass Filter

∼λ/4


Basics Of Transmitting Combiners

Allows multiple transmitters to feed single antenna, providing

• Minimum power loss from transmitter to antenna

• Maximum isolation between transmitters

Combiner types• Tuned

– low insertion loss ~1-3 dB– transmitter frequencies must be

significantly separated• Hybrid

– insertion loss -3 dB per stage– no restriction on transmitter

frequencies• Linear amplifier

– linearity and intermodulation are major design and operation issues

Typical tuned combinerapplication

TX TX TX TX TX TX TX TX

Antenna

Typical hybrid combinerapplication

TX TX TX TX TX TX TX TX

Antenna

~-3 dB

~-3 dB

~-3 dB


Duplexer Basics

Duplexer allows simultaneous transmitting and receiving on one antenna

• Nortel 1900 MHz BTS RFFEsinclude internal duplexer

• Nortel 800 MHz BTS does not include duplexer but commercial units can be used if desired

Important duplexer specifications• TX pass-through insertion loss• RX pass-through insertion loss• TX-to-RX isolation at TX

frequency (RX intermodulationissue)

• TX-to-RX isolation at RX frequency (TX noise floor issue)

• Internally-generated IMP limit specification

fR fT

RX TX

Antenna

Duplexer

Principle of operationDuplexer is composed of individualbandpass filters to isolate TX fromRX while allowing access to antennafor both. Filter design determinesactual isolation between TX and RX,and insertion loss TX-to-Antennaand RX-to-Antenna.


Directional Couplers

Couplers are used to measure forward and reflected energy in a transmission line; it has 4 ports:

• Input (from TX), Output (to load)

• Forward and Reverse SamplesSensing loops probe E& I in line

• Equal sensitivity to E & H fields• Terminations absorb induced

current in one direction, leaving only sample of other direction

Typical performance specifications• Coupling factor ~20, ~30,

~40 dB., order as appropriate for application

• Directivity ~30-~40 dB., f($)– defined as relative

attenuation of unwanteddirection in each sample

Principle of operation

ZLOAD= 50Ω

Input

Reverse Sample

Forward Sample

RT

RT

Typical directional coupler

Main line’s E & I induce equal signals in sense loops. E is direction-independent, but I’s polarity depends on direction andcancels sample induced in one direction.Thus sense loop signals are directional.One end is used, the other terminated.


Basics of Antenna TestingBasics of Antenna Testing

Chapter 5 Section C


Testing Communications Feedlines and Antennas

AC power wiring and voice telephone wiring do not require extremely critical wiring practices

• just make sure the connections and insulation are good, heat is not allowed to build up, and you’ll have good results

• AC power frequencies and audio signal frequencies have wavelengths of many miles

– a few feet of wire won’t radiate much energyHigh frequency RF wiring practice is much more critical since signal wavelengths are only a few inches or feet

• any bend or protruding bit of wire can serve as an unintentional antenna, “leaking” energy

• even splices and connections can leak energy unless their shape and dimensions are closely controlled

• abrupt changes in cable shape “reflect” energy back down the transmission line, causing many problems

Precisely shaped cables and connectors, careful installation and accurate testing are required to avoid significant antenna system performance problems


Forward and Reflected Energy

In a perfect antenna system, the transmission line and the antenna have the same impedance

• we say they are “impedance matched”All the energy from the transmitter passes through and is radiated from the antenna

• virtually no energy is reflected back to the transmitter

Transmission Line

Antenna

TransmitterForward PowerVirtually no reflected power

50Ω50Ω

50Ω


Forward and Reflected Energy

Transmission Line

Antenna

Transmitter

Significant Reflected Power

50Ω

42-j17Ω

Forward Power

dent or kink37Ω

In a damaged antenna system, the impedance match is not good• there could be a dent, kink, or a spot with water in the transmission

line– the different impedance in the line at this spot will cause some of

the energy to be reflected backwards• the antenna could be damaged or dangling, causing it to have an

altered impedance– the antenna’s different impedance will reflect some of the energy

backwards down the lineThe Site Master® Distance-To-Fault mode will be helpful in finding the location of the damage


How Much Reflection? Four Ways to Say ItThere are four ways of expressing how much energy is being reflected

• different users like different methodsVoltage Standing Wave Ratio (VSWR) (used by hobbyists and consumers)

• the reflected voltage is in phase with the incident voltage at some places and out of phase at others

• VSWR is the ratio of Vmax/VminReflected Power as % of Forward Power (used by field personnel in some industries)

• just divide Rev by Fwd, use percentReturn Loss (used by field personnel)

• how many db weaker is the reflected energy than the forward energy

Reflection Coefficient (academic users)• vector ratio of reflected/incident voltage

or current• usually expressed as a polar vector, with

magnitude and phase

Vmax

Vmin

SWR: Standing Wave Ratio

= Vmax/ Vmin

FORWARD

REFLECTED

Reflected Power (%)

= 100 x RevPwr

FwdPwr

FORWARD

REFLECTED

Return Loss (db)

= 10 x Log10

RevPwrFwdPwr

FORWARD

REFLECTED

Reflection Coefficient (vector ratio)Vreflected

Vincident

=


Comparing Reflection Reports in Different FormsReflection expressed in one form can be converted and expressed in the other formsFor example, consider a VSWR of 1.5 : 1

• this is 4% reflected power• this is a return loss of 14 db• to calculate the reflection coefficient, the

phase of the reflection is also needed

VSWR vs. Return Loss

VSWR

0

10

20

30

40

50

1 1.5 2 2.5 3

FORWARD

REFLECTED

Reflected Power (%)

= 100 x RevPwr

FwdPwr

FORWARD

REFLECTED

Return Loss (db)

= 10 x Log10

RevPwrFwdPwr

FORWARD

REFLECTED

Reflection Coefficient (vector ratio)Vreflected

Vincident

=

Vmax

Vmin

SWR: STANDING WAVE RATIO= Vmax/ Vmin

=

Reflected PowerForward Power

Reflected PowerForward Power

1 +

1 -


Swept Return Loss and TDR Measurements

It’s a good idea to take swept and TDR return loss measurements of a new antenna at installation and to recheck periodically

• maintain a printed or electronically stored copy of the analyzer output for comparison

• most types of antenna or transmission line failures are easily detectable by comparison with stored data

What is the maximum acceptable value of return loss as seen in sketch above?Given:

Antenna VSWR max spec is 1.5 : 1 between f1 and f2Transmission line loss = 3 dB.

Consideration & Solution:From chart, VSWR of 1.5 : 1 is a return loss of -14 dB, measured at the antennaPower goes through the line loss of -3 db to reach the antenna, and -3 db to returnTherefore, maximum acceptable observation on the ground is -14 -3 -3 = - 20 dB.

Site Master®-10

-20

-30f1 f2

Jumper

Feedline

Jumper

Antenna


Example Frequency Sweep Test Plot


Example Distance-to-Fault Plot


Some Antenna Application Considerations

Some Antenna Application Considerations

Chapter 5 Section D


Near-Field/Far-Field Considerations

Antenna behavior is very different close-in and far outNear-field region: the area within about 10 times the spacing between antenna’s internal elements

• Inside this region, the signal behaves as independent fields from each element of the antenna, with their individual directivity

Far-field region: the area beyond roughly 10 times the spacing between the antenna’s internal elements

• In this region, the antenna seems to be a point-source and the contributions of the individual elements are indistinguishable

• The pattern is the composite of the arrayObstructions in the near-field can dramatically alter the antenna performance

Near-field

Far-field


Local Obstruction at a Site

Obstructions near the site are sometimes unavoidable Near-field obstructions can seriously alter pattern shapeMore distant local obstructions can cause severe blockage, as for example roof edge in the figure at right

• Knife-edge diffraction analysis can help estimate diffraction loss in these situations

• Explore other antenna mounting positions

Diffractionover

obstructing edge

Local obstruction example


Estimating Isolation Between Antennas

Often multiple antennas are needed at a site and interaction is troublesomeElectrical isolation between antennas

• Coupling loss between isotropic antennas one wavelength apart is 22 dB

• 6 dB additional coupling loss with each doubling of separation

• Add gain or loss referenced from horizontal plane patterns

• Measure vertical separation between centers of the antennas

– vertical separation usually is very effective

One antenna should not be mounted in main lobe and near-field of another

• Typically within 10 feet @ 800 MHz• Typically 5-10 feet @ 1900 MHz


Visually Estimating Depression Anglesin the field

Before considering downtilt, beamwidths, and depression angles, do some personal experimentation at a high site to gain a sense of the angles involvedVisible width of fingers, etc. can be useful approximate benchmark for visual evaluationMeasure and remember width of your own chosen referencesStanding at a site, correlate your sightings of objects you want to cover with angles in degrees and the antenna pattern

distance

width

angle = arctangent (width / distance)

Visually estimating angleswith tools always at hand

Typical AnglesThumb widthNail of forefingerAll knuckles

~2 degrees~1 degree~10 degrees

“Calibrate” yourself using the formula!


Antenna DowntiltWhat’s the goal?

Downtilt is commonly used for two reasons1. Reduce Interference

• Reduce radiation toward a distant co-channel cell

• Concentrate radiation within the serving cell

2. Prevent “Overshoot”• Improve coverage of

nearby targets far below the antenna

– otherwise within “null” of antenna pattern

Are these good strategies?How is downtilt applied?

Scenario 2

Cell AScenario 1

Cell B


Consider Vertical Depression Angles

Basic principle: important to match vertical pattern against intended coverage targets

• Compare the angles toward objects against the antenna vertical pattern -- what’s radiating toward the target?

• Don’t position a null of the antenna toward an important coverage target!

Sketch and formula • Notice the height and horizontal

distance must be expressed in the same units before dividing (both in feet, both in miles, etc.)

θ = ArcTAN ( Vertical distance / Horizontal distance )

Horizontaldistance

Verticaldistance

θ Depression angle


Types Of Downtilt

Mechanical downtilt• Physically tilt the antenna• The pattern in front goes

down, and behind goes up• Popular for sectorization

and special omni applications

Electrical downtilt• Incremental phase shift is

applied in the feed network• The pattern “droops” all

around, like an inverted saucer

• Common technique when downtilting omni cells


Reduce Interference Scenario 1

The Concept:Radiate a strong signal toward everything within the serving cell, but significantly reduce the radiation toward the area of Cell B

The Reality:When actually calculated, it’s surprising how small the difference in angle is between the far edge of cell A and the near edge of Cell B

• Delta in the example is only 0.3 degrees!!

• Let’s look at antenna patterns

Cell A ConceptCell B

weakstrong

θ1 = ArcTAN ( 150 / ( 4 * 5280 ) ) = -0.4 degrees

θ2 = ArcTAN ( 150 / ( 12 * 5280 ) ) = -0.1 degrees

Reality

12 miles4

height difference

150 ft θ2θ1


Reduce InterferenceScenario 1 , Continued

It’s an attractive idea, but usually the angle between edge of serving cell and nearest edge of distant cell is just too small to exploit

• Downtilt or not, can’t get much difference in antenna radiation between θ1 and θ2

• Even if the pattern were sharp enough, alignment accuracy and wind-flexing would be problems

– delta θ in this example is less than one degree!

• Also, if downtilting -- watch out for excessive RSSI and IM involving mobiles near cell!

Soft handoff and good CDMA power control is more important

-0.4-0.1

θ1 = -0.4 degrees

θ2 = -0.1 degrees


Avoid Overshoot Scenario 2

Application concern: too little radiation toward low, close-in coverage targetsThe solution is common-sense matching of the antenna vertical pattern to the angles where radiation is needed

• Calculate vertical angles to targets!!• Watch the pattern nulls -- where do

they fall on the ground?• Choose a low-gain antenna with a

fat vertical pattern if you have a wide range of vertical angles to “hit”

• Downtilt if appropriate• If needed, investigate special “null-

filled” antennas with smooth patterns

Scenario 2


Other Antenna Selection Considerations

Before choosing an antenna for widespread deployment, investigate:

Manufacturer’s measured patterns• Observe pattern at low end of band, mid-band, and high end of band• Any troublesome back lobes or minor lobes in H or V patterns?• Watch out for nulls which would fall toward populated areas• Be suspicious of extremely symmetrical, “clean” measured patterns• Obtain Intermod Specifications and test results (-130 or better)• Inspect return loss measurements across the band

Inspect a sample unit• Physical integrity? weatherproof? • Dissimilar metals in contact anywhere?• Collinear vertical antennas: feed method? • End (compromise) or center-fed (best)?• Complete your own return loss measurements, if possible• Ideally, do your own limited pattern verification

Check with other users for their experiences

February, 2005 6 - 1RF100 v2.0 (c)2005 Scott Baxter

Traffic EngineeringTraffic Engineering

Chapter 6

Typical Traffic Distributionon a Cellular System

0%10%20%30%40%50%60%70%80%90%

100%

Hour

SUN

MON

TUE

WED

THU

FRI

SAT

# Trunks

Efficiency %

Capacity,Erlangs

1 50

80%

41


A Game of Avoiding Extremes

The traffic engineer must walk a fine line between two problems:Overdimensioning

• too much cost• insufficient resources to construct• traffic revenue is too low to

support costs• very poor economic efficiency!

Underdimensioning• blocking• poor technical performance

(interference)• capacity for billable revenue is low• revenue is low due to poor quality• users unhappy, cancel service• very poor economic efficiency!


Dimensioning the System:An Interactive, Iterative Process

Some traffic engineering decisions trigger resource acquisition

• additional blocks of numbers from the local exchange carrier

• additional cards for various functions in the switch and peripherals

• additional members in PSTN trunk groups; additional T-1/E-1s to busy sites

Some traffic engineering decisions trigger more engineering

• adding additional carriers to congested areas

• adding additional cells to relieve blocking• finding short-term fixes for unanticipated

problemsThis course is concerned primarily with determining the number of voice channels required in cells, with the related site engineering and frequency or code planning

DMS-MTXCell

PSTN Office


Basics of Traffic EngineeringTerminology & Concept of a Trunk

Traffic engineering in telephony is focused on the voice paths which users occupy. They are called by many different names:• trunks• circuits• radios (AMPS, TDMA), transceivers (“TRXs” in GSM),

channel elements (CDMA)Some other common terms are:• trunk group

– a trunk group is several trunks going to the same destination, combined and addressed in switch translations as a unit , for traffic routing purposes

• member– one of the trunks in a trunk group


Units of Traffic Measurement

General understanding of telephone traffic engineering began around 1910. An engineer in the Danish telephone system, Mr. Erlang, was one of the first to master the science of trunk dimensioning and publish the knowledge for others. In his honor,the basic unit of traffic is named the Erlang. An Erlang of traffic is one circuit continuously used during an observation period one hour long.

Other units have become popular among various users:CCS (Hundred-Call-Seconds)MOU (Minutes Of Use)It’s easy to convert between traffic units if the need arises:

1 Erlang = 60 MOU = 36 CCS

Traffic is expressed in units of Circuit Time


How Much Traffic Can One Trunk Carry?Traffic studies are usually for periods of one hourIn one hour, one trunk can carry one hour of traffic -- One ErlangIf nothing else matters, this is the limit!If anyone else wants to talk -- sorry!

Absolute Maximum Capacityof One Trunk

One Trunk

One ErlangConstantTalker

It’s not acceptable to keep all trunks busy all the time. There must be a reserve to accommodate new talkers! How much?


Traffic Engineering And Queuing Theory

Traffic engineering is an application of a science called queuing theory

• Queuing theory relates user arrival statistics, number of servers, and various queue strategies, with the probability of a user receiving service

• If waiting is not allowed, and a blocked call simply goes away, Erlang-Bformula applies (popular in wireless)

• If unlimited waiting is allowed before a call receives service, the Erlang-Cformula applies

• If a wait is allowed but is limited in time, Binomial & Poisson formulae apply

• Engset formulae apply to rapid, packet-like transactions such as paging channels

Ticket counter analogy

User population

Queue

Servers

Queues we face in everyday life

1) for telephone calls2) at the bank3) at the gas station4) at the airline counter


Offered And Carried TrafficOffered traffic is what users attempt to originateCarried traffic is the traffic actually successfully handled by the systemBlocked traffic is the traffic that could not be handled

• Since blocked call attempts never materialize, blocked traffic must be estimated based on number of blocked attempts and average duration of successful calls

CarriedTraffic

BTS BTS BTS BTS BTS BTS

OfferedTraffic

BSCMTX

BlockedTraffic

PSTN or otherWireless user

TOff = NCA x TCD

TOff = Offered trafficNCA = Number of call attemptsTCD = Average call duration

Offered Traffic = Carried Traffic + Blocked Traffic


Blocking is inability to get a circuit when one is neededProbability of Blocking is the likelihood that blocking will happenIn principle, blocking can occur anywhere in a wireless system:

• not enough radios, the cell is full• not enough paths between cell site and switch• not enough paths through the switching complex• not enough trunks from switch to PSTN

Blocking probability is usuallyexpressed as a percentage

using a “shorthand” notation:• P.02 is 2% probability, etc.• Blocking probability sometimes

is called “Grade Of Service”Most blocking in cellular systems

occurs at the radio level.• P.02 is a common goal at the

radio level in a system

Principles of Traffic EngineeringBlocking Probability / Grade of Service

PSTN Office

DMS-MTX

Cell

Cell

Cell

P.001 P.005

P.02

P.005

Typical Wireless SystemDesign Blocking Probabilities


Number of Trunks vs. Utilization Efficiency

Imagine a cell site with just one voice channel. At a P.02 Grade of Service, how much traffic could it carry?

• The trunk can only be used 2% of the time, otherwise the blocking will be worse than 2%.

• 98% availability forces 98% idleness. It can only carry .02 Erlangs. Efficiency 2%!

Adding just one trunk relieves things greatly. Now we can use trunk 1 heavily, with trunk 2 handling the overflow. Efficiency rises to 11%

The Principle of Trunking EfficiencyFor a given grade of service, trunk

utilization efficiency increases as the number of trunks in the pool grows larger.

• For trunk groups of several hundred, utilization approaches 100%.

# Trunks

Efficiency %

Capacity,Erlangs

1 50

80%

41

Erl Eff%Trks12

0.020.22

2%11%

Erlang-B P.02 GOS


Number of Trunks,Capacity, and Utilization Efficiency

The graph at left illustrates the capacity in Erlangs of a given number of trunks, as well as the achievable utilization efficiencyFor accurate work, tables of traffic data are available

• Capacity, Erlangs• Blocking Probability

(GOS)• Number of Trunks

Notice how capacity and utilization behave for the numbers of trunks in typical cell sites

051015202530354045

Capacity and Trunk UtilizationErlang-B for P.02 Grade of Service

Trunks

0102030405060708090

50403020100UtilizationEfficiencyPercent

Capacity,Erlangs


Traffic Engineering & System Dimensioning

Using Erlang-B Tables to determine Number of Circuits Required

A = f (E,n)

Probability of blocking

0.0001 0.002 0.02

7

E

n

12

300

2.935

0.2

Capacity in Erlangs

Number of available circuits


Erlang-B Traffic TablesAbbreviated - For P.02 Grade of Service Only

#TrunksErlangs #TrunksErlangs #Trunks #TrunksErlangs #TrunksErlangs #TrunksErlangs #TrunksErlangs #TrunksErlangs1 0.0204 26 18.4 51 41.2 76 64.9 100 88 150 136.8 200 186.2 250 235.82 0.223 27 19.3 52 42.1 77 65.8 102 89.9 152 138.8 202 188.1 300 285.73 0.602 28 20.2 53 43.1 78 66.8 104 91.9 154 140.7 204 190.1 350 335.74 1.09 29 21 54 44 79 67.7 106 93.8 156 142.7 206 192.1 400 385.95 1.66 30 21.9 55 44.9 80 68.7 108 95.7 158 144.7 208 194.1 450 436.16 2.28 31 22.8 56 45.9 81 69.6 110 97.7 160 146.6 210 196.1 500 486.47 2.94 32 23.7 57 46.8 82 70.6 112 99.6 162 148.6 212 198.1 600 587.28 3.63 33 24.6 58 47.8 83 71.6 114 101.6 164 150.6 214 200 700 688.29 4.34 34 25.5 59 48.7 84 72.5 116 103.5 166 152.6 216 202 800 789.310 5.08 35 26.4 60 49.6 85 73.5 118 105.5 168 154.5 218 204 900 890.611 5.84 36 27.3 61 50.6 86 74.5 120 107.4 170 156.5 220 206 1000 999.112 6.61 37 28.3 62 51.5 87 75.4 122 109.4 172 158.5 222 208 1100 109313 7.4 38 29.2 63 52.5 88 76.4 124 111.3 174 160.4 224 21014 8.2 39 30.1 64 53.4 89 77.3 126 113.3 176 162.4 226 21215 9.01 40 31 65 54.4 90 78.3 128 115.2 178 164.4 228 213.916 9.83 41 31.9 66 55.3 91 79.3 130 117.2 180 166.4 230 215.917 10.7 42 32.8 67 56.3 92 80.2 132 119.1 182 168.3 232 217.918 11.5 43 33.8 68 57.2 93 81.2 134 121.1 184 170.3 234 219.919 12.3 44 34.7 69 58.2 94 82.2 136 123.1 186 172.4 236 221.920 13.2 45 35.6 70 59.1 95 83.1 138 125 188 174.3 238 223.921 14 46 36.5 71 60.1 96 84.1 140 127 190 176.3 240 225.922 14.9 47 37.5 72 61 97 85.1 142 128.9 192 178.2 242 227.923 15.8 48 38.4 73 62 98 86 144 130.9 194 180.2 244 229.924 16.6 49 39.3 74 62.9 99 87 146 132.9 196 182.2 246 231.825 17.5 50 40.3 75 63.9 100 88 148 134.8 198 184.2 248 233.8

Erlangs


The Equation behind the Erlang-B Table

Pn(A) =

An

n!

1 + + ... +A1!

An

n!

Pn(A) = Blocking Rate (%)with n trunksas function of traffic A

A = Traffic (Erlangs)n = Number of Trunks

Offered Traffic lost due to blocking

Numberof

Trunks

time

max # oftrunks

average# of busychannelsOffered

Traffic,A

The Erlang-B formula is fairly simple to implement on hand-held programmable calculators, in spreadsheets, or popular programming languages.


Wireless Traffic Variation with Time:A Cellular Example

Peak traffic on cellular systems is usually daytime business-related traffic; on PCS systems, evening traffic becomes much more important and may actually contain the system busy hourEvening taper is more gradual than morning riseWireless systems for PCS and LEC-displacement have peaks of residential traffic during early evening hours, like wirelinesystemsFriday is the busiest day, followed by other weekdays in backwards order, then Saturday, then SundayThere are seasonal and annual variations, as well as long term growth trends

Typical Traffic Distributionon a Cellular System

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

100%

Hour

SUN

MON

TUE

WED

THU

FRI

SAT

Actual traffic from a cellular system in the mid-south USA in summer 1992. This system had 45 cells and served an area of approximately 1,000,000 population.


Busy-Hour

In telephony, it is customary to collect and analyze traffic in hourly blocks, and to track trends over months, quarters, and years

• When making decisions about number of trunks required, we plan the trunks needed to support the busiest hour of a normalday

• Special events (disasters, one-of-a-kind traffic tie-ups, etc.) are not considered in the analysis (unless a marketing-sponsored event)

Which Hour should be used as the Busy-Hour?• Some planners choose one specific hour and use it every day• Some planners choose the busiest hour of each individual day

(“floating busy hour”)• Most common preference is to use “floating (bouncing)” busy

hour determined individually for the total system and for each cell, but to exclude special events and disasters

• In the example just presented, 4 PM was the busy hour every day


Wireline telephone systems have a big advantage in traffic planning.

• They know the addresses where their customers generate the traffic!

Wireless systems have to guess where the customers will be next

• on existing systems, use measured traffic data by sector and cell

– analyze past trends

– compare subscriber forecast

– trend into future, find overloads

• for new systems or new cells, we must use all available clues

11 711

1019

85 7

652

73

8 167 166

99

7

Existing SystemTraffic In Erlangs

Where is the Traffic?


Traffic Clues

Subscriber Profiles: • Busy Hour Usage, Call Attempts, etc.

Market Penetration: • # Subscribers/Market Population• use Sales forecasts, usage forecasts

Population Density• Geographic Distribution

Construction ActivityVehicular Traffic Data

• Vehicle counts on roads• Calculations of density on major

roadways from knowledge of vehicle movement, spacing, market penetration

Land Use Database: Area ProfilesAerial Photographs: Count Vehicles!

22,100

3620 66201230

51104215

920

Vehicular Traffic

Land UseDatabases

Population Density

27 mE/Sub in BH

103,550 Subscribers1,239,171 Market Population

adding 4,350 subs/month

new Shopping Center


Traffic Density Along RoadwaysNumber of lanes and speed are the main variable determining number of vehicles on major highways

• Typical headway ~1.5 seconds• Table and figure show capacity of 1

lane When traffic stops, users generally increase calling activityMultiply number of vehicles by percentage penetration of population to estimate number of subscriber vehicles

Vehicle Speed,MPH

Vehicle Spacing,

feet

Vehicles per mile,per lane

0 20 26410 42 12620 64 8330 86 6145 119 4460 152 35

Vehicle spacing 20 ft. @stopRunning Headway 1.5 seconds

Vehicles per mile

Vehicle Spacing At Common Roadway Speeds0

50 MPH40 MPH30 MPH20 MPH10 MPH0 MPH

100 200 300 400 500 600 700 800 feet


Methodical Estimation of Required Trunks

Modern propagation prediction tools allow experimentation and estimation of traffic levelsEstimate total overall traffic from subscriber forecastsForm traffic density outlines from market knowledge, forecastsOverlay traffic density on land use data; weight by land useAccumulate intercepted traffic into serving cells,

• obtain Erlangs per cell & sector

From tables, determine number of trunks required per cell/sectorModern software tools automate major parts of this process

Cell Grid

Land Use

TrafficDensity 3.5%

27mE


Determining Number of Trunksrequired for a new Growth Cell

When new growth cells are added, they absorb some of the traffic formerly carried by surrounding cellsTwo approaches to estimating traffic on the new cell and on its older neighbors:

• if blocking was not too severe, you can estimate redistributed traffic in the area based on the new division of coverage

• if blocking is severe, (often the case), users will stop trying to call in locations where they’ve learned to expect blocking. Users are self-programming!!

– reapply basic traffic assumptions in the area, like engineering new system, for every nearby cell

– watch out! overall traffic in the area may increase to fill the additional capacity and the new cell itself may block as soon as it goes in service


Dimensioning System Administrative Functions

System administrative functions also require traffic engineering input. While these functions are not necessarily performed by the RF engineer, they require RF awareness and understanding.Paging

• The paging channel has a definite capacity which must not be exceeded. When occupancy approaches this limit, the system mustbe divided into zones, and zone paging implemented.

• Impact of Short Message Service (and others) must be consideredAutonomous Registration

• Autonomous registration involves numerous parameters and the registration attempts must be monitored and controlled to avoid overloading.


Technical Introduction to CDMA

Technical Introduction to CDMA

Course RF100 Chapter 7


Course Outline

Basic CDMA Principles• Coding• Forward and Reverse Channels

CDMA Operational Details• Multiplexing, Forward and Reverse Power Control

CDMA Handset ArchitectureCDMA HandoffsCDMA Network ArchitectureCDMA Messaging and Call FlowOptional TopicsWireless Multiple Access TechnologiesOverview of Current Technologies

• Capacity; CDMA Overlays, Spectrum Clearing


Section A

How Does CDMA Work?Introduction to Basic Principles

How Does CDMA Work?Introduction to Basic Principles


CDMA: Using A New Dimension

All CDMA users occupy the same frequency at the same time! Frequency and time are not used as discriminatorsCDMA operates by using CODING to discriminate between usersCDMA interference comes mainly from nearby usersEach user is a small voice in a roaring crowd -- but with a uniquely recoverable code

CDMA

Figure of Merit: C/I(carrier/interference ratio)

AMPS: +17 dBTDMA: +14 to +17 dB

GSM: +7 to 9 dB.CDMA: -10 to -17 dB.CDMA: Eb/No ~+6 dB.


Two Types of CDMA

There are Two types of CDMA:Frequency-Hopping

• Each user’s narrowband signal hops among discrete frequencies, and the receiver follows in sequence

• Frequency-Hopping Spread Spectrum (FHSS) CDMA is NOTcurrently used in wireless systems, although used by the military

Direct Sequence• narrowband input from a user is

coded (“spread”) by a user-unique broadband code, then transmitted

• broadband signal is received; receiver knows, applies user’s code, recovers users’ data

• Direct Sequence Spread Spectrum(DSSS) CDMA IS the method used in IS-95 commercial systems

User 1

Code 1

Composite

Time Frequency

+=

Direct Sequence CDMA

User 1 User 2 User 3 User 4 Frequency Hopping CDMA

User 3 User 4 User 1 unused User 2

User 1 User 4 User 3 User 2 unused

Frequency

unused User 1 User 2 User 4 User 3


DSSS Spreading: Time-Domain View

At Originating Site:Input A: User’s Data @ 19,200 bits/secondInput B: Walsh Code #23 @ 1.2288 McpsOutput: Spread spectrum signal

At Destination Site:Input A: Received spread spectrum signalInput B: Walsh Code #23 @ 1.2288 McpsOutput: User’s Data @ 19,200 bits/second just as originally sent Drawn to actual scale and time alignment

via air interface

XORExclusive-OR

Gate

1

1

Input A: Received Signal

Input B: Spreading Code

Output: User’s Original Data

Input A: User’s Data

Input B: Spreading Code

Spread Spectrum Signal

XORExclusive-OR

Gate

Originating Site

Destination Site


Spreading from a Frequency-Domain View

Traditional technologies try to squeeze signal into minimum required bandwidthCDMA uses larger bandwidth but uses resulting processing gain to increase capacity

Spread Spectrum Payoff:Processing Gain

Spread SpectrumTRADITIONAL COMMUNICATIONS SYSTEM

SlowInformation

SentTX

SlowInformationRecovered

RX

NarrowbandSignal

SPREAD-SPECTRUM SYSTEM

FastSpreadingSequence

SlowInformation

SentTX

SlowInformationRecovered

RX

FastSpreadingSequence

WidebandSignal


The CDMA Spread Spectrum Payoff:Would you like a lump-sum, or monthly payments?

Shannon's work suggests that a certain bit rate of information deserves a certain bandwidthIf one CDMA user is carried alone by a CDMA signal, the processing gain is large - roughly 21 db for an 8k vocoder.

• Each doubling of the number of users consumes 3 db of the processing gain

• Somewhere above 32 users, the signal-to-noise ratio becomes undesirable and the ultimate capacity of the sector is reached

Practical CDMA systems restrict the number of users per sector to ensure processing gain remains at usable levels

# Users Processing Gain1 21 db

2 18 db

4 15 db

8 12 db

16 9 db

32 6 db

64…..Uh, Regis, can I justtake the money I've already

won, and go home now?

CDMA Spreading Gain

Consider a user with a 9600 bps vocoder talking on a

CDMA signal 1,228,800 hzwide. The processing gain is 1,228,800/9600 = 128, which

is 21 db. What happens if additional users are added?


CDMA Uses Code Channels

A CDMA signal uses many chips to convey just one bit of information Each user has a unique chip pattern, in effect a code channelTo recover a bit, integrate a large number of chips interpreted by the user’s known code patternOther users’ code patterns appear random and integrate in a random self-canceling fashion, don’t disturb the bit decoding decision being made with the proper code pattern

Building aBuilding aCDMA SignalCDMA Signal

Bitsfrom User’s Vocoder

Symbols

Chips

Forward Error Correction

Coding and Spreading


CDMA: The Code “Magic” “behind the Veil”

Σ

if 1 =if 0 =

1

AnalogSummingUsers

QPSK RF

Σ

DemodulatedReceived

CDMA SignalDespreading Sequence(Locally Generated, =0)

matchesopposite

Decision:

Matches!( = 0 )

TimeIntegration

1

Opposite( =1)

+10

-26

Received energy: Correlation

-16

BTS

This figure illustrates the basic technique of CDMA signal generation and recovery.The actual coding process used in IS-95 CDMA includes a few additional layers, as we’ll see in following slides.


Spreading: What we do, we can undo

Sender combines data with a fast spreading sequence, transmits spread data streamReceiver intercepts the stream, uses same spreading sequence to extract original data

ORIGINATING SITE DESTINATION

SpreadingSequence

SpreadingSequence

InputData

RecoveredData

Spread Data Stream


“Shipping and Receiving” via CDMA

Whether in shipping and receiving, or in CDMA, packaging is extremely important!Cargo is placed inside “nested” containers for protection and to allow addressingThe shipper packs in a certain order, and the receiver unpacks in the reverse orderCDMA “containers” are spreading codes

FedE

x

Data Mailer

FedE

x

DataMailer

Shipping Receiving


CDMA’s Nested Spreading Sequences

CDMA combines three different spreading sequences to create unique, robust channelsThe sequences are easy to generate on both sending and receivingends of each link“What we do, we can undo”

SpreadingSequence

ASpreadingSequence

BSpreadingSequence

CSpreadingSequence

CSpreadingSequence

BSpreadingSequence

A

InputDataX

RecoveredDataX

X+A X+A+B X+A+B+C X+A+B X+ASpread-Spectrum Chip Streams

ORIGINATING SITE DESTINATION


One of the CDMA Spreading Sequences:Walsh Codes

64 “Magic” Sequences, each 64 chips longEach Walsh Code is precisely Orthogonal with respect to all other Walsh Codes

• it’s simple to generate the codes, or• they’re small enough to use from ROM

WALSH CODES# ---------------------------------- 64-Chip Sequence ------------------------------------------0 00000000000000000000000000000000000000000000000000000000000000001 01010101010101010101010101010101010101010101010101010101010101012 00110011001100110011001100110011001100110011001100110011001100113 01100110011001100110011001100110011001100110011001100110011001104 00001111000011110000111100001111000011110000111100001111000011115 01011010010110100101101001011010010110100101101001011010010110106 00111100001111000011110000111100001111000011110000111100001111007 01101001011010010110100101101001011010010110100101101001011010018 00000000111111110000000011111111000000001111111100000000111111119 0101010110101010010101011010101001010101101010100101010110101010

10 001100111100110000110011110011000011001111001100001100111100110011 011001101001100101100110100110010110011010011001011001101001100112 000011111111000000001111111100000000111111110000000011111111000013 010110101010010101011010101001010101101010100101010110101010010114 001111001100001100111100110000110011110011000011001111001100001115 011010011001011001101001100101100110100110010110011010011001011016 000000000000000011111111111111110000000000000000111111111111111117 010101010101010110101010101010100101010101010101101010101010101018 001100110011001111001100110011000011001100110011110011001100110019 011001100110011010011001100110010110011001100110100110011001100120 000011110000111111110000111100000000111100001111111100001111000021 010110100101101010100101101001010101101001011010101001011010010122 001111000011110011000011110000110011110000111100110000111100001123 011010010110100110010110100101100110100101101001100101101001011024 000000001111111111111111000000000000000011111111111111110000000025 010101011010101010101010010101010101010110101010101010100101010126 001100111100110011001100001100110011001111001100110011000011001127 011001101001100110011001011001100110011010011001100110010110011028 000011111111000011110000000011110000111111110000111100000000111129 010110101010010110100101010110100101101010100101101001010101101030 001111001100001111000011001111000011110011000011110000110011110031 011010011001011010010110011010010110100110010110100101100110100132 000000000000000000000000000000001111111111111111111111111111111133 010101010101010101010101010101011010101010101010101010101010101034 001100110011001100110011001100111100110011001100110011001100110035 011001100110011001100110011001101001100110011001100110011001100136 000011110000111100001111000011111111000011110000111100001111000037 010110100101101001011010010110101010010110100101101001011010010138 001111000011110000111100001111001100001111000011110000111100001139 011010010110100101101001011010011001011010010110100101101001011040 000000001111111100000000111111111111111100000000111111110000000041 010101011010101001010101101010101010101001010101101010100101010142 001100111100110000110011110011001100110000110011110011000011001143 011001101001100101100110100110011001100101100110100110010110011044 000011111111000000001111111100001111000000001111111100000000111145 010110101010010101011010101001011010010101011010101001010101101046 001111001100001100111100110000111100001100111100110000110011110047 011010011001011001101001100101101001011001101001100101100110100148 000000000000000011111111111111111111111111111111000000000000000049 010101010101010110101010101010101010101010101010010101010101010150 001100110011001111001100110011001100110011001100001100110011001151 011001100110011010011001100110011001100110011001011001100110011052 000011110000111111110000111100001111000011110000000011110000111153 010110100101101010100101101001011010010110100101010110100101101054 001111000011110011000011110000111100001111000011001111000011110055 011010010110100110010110100101101001011010010110011010010110100156 000000001111111111111111000000001111111100000000000000001111111157 010101011010101010101010010101011010101001010101010101011010101058 001100111100110011001100001100111100110000110011001100111100110059 011001101001100110011001011001101001100101100110011001101001100160 000011111111000011110000000011111111000000001111000011111111000061 010110101010010110100101010110101010010101011010010110101010010162 001111001100001111000011001111001100001100111100001111001100001163 0110100110010110100101100110100110010110011010010110100110010110

EXAMPLE:Correlation of Walsh Code #23 with Walsh Code #59

#23 0110100101101001100101101001011001101001011010011001011010010110#59 0110011010011001100110010110011010011001011001100110011010011001Sum 0000111111110000000011111111000011110000000011111111000000001111

Correlation Results: 32 1’s, 32 0’s: Orthogonal!!

Unique Properties:Mutual Orthogonality


Other Sequences: Generation & Properties

Other CDMA sequences are generated in shift registersPlain shift register: no fun, sequence = length of registerTapped shift register generates a wild, self-mutating sequence 2N-1 chips long (N=register length)

• Such sequences match if compared in step (no-brainer, any sequence matches itself)

• Such sequences appear approximately orthogonal if compared with themselves not exactly matched in time

• false correlation typically <2%

A Tapped, Summing Shift Register

Sequence repeats every 2N-1 chips,where N is number of cells in register

An Ordinary Shift Register

Sequence repeats every N chips,where N is number of cells in register

A Special Characteristic of SequencesGenerated in Tapped Shift Registers

Compared In-Step: Matches Itself

Complete Correlation: All 0’sSum:Self, in sync:

Sequence:

Compared Shifted: Little Correlation

Practically Orthogonal: Half 1’s, Half 0’sSum:Self, Shifted:

Sequence:


Original IS-95 CDMA PN Scrambling

Short PN Scrambling

New CDMA2000 1x Complex Scrambling

Another CDMA Spreading Sequence:The Short PN Code, used for Scrambling

The short PN code consists of two PN Sequences, I and Q, each 32,768 chips long

• Generated in similar but differently-tapped 15-bit shift registers

• the two sequences scramble the information on the I and Q phase channels

Figures to the right show how one user’s channel is built at the bTS

IQ

32,768 chips long26-2/3 ms.

(75 repetitions in 2 sec.)Σ

RF: cos ωt

RF: sin ωt

user’ssymbols

QPSK-modulated

RFOutput

Same information duplicatedon I and Q

Walsh

I-sequence

Q-sequence

Σ

RF:cos ωt

sin ωtRF

user’ssymbols

QPS

K

Out

put

Walsh

Seria

l to

Para

llel

Σ

Σ

+

DifferentInformationon I and Q

Complex Scrambling

I-sequence

Q-sequence

-+

+


Generating the PN Long Codeat a desired Timing Offset

Every phone and every BTS channel element has a Long Code generator• Long Code State Register makes long code at system reference timing• A Mask Register holds a user-specific unique pattern of bits

Each clock pulse drives the Long Code State Register to its next state• State register and Mask register contents are added in the Summer• Summer contents are modulo-2 added to produce just a single bit output

The output bits are the Long Code, but shifted to the user’s unique offset

LONG CODE STATE REGISTER dynamic contents, zero timing shift

MASK REGISTER unique steady contents cause unique timing shift

SUMMER holds dynamic modulo-2 sum of LC State and Mask registers

Each clock cycle, all the Summer bits are added into a single-bit modulo-2 sum

The shifted Long Code emerges, chip by chip!

clock


Different Masks ProduceDifferent Long PN Offsets

Ordinary mobiles use their ESNs and the Public Long Code Mask to produce their unique Long Code PN offsets

• main ingredient: mobile ESNMobiles needing greater privacy use the Private Long Code Mask

• instead of 32-bit ESN, the mask value is produced from SSD Word B in a calculation similar to authentication

Each BTS sector has an Access Channel where mobiles transmit for registration and call setup

• the Access Channel Long Code Mask includes Access Channel #, Paging Channel #, BTS ID, and Pilot PN

• The BTS transmits all of these parameters on the Paging Channel

fixed AC# PC# BASE_ID PILOT PN

LONG CODE STATE REGISTER

SUMMING REGISTER


SUMMING REGISTER

fixed PERMUTED ESN


SUMMING REGISTER

calculated PRIVATE LONG CODE MASK

ACCESS CHANNEL (IDLE MODE)USING THE ACCESS CHANNEL LONG CODE MASK

TRAFFIC CHANNEL – NORMALUSING THE PUBLIC LONG CODE MASK

TRAFFIC CHANNEL – PRIVATEUSING THE PRIVATE LONG CODE MASK


Putting it All Together: CDMA Channels

The three spreading codes are used in different ways to create the forward and reverse linksA forward channel exists by having a specific Walsh Code assigned to the user, and a specific PN offset for the sectorA reverse channel exists because the mobile uses a specific offset of the Long PN sequence

BTS

WALSH CODE: Individual UserSHORT PN OFFSET: Sector

LONG CODE OFFSET: individual handset

FORWARD CHANNELS

REVERSE CHANNELS

LONG CODE:Data

Scrambling

WALSH CODES:used as symbolsfor robustness

SHORT PN:used at 0 offset

for tracking

OneSector


Section B

IS-95 CDMA Forward and Reverse Channels

IS-95 CDMA Forward and Reverse Channels


How a BTS Builds the Forward Code Channels

BSC orAccess Manager

BTS (1 sector)

FECWalsh #1

Sync FECWalsh #32

FECWalsh #0

FECWalsh #12

FECWalsh #27

FECWalsh #44

Pilot

Paging

Vocoder

Vocoder

Vocoder

Vocoder

more more

Short PN CodePN Offset 246

Trans-mitter,

Sector X

Switch

more

a Channel Element

A Forward Channel is identified by:its CDMA RF carrier Frequencythe unique Short Code PN Offset of the sectorthe unique Walsh Code of the user

FECWalsh #23

ΣQ

ΣI

x

x+

cos ωt

sin ωt

I Q


Functions of the CDMA Forward Channels

PILOT: WALSH CODE 0• The Pilot is a “structural beacon” which

does not contain a character stream. It is a timing source used in system acquisition and as a measurement device during handoffs

SYNC: WALSH CODE 32• This carries a data stream of system

identification and parameter information used by mobiles during system acquisition

PAGING: WALSH CODES 1 up to 7• There can be from one to seven paging

channels as determined by capacity needs. They carry pages, system parameters information, and call setup orders

TRAFFIC: any remaining WALSH codes• The traffic channels are assigned to

individual users to carry call traffic. All remaining Walsh codes are available, subject to overall capacity limited by noise

Pilot Walsh 0

Walsh 19

Paging Walsh 1Walsh 6

Walsh 11

Walsh 20Sync Walsh 32

Walsh 42

Walsh 37Walsh 41

Walsh 56Walsh 60

Walsh 55


Code Channels in the Reverse DirectionBSC, CBSC,Access

Manager

Switch BTS (1 sector)

Channel Element

Access Channels

Vocoder

Vocoder

Vocoder

Vocoder

more more

Receiver,Sector X

A Reverse Channel is identified by:its CDMA RF carrier Frequencythe unique Long Code PN Offsetof the individual handset

Channel Element

Channel Element

Channel Element

Long Code Gen

Long Code Gen

Long Code Gen

Long Code Gen

more

a Channel Element

LongCodeoffset Long

Codeoffset Long

Codeoffset

LongCodeoffset

LongCodeoffset

LongCodeoffset

Channel Element

Long Code Gen


REG

1-800242

4444

BTS

Although a sector can have up to seven paging channels, and each paging channel can have up to 32 access channels, nearly all systems today use only one paging

channel per sector and only one access channel per paging channel.

Functions of the CDMA Reverse ChannelsThere are two types of CDMA Reverse Channels:

TRAFFIC CHANNELS are used by individual users during their actual calls to transmit traffic to the BTS

• a reverse traffic channel is really just a user-specific public or private Long Code mask

• there are as many reverse Traffic Channels as there are CDMA phones in the world!

ACCESS CHANNELS are used by mobiles not yet in a call to transmit registration requests, call setup requests, page responses, order responses, and other signaling information

• an access channel is really just a public long code offset unique to the BTS sector

• Access channels are paired to Paging Channels. Each paging channel can have up to 32 access channels.


Summing Up Original IS-95 CDMA Channels

Existing IS-95A/JStd-008 CDMA uses the channels above for call setup and traffic channels – all call processing transactions use these channels

• traffic channels are 9600 bps (rate set 1) or 14400 bps (rate set 2)IS-2000 CDMA is backward-compatible with IS-95, but offers additional radio configurations and additional kinds of possible channels

• These additional modes are called Radio Configurations• IS-95 Rate Set 1 and 2 are IS-2000 Radio Configurations 1 & 2

FORWARD CHANNELS

BTS

W0: PILOT

W32: SYNC

W1: PAGING

Wn: TRAFFIC

REVERSE CHANNELS

ACCESS

TRAFFIC


The Channels at Phase One 1xRTT Launch

CDMA2000 1xRTT has a rich variety of traffic channels for voice and fast dateThere are also optional additional control channels for more effective operation

Includes PowerControl Subchannel

Enhanced Access Channel

CommonControl Channel

DedicatedControl Channel

Reverse FundamentalChannel (IS95B comp.)

Reverse Supplemental Channel

Access Channel(IS-95B compatible)

R-TRAFFIC

REVERSE CHANNELS

R-Pilot

R-CCCH

R-DCCH

R-FCH

R-SCH

R-EACH

1

1

0 or 1

0 or 1

0 to 2

R-ACH or

1

BTS

Dedicated Control Channel

Same coding as IS-95B,Backward compatible



Broadcast Channel

Quick Paging Channel

Common Power Control Channel

Common Assignment Channel

Common Control Channels

Forward Traffic Channels

Fundamental Channel

SupplementalChannels IS-95B only

SupplementalChannels RC3,4,5

F-TRAFFIC

FORWARD CHANNELS

F-Pilot

F-Sync

PAGING

F-BCH

F-QPCH

F-CPCCH

F-CACH

F-CCCH

F-DCCH

1

1

1 to 7

0 to 8

0 to 3

0 to 4

0 to 7

0 to 7

0 or 1

F-FCH

F-SCH

F-SCH

1

0 to 7

0 to 2

IS-95B only

Users:Users:0 to many0 to many

How manyPossible:

See Course 332 for more details.


Basic CDMA Network Architecture

Access Manageror (C)BSC

Switch BTS

Ch. Card ACC

Σα

Σβ

Σχ

TFU1

GPSRBSM

CDSU

CDSU

SBSVocodersSelectors

CDSU

CDSU

CDSU

CDSU

CDSU

CMSLM

LPP LPPENET

DTCs

DMS-BUS

TxcvrA

TxcvrB

TxcvrC

RFFEA

RFFEB

RFFEC

TFU

GPSR

GPS GPS

IOC

PSTN

CDSU DISCOCDSU

DISCO 1

DISCO 2

DS0 in T1Packets

ChipsRFChannel

ElementVocoder


Forward Traffic Channel: Generation Details from IS-95

Walshfunction

PowerControl

Bit

I PN

9600 bps4800 bps2400 bps1200 bps

or14400 bps7200 bps3600 bps1800 bps

(From Vocoder)

ConvolutionalEncoding and

Repetition SymbolPuncturing(13 kb only)

1.2288 McpsLong PN Code

Generation

19.2ksps

800 Hz

R = 1/2

Q PNDecimator Decimator

User AddressMask

(ESN-based)

19.2ksps

1.2288 Mcps

Scrambling

bits symbols chips

19.2ksps

28.8ksps

CHANNEL ELEMENT

MUX

BlockInterleaving


Reverse Traffic Channel: Generation Details from IS-95

9600 bps4800 bps2400 bps1200 bps

or 14400 bps7200 bps3600 bps1800 bps

28.8ksps

R = 1/3

1.2288McpsUser Address

MaskLong

PN CodeGenerator

28.8ksps Orthogonal

ModulationData Burst

Randomizer

307.2kcps

1.2288Mcps

Q PN(no offset)

I PN(no offset)

D

1/2 PNChipDelay

DirectSequenceSpreading

R = 1/2

ConvolutionalEncoder &Repetition

BlockInterleaver


Section C

IS-95 Operational DetailsVocoding, Multiplexing, Power Control

IS-95 Operational DetailsVocoding, Multiplexing, Power Control


Variable Rate Vocoding & Multiplexing

Vocoders compress speech, reduce bit rate, greatly increasing capacityCDMA uses a superior Variable Rate Vocoder

• full rate during speech• low rates in speech pauses• increased capacity• more natural sound

Voice, signaling, and user secondary data may be mixed in CDMA frames

DSP QCELP VOCODER

Codebook

PitchFilter

FormantFilter

Coded Result Feed-back

20ms Sample

Frame Sizesbits

Full Rate Frame1/2 Rate Frame1/4 Rt.1/824/36

48/7296/144

192/288

Frame Contents: can be a mixture ofPrimaryTraffic(Voice or

data)

Signaling(System

Messaging)

Secondary(On-Air

activation, etc)


How Power Control Works

800 Power Control Bits per second!

TX RF Digital

BTSBSC

Eb/NoSetpoint

Bad FER?Raise Setpoint

Stronger thansetpoint?

OpenLoop Closed

LoopReverse Link

REVERSE LINK POWER ADJUSTMENT

RX RF Digital

IS-95, 1xRTTALL SAME METHOD

TXPO = -(RXdbm) -C + TXGA

MOBILE

FEI Bits Mark Bad Frames Received

BSCSyncPilot

Paging

Short PN

Trans-mitter,

Sector XΣ I QUser 1User 2User 3

Voc-oder

BTS (1 sector)

Forward Link

FORWARD LINK POWER ADJUSTMENT

Selec-tor

MOBILE

Eb/NoSetpoint

FEI Bits

Bad FrameCounterPMRM POWER MEAS. REPORT MSG “2 bad in last 4, Help!!”

POWER CONTROL BITSTREAM RIDING ON MOBILE PILOT

DGU

IS-95 RS1Method

IS-95 RS2Method1xRTTMethod


Details of Reverse Link Power Control

TXPO Handset Transmit Power• Actual RF power output of the

handset transmitter, including combined effects of open loop power control from receiver AGC and closed loop power control by BTS

• can’t exceed handset’s maximum (typ. +23 dBm)

TXGA Transmit Gain Adjust• Sum of all closed-loop

power control commands from the BTS since the beginning of this call

TXPODUP x ≈ IF

LNA

Subscriber Handset

R

R

R

S

Rake

Σ ViterbiDecoder

Vocoder

∼

FECOrthMod

Long PN

xx

xIF Mod

I

Q

x ~LO Open Loop

LO

Closed Loop Pwr Ctrl

IF

Receiver>>

<<Transmitter

PA

BTS

Typical TXPO:+23 dBm in a coverage hole0 dBm near middle of cell-50 dBm up close to BTS

0 dB

-10 dB

-20 dB

Typical Transmit Gain Adjust

Time, Seconds

TXPO = -(RXdbm) -C + TXGAC = +73 for 8K vocoder systems= +76 for 13K vocoder systems


Section D

A Quick Introduction to CDMA Messages and Call Processing

A Quick Introduction to CDMA Messages and Call Processing


Messages in CDMA

In CDMA, most call processing events are driven by messagesSome CDMA channels exist for the sole purpose of carrying messages; they never carry user’s voice traffic

• Sync Channel (a forward channel)• Paging Channel (a forward channel)• Access Channel (a reverse channel)• On these channels, there are only messages, continuously all

of the timeSome CDMA channels exist just to carry user traffic

• Forward Traffic Channel• Reverse Traffic Channel• On these channels, most of the time is filled with traffic and

messages are sent only when there is something to doAll CDMA messages have very similar structure, regardless of thechannel on which they are sent


How CDMA Messages are Sent

CDMA messages on both forward and reverse traffic channels are normally sent via dim-and-burstMessages include many fields of binary dataThe first byte of each message identifies message type: this allows the recipient to parse the contentsTo ensure no messages are missed, all CDMA messages bear serial numbers and important messages contain a bit requesting acknowledgmentMessages not promptly acknowledged are retransmitted several times. If not acknowledged, the sender may release the callField data processing tools capture and display the messages for study

MSG_TYPE (‘00000110’)

ACK_SEQ

MSG_SEQ

ACK_REQ

ENCRYPTION

ERRORS_DETECTED

POWER_MEAS_FRAMES

LAST_HDM_SEQ

NUM_PILOTS

PILOT_STRENGTH

RESERVED (‘0’s)

8

3

3

1

2

5

10

2

4

6

0-7

NUM_PILOTS occurrences of this field:

Field Length (in bits)

EXAMPLE: A POWER MEASUREMENT

REPORT MESSAGE

t


Message Vocabulary: Acquisition & Idle StatesSync Channel

Sync Channel Msg

Pilot Channel

No Messages

Paging Channel

Access Parameters Msg

System Parameters Msg

CDMA Channel List Msg

Extended SystemParameters Msg

Extended NeighborList Msg

Global ServiceRedirection Msg

Order Msg•Base Station Acknowledgment

•Lock until Power-Cycled• Maintenance required

many others…..

AuthenticationChallenge Msg

Status Request Msg

Feature Notification Msg

TMSI Assignment Msg

Channel AssignmentMsg

SSD Update Msg

Service Redirection Msg

General Page Msg

Null Msg Data Burst Msg

Access Channel

Registration Msg

Order Msg• Mobile Station Acknowldgment• Long Code Transition Request

• SSD Update Confirmationmany others…..

Origination Msg

Page Response Msg

Authentication ChallengeResponse Msg

Status Response Msg

TMSI AssignmentCompletion Message

Data Burst Msg

BTS


Message Vocabulary: Conversation State

Reverse Traffic Channel

Order Message• Mobile Sta. Acknowledgment

•Long Code Transition Request

• SSD Update Confirmation• Connect

Authentication ChallengeResponse Msg

Flash WithInformation Msg

Data Burst Message

Pilot StrengthMeasurement Msg

Power MeasurementReport Msg

Send Burst DTMF Msg

OriginationContinuation Msg

Handoff Completion Msg

Parameters ResponseMessage

Service Request Msg

Service Response Msg

Service ConnectCompletion Message

Service Option ControlMessage

Status Response Msg

TMSI AssignmentCompletion Message

Forward Traffic ChannelOrder Msg

• Base Station Acknowledgment • Base Station Challenge

Confirmation• Message Encryption Mode

AuthenticationChallenge Msg

Alert WithInformation Msg

Data Burst Msg

Analog HandoffDirection Msg

In-Traffic SystemParameters Msg

Neighbor ListUpdate Msg

Send Burst DTMF Msg

Power ControlParameters Msg.

Retrieve Parameters Msg

Set Parameters Msg

SSD Update Msg

Flash WithInformation Msg

Mobile StationRegistered Msg

Status Request Msg

Extended HandoffDirection Msg

Service Request Msg

Service Response Msg

Service Connect Msg

Service OptionControl Msg

TMSI Assignment Msg


Section E

CDMA Handset ArchitectureCDMA Handoffs

CDMA Handset ArchitectureCDMA Handoffs


What’s In a Handset? How does it work?

ReceiverRF SectionIF, Detector

TransmitterRF Section

Vocoder

Digital Rake Receiver

Traffic CorrelatorPN xxx Walsh xx ΣTraffic CorrelatorPN xxx Walsh xxTraffic CorrelatorPN xxx Walsh xx

Pilot SearcherPN xxx Walsh 0

Viterbi Decoder,Convl. Decoder,Demultiplexer

CPUDuplexer

TransmitterDigital Section

Long Code Gen.

Open Loop Transmit Gain Adjust

Messages

Messages

Audio

Audio

Packets

Symbols

SymbolsChips

RF

RF

AGC

time-

alig

ned

su

mm

ing

pow

er

Traffic CorrelatorPN xxx Walsh xx

∆tcont

rol

bits


The Rake Receiver

Every frame, handset uses combined outputs of the three traffic correlators (“rake fingers”)Each finger can independently recover a particular PN offset andWalsh codeFingers can be targeted on delayed multipath reflections, or even on different BTSsSearcher continuously checks pilots

Handset Rake Receiver

RF

PN Walsh

PN Walsh

PN Walsh

SearcherPN W=0

ΣVoice,Data,

Messages

Pilot Ec/Io

BTS

BTS


CDMA Soft Handoff Mechanics

CDMA soft handoff is driven by the handset• Handset continuously checks available pilots• Handset tells system pilots it currently sees• System assigns sectors (up to 6 max.), tells handset• Handset assigns its fingers accordingly• All messages sent by dim-and-burst, no muting!

Each end of the link chooses what works best, on a frame-by-frame basis!

• Users are totally unaware of handoff


RFPN Walsh

PN Walsh

PN Walsh

SearcherPN W=0

ΣVoice,Data,

Messages

Pilot Ec/Io

BTS

BSCSwitch

BTS

Sel.


The Complete Rules of Soft Handoff

The Handset considers pilots in sets• Active: pilots of sectors actually in use• Candidates: pilots mobile requested, but

not yet set up & transmitting by system• Neighbors: pilots told to mobile by system,

as nearby sectors to check• Remaining: any pilots used by system but

not already in the other sets (div. by PILOT_INC)

Handset sends Pilot Strength Measurement Message to the system whenever:

• It notices a pilot in neighbor or remaining set exceeds T_ADD

• An active set pilot drops below T_DROP for T_TDROP time

• A candidate pilot exceeds an active by T_COMP

The System may set up all requested handoffs, or it may apply special manufacturer-specific screening criteria and only authorize some

65

Remaining

ActiveCandidateNeighbor 20

PILOT SETS

Min. M

embers

Req’d. B

y Std.

T_COMPT_ADD T_DROPT_TDROP

HANDOFF PARAMETERS

Exercise: How does a pilot in one set migrate into another set, for all cases? Identify the trigger, and the messages involved.


Softer Handoff

Each BTS sector has unique PN offset & pilot Handset will ask for whatever pilots it wantsIf multiple sectors of one BTS simultaneously serve a handset, this is called Softer HandoffHandset can’t tell the difference, but softer handoff occurs in BTS in a single channel elementHandset can even use combination soft-softer handoff on multiple BTS & sectors


RFPN Walsh

PN Walsh

PN Walsh

SearcherPN W=0

ΣVoice,Data,

Messages

Pilot Ec/Io

BTS

BSCSwitchSel.


What is Ec/Io?

Ec/Io• “cleanness” of the pilot

– foretells the readability of the associated traffic channels

• guides soft handoff decisions• digitally derived: ratio of good

to bad energy seen by the search correlator at the desired PN offset

• Never appears higher than Pilot’s percentage of serving cell’s transmitted energy

• Can be degraded by strong RF from other cells, sectors

– Imperfect orthogonality, other PNs are ~-20 dB.

• Can be degraded by noise

Ec/Io dB

-25 -15 -10 0

Ec

Io

Energy of desired pilot alone

Total energy received


CDMA Call ProcessingCDMA Call Processing

Section F


Let’s Acquire the System!Let’s Acquire the System!

Example 1


Find a Frequency with a CDMA RF Signal

Mobile scans forward link frequencies:(Cellular or PCS, depending on model)

History ListPreferred Roaming List

until a CDMA signal is found.NO CDMA?! Go to AMPS,

or to a power-saving standby mode

HISTORYLIST/MRU

Last-used:FreqFreqFreqFreqFreqetc.

FREQUENCY LISTS:PREFERREDROAMINGLIST/PRL

System1System2System3System4System5etc.

Forward Link Frequencies(Base Station Transmit)

A D B E F C unlic.data

unlic.voice A D B E F C

1850MHz. 1910MHz. 1990 MHz.1930MHz.

1900 MHz. PCS Spectrum

824 MHz. 835 845 870 880 894

869

849

846.5825

890

891.5

Paging, ESMR, etc.A B A B

800 MHz. Cellular Spectrum

Reverse Link Frequencies(Mobile Transmit)


How Idle Mobiles Choose CDMA CarriersAt turnon, Idle mobiles use proprietary algorithms to find the initial CDMA carrier intended for them to useWithin that CDMA signal, two types of paging channel messages could cause the idle mobile to choose another frequency: CDMA Channel List Message and GSRM

Go to last frequency from MRU

Strongest PN, read

SyncIs SID

permitted?

No Signal

Preferred Only Bit 0

Denied SIDRead

Paging Channel

CDMA Ch List Message

Global Svc Redir Msg

HASH using IMSI

my ACCOLC? redirect

Is better SID

available?

PRLMRU Acq IdxYes

NoF1F2F3

to Analog

to another CDMA frequency or system

ConfigMessages:

remain

Steps from the CDMA standards

Steps from proprietary

SDAs

Proprietary SDA

databases

Start

LegendTypical MobileSystem Determination Algorithm


4. Is This the Right System to Use?Scan the PRL for Anything Better

It’s not enough just to find a CDMA signal

• We want the CDMA signal of our own system or a favorite roaming partner

Phones look in the PRL to see if there is a more preferred signal than whatever they find first

• They check frequencies in the Acquisition Table until they find the best system, or look down the list level by level

ROAMING LIST

Roaming List Type: IS-683APreferred Only: FALSEDefault Roaming Indicator: 0Preferred List ID: 10018

ACQUISITION TABLE

INDEX ACQ TYPE CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8 CH90 6 500 425 825 575 850 325 6251 6 575 625 500 4252 6 50 100 75 475 825 850 175 2503 6 25 200 350 375 725 50 475 175 2504 1 Both5 6 450 500 350 575 6506 6 675 500 600 575 4757 6 250 50 1758 6 550 375 425 6259 6 75 50 175 250

10 6 200 250 175 5011 6 425 500 575 25 325 65012 6 500 575 475 25 67513 6 500 625 350 50 375 775 575 725 42514 6 650 500 675 25 75 425 50 57515 6 25 50 375 350 250 17516 6 425 550 225 725 750 77517 6 200 50 175 375 25018 6 825 850 92519 6 350 325 375 675 25 1175 725 600 10020 6 750 725 77521 6 325 725 350 750 375 775 425 575 62522 6 1150 117523 6 350 875 325 375 117524 6 25 1175 825 200 75 175 25025 6 50 200 25 100 250 7526 6 500 1075 850 82527 1 A28 1 B29 5 A30 5 B31 5 C32 5 D33 5 E34 5 F35 4 A36 4 B37 4 Both38 6 350 82539 6 25 10040 6 675 600 750 850 1175 77541 6 85042 6 65043 6 450 47544 6 325 350 375 1025 1050 107545 6 150 475 625 67546 6 1025 1050 1075

SYSTEM TABLE

INDEX SID NIDNEG/ PREF GEO PRI

ACQ INDEX

ROAM IND

296 4144 65535 Pref NEW SAME 13 1297 4812 65535 Pref SAME MORE 21 1298 205 65535 Pref SAME SAME 4 0299 208 65535 Pref SAME MORE 37 0300 208 65535 Pref SAME SAME 4 0301 342 65535 Pref SAME MORE 37 0302 342 65535 Pref SAME SAME 4 0303 478 65535 Pref SAME SAME 4 0304 1038 65535 Pref SAME SAME 4 0305 1050 65535 Pref SAME SAME 4 0306 1058 65535 Pref SAME SAME 4 0307 1375 65535 Pref SAME SAME 4 0308 1385 65535 Pref SAME MORE 4 0309 143 65535 Pref SAME MORE 37 0310 143 65535 Pref SAME MORE 4 0311 4103 65535 Pref NEW SAME 3 1312 4157 65535 Pref SAME MORE 2 1313 312 65535 Pref SAME SAME 4 0314 444 65535 Pref SAME MORE 37 0315 444 65535 Pref SAME SAME 4 0316 1008 65535 Pref SAME SAME 4 0317 1012 65535 Pref SAME SAME 4 0318 1014 65535 Pref SAME SAME 4 0319 1688 65535 Pref SAME MORE 4 0320 113 65535 Pref SAME MORE 37 0321 113 65535 Pref SAME SAME 4 0322 179 65535 Pref SAME MORE 37 0323 179 65535 Pref SAME SAME 4 0324 465 65535 Pref SAME SAME 4 0325 2119 65535 Pref SAME MORE 4 0326 2094 65535 Pref SAME MORE 4 0327 1005 65535 Pref SAME SAME 4 0328 1013 65535 Pref SAME SAME 4 0

a G

EO G

RO

UP

a G

EO G

RO

UP

Clim

b!

PRL: Preferred Roaming ListProgrammed into each phone by the system

operator; can be updated over the air.


Find Strongest Pilot, Read Sync Channel

Rake Fingers

Reference PN

Active Pilot

Ec/

Io

00

32K512

ChipsPN

1. Pilot Searcher Scans the Entire Range of PNs

All PN Offsets0

-20

98/05/24 23:14:09.817 [SCH] MSG_LENGTH = 208 bitsMSG_TYPE = Sync Channel MessageP_REV = 3MIN_P_REV = 2SID = 179NID = 0PILOT_PN = 168Offset IndexLC_STATE = 0x0348D60E013SYS_TIME = 98/05/24 23:14:10.160LP_SEC = 12LTM_OFF = -300 minutesDAYLT = 0PRAT = 9600 bpsRESERVED = 1

2. Put Rake finger(s) on strongest available PN, decode Walsh 32, and read Sync Channel Message

SYNC CHANNEL MESSAGE


RF≈ x ≈

LO Srch PN??? W0

F1 PN168 W32F2 PN168 W32F3 PN168 W32


The Configuration Messages

After reading the Sync Channel, the mobile is now capable of reading the Paging Channel, which it now monitors constantlyBefore it is allowed to transmit or operate on this system, the mobile must collect a complete set of configuration messages Collection is a short process -- all configuration messages are repeated on the paging channel every 1.28 secondsThe configuration messages contain sequence numbers so the mobile can recognize if any of the messages have been freshly updated as it continues to monitor the paging channel

• Access parameters message sequence number• Configuration message sequence number• If a mobile notices a changed sequence number, or if 600

seconds passes since the last time these messages were read, the mobile reads all of them again


Go to Paging Channel, Get Configured

Rake Fingers

Reference PN

Active Pilot

Ec/

Io

00

32K512

ChipsPN

All PN Offsets0

-20

Keep Rake finger(s) on strongest available PN, decode Walsh 1,

and monitor the Paging Channel

Read the Configuration Messages

Access Parameters Msg

System Parameters Msg

CDMA Channel List Msg

Extended SystemParameters Msg (*opt.)

(Extended*) NeighborList Msg

Global ServiceRedirection Msg (*opt.)

Now we’re ready to operate!!


RF≈ x ≈

LO Srch PN??? W0

F1 PN168 W01F2 PN168 W01F3 PN168 W01


Two Very Important Configuration Messages

98/05/24 23:14:10.427 [PCH] MSG_LENGTH = 184 bitsMSG_TYPE = Access Parameters MessagePILOT_PN = 168 Offset IndexACC_MSG_SEQ = 27ACC_CHAN = 1 channelNOM_PWR = 0 dB INIT_PWR = 0 dB PWR_STEP = 4 dBNUM_STEP = 5 Access Probes MaximumMAX_CAP_SZ = 4 Access Channel Frames MaximumPAM_SZ = 3 Access Channel FramesPersist Val for Acc Overload Classes 0-9 = 0Persist Val for Acc Overload Class 10 = 0Persist Val for Acc Overload Class 11 = 0Persist Val for Acc Overload Class 12 = 0Persist Val for Acc Overload Class 13 = 0Persist Val for Acc Overload Class 14 = 0Persist Val for Acc Overload Class 15 = 0Persistance Modifier for Msg Tx = 1 Persistance Modifier for Reg = 1 Probe Randomization = 15 PN chipsAcknowledgement Timeout = 320 msProbe Backoff Range = 4 Slots MaximumProbe Sequence Backoff Range = 4 Slots Max.Max # Probe Seq for Requests = 2 SequencesMax # Probe Seq for Responses = 2 SequencesAuthentication Mode = 1Random Challenge Value = Field OmittedReserved Bits = 99

ACCESS PARAMETERS MESSAGE98/05/24 23:14:11.126 [PCH] MSG_LENGTH = 264 bitsMSG_TYPE = System Parameters MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0SID = 179 NID = 0REG_ZONE = 0 TOTAL_ZONES = 0 ZONE_TIMER = 60 minMULT_SIDS = 0 MULT_NID = 0 BASE_ID = 8710BASE_CLASS = Public MacrocellularPAGE_CHAN = 1 channelMAX_SLOT_CYCLE_INDEX = 0HOME_REG = 0 FOR_SID_REG = 0 FOR_NID_REG = 1POWER_UP_REG = 0 POWER_DOWN_REG = 0PARAMETER_REG = 1 REG_PRD = 0.08 secBASE_LAT = 00D00'00.00N BASE_LONG = 000D00'00.00EREG_DIST = 0SRCH_WIN_A = 40 PN chipsSRCH_WIN_N = 80 PN chipsSRCH_WIN_R = 4 PN chipsNGHBR_MAX_AGE = 0PWR_REP_THRESH = 2 framesPWR_REP_FRAMES = 56 framesPWR_THRESH_ENABLE = 1PWR_PERIOD_ENABLE = 0PWR_REP_DELAY = 20 framesRESCAN = 0T_ADD = -13.0 Db T_DROP = -15.0 dB T_COMP = 2.5 dBT_TDROP = 4 secEXT_SYS_PARAMETER = 1RESERVED = 0GLOBAL_REDIRECT = 0

SYSTEM PARAMETERS MESSAGE


Four Additional Configuration Messages

98/05/24 23:14:10.946 [PCH] MSG_LENGTH = 104 bitsMSG_TYPE = Extended System Parameters MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0 RESERVED = 0PREF_MSID_TYPE = IMSI and ESNMCC = 000 IMSI_11_12 = 00 RESERVED_LEN = 8 bitsRESERVED_OCTETS = 0x00 BCAST_INDEX = 0RESERVED = 0

EXTENDED SYSTEM PARAMETERS

98/05/17 24:21.566 Paging Channel: Global Service RedirectionPILOT_PN: 168, MSG_TYPE: 96, CONFIG_MSG_SEQ: 0Redirected access overload classes: 0, 1 , RETURN_IF_FAIL: 0, DELETE_TMSI: 0, Redirection to an analog system: EXPECTED_SID = 0 Do not ignore CDMA Available indicator on the redirected analog systemAttempt service on either System A or B with the custom system selection process

GLOBAL SERVICE REDIRECTION

98/05/24 23:14:11.486 [PCH]MSG_LENGTH = 216 bitsMSG_TYPE = Neighbor List MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0PILOT_INC = 4 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 220 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 52 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 500 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 8 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 176 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 304 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 136 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 384 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 216 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 68 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 328 Offset IndexNGHBR_CONFIG = 0 NGHBR_PN = 112 Offset IndexRESERVED = 0

NEIGHBOR LIST

98/05/24 23:14:10.786 [PCH]MSG_LENGTH = 72 bitsMSG_TYPE = CDMA Channel List MessagePILOT_PN = 168 Offset IndexCONFIG_MSG_SEQ = 0CDMA_FREQ = 283RESERVED = Field Omitted

CDMA CHANNEL LIST MESSAGE


Let’s do an Idle Mode Handoff!

Let’s do an Idle Mode Handoff!

Example 2


Idle Mode Handoff

An idle mobile always demodulates the best available signal• In idle mode, it isn’t possible to do soft handoff and listen to

multiple sectors or base stations at the same time -- the paging channel information stream is different on each sector, not synchronous -- just like ABC, NBC, CBS, and CNN TV news programs aren’t in word-sync for simultaneous viewing

• Since a mobile can’t combine signals, the mobile must switch quickly, always enjoying the best available signal

The mobile’s pilot searcher is constantly checking neighbor pilotsIf the searcher notices a better signal, the mobile continues on the current paging channel until the end of the current superframe, then instantly switches to the paging channel of the new signal

• The system doesn’t know the mobile did this! (Does NBC’s Tom Brokaw know you just switched your TV to CNN?)

On the new paging channel, if the mobile learns that registration is required, it re-registers on the new sector


Idle Mode on the Paging Channel: Meet the Neighbors, track the Strongest Pilot

Ec/

IoAll PN Offsets

00

32K512

ChipsPN

0

-20

Neighbor Set

The phone’s pilot searcher constantly checks the pilots listed in the Neighbor List Message

If the searcher ever notices a neighbor pilot substantially stronger than the current reference pilot, it becomes the new reference pilot

and the phone switches over to its paging channel on the next superframe.This is called an idle mode handoff.

Rake Fingers

Reference PN

Active Pilot

SRCH_WIN_A

SRCH_WIN_N

Mobile Rake RX

Srch PN??? W0

F1 PN168 W01F2 PN168 W01F3 PN168 W01


Phone Operation on the Access Channel

A sector’s Paging Channel announces 1 (typ) to 32 (max) Access Channels: PN Long Code offsets for mobiles to use if accessing the system.

• For mobiles sending Registration, Origination, Page Responses

• Base Station always listening!On the access channel, phones are not yet under BTS closed-loop power control!Phones access the BTS by “probing” at power levels determined by receive power and an open loop formula

• If “probe” not acknowledged by BTS within ACC_TMO (~400 mS.), phone will wait a random time (~200 mS) then probe again, stronger by PI db.

• There can be 15 max. (typ. 5) probes in a sequence and 15 max. (typ. 2) sequences in an access attempt

• most attempts succeed on first probe!The Access Parameters message on the paging channel announces values of all related parameters

ACCESS

RV TFC

BTS

Channel Assnmt. Msg.

Origination Msg

Base Sta. Acknlgmt. Order

TFC frames of 000s

TFC preamble of 000s


Mobile Sta. Ackngmt. Order

Service Connect Msg.

Svc. Connect Complete Msg


Call is Established!

MSProbing

PAGING

FW TFC

PAGING

RV TFC

FW FC

RV TFC

FW TFC

FW TFC

A Successful Access Attempt

a Probe Sequencean Access Attempt

Success!

an Access Probe


Let’s Register!Let’s Register!

Example 3


Registration

Registration is the process by which an idle mobile lets the system know it’s awake and available for incoming calls

• this allows the system to inform the mobile’s home switch of the mobile’s current location, so that incoming calls can be delivered

• registration also allows the system to intelligently page the mobile only in the area where the mobile is currently located, thereby eliminating useless congestion on the paging channels in other areas of the system

There are many different conditions that could trigger an obligation for the mobile to register

• there are flags in the System Parameters Message which tell the mobile when it must register on the current system


An Actual Registration

16:18:27.144 Access Channel: Registration ACK_SEQ: 7 MSG_SEQ: 1 ACK_REQ: 1 VALID_ACK: 0ACK_TYPE: 0MSID_TYPE: 3, ESN: [0x 01 99 0d fc]MFR 1, Reserved 38, Serial Number 69116,IMSI: (Class: 0, Class_0_type: 1) [0x 01 8d 31 74 29 36]00-416-575-0421AUTH_MODE: 0REG_TYPE: Timer-basedSLOT_CYCLE_INDEX: 2MOB_P_REV: 1EXT_SCM: 1SLOTTED_MODE: 1MOB_TERM: 1

REGISTRATION MESSAGE

18:26.826 [PCH] System Parameters Message Pilot_PN: 32CONFIG_MSG_SEQ: 14 SID: 16420 NID: 0,REG_ZONE: 0 TOTAL_ZONES: 0 Zone timer length (min): 1MULT_SIDS: 0 MULT_NIDS: 0 BASE_ID: 1618 BASE_CLASS: ReservedPAG_CHAN: 1 MAX_SLOT_CYCLE_INDEX: 2 HOME_REG: 1 FOR_SID_REG: 1 FOR_NID_REG: 1, POWER_UP_REG: 1 POWER_DOWN_REG: 1 PARAMETER_REG: 1 Registration period (sec): 54 Base station 0°00´00.00¨ Lon., 0°00´00.00° Lat. REG_DIST: 0SRCH_WIN_A (PN chips): 28 SRCH_WIN_N (PN chips): 100, SRCH_WIN_R (PN chips): 130 NGHBR_MAX_AGE: 2PWR_REP_THRESH: 2 PWR_REP_FRAMES (frames): 15PWR_THRESH_ENABLE: 1 PWR_PERIOD_ENABLE: 0, PWR_REP_DELAY: 1 (4 frames) RESCAN: 0, T_ADD: -14.0dB T_DROP: -16.0dB T_COMP: 2.5dB, T_TDROP: 4s EXT_SYS_PARAMETER: 1 EXT_NGHBR_LIST: 1 GLOBAL_REDIRECT: 0

SYSTEM PARAMETERS MESSAGE

16:18:27.506 Paging Channel: Order ACK_SEQ: 1 MSG_SEQ: 0 ACK_REQ: 0 VALID_ACK: 1 MSID_TYPE: 2 IMSI: (Class: 0, Class_0_type: 3) [0x 02 47 8d 31 74 29 36] (302) 00-416-575-0421Order type: Base Station Acknowledgement Order

BASE STATION ACKNOWLEDGMENT

The System Parameters Message tells all mobiles when they should register.

This mobile notices that it is obligated to register, so it transmits a Registration

Message.

The base station confirms that the mobile’s registration message was received. We’re officially registered!


Let’s Receive an incoming Call!

Let’s Receive an incoming Call!

Example 4


Receiving an Incoming Call

All idle mobiles monitor the paging channel to receive incoming calls.When an incoming call appears, the paging channel notifies the mobile in a General Page Message.A mobile which has been paged sends a Page Response Message on the access channel.The system sets up a traffic channel for the call, then notifies the mobile to use it with a Channel Assignment Message.The mobile and the base station notice each other’s traffic channel signals and confirm their presence by exchanging acknowledgment messages.The base station and the mobile negotiate what type of call this will be -- I.e., 13k voice, etc.The mobile is told to ring and given a “calling line ID” to display.When the human user presses the send button, the audio path is completed and the call proceeds.


An Actual Page and Page Response

98/05/24 23:14:46.425 [ACH] Page Response MessageMSG_LENGTH = 216 bitsMSG_TYPE = Page Response MessageACK_SEQ = 1 MSG_SEQ = 2 ACK_REQ = 1VALID_ACK = 1 ACK_TYPE = 2MSID_TYPE = IMSI and ESN MSID_LEN = 9 octetsESN = 0xD30E415C IMSI_CLASS = 0IMSI_CLASS_0_TYPE = 0 RESERVED = 0IMSI_S = 6153300644AUTH_MODE = 1AUTHR = 0x307B5 RANDC = 0xC6 COUNT = 0MOB_TERM = 1 SLOT_CYCLE_INDEX = 0MOB_P_REV = 3 SCM = 106REQUEST_MODE = Either Wide Analog or CDMA OnlySERVICE_OPTION = 32768 PM = 0NAR_AN_CAP = 0 RESERVED = 0

PAGE RESPONSE MESSAGE

98/05/24 23:14:46.127 [PCH] General Page MessageMSG_LENGTH = 128 bits MSG_TYPE = General Page MessageCONFIG_MSG_SEQ = 1 ACC_MSG_SEQ = 20CLASS_0_DONE = 1CLASS_1_DONE = 1 RESERVED = 0BROADCAST_DONE = 1 RESERVED = 0ADD_LENGTH = 0 bits ADD_PFIELD = Field OmittedPAGE_CLASS = 0 PAGE_SUBCLASS = 0MSG_SEQ = 1 IMSI_S = 6153300644SPECIAL_SERVICE = 1SERVICE_OPTION = 32768RESERVED = Field Omitted

GENERAL PAGE MESSAGE

98/05/24 23:14:46.768 [PCH] Order MessageMSG_LENGTH = 112 bitsMSG_TYPE = Order MessageACK_SEQ = 2 MSG_SEQ = 0 ACK_REQ = 0VALID_ACK = 1 ADDR_TYPE = IMSI ADDR_LEN = 40 bitsIMSI_CLASS = 0 IMSI_CLASS_0_TYPE = 0 RESERVED = 0 IMSI_S = 6153300644ORDER = Base Station Acknowledgement OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field Omitted RESERVED = 0


The system pages the mobile, 615-330-0644.

The base station confirms that the mobile’s page response was received. Now the

mobile is waiting for channel assignment,expecting a response within 12 seconds.

The mobile responds to the page.


Channel Assignment and Traffic Channel Confirmation

18:14:47.598 Reverse Traffic Channel: Order ACK_SEQ: 0 MSG_SEQ: 0 ACK_REQ: 0 ENCRYPTION: 0Mobile Station Acknowledgement Order

MOBILE STATION ACKNOWLEDGMENT

18:14:47.027 Paging Channel: Channel Assignment ACK_SEQ: 2 MSG_SEQ: 1 ACK_REQ: 0 VALID_ACK: 1MSID_TYPE: 2 IMSI: (Class: 0, Class_0_type: 0) [0x 01 f8 39 6a 15] 615-330-0644 ASSIGN_MODE: Traffic Channel AssignmentADD_RECORD_LEN: 5 FREQ_INCL: 1 GRANTED_MODE: 2CODE_CHAN: 43 FRAME_OFFSET: 2ENCRYPT_MODE: Encryption disabledBAND_CLASS: 800 MHz cellular bandCDMA_FREQ: 283

CHANNEL ASSIGNMENT MESSAGE

18:14:47.581 Forward Traffic Channel: Order ACK_SEQ: 7 MSG_SEQ: 0 ACK_REQ: 1 ENCRYPTION: 0 USE_TIME: 0 ACTION_TIME: 0Base Station Acknowledgement Order


Only about 400 ms. after the base station acknowledgment order, the mobile receives

the channel assignment message.

The base station is already sending blank frames on

the forward channel,using the assigned Walsh code.

The mobile sees at least two good blank frames in a row on

the forward channel, and concludes this is the right traffic channel. It sends a preamble of two blank frames of its own on the reverse traffic channel.

The base station acknowledges receiving the mobile’s preamble.

The mobile station acknowledges the base station’s acknowledgment.

Everybody is ready!


Service Negotiation and Mobile Alert

18:14:47.835 Reverse Traffic Channel: Service Connect Completion ACK_SEQ: 1 MSG_SEQ: 3 ACK_REQ: 1 ENCRYPTION: 0 SERV_CON_SEQ: 0

SERVICE CONNECT COMPLETE MSG.

18:14:47.760 Forward Traffic Channel: Service Connect ACK_SEQ: 0 MSG_SEQ: 1 ACK_REQ: 0 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0 SERV_CON_SEQ: 0Service Configuration: supported Transmission: Forward Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bps Reverse Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bps Service option: (6) Voice (13k) (0x8000) Forward Traffic Channel: Primary Traffic Reverse Traffic Channel: Primary Traffic

SERVICE CONNECT MESSAGENow that both sides have arrived on the

traffic channel, the base station proposes that the requested call

actually begin.

The mobile agrees and says its ready to play.

18:14:47.961 Forward Traffic Channel: Alert With Information ACK_SEQ: 3 MSG_SEQ: 1 ACK_REQ: 1 ENCRYPTION: 0SIGNAL_TYPE = IS-54B Alerting ALERT_PITCH = Medium Pitch (Standard Alert)SIGNAL = Long RESERVED = 0RECORD_TYPE = Calling Party NumberRECORD_LEN = 96 bitsNUMBER_TYPE = National NumberNUMBER_PLAN = ISDN/Telephony Numbering PlanPI = Presentation Allowed SI = Network ProvidedCHARi = 6153000124 RESERVED = 0 RESERVED = 0

ALERT WITH INFORMATION MESSAGE

The base station orders the mobile to ring, and gives it the calling party’s number to display.

18:14:48.018 Reverse Traffic Channel: Order ACK_SEQ: 1 MSG_SEQ: 4 ACK_REQ: 0ENCRYPTION: 0 Mobile Station Acknowledgement Order

The mobile says it’s ringing.

SERVICE CONNECT COMPLETE is a major milestone in call processing. Up until now, this was an access attempt.

Now it is officially a call.


The Human Answers! Connect Order

The mobile has been ringing for several seconds. The human user finally comes over and presses the send

button to answer the call.

Now the switch completes the audio circuit and the two callers can talk!

18:14:54.920 Forward Traffic Channel: Order ACK_SEQ: 0 MSG_SEQ: 1 ACK_REQ: 0 ENCRYPTION: 0 USE_TIME: 0 ACTION_TIME: 0 Base Station Acknowledgement Order


18:14:54.758 Reverse Traffic Channel: Order ACK_SEQ: 6 MSG_SEQ: 0 ACK_REQ: 1 ENCRYPTION: 0 Connect Order

CONNECT ORDER


Let’s make an Outgoing Call!Let’s make an Outgoing Call!

Example 5


Placing an Outgoing Call

The mobile user dials the desired digits, and presses SEND.Mobile transmits an Origination Message on the access channel.The system acknowledges receiving the origination by sending a base station acknowledgement on the paging channel.The system arranges the resources for the call and starts transmitting on the traffic channel.The system notifies the mobile in a Channel Assignment Message on the paging channel.The mobile arrives on the traffic channel.The mobile and the base station notice each other’s traffic channel signals and confirm their presence by exchanging acknowledgment messages.The base station and the mobile negotiate what type of call this will be -- I.e., 13k voice, etc.The audio circuit is completed and the mobile caller hears ringing.


Origination17:48:53.144 Access Channel: Origination ACK_SEQ: 7 MSG_SEQ: 6 ACK_REQ: 1 VALID_ACK: 0 ACK_TYPE: 0 MSID_TYPE: 3 ESN: [0x 00 06 98 24] MFR 0 Reserved 1 Serial Number 170020 IMSI: (Class: 0, Class_0_type: 0) [0x 03 5d b8 97 c2] 972-849-5073AUTH_MODE: 0 MOB_TERM: 1SLOT_CYCLE_INDEX: 2 MOB_P_REV: 1 EXT_SCM: 1DualMode: 0 SLOTTED_MODE: 1 PowerClass: 0REQUEST_MODE: CDMA only SPECIAL_SERVICE: 1 Service option: (6) Voice (13k) (0x8000) PM: 0 DIGIT_MODE: 0 MORE_FIELDS: 0 NUM_FIELDS: 11Chari: 18008900829 NAR_AN_CAP: 0

ORIGINATION MESSAGE

17:48:53.487 Paging Channel: Order ACK_SEQ: 6 MSG_SEQ: 0 ACK_REQ: 0 VALID_ACK: 1 MSID_TYPE: 2IMSI: (Class: 0, Class_0_type: 0) [0x 03 5d b8 97 c2] 972-849-5073 Base Station Acknowledgment Order


The mobile sends an origination message

on the access channel.

The base station confirms that the origination message

was received.17:48:54.367 Paging Channel: Channel Assignment ACK_SEQ: 6 MSG_SEQ: 1 ACK_REQ: 0 VALID_ACK: 1MSID_TYPE: 2 IMSI: (Class: 0, Class_0_type: 0) [0x 03 5d b8 97 c2] 972-849-5073 ASSIGN_MODE: Traffic Channel Assignment, ADD_RECORD_LEN: 5 FREQ_INCL: 1 GRANTED_MODE: 2CODE_CHAN: 12 FRAME_OFFSET: 0 ENCRYPT_MODE: Encryption disabled BAND_CLASS: 1.8 to 2.0 GHz PCS band CDMA_FREQ: 425

CHANNEL ASSIGNMENT MESSAGE

The base station sends a Channel Assignment

Message and the mobile goes to the traffic channel.


Traffic Channel Confirmation

17:48:54.835 Reverse Traffic Channel: Order ACK_SEQ: 0 MSG_SEQ: 0 ACK_REQ: 0 ENCRYPTION: 0 Mobile Station Acknowledgment Order

MOBILE STATION ACKNOWLEDGMENT17:48:54.757 Forward Traffic Channel: Order ACK_SEQ: 7 MSG_SEQ: 0 ACK_REQ: 1 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0 Base Station Acknowledgment Order


The base station is already sending blank frames on

the forward channel,using the assigned Walsh code.

The mobile sees at least two good blank frames in a row on

the forward channel, and concludes this is the right traffic channel. It sends a preamble of two blank frames of its own on the reverse traffic channel.

The base station acknowledges receiving the mobile’s preamble.

The mobile station acknowledges the base station’s acknowledgment.

Everybody is ready!


Service Negotiation and Connect Complete

17:48:55.137 Reverse Traffic Channel: Service Connect Completion ACK_SEQ: 1, MSG_SEQ: 0, ACK_REQ: 1, ENCRYPTION: 0, SERV_CON_SEQ: 0

SERVICE CONNECT COMPLETE MSG.

17:48:55.098 Forward Traffic Channel: Service Connect ACK_SEQ: 7 MSG_SEQ: 1 ACK_REQ: 1 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0 SERV_CON_SEQ: 0 Service Configuration Supported Transmission: Forward Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bpsReverse Traffic Channel Rate (Set 2): 14400, 7200, 3600, 1800 bpsService option: (6) Voice (13k) (0x8000) Forward Traffic Channel: Primary TrafficReverse Traffic Channel: Primary Traffic

SERVICE CONNECT MESSAGENow that the traffic channel is working

in both directions, the base station proposes that the requested call

actually begin.

The mobile agrees and says its ready to play.

17:48:55.779 Forward Traffic Channel: Order ACK_SEQ: 0 MSG_SEQ: 0 ACK_REQ: 0 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0 Base Station Acknowledgment Order


The base station agrees. SERVICE CONNECT COMPLETE is a major milestone in call processing. Up until now, this was an access attempt.

Now it is officially a call.

Now the switch completes the audio circuit and the two callers can talk!


Let’s End a Call!Let’s End a Call!

Example 6


Ending A Call

A normal call continues until one of the parties hangs up. Thataction sends a Release Order, “normal release”. The other side of the call sends a Release Order, “no reason given”.

• If a normal release is visible, the call ended normally.At the conclusion of the call, the mobile reacquires the system.

• Searches for the best pilot on the present CDMA frequency• Reads the Sync Channel Message• Monitors the Paging Channel steadily

Several different conditions can cause a call to end abnormally:• the forward link is lost at the mobile, and a fade timer acts• the reverse link is lost at the base station, and a fade timer acts• a number of forward link messages aren’t acknowledged, and the

base station acts to tear down the link• a number of reverse link messages aren’t acknowledged, and the

mobile station acts to tear down the link


A Beautiful End to a Normal Call

17:49:21.715 Reverse Traffic Channel: Order ACK_SEQ: 1 MSG_SEQ: 1 ACK_REQ: 1 ENCRYPTION: 0 Release Order (normal release)

MOBILE RELEASE ORDER

BASE STATION ACKNOWLEDGMENT17:49:21.936 Forward Traffic Channel: Order ACK_SEQ: 1 MSG_SEQ: 2 ACK_REQ: 0 ENCRYPTION: 0, USE_TIME: 0 ACTION_TIME: 0 Base Station Acknowledgement Order

At the end of a normal call, this mobile user pressed end.

The mobile left the traffic channel, scanned to find the best pilot, and read

the Sync Channel Message.

BASE STATION RELEASE ORDER17:49:21.997 Forward Traffic Channel: Order ACK_SEQ: 1 MSG_SEQ: 3 ACK_REQ: 0 ENCRYPTION: 0USE_TIME: 0 ACTION_TIME: 0 Release Order (no reason given)

17:49:22.517 Sync Channel MSG_TYPE: 1 Sync Channel MessageP_REV: 1 MIN_P_REV: 1SID: 4112 NID: 2 Pilot_PN: 183 LC_STATE: 0x318fe5d84a5 SYS_TIME: 0x1ae9683dcLP_SEC: 9 LTM_OFF: -10 DAYLT: 1 Paging Channel Data Rate: 9600 CDMA_FREQ: 425

SYNC CHANNEL MESSAGE

The base station acknowledged receiving the message, then sent

a release message of its own.


Let’s receive Notificationof a Voice Message!

Let’s receive Notificationof a Voice Message!

Example 7


Feature Notification

98/06/30 21:16:44.368 [PCH] Feature Notification MessageMSG_LENGTH = 144 bitsMSG_TYPE = Feature Notification MessageACK_SEQ = 0MSG_SEQ = 0ACK_REQ = 1VALID_ACK = 0ADDR_TYPE = IMSIADDR_LEN = 56 bitsIMSI_CLASS = 0IMSI_CLASS_0_TYPE = 3RESERVED = 0MCC = 302IMSI_11_12 = 00IMSI_S = 9055170325RELEASE = 0RECORD_TYPE = Message WaitingRECORD_LEN = 8 bitsMSG_COUNT = 1RESERVED = 0

FEATURE NOTIFICATION MESSAGE

The Feature Notification Message on the Paging Channel tells a specific mobile it has voice messages waiting.

There are other record types to notify the mobile of other features.

The mobile confirms it has received the notification by sending a Mobile Station Acknowledgment Order on the access

channel.



Let’s do a Handoff!Let’s do a Handoff!

Example 8


The Call is Already Established. What Next?E

c/Io

All PN Offsets

0

032K

512Chips

PN

0

-20

Neighbor Set

The call is already in progress. PN 168 is the only active signal,and also is our timing reference.

Continue checking the neighbors.

If we ever notice a neighbor with Ec/Io above T_ADD,ask to use it! Send a Pilot Strength Measurement Message!

T_ADD

Rake Fingers

Reference PN

Active Pilot

10752

16832002

50014080

220

! !

Mobile Rake RX

Srch PN??? W0

F1 PN168 W61F2 PN168 W61F3 PN168 W61


Mobile Requests the Handoff!

98/05/24 23:14:02.205 [RTC] Pilot Strength Measurement MessageMSG_LENGTH = 128 bitsMSG_TYPE = Pilot Strength Measurement MessageACK_SEQ = 5 MSG_SEQ = 0 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledREF_PN = 168 Offset Index (the Reference PN)PILOT_STRENGTH = -6.0 dBKEEP = 1PILOT_PN_PHASE = 14080 chips (PN220+0chips)PILOT_STRENGTH = -12.5 dBKEEP = 1PILOT_PN_PHASE = 32002 chips (PN500 + 2 chips)PILOT_STRENGTH = -11.0 dBKEEP = 1RESERVED = 0

PILOT STRENGTH MEASUREMENT MESSAGE

98/05/24 23:14:02.386 [FTC] Order MessageMSG_LENGTH = 64 bitsMSG_TYPE = Order MessageACK_SEQ = 0 MSG_SEQ = 0 ACK_REQ = 0ENCRYPTION = Encryption Mode DisabledUSE_TIME = 0 ACTION_TIME = 0ORDER = Base Station Acknowledgment OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field Omitted RESERVED = 0


Just prior to this message, this particular mobile already was in handoff with PN 168 and 220. This pilot strength measurement message reports PN 500 has increased above T_Add, and the mobile wants to use it too.

The base station acknowledges receiving the Pilot Strength Measurement Message.


System Authorizes the Handoff!

98/05/24 23:14:02.926 [FTC] Extended Handoff Direction MessageMSG_LENGTH = 136 bitsMSG_TYPE = Extended Handoff Direction MessageACK_SEQ = 0 MSG_SEQ = 6 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledUSE_TIME = 0 ACTION_TIME = 0 HDM_SEQ = 0SEARCH_INCLUDED = 1 SRCH_WIN_A = 40 PN chipsT_ADD = -13.0 dB T_DROP = -15.0 dB T_COMP = 2.5 dBT_TDROP = 4 secHARD_INCLUDED = 0 FRAME_OFFSET = Field OmittedPRIVATE_LCM = Field Omitted RESET_L2 = Field OmittedRESET_FPC = Field Omitted RESERVED = Field OmittedENCRYPT_MODE = Field Omitted RESERVED = Field OmittedNOM_PWR = Field Omitted NUM_PREAMBLE = Field OmittedBAND_CLASS = Field Omitted CDMA_FREQ = Field OmittedADD_LENGTH = 0PILOT_PN = 168 PWR_COMB_IND = 0 CODE_CHAN = 61PILOT_PN = 220 PWR_COMB_IND = 1 CODE_CHAN = 20PILOT_PN = 500 PWR_COMB_IND = 0 CODE_CHAN = 50RESERVED = 0

HANDOFF DIRECTION MESSAGEThe base station sends a HandofDirection Message authorizing the mobile to begin soft handoff with all three requested PNs. The pre-existing link on PN 168 will continue to use Walsh code 61, the new link on PN220 will use Walsh Code 20, and the new link on PN500 will use Walsh code 50.

The mobile acknowledges it has received the Handoff Direction Message.

98/05/24 23:14:02.945 [RTC] Order MessageMSG_LENGTH = 56 bits MSG_TYPE = Order MessageACK_SEQ = 6 MSG_SEQ = 6 ACK_REQ = 0ENCRYPTION = Encryption Mode DisabledORDER = Mobile Station Acknowledgment OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field Omitted RESERVED = 0



Mobile Implements the Handoff!

The mobile searcher quickly re-checks all three PNs. It still hears their pilots!

The mobile sends a Handoff Completion Message, confirming it still wants to go

ahead with the handoff.


98/05/24 23:14:02.985 [RTC] Handoff Completion MessageMSG_LENGTH = 72 bits MSG_TYPE = Handoff Completion MessageACK_SEQ = 6 MSG_SEQ = 1 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledLAST_HDM_SEQ = 0PILOT_PN = 168 Offset IndexPILOT_PN = 220 Offset IndexPILOT_PN = 500 Offset IndexRESERVED = 0

HANDOFF COMPLETION MESSAGE

The base station confirms it has received the mobile’s Handoff Completion message, and will continue with all of the links active.

98/05/24 23:14:03.085 [FTC] Forward Traffic Channel: Order ACK_SEQ: 1 MSG_SEQ: 1 ACK_REQ: 0 ENCRYPTION: 0 USE_TIME: 0 ACTION_TIME: 0 Base Station Acknowledgement Order


Neighbor List Updated, Handoff is Complete!

98/05/24 23:14:03.245 [RTC] Order MessageMSG_LENGTH = 56 bits MSG_TYPE = Order MessageACK_SEQ = 7 MSG_SEQ = 7 ACK_REQ = 0ENCRYPTION = Encryption Mode DisabledORDER = Mobile Station Acknowledgement OrderADD_RECORD_LEN = 0 bitsOrder-Specific Fields = Field OmittedRESERVED = 0


98/05/24 23:14:03.166 [FTC] Neighbor List Update MessageMSG_LENGTH = 192 bitsMSG_TYPE = Neighbor List Update MessageACK_SEQ = 1 MSG_SEQ = 7 ACK_REQ = 1ENCRYPTION = Encryption Mode DisabledPILOT_INC = 4 Offset IndexNGHBR_PN = 164 Offset IndexNGHBR_PN = 68 Offset IndexNGHBR_PN = 52 Offset IndexNGHBR_PN = 176 Offset IndexNGHBR_PN = 304 Offset IndexNGHBR_PN = 136 Offset IndexNGHBR_PN = 112 Offset IndexNGHBR_PN = 372 Offset IndexNGHBR_PN = 36 Offset IndexNGHBR_PN = 8 Offset IndexNGHBR_PN = 384 Offset IndexNGHBR_PN = 216 Offset IndexNGHBR_PN = 328 Offset IndexNGHBR_PN = 332 Offset IndexNGHBR_PN = 400 Offset IndexNGHBR_PN = 96 Offset IndexRESERVED = 0

NEIGHBOR LIST UPDATE MESSAGE

In response to the mobile’s Handoff Completion Message, the base station assembles a new composite neighbor list including all the neighbors of each of the three active pilots.This is necessary since the mobile could be traveling toward any one of these pilots and may need to request soft handoff with any of them soon.

The mobile confirms receiving the Neighbor List Update Message. It is

already checking the neighbor list and will do so continuously from now on.

The handoff is fully established.


Handoff Now In Effect, but still check Pilots!E

c/Io

All PN Offsets

0

032K

512Chips

PN

0

-20

Neighbor Set

Continue checking each ACTIVE pilot. If any are less than T_DROP and remain so for T_TDROP time, send Pilot Strength Measurement Message, DROP IT!!

Continue looking at each NEIGHBOR pilot. If any ever rises above T_ADD, send Pilot Strength Measurement Message, ADD IT!

T_ADD

Rake Fingers

Reference PN

Active Set

10752

16832002

50014080

220

T_DROP

Mobile Rake RX

Srch PN??? W0

F1 PN168 W61F2 PN500 W50F3 PN220 W20


The Complete Picture of Handoff & Pilot Sets

T_ADD

Ec/

IoAll PN Offsets

00

32K512

ChipsPN

0

-20

Neighbor Set

SRCH_WIN_N

Active Set

Candidate SetT_DROP

SRCH_WIN_A

Remaining SetT_ADD

SRCH_WIN_R

SRCH_WIN_A

T_DROP

Rake Fingers

Reference PN

Pilots of sectors now used for communication

Pilots requested by mobile but not set up by system

Pilots suggested by system for more checking

All other pilots divisible by PILOT_INC but not presently in Active, Candidate, or Neighbor sets

Mobile Rake RX

Srch PN??? W0

F1 PN168 W61F2 PN500 W50F3 PN220 W20


Deeper Handoff Details:Search Windows & TimingDeeper Handoff Details:

Search Windows & Timing

Section G


The Pilot Searcher’s Measurement Process

The searcher checks pilots in nested loops, much like meshed gears. Actives and candidatesoccupy the fastest-spinning wheel. Neighbors are next, advancingone pilot for each Act+Cand. revolution.Remaining is slowest, advancing one pilot each time the Neighbors revolve.

CURRENT PILOT SET CONTENTSA A A

C

N N N N N N N N N N N N

R R R R R R R R R R R R









R R R R

31

12112

PILOT SEARCHER VIEWED IN SEQUENCE: Typical Elapsed Time = 4 secondsA A A C N

R

A A A C A A A C A A A C A A A C A A A C A A A CN N N N N N

A A A C N A A A C A A A C A A A C A A A C A A A C A A A CN N N N N

A A A CN A A A C A A A C A A A C A A A C A A A C A A A CN N N N N N

N A A A C A A A C A A A CN N N R A A A C N A A A C A A A C A A AN N

C A A A C A A A CN N N

R

A A A C N A A A C A A A C A A AN N C A A AN

C A A A CN N Only 3 of 112 remaining set pilots have been checked thus far!

A

N

R

R

R

R

R

R

R

NN

N

N

NN N N

AA


A Quick Primer on Pilot Search WindowsThe phone chooses one strong sector and “locks” to it, accepting its offset at “face value”and interpreting all other offsets by comparison to itIn messages, system gives to handset a neighbor list of nearby sectors’ PNsPropagation delay “skews” the apparent PN offsets of all other sectors, making them seem earlier or later than expectedTo overcome skew, when the phone searches for a particular pilot, it scans an extra wide “delta” of chips centered on the expected offset (called a “search window”) Search window values can be datafilledindividually for each Pilot set:There are pitfalls if the window sizes are improperly set

• too large: search time increases• too small: overlook pilots from far away• too large: might misinterpret identity of a

distant BTS’ signal One chip is 801 feet or 244.14 m

1 mile=6.6 chips; 1 km.= 4.1 chips

PROPAGATION DELAYSKEWS APPARENT PN OFFSETS

BTSBTSA

B

33Chips

4 Chips

If the phone is locked to BTS A, thesignal from BTS B will seem 29 chipsearlier than expected.If the phone is locked to BTS B, thesignal from BTS A will seem 29 chipslater than expected.


Setting Pilot Search Window SizesWhen the handset first powers up, it does an exhaustive search for the best pilot. No windows are used in this process.On the paging channel, the handset learns the window sizes SRCH_WIN_A, N, R and uses them when looking for neighbors both in idle mode and during calls.When a strong neighbor is requested in a PSMM, the former neighbor pilot is now a candidate. Its offset is precisely remembered and frequently rechecked and tracked by the phone.Window size for actives and candidates can be small, since their exact position is known. Only search wide enough to include multipath energy!

• This greatly speeds up overall searching!Most post-processing tools deliver statistics on the spread (in chips) between fingers locked to the same pilot. These statistics literally show us how wide the SRCH_WIN_A should be set.Neighbor and Remaining search windows should be set to accommodate the maximum intercelldistances which a mobile might experience

SEARCH WINDOW SETTINGSAND PROPAGATION DISTANCES

Window Size (Chips)

14 (±7)

DatafillValue

N,R Delta Distance

4 1.0620 (±10)

40 (±20)28 (±14)

Miles KM.

56789101112131415

60 (±30)80 (±40)

100 (±50)130 (±65)160 (±80)226 (±113)320 (±160)452 (±226)

1.711.52 2.442.12 3.423.03 4.884.55 7.326.07 9.777.59 12.29.86 15.912.1 19.517.1 27.624.3 39.134.3 55.2


Handoff Problems: “Window” Dropped Calls

Calls often drop when strong neighbors suddenly appear outside the neighbor search window and cannot be used to establish soft handoff.Neighbor Search Window SRCH_WIN_N should be set to a width at least twice the propagation delay between any site and its most distant neighbor site Remaining Search Window SRCH_WIN_R should be set to a width at least twice the propagation delay between any site and another site which might deliver occasional RF into the service area

A

B

1 mi.7 Chips

BTS

BTS

SITUATION 1 Locked to distant site, can’t see

one nearby12 miles80 ChipsSRCH_WIN_N = 130BTS A is reference.BTS B appears (7-80) chipsearly due to its closer distance.This is outside the 65-chip window.Mobile can’t see BTS B’s pilot, but its strong signal blinds us and the call drops.

Travel

mountains

A

B

1 mi.7 Chips

BTS

BTS

SITUATION 2Locked to nearby

site, can’t see distant one12 miles80 Chips

Travel

SRCH_WIN_N = 130BTS B is reference.BTS A appears (80-7) chipslate due to its farther distance.This is outside the 65-chip window.Mobile can’t see BTS A’s pilot.

mountains


Overall Handoff Perspective

Soft & Softer Handoffs are preferred, but not always possible• a handset can receive BTS/sectors simultaneously only on one

frequency • all involved BTS/sectors must connect to a networked BSCs.

Some manufacturers do not presently support this, and so are unable to do soft-handoff at boundaries between BSCs.

• frame timing must be same on all BTS/sectorsIf any of the above are not possible, handoff still can occur but can only be “hard” break-make protocol like AMPS/TDMA/GSM

• intersystem handoff: hard• change-of-frequency handoff: hard• CDMA-to-AMPS handoff: hard, no handback

– auxiliary trigger mechanisms available (RTD)


Section H

CDMA Network ArchitectureCDMA Network Architecture


BASE STATIONCONTROLLER

SUPPORTFUNCTIONS

BASE STATIONS

Mobile TelephoneSwitching Office

PSTNLocal CarriersLong Distance

CarriersATM Link

to other CDMANetworks(Future)

Structure of a Typical Wireless SystemHLR

Voice Mail System SWITCH

HLR Home Location Register(subscriber database)


Signal Flow: Two-Stage Metamorphosis

BSC-BSMMTX BTS

Ch. Card ACC

Σα

Σβ

Σχ

TFU1

GPSRBSM

CDSU

CDSU


CDSU

CDSU

CDSU

CDSU

CDSU

CMSLM

LPP LPPENET

DTCs

DMS-BUS

TxcvrA

TxcvrB

TxcvrC

RFFEA

RFFEB

RFFEC

TFU

GPSR

GPS GPS

IOC

PSTN

CDSU DISCOCDSU

DISCO 1

DISCO 2

DS0 in T1Packets

ChipsRFChannel

ElementVocoder


Nortel CDMA Network Architecture

Nortel CDMA Network Architecture

www.nortel.com


NORTEL CDMA System Architecture

BSC-BSMMTX BTS

CDSU DISCO

Ch. Card ACC

Σα

Σβ

Σχ

TFU1

GPSRBSM

CDSU

CDSU

DISCO 1

DISCO 2


CDSU

CDSU

CDSU

CDSU

CDSU

CDSU

CMSLM

LPP LPPENET

DTCs

DMS-BUS

TxcvrA

TxcvrB

TxcvrC

RFFEA

RFFEB

RFFEC

TFU

GPSR

PSTN & Other MTXs

GPS GPS

IOC

Billing


Switch: The Nortel MTX

Primary functions• Call Processing• Mobility Management

– HLR-VLR access– Intersystem call delivery (IS-41C)– Inter-MTX handover (IS-41C)

• Billing Data Capture• Calling Features & Services• Collecting System OMs, Pegs

High reliability, redundancy

MTX

CMSLM

LPP ENET

DTCs

DMS-BUS

PSTN & Other MTXs

CDMABSC

Unch. T1

IOC

CDMASBS

MAP,VDUs

Billing

LPP

CCS7

Ch.T1

ChT1


The Nortel BSC

Primary functions• vocoding• soft handoff management• FER-based power control• routing of all traffic and control

packetsScaleable architecture

• expand SBS to keep pace with traffic growth

• expandable DISCO

BSC

TFU1

GPSRBSM

CDSUCDSU

DISCO 1

DISCO 2


CDSU

CDSU

CDSU

CDSU

CDSU

CDSU

GPS

MTX(voicetrunks)

MTXLPP

BTSs

T1 channelized (24 DS0)T1 unchannelizedBCN link (HDLC)


The Nortel BTS

Base Transceiver StationPrimary function: Air link

• generate, radiate, receive CDMA RF signal IS-95/J.Std. 8

• high-efficiency T1 backhaul• test capabilities

Configurations• 1, 2, or 3 sectors• 800 MHz.: indoor• 1900 MHz.: self-contained outdoor,

remotable RFFEs• new 1900 MHz. indoor, 800 MHz. &

1900 MHz. multi-carrier options

BTS

CDSU DISCO

Ch. Card ACC

Σα

Σβ

Σχ

TxcvrA

TxcvrB

TxcvrC

RFFEA

RFFEB

RFFEC

TFU

GPSRGPS

BSC


The Nortel BSM

Base Station ManagerPrimary functions: OA&M for CDMA components

• Configuration management– BSC, BTS configuration and

parameters• Fault management

– Alarm Reporting• Performance management

– interface for CDMA statistics and peg counts collection

• Security management• Unix-based

BSC BTS

CDSU DISCO

Ch. Card ACC

Σα

Σβ

Σχ

TFU1

GPSR

CDSU

CDSU

DISCO 1

DISCO 2


CDSU

CDSU

CDSU

CDSU

CDSU

CDSU

TxcvrA

TxcvrB

TxcvrC

RFFEA

RFFEB

RFFEC

TFU

GPSR

GPS GPS

BSM

X-Windows terminals

Ethernet LAN

BSM Workstation

GNP TELCOWORKSERVER

SHELF---------HIGH

AVAILABILITY

NORTEL CDMA BSM

BCN Links


Summary of CDMA Capacity Considerations

BSC-BSMMTX BTS

Ch. Card ACC

Σα

Σβ

Σχ

TFU1

GPSRBSM

CDSU

CDSU


CDSU

CDSU

CDSU

CDSU

CDSU

CMSLM

LPP LPPENET

DTCs

DMS-BUS

TxcvrA

TxcvrB

TxcvrC

RFFEA

RFFEB

RFFEC

TFU

GPSR

GPSGPS

IOC

PSTN

CDSU DISCOCDSU

DISCO 1

DISCO 2

Sufficient vocoders/selectors required in BSC SBS, one per

simultaneous call on the system. 8 Vocoders per SBS card, 12 cards per shelf, 4 shelves per

SBS cabinet.

One T-1 can carry all traffic originated by a

one-carrier BTS; special consideration required if

daisy-chaining

Forward RF Capacity: links use available

BTS TX power

Sufficient channel elements required for traffic of all sectors: one CE per link; 20

CE per Channel Card

64 Walsh Codes/sector



DISCO has 192 ports

max. Each BTS uses 1, SBS shelf 1, LPP CIU 1,

Link 2, Ctrl. 2, BSM 4.

Typical CM processorcapacity considerations

PSTN trunk groups must be dimensioned to

support erlang load.

DTC & ENET: One port per Vocoder plus one port per

outgoing trunk.

CDMA LPP: One pair CIUs and One pair CAUs per

approx. 600 erlangs

Reverse RF Capacity: links cause noise floor rise, use mobile power


Lucent CDMA Network Architecture

Lucent CDMA Network Architecture

www.lucent.com


Lucent CDMA System Architecture

5ESS-2000 DCSECP BTS

ChannelUnit

Cluster

ACU

Σα

Σβ

Σχ

Baseband Combiner & Radio



PSTN & Other MTXs

ExecutiveCellular

Processor Complex (ECPC)

Circuit SwitchPlatform

CDMA SpeechHandling Equipment

Packet SwitchPlatform


The Lucent ECP

Executive Cellular ProcessorPrimary functions

• Call Processing• Mobility Management

– HLR-VLR access– Intersystem call delivery (IS-41C)– Inter-MTX handover (IS-41C)

• Billing Data Capture• Calling Features & Services• Collecting System OMs, Pegs

High reliability, redundancy

ECP

ExecutiveCellular

Processor Complex (ECPC)


The Lucent #5ESS and Access Manager

Primary functions• vocoding• soft handoff management• FER-based power control• routing of all traffic and control

packetsScaleable architecture

• expand speech handlers• expandable packet switch

5ESS-2000 DCS

PSTN & Other MTXs

Circuit SwitchPlatform

CDMA SpeechHandling Equipment

Packet SwitchPlatform


The Lucent BTS

Primary function: Air link • generate, radiate, receive

CDMA RF signal IS-95/J.Std. 8• high-efficiency T1 backhaul• test capabilities

BTSChannel

UnitCluster

ACU

Σα

Σβ

Σχ





Motorola CDMA Network Architecture

Motorola CDMA Network Architecture

www.motorola.com


Motorola CDMA System ArchitectureOMC-R

CBSC

PCSCPersonal

CommunicationsSwitching

Center

PSTNDSC

EMX-2500or

EMX-5000

Mobility Manager

Transcoder

OMC-RProcessor

ApplicationProcessor

(or SC-UNO)

BTS (SC9600/4800/2400)

Group LineInterface (GLI)

MultichannelCDMA Card (MCC)

BTS (SC614T/611)

MotorolaAdvancedWidebandInterface(MAWI)

PCLocal

MaintenanceFacility


The Motorola PCSC

Personal Communications Switching CenterPrimary functions

• Call Processing• HLR-VLR access• Intersystem call delivery (IS-41C)• Billing Data Capture• Calling Features & Services

PSTNDSC

EMX-2500or

EMX-5000

EMX-2500

EMX-5000


The Motorola CBSC

Centralized Base Station ControllerMobility Manager

• allocation of BTS resources• handoff management• Call management & supervision

Transcoder• vocoding• soft handoff management• FER-based power control• routing of all traffic and control

packets

CBSC

Mobility Manager

Transcoder


The Motorola BTS Family

Primary function: Air link • generate, radiate, receive

CDMA RF signal IS-95/J.Std. 8

• high-efficiency T1 backhaul

• test capabilitiesBTS (SC9600/4800/2400)

Group LineInterface (GLI)

MultichannelCDMA Card (MCC)

BTS (SC614T/611)

MotorolaAdvancedWidebandInterface(MAWI)

PCLocal

MaintenanceFacility

SC611 Microcell

SC4852SC614T


Section I

Introduction to OptimizationIntroduction to Optimization


What is Performance Optimization?

The words “performance optimization” mean different things to different people, viewed from the perspective of their own jobsSystem Performance Optimization includes many different smaller processes at many points during a system’s life

• recognizing and resolving system-design-related issues (can’t build a crucial site, too much overlap/soft handoff, coverage holes, etc.)

• “cluster testing” and “cell integration” to ensure that new base station hardware works and that call processing is normal

• “fine-tuning” system parameters to wring out the best possible call performance

• identifying causes of specific problems and customer complaints, and fixing them

• carefully watching system traffic growth and the problems it causes - implementing short-term fixes to ease “hot spots”, and recognizing problems before they become critical


Performance Optimization Phases/Activities

hello

RF Design and Cell Planning

New Cluster Testing and

Cell Integration

Solve SpecificPerformance

Problems

Well-System Performance Management

Capacity Optimization

Growth Management:

Optimizing both Performance and Capital

Effectiveness

Cover desired area; have capacity for anticipated traffic

Ensure cells properly constructed and

configured to give normal performance

Identify problems from complaints or statistics; fix them!

Ensure present ‘plant’is giving best possible

performance

Manage congested areas for most

effective performance

Overall traffic increases and congestion;

competition for capital during tight times

Phase Drivers/Objectives Activities Main Tools Success Indicators

Plan cells to effectively cover as needed and divide traffic

load appropriately

Drive-test: coverage, all handoff boundaries, all call

events and scenarios

Detect, Investigate, Resolve performance problems

Watch stats: Drops, Blocks, Access Failures; identify/fix hot

spots

Watch capacity indicators; identify problem areas, tune parameters & configuration

Predict sector and area exhaustion: plan and validate effective growth plan, avoid

integration impact

Prop. Models,Test Transmitters,

planning tools Model results

Drive-test tools;cell diagnostics and

hardware test

All handoffs occur; all test cases

verified

Drive-test tools, system stats,

customer reports

Identified problems are

resolved

System statisticsAcceptable levels and good trends for all indicators

Smart optimization of parameters;

system statistics

Stats-Derived indicators; carried

traffic levels

Traffic analysis and trending tools;

prop. models for cell spliiting; carrier

additions

Sectors are expanded soon

after first signs of congestion;

capital budget remains within

comfortable bounds


Good Performance is so Simple!!

One, Two, or Three good signals in handoff• Composite Ec/Io > -10 db

Enough capacity• No resource problems – I’ve got what I

need

BTS BTS

BTS

Pilot

Paging

TrafficChannels

In use

availablepower

Sync

BTS

A

BTS

B

BTS

C

Ec/Io -10

FORWARDLINK


Bad Performance Has Many CausesWeak Signal / Coverage HolePilot Pollution

• Excessive Soft HandoffHandoff Failures, “Rogue” mobiles

• Missing Neighbors• Search Windows Too Small• BTS Resource Overload / No Resources

– No Forward Power, Channel Elements

– No available Walsh Codes– No space in Packet Pipes

Pilot “Surprise” ambush; Slow HandoffsPN Plan errorsSlow Data Problems: RF or IP congestionImproper cell or reradiator configurationHardware and software failuresBut on analysis, all of these problems’ bad effects happen because the simple few-signal ideal CDMA environment isn’t possible.

360

+41

+8

360+33cA

BBTS

BTS

BTS BPN 99

BTS APN 100

1 mile 11 miles

ACTIVE SEARCH WINDOW

xPilot

PagingSync

TrafficChannels

In Use

NoAvailablePower!B

TS Sector Transmitter

CEsVocodersSelectors

BTS Rx PwrOverload


Aeronautical Analogy: Tools for Problem Investigation

To study the cause of an aeronautical accident, we try to recover the Flight Data Recorder and the Cockpit Voice Recorder.

To study the cause of a CDMA call processing accident, we review data from the Temporal Analyzer and the Layer 3 Message Files -- for the same reasons.

Control & Parameters Messaging

BTS

1150011500

114.50118.25125.75

AeronauticalInvestigations

CDMAInvestigations

Flight Data Recorder Cockpit Voice Recorder

Temporal Analyzer Data Layer 3 Message Files


Starting Optimization on a New SystemRF Coverage Control

• try to contain each sector’s coverage, avoiding gross spillover into other sectors

• tools: PN Plots, Handoff State Plots, Mobile TX plotsSearch Window Settings

• find best settings for SRCH_WIN_A, _N, _R• especially optimize SRCH_WIN_A per sector using collected

finger separation data; has major impact on pilot search speedNeighbor List Tuning

• try to groom each sector’s neighbors to only those necessary but be alert to special needs due to topography and traffic

• tools: diagnostic data, system logsAccess Failures, Dropped Call Analysis

• finally, iterative corrections until within numerical goals

Getting these items into shape provides a solid baseline and foundation from which future performance issues can be addressed.


Solving Problems on Existing Systems

CDMA optimization is very different from optimization in analog technologies such as AMPS

AMPS: a skilled engineer with a handset or simple equipment can hear, diagnose, and correct many common problems

• co-channel, adjacent channel, external interferences• dragged handoffs, frequency plan problems

CDMA impairments have one audible symptom: Dropped Call• voice quality remains excellent with perhaps just a hint of garbling

even as the call approaches dropping in a hostile RF environment

Successful CDMA Optimization requires:• recognition and understanding of common reasons for call failure• capture of RF and digital parameters of the call prior to drop• analysis of call flow, checking messages on both forward and reverse

links to establish “what happened”, where, and why


CDMA Problems Attacked in Optimization

Excessive Access Failures• typical objectives: <2% (IS-95B will bring improvements)

Excessive Dropped Calls• typical objective: ~1%, <2%

Forward Link Interference• typical objective: eliminate situations which prevent handoff!

Slow Handoff• typical objective: eliminate situations which delay handoff!

Handoff Pilot Search Window Issues• avoid handoff drops!

Excessive Soft Handoff• control coverage, not T_Add/T_Drop, to manage soft handoff levels (~<50%)

Grooming Neighbor Lists• “if you need it, use it!”

Software Bugs, Protocol Violations• Neither system software, nor mobile software, nor the CDMA standard is

perfect. Don’t humbly accept problems -- dig in and find out what’s happening!


Sources of CDMA Data and Tools for Processing

CDMA optimization data flows from three places:• Switch• CDMA peripherals (CBSC & BTS)• Handset

Each stream of data has a family of software and hardware tools for collection and analysis

CBSCSwitch BTS

CDSU DISCO

Ch. Card ACC

ΣαΣβΣχ

TFU1GPSR

CDSUCDSU

DISCO 1DISCO 2


CDSUCDSUCDSUCDSUCDSUCDSU

CMSLM

LPP LPPENET

DTCs

DMS-BUS

Txcvr ATxcvr BTxcvr C

RFFE ARFFE BRFFE C

TFU1GPSR

IOC

BSM

Data AnalysisPost-Processing

Tools

IS-95/J-STD-008 Messages

IS-95/J-STD-8 Messages

Switch Datapegs, logs

Mobile DataPost-Processing

Tools

Mobile Data Capture Tools

HandsetMessages

ExternalAnalysis

Tools

PC-based

PC-based

Unix-based,PC-basedVarious

CDMA NETWORK EQUIPMENT HANDSET

System Internal Messages


Department Store Analogy: Tops-Down, Bottoms-Up

Some things are easier to measure from the customer side!

Complex!!! Simpler

System Phone

Neighbor ListsData Analysis

SoftwareTrans-

mission

Configuration

Provisioning

PSTN Trunking

Dropped Calls

CoverageAccess Failures

Switch

BTS

CBSC

InterferenceAdministration

Data CaptureField Tools

Profits

Complex!!! Simpler

Management Test Shopper

Labor Relations

Cost

sTaxe

s Insurance

Suppliers

Leases

Capital

Stocking

Distribution

Loss

esAdvertis

ing

Selection

ConveniencePrice

Service


Aeronautical Analogy: Tools for Problem Investigation

To study the cause of an aeronautical accident, we try to recover the Flight Data Recorder and the Cockpit Voice Recorder.

To study the cause of a CDMA call processing accident, we review data from the Temporal Analyzer and the Layer 3 Message Files -- for the same reasons.

Control & Parameters Messaging

BTS

1150011500

114.50118.25130.75

AeronauticalCase

CDMA Case

Flight Data Recorder Cockpit Voice Recorder

Temporal Analyzer Data Layer 3 Message Files


So S L O W ! ! Where’s My Data?!!

Some sessions are tormented by long latency and slow throughputWhere is the problem? Anywhere between user and distant host:

• Is the mobile user’s data device mis-configured and/or congested?• Is the BTS congested, with no power available to produce an SCH?• Poor RF environment, causing low rates and packet retransmission?• Congestion in the local IP network (PCU, R-P, PDSN FA)?• Congestion in the wireless operator’s backbone (‘OSSN’) network?• Congestion in the PDSN HA?• Congestion in the outside-world internet or Private IP network?• Is the distant host congested, with long response times?

IP D

ata

Envir

onm

entCDMA RF Environment

CDMA IOS PPPTraditional Telephony

IP Data Environment

t1t1 v CESEL

t1

R-P Interface

PDSN/Foreign Agent

PDSNHome Agent

BackboneNetworkInternet

VPNs

PSTN

T TSECURE TUNNELS

AuthenticationAuthorization

AccountingAAA

BTS

(C)BSC/Access ManagerSwitch WirelessMobile Device

•Coverage Holes•Pilot Pollution•Missing Neighbors•Fwd Pwr Ovld•Rev Pwr Ovld•Search Windows•Island Cells•Slow Handoff


Finding Causes of Latency and Low Throughput

IP network performance can be measured using test serversProblems between mobile a local test server? The problem is local

• check RF conditions, stats: poor environment, SCH blocking?• if the RF is clean, investigate BSC/PCU/R-P/PDSN-FA

Local results OK, problems accessing test server at PDSN-HA?• problem is narrowed to backbone network, or PDSN-HA

Results OK even through test server at PDSN-HA• then the problem is in the public layers beyond.

IP D

ata

Envir

onm

entCDMA RF Environment

CDMA IOS PPPTraditional Telephony

IP Data Environment

t1t1 v CESEL

t1

R-P Interface

PDSN/Foreign Agent

PDSNHome Agent


VPNs

PSTN

T TSECURE TUNNELS


AccountingAAA

BTS

(C)BSC/Access ManagerSwitch WirelessMobile Device

•Coverage Holes•Pilot Pollution•Missing Neighbors•Fwd Pwr Ovld•Rev Pwr Ovld•Search Windows•Island Cells•Slow Handoff

TestServer

TestServer

TestServer


Autonomous Data CollectionBy Subscriber Handsets

Autonomous Data CollectionBy Subscriber Handsets


Autonomous Collection:A New Way to See Network Performance

An exciting new trend in network RF performance is to embed datacollection software on mobile platformsOffers big advantages for RF optimization cost/effectiveness

t1t1 v SEL

t1

R-P Interface

PDSN/Foreign Agent

PDSNHome Agent


VPNs

PSTN

T TSECURE TUNNELS


AccountingAAA

BTS

(C)BSC/Access ManagerSwitch

Collection Server•software download•collected data upload•data management, analysis

BTS

BTS

BTS


Using Autonomous Collection

A Server downloads software to a large population of subscriber mobilesMobiles collect on custom profiles

• all or groups of mobiles can be enabled/disabled• new triggers can be rapidly developed and downloaded when desired

Mobiles upload compacted packets to server driven by custom triggers• may be immediately if needed, or at low-traffic pre-programmed times• collected data can include location/GPS/call event/L3

messaging/timestamps/etc.Server manages data, provides filtering and reportingPerformance optimizers use terminals and post-processing software

t1t1 vSELt1

R-P Interface

PDSN/Foreign Agent

PDSNHome Agent


VPNs

PSTN

T TSECURE TUNNELSAuthentication

AuthorizationAccounting

AAABTS


Collection Server•software download•collected data upload•data management, analysis

BTS

BTS

BTS


Advantages of Autonomous Collection

Mobile-reported data can be location-binned

• post-processing provides visual identification of problem areas

Collection can be rapidly enabled per cell or area for immediate investigation of problem reportsRequires less employee drive time for collectionCustomer mobiles cover area more densely than drivetestersCustomer mobiles include in-building populationsIndividual mobile identification can be included with customer permission for direct customer service interaction


Conventional Field ToolsConventional Field Tools


CDMA Field Test ToolsField Collection Tools using Handset Data

There are many commercial CDMA field test toolsCharacteristics of many test tools:

• capture data from data ports on commercial handsets• log data onto PCs using proprietary software• can display call parameters, messaging, graphs, and maps• store data in formats readable for post-processing analysis• small and portable, easy to use in vehicles or even on foot

A few considerations when selecting test tools:• does it allow integration of network and mobile data?• Cost, features, convenience, availability, and support• new tools are introduced every few months - investigate!

QualcommMDM, CAIT

Grayson

Comarco

Willtech

EricssonTEMS

Motorola

PN Scanners

Agilent(HP + SAFCO)

Agilent(HP + SAFCO)

BerkeleyVaritronics

Grayson Qualcomm

DTI Willtech


Qualcomm’s MDM: Mobile Diagnostic Monitor

The Qualcomm Mobile Diagnostic Monitor was the industry’s first field diagnostic tool

• used industry-wide in the early deployment of CDMA

• pictures at right from Sprint’s first 1996-7 CDMA trials in Kansas City

Qualcomm’s Mobile Diagnostic Monitor • CDMA handset (customer provided)• Proprietary connecting cable• PC software for collection and field pre-

analysis– Temporal analyzer display mode– Messaging


Grayson’s Invex3G Tool

100 MB ethernet connection to PCthe eight card slots can hold receivers or dual-phone cardsthere’s also room for two internal PN scannersMultiple Invex units can be cascaded for multi-phone load-test applicationsCards are field-swappable -Users can reconfigure the unit in the field for different tasks without factory assistance


This mobile is in a 2-way soft handoff (two green FCH walsh codes assigned) in the middle of a downlink SCH burst. Notice walsh code #3, 4 chips long, is assigned as an SCH but only on one sector, and the downlink data speed is 153.6kb/s.

153.6kb/s

Grayson Invex 1x Data Example

February, 2005RF100 v2.0 (c) 2005 Scott BaxterTechnical Introduction to Wireless -- ©1997 Scott Baxter - V0.0 136

F-SCH rates 153.6 kbps; R-SCH 76.8kbps

PN Scanner Data

Grayson Invex 1xData Example

Current Data Task StatusLayer-3 Messages

CDMA Status


WillTech Tools

Blue Rose platform can manage multiple phones and collect data

• Internal processor manages test operations independently for stand-alone operation

• Internal PCMCIA flash card provides storage

• An external PC can display collected data during or after data collection


Agilent Drive-Test Tools

Agilent offers Drive-Test tools• Serial interfaces for up to four

CDMA phones• A very flexible digital receiver

with several modesPN Scanner

• Fast, GPS-locked, can scan two carrier frequencies

Spectrum Analyzer• Can scan entire 800 or 1900

mHz. BandsBase-Station Over-Air Tester (BOAT)

• Can display all walsh channel activity on a specific sector

• Useful for identifying hardware problems, monitoring instantaneous traffic levels, etc.

Post-Processing tool: OPAS32


Comarco Mobile Tools

X-Series Units for more data-intensive collection activities

• Multiple handsets can be collected

• Data is displayed and collected on PC

LT-Series provides integrated display and logging"Workbench" Post-Processing tool analyzes drive-test files


PN Scanners

Why PN scanners? Because phones can’t scan remaining set fast enough, miss transient interfering signalsBerkeley Varitronics

• high-resolution, GPS-locked– full-PN scan speed 26-2/3 ms.

• 2048 parallel processors for very fast detection of transient interferors

Agilent (formerly Hewlett-Packard)• high resolution, GPS-locked

– full-PN scan speed 1.2 sec.• Integrated with spectrum analyzer and

phone call-processing toolGrayson Wireless

• New digital receiver provides CDMA PN searcher and and sector walsh domain displays


Post-Processing ToolsPost-Processing tools display drive-test files

for detailed analysis - Faster, more effective than studying data playback with collection tools aloneActix Analyzer

• Imports/analyzes data from almost every brand of drive-test collection tool

Grayson Interpreter• Imports/analyzes data from Grayson

Wireless Inspector, Illuminator, and Invex3G

Agilent OPAS32• Imports/analyzes a variety of data

Nortel RF Optimizer• Can merge/analyze drive-test and

Nortel CDMA system dataWavelinkComarco "Workbench" ToolVerizon/Airtouch internal tool “DataPro”

OPAS32

COMARCO


Maintenance Features of CDMA Handsets

Maintenance Features of CDMA Handsets

Drive-Tests: Phones


Handsets as Tools: Simple but always Available!

Most CDMA handsets provide some form of maintenance display (“Debug Mode”) as well as instrumentation access

• all CDMA drive-test tools use handsets as their “front-ends”Using the handset as a manual tool without Commercial Test Tools:

Enter the maintenance mode by special sequence of keystrokesDisplayed Parameters

• PN Offset, Handset Mode, Received RF Level , Transmit Gain AdjustMaintenance Display Applications

• best serving cell/sector• simple call debugging (symptoms of weak RF, forward link

interference, etc.)Handset Limitations during manual observation

• no memory: real-time observations only; no access to messages or call details; serving PN offset not updated during voice calls


Older Qualcomm/Sony Maintenance Displays

MAIN MENU 1:Volume2:Call Info3:Security

D

FEATURES 41:AutoAnswer2:AutoRetry3:Scratch

D

Menu

4

0

ENTER FIELDSERVICE CODE

******

D

DEBUG 01:Screen2:Test Calls3:CDMA Only

D

DEBUG 04:Errors5:Clr Errors6:13K Voice

D

318 2 9DX A 7F

D

1

00000 0See following

legend for maintenance

display values(* or correct code, if different)

Press This: See This: continue: See This:

*

*


Qualcomm & Sony Phones with Jog Dials

Enter 111111Press dial in for OPTIONSDial to FIELD DEBUG, pressenter Field Debug Security Codepress Screen


Interpreting the QCP Maintenance Display

318 2 94X A 7F

D

PN Offset

0 - Pilot Channel Acquisition Substate1 - Sync Channel Acquisition Substate2 - MS Idle State3 - System Access State4 - Traffic Channel State

Receive State

Receive Power

UnsupportedA = active pilotsX = exit reason

Transmit Adjust80 -10980 -10900 00A -514 -101E -1528 -20

FFF5E6D7C8B9AA9B8C80

-67-70-75-80-85-90-95-100-105-109

QCP-1900

QCP-800

-64-67-72-77-82-87-92-97-102-106

Receive Power Conversion:RXdbm=XXDEC / 3 - 63.25 (800 MHz)RXdbm=XXDEC / 3 - 66.25 (1900 MHz)(if XX>7F, use XX = XXDEC-256)Transmit Gain Adjust Conversion:TXADJdb=XXDEC / 2Transmit Power Output Conversion:TXdbm= -73 -RXDBM - TXADJdb (800 MHz)TXdbm= -76 -RXDBM - TXADJdb (1900 MHz)


Kyocera 2035 Maintenance Mode

Steps to enter maintenance mode:111111EnterOptions: DebugEnterEnter Field Debug Code

• 000000Field DebugDebug ScreenEnterBasicEnter


Kyocera 6035 Maintenance Mode

111111Jog > OptionsJog > DebugOpen flip to continueEnter Code

• 0 0 0 0 0 0OKSCREEN


Early Samsung Maintenance Display

8

01

00000 0See following

legend for maintenance

display values(* or correct code, if different)

Press This: See This: continue: See This:

*

*

Menu Main Menu ↑1:Call Logs2:Phone Book

SVC

Setup ↑1:Auto Retry2:Anykey Ans

SVC

Service Code??????

SVC

Debug Menu ↑1:Screen2:Test Calls

SVC

Debug Menu ↑3:Errors4:Erase Error

SVC

S04379 SI0 1T-63 D105-06P016 CH0600

SVC


Samsung SCH-3500 Maintenance Display

Here are the steps to enter maintenance mode:MENUSETUP0 (undocumented “trap door”)000000 (operator’s code)Screen

See the Samsung idle and in-call maintenance screens at the end of the Samsung phones.


Samsung SCH-8500 Maintenance Display

Here are the steps to enter maintenance mode:[Menu] [down][down][down][down] [down][down][down] Setup/Tool [OK] [0] Service Code ?????? [0] [4] [0] [7] [9] [3] Screen [OK]



Samsung SCH-A500 Maintenance Display

Here are the steps to enter maintenance mode:Select settingsselect displayselectenter 0enter 040793



Samsung SCH-A460 Maintenance Display

Enter the following to enter maintenance mode:# # D E B U G[OK][OK]

See the Samsung idle and in-call maintenance screens at the end of the Samsung pages.


Samsung “Uproar” Maintenance Display

The “uproar” is no longer in production but included an MP3 player -- the ultimate consumer device.If you’re still enjoying one, here are the steps to enter the maintenance display:

1. Press the MENU button.2. Press 9 on the keypad.3. Then press and hold the * key

until the field service code screen appears.

4. Then type in the field service code 040793


Interpreting Samsung Maintenance Display:Acquisition, Idle, and Access States

Transmit Power Output Calculation:TXdbm= -73 -RXDBM - TXADJdb (800 MHz)TXdbm= -76 -RXDBM - TXADJdb (1900 MHz)

S04379 SI0 1T-63 D085-06P016 CH0600

svc

PN Offset

0 - Pilot Channel Acquisition Substate1 - Sync Channel Acquisition Substate2 - MS Idle State3 - System Access State4 - Traffic Channel State5,6,7 - various call service options

Processing StateReceive Power,

dbmTransmit

Gain Adjust,db

Display toggles between:System Identifier (SID)Network Identifier (NID)

Frequency(channel #)

Ec/Io, db(primary PN only)

Slot Cycle Index


Interpreting Samsung Maintenance Display:Traffic Channel State

Transmit Power Output Calculation:TXdbm= -73 -RXDBM - TXADJdb (800 MHz)TXdbm= -76 -RXDBM - TXADJdb (1900 MHz)

TV1 RV8 08 7T-63 D085-06P016 CH0600

svc

PN Offset

0 - Pilot Channel Acquisition Substate1 - Sync Channel Acquisition Substate2 - MS Idle State3 - System Access State4 - Traffic Channel State5,6,7 - various call service options

Processing StateReceive Power,

dbmTransmit Gain Adjust,

db

TransmitVocoder Rate

1 = 1/82 = 1/44 = 1/28 = Full

Frequency(channel #)

Walshcode

assigned

Receive Vocoder

Rate

Ec/Io, db(primary PN only)


Entering Denso Debug Mode

Enter ##DEBUG (##33284)Scroll down to SAVEPress OKHighlight SERVICE SCREENPress OK

If you want to make a test call, dial the digits and press OK while in idle mode

CBV: 3957ABU: 3954 ABT: 031ARF: 0000 CCL: 01SID: 04157NID: 00001CH: 0100 RSSI: 093DPN: 084 TX:-46BFRM:0000000968TFRM:0000135712FER:% 000.71LT: 036:06:36LG: -086:45:36EC: -16 -63 -63PN: 084 084 084FNGLK: Y Y NWLSH: 01 01 01ACT: 084 484 096-01 -01 200CND: 220 332 200200 332 NGH: 076080 340 068 196O56 320 220 316344 488 196 200392 124 128 084224 008 084

D


Denso Maintenance Display

CBV: 3957ABV: 3954 ABT: 031ARF: 0000 CCL: 01SID: 04157NID: 00001CH: 0100 RSSI: 093DPN: 084 TX:-46BFRM:0000000968TFRM:0000135712FER:% 000.71LT: 036:06:36LG: -086:45:36EC: -16 -63 -63PN: 084 084 084FNGLK: Y Y NWLSH: 01 01 01ACT: 084 484 096-01 -01 200CND: 220 332 200200 332 NGH: 076080 340 068 196O56 320 220 316344 488 196 200392 124 128 084224 008 084

DCharging Battery Voltage

Average Battery Voltage Average Battery Temperature

System IDNetwork ID

RF Channel FrequencyDigital PN Offset

Received Signal StrengthEstimated Transmitter

Power OutputNumber of Bad Frames

Number of Good Frames Frame Erasure Rate, PercentBase Station coordinates

Current status of Rake Fingers

Active Pilot Set

Candidate Pilot SetNeighbor Pilot Set


Early Sanyo Dual-Band Phones

press menu 7, 0enter in DEBUGM (332846) screens are similar to QCP phones

7

0

48233 6

Press This:

Menu

318 2 94X A 7F

D


Sanyo SPC-4500 Maintenance Display

Choose the following:DISPLAYOK0OKEnter Code: 0 0 0 0 0 0Debug MenuSCREENOK


Sanyo SPC-4900 Maintenance Display

##040793select MENU/OK buttonscroll to save Phone #select

PN offset

Call Proc. StateReceivePower

Io

ChannelFrequency


Entering Maintenance Mode: Motorola StarTacContact your service provider to obtain your phone’s Master

Subscriber entity Lock (MSL). Then enter the following:FCN 000000 000000 0 RCL You'll be prompted for your MSL, enter it and press STO.

• New prompts will appear, Press STO in response to each prompt until no more appear. Don’t delay -continue quickly and enter:

FCN 0 0 * * T E S T M O D E STO • The display will briefly show US then just '.

Press 55#.• Step 1 will appear with its current setting displayed.

Press * to accept and move on to the next step. Repeat for steps 2-8.

Step 9 (Option byte 2) is the only step requiring manual changes. Enter 1 0 0 0 0 0 0 0 (The leftmost bit now set to '1' is what enables test mode.)Now press STO to accept the entry and exit back to the ' prompt.Power off and back on.You should now be in test mode!



RX Power BatteryCondition

N5 N5M failureBS BS Ack failureWO L3 WFO State TimeoutMP Max Probe FailurePC Paging Channel lossRR Reorder or Release on PCH?? Unknown Condition

ChannelNumber

#Neighbors

Local Time#

ActivesStrongest Active

PN Ec/IoStrongest NeighborPN Ec/Io

# Cand-idates Call Proc

StateLast Call

Exit Reason# Drops

# CallsLast Call FER%

NIDSIDRx Powerdbm (Io)

Tx Powerdbm

CurrentService Option

Last Call IndicatorNI No Indication yetMR Mobile ReleaseBR Base Sta. ReleaseTC Traffic Channel LostL2 Layer 2 Ack FailNC No Channel Assn Msg

Current Service Option8V 8K voice originalIL 8K loopback8EV 8K EVRC8S 8K SMS13L 13K loopback

13S 13K SMS8MO 8K Markov OldDAT Data8M 8K Markov New13M 13K Markov New13V 13K Voice

Call Processing StatesCP CP ExitRST CP RestartRTC RestrictedPLT Pilot AcquisitionSYN Sync AcquisitionTIM Timing ChangeBKS Background SchIDL IdleOVD OverheadPAG Paging

ORG Call OriginationSMS Short Message SvcORD Order ResponseREG RegistrationTCI Tfc Ch InitializationWFO Waiting for OrderWFA Waiting for AnswerCON Conversation stateREL ReleaseNON No State


Motorola V120C Series

MENU 073887* Enter 000000 for security code. Scroll down to Test Mode. Enter subscriber entity lock code if required by your phone

Same maintenance display as shown for Startac


Motorola V60C

MENU 073887* Enter 000000 for security code. Scroll down to Test Mode. Enter subscriber entity lock code if required by your phone

Same maintenance display as shown for Startac


Audiovox 8100, 9155

Press ##27732726 [End] Select the Debug screen.PN, channel#, SID, NID, mode (13K, EVRC, etc) Ec/Io, RX Level, TX Level.You cannot make a call while in any of the maintenance screens.


NeoPoint Phones

Although NeoPoint went out of business in June, 2001, there are still some NeoPointhandsets in general usePress the M (menu) keySelect Preferences (using the up-arrow key)Enter 040793Choose Debug Screen [Select]Now you’re in maintenance mode!


GoldStar TouchPoint

To enter maintenance mode, just key in: # # D E B U G SAVE


Nokia 6185 Maintenance Display

Enter *3001#12345# MENUScroll down to Field testPress SelectScroll up to EnabledPress OKPower the phone off and onYou should now be in Field test mode


Older Nokia Models Maintenance Display

Enter *3001#12345# MENUScroll down to Field testPress SelectScroll up to EnabledPress OKPower the phone off and onYou should now be in Field test mode and the following screens will be available:


Maintenance Display Screens of Nokia Handsets

CSST

XXXXX

RSSICCCC

RXTX

CS StateIdle: PN Offset

TFC: #Actv, FERRSSI dBm

Paging Channel #RX power, dbmTX power, dbm

Screen 1: General

CSSTPGCH

CURSOFER

CS StatePaging Channel #

Current Service OptionFrame Error Rate

Screen 2: Paging CH Info

Mobile MINMobile Station ESN

Preferred Sys 1=AMPS, 2=CDMA

OwnNumberESN

P

A Operator Selected(1=A, 2=B, 3=both

Screen 4: NAM Info

Primary Channel ASecondary Channel A

PPCASPCA

Screen 5: NAM Info

Primary Channel BSecondary Channel B

PPCBSPCB

Local UseAccess Overload Class

LA

Current SIDCurrent NID

SIDNID

Screen 6: BS & Access. Info.

DBUS (Handsfree?)DBUS

BASE_ID (sys par msg)P_REV (sync msg)

BASE#P_REV

Screen 7: BS Protocol Rev. Level

MIN_P_REV (sync msg.MIN_P_REV

CS StateDate from System Time

CSSTMMDDYY

Screen 8: Time Information

System TimeHHMMSS

The following screens appear in field test mode on Nokia HD881 series of Handsets:


Nokia Maintenance Display Screens (continued)

TADDTDROP

TATD

Screen 9: Acquisition Information

TCOMPTCTTDROPTT

Active WindowWW1Neighbor WindowWW2

Remaining WindowWW3

Pilot PN OffsetEc/Io in 1/2 db units

PPNEC

Screen 10: Active Set (#1-3)

Keep? 1KPilot PN Offset

Ec/Io in 1/2 db unitsPPNEC



Keep? 1K

Pilot PN OffsetEc/Io in 1/2 db units

PPNEC

Screen 11: Active Set (#4-6)





Keep? 1K



NBR 1 PN OffsetEc/Io in 1/2 db units

PPNEC

Screen 12: Neighbor Set (#1-5)


PPNEC


PPNEC


PPNEC


PPNEC


PPNEC



PPNEC


PPNEC


PPNEC


PPNEC


PPNEC



PPNEC


PPNEC


PPNEC


PPNEC


PPNEC



PPNEC


PPNEC


PPNEC


PPNEC



CAND 1 PN OffsetEc/Io in 1/2 db units

PPNEC

Screen 16: Candidate Set (#1-5)


PPNEC


PPNEC


PPNEC


PPNEC

Task NameWorst-Cs Stack Free Sp

TASKNFREE

Screen 17-22: Task Stack Ck Info

Overflow ind. by shift2=sys stack overflow

Task StackSys Stack

Screen 23: Stack Status Info.

Screen 24: Codec Registers


Novatel Merlin C201 Card

Enter # # D E B U G to enter maintenance mode.To exit, just click “OK” box in the Debug window.


Audiovox Thera Maintenance Mode Screens

How to enterDebug Mode:

[ctrl] [D] [enter]

Advanced Usr Pwd:##DEBUG [enter]

Protocol Statistics


What’s New in CDMA2000?What’s New in CDMA2000?

The Future is Here! CDMA2000


What’s New in CDMA2000?

CDMA2000 is the next-generation family of CDMA standardsCDMA2000 Phase I: 1xRTT

Independent I and Q modulation almost doubles capacity, compared to old IS-95 modulation with I and Q duplicationNew types of channels are provided

• “fundamental” channels like IS-95 traffic channels, but better coded so they require less air-interface capacity; circuit-switched

• new “supplemental” channels can carry fast data (153K, 230K, even 307Kbps); assigned for packet bursts, not continuously

• also optional new administrative channels for smoother operations• a sector can carry a dynamic “mix” of both new channel types, as well

as old IS-95 traffic channels simultaneously!CDMA2000 Phase II: 1xEV DO, 1xEV DV, and 3xRTT

3xRTT: Faster data on a bundle of 3 1x carriers; probably won’t be used1xEV DO: 1x Evolution, Data Only (IS-856) Qualcomm & Lucent

• Fast data up to 2.4 Mbps on a dedicated 1.2 MHz. CDMA Carrier1xEV DV: 1x Evolution, Data and Voice “1Xtreme” Motorola & Nokia

• Fast data up to 5 Mbps on a 1.2 MHz. carrier still supporting a mix of fast data and voice traffic


The CDMA Migration Path to 3G

1xEV-DORev. A

IS-856

1250 kHz.59 active

users

Higher data rates on data-

only CDMA carrier

3.1 Mb/sDL

1.8 Mb/sUL

RL FLSpectrum

1xEV-DORev. 0IS-856

1250 kHz.59 active

users

High data rates on data-only

CDMA carrier

2.4 Mb/sDL

153 Kb/sUL

CDMAone CDMA2000 / IS-2000

Technology

Generation

SignalBandwidth,

#Users


Progress

1G

AMPS

DataCapabilities

30 kHz.1


&Handoffs

None,2.4K by modem

2G

IS-95A/J-Std008

1250 kHz.20-35

First CDMA,

Capacity,Quality

14.4K

2G

IS-95B

1250 kHz.25-40

•Improved Access•Smarter Handoffs

64K

2.5G? 3G

IS-2000:1xRTT

1250 kHz.50-80 voice

and data

•Enhanced Access

•Channel Structure

153K307K230K

3G

1xEV-DV1xTreme

1250 kHz.Many packet

users

High data rates on

Data-Voice shared CDMA carrier

5 Mb/s

3G

IS-2000:3xRTT

F: 3x 1250kR: 3687k

120-210 per 3 carriers

Faster data rates on shared 3-carrier bundle

1.0 Mb/s

RL FLRL FLRL FLRL FLRL FLRL FLRL FL


Modulation Techniques of 1xEV Technologies

1xEV, “1x Evolution”, is a family of alternative fast-data schemes that can be implemented on a 1x CDMA carrier.1xEV DO means “1x Evolution, Data Only”, originally proposed by Qualcomm as “High Data Rates” (HDR).

• Up to 2.4576 Mbps forward, 153.6 kbps reverse

• A 1xEV DO carrier holds only packet data, and does not support circuit-switched voice

• Commercially available in 20031xEV DV means “1x Evolution, Data and Voice”.

• Max throughput of 5 Mbps forward, 307.2k reverse

• Backward compatible with IS-95/1xRTT voice calls on the same carrier as the data

• Not yet commercially available; work continues

All versions of 1xEV use advanced modulation techniques to achieve high throughputs.

QPSKCDMA IS-95,

IS-2000 1xRTT,and lower ratesof 1xEV-DO, DV

16QAM1xEV-DOat highest

rates

64QAM1xEV-DVat highest

rates


Channel Structure of 1xEV-DO vs. 1xRTTCHANNEL STRUCTURE

IS-95 and 1xRTT• many simultaneous users, each

with steady forward and reverse traffic channels

• transmissions arranged, requested, confirmed by layer-3 messages – with some delay……

1xEV-DO -- Very Different:• Forward Link goes to one user at a

time – like TDMA!• users are rapidly time-multiplexed,

each receives fair share of available sector time

• instant preference given to user with ideal receiving conditions, to maximize average throughput

• transmissions arranged and requested via steady MAC-layer walsh streams – very immediate!

BTS

IS-95 AND 1xRTTMany users’ simultaneous forward

and reverse traffic channelsW0W32W1W17W25W41

W3

W53

PILOTSYNC

PAGINGF-FCH1F-FCH2F-FCH3

F-SCH

F-FCH4

AP

1xEV-DO AP (Access Point)

ATs (Access Terminals)

1xEV-DO Forward Link


Power Management of 1xEV-DO vs. 1xRTT

POWER MANAGEMENTIS-95 and 1xRTT:

• sectors adjust each user’s channel power to maintain a preset target FER

1xEV-DO IS-856:• sectors always operate at

maximum power• sector output is time-

multiplexed, with only one user served at any instant

• The transmission data rate is set to the maximum speed the user can receive at that moment

PILOT

PAGINGSYNC

Maximum Sector Transmit Power

User 123

45 5 5678

time

pow

er

IS-95: VARIABLE POWER TO MAINTAIN USER FER

time

pow

er

1xEV-DO: MAX POWER ALWAYS,DATA RATE OPTIMIZED


CDMA Network for Circuit-Switched Voice Calls

The first commercial IS-95 CDMA systems provided only circuit-switched voice calls

t1t1 v CESEL

t1PSTN

BTS



CDMA 1xRTT Voice and Data Network

CDMA2000 1xRTT networks added two new capabilities:• channel elements able to generate and carry independent streams of

symbols on the I and Q channels of the QPSK RF signal– this roughly doubles capacity compared to IS-95

• a separate IP network implementing packet connections from the mobile through to the outside internet

– including Packet Data Serving Nodes (PDSNs) and a dedicated direct data connection (the Packet-Radio Interface) to the heart of the BSC

The overall connection speed was still limited by the 1xRTT air interface

t1t1 v CESEL

t1

PDSNForeign Agent

PDSNHome Agent


VPNs

PSTN


AccountingAAA

BTS



1xEV-DO Overlaid On Existing 1xRTT Network

1xEV-DO requires faster resource management than 1x BSCs can give• this is provided by the new Data Only Radio Network Controller (DO-RNC)

A new controller and packet controller software are needed in the BTS to manage the radio resources for EV sessions

• in some cases dedicated channel elements and even dedicated backhaul is used for the EV-DO traffic

The new DO-OMC administers the DO-RNC and BTS PCF additionExisting PDSNs and backbone network are used with minor upgradingThe following sections show Lucent, Motorola, and Nortel’s specific solutions

t1t1 v CESEL

t1

PDSNForeign Agent

PDSNHome Agent


VPNs

PSTN


AccountingAAA

BTS

(C)BSC/Access ManagerSwitch CE

DORadio

NetworkController

DO-OMC


3G Information ResourcesBibliography - Articles - Web Links

3G Information ResourcesBibliography - Articles - Web Links


Bibliography, 3G Air Interface Technologies“3G Wireless Demystified” by Lawrence Harte, Richard Levine, and Roman Kitka488pp. Paperback, 2001 McGraw Hill, ISSBN 0-07-136301-7 $50. For both non-technical and

technical readers. An excellent starting point for understanding all the major technologies and the whole 3G movement. Comfortable plain-language explanations of all the 2G and 3G air interfaces, yet including very succinct, complete, and rigorously correct technical details. You will still want to read books at a deeper technical level in your chosen technology, and may sometimes turn to the applicable standards for finer details, but this book will give you what you won’t find elsewhere -- how everything relates in the big picture, and probably everything you care to know about technologies other than your own.

"Wireless Network Evolution 2G to 3G" by Vijay K. Garg. 764pp. 2002 Prentice-Hall, Inc. ISBN 0-13-028077-1. $80. Excellent technical tutorial and reference. The most complete and comprehensive technical detail seen in a single text on all these technologies: IS-95 2G CDMA, CDMA2000 3G CDMA, UMTS/WCDMA, Bluetooth, WLAN standards (802.11a, b, WILAN). Includes good foundation information on CDMA air interface traffic capacity, CDMA system design and optimization, and wireless IP operations. Excellent level of operational detail for IS-95 systems operating today as well as thorough explanations of 2.5G and 3G enhancements.

"3G Wireless Networks" by Clint Smith and Daniel Collins. 622pp. Paperback. 2002 McGraw-Hill, ISBN 0-07-136381-5. $60. An excellent overview of all 3G technologies coupled with good detail of network architectures, channel structures, and general operational details. Good treatment of both CDMA2000 and UMTS/WCDMA systems.

“WCDMA: Towards IP Mobility and Mobile Internet” by Tero Ojanpera and Ramjee Prasad. 476pp. 2001 Artech House, ISSBN 1-58053-180-6. $100. The most complete and definitive work on UMTS (excellent CDMA2000, too!). CDMA principles, Mobile Internet, RF Environment & Design, Air Interface, WCDMA FDD standard, WCDMA TDD, CDMA2000, Performance, Heirarchical Cell Structures, Implementation, Network Planning, Basic IP Principles, Network Architectures, Standardization, Future Directions. This is a MUST HAVE for a one-book library!


More Bibliography, 3G Air Interface Technologies

“The UMTS Network and Radio Access Technology” by Dr. Jonathan P. Castro, 354 pp. 2001 John Wiley, ISBN 0 471 81375 3, $120. An excellent, well-organized, and understandable exploration of UMTS. Includes radio interface, channel explanations, link budgets, network architecture, service types, ip network considerations, a masterful tour de force through the entire subject area. Very readable, too!

“WCDMA for UMTS” by Harri Holma and Antti Toskala, 322 pp. 2000 Wiley, ISBN 0 471 72051 8, $60. Very good overall treatment of UMTS. Excellent introduction to 3G and summary of standardization activities, every level of UMTS/UTRA. Good overview of CDMA-2000, too!

“The GSM Network - GPRS Evolution: One Step Towards UMTS” 2nd Edition by Joachim Tisal, 227pp. paperback, 2001 Wiley, ISBN 0 471 49816 5, $60. Readable but not overwhelming introduction to GSM in all its aspects (140pp), DECT (11pp), GPRS (6pp), UMTS (7pp), WAP (25pp), EDGE (10pp).


Bibliography, The IP Aspect of 3G“Mobile IP: Design, Principles and Practices” by Charles E. Perkins, 275 pp., 200, 1998 Addison-

Wesley, ISBN 0-201-63469-4. $60. Comprehensive view of Mobile IP including home and foreign agents, advertisement, discovery, registration, datagrams, tunneling, encapsulation, route optimization, handoffs, firewalls, IPv6, DHCP. Tour-de-force of mobile IP techniques.

“Mobile IP Technology for M-Business” by Mark Norris, 291 pp., 2001 Artech House, ISSBN 1-58053-301-9. $67. GPRS overview and background, Mobile IP, Addressing, Routing, M-business, future prospects, IPv4, IPv6, Bluetooth & IrDA summaries.

“TCP/IP Explained” by Phillip Miller, 1997 Digital Press, ISBN 1-55558-166-8, 518pp. $50. In-depth understanding of the Internet protocol suite, network access and link layers, addressing, subnetting, name/address resolution, routing, error reporting/recovery, network management. IF you’re not already strong in TCP/IP, you’ll need this to fully master Mobile IP.

“Cisco Networking Academy Program: First-Year Companion Guide” edited by Vito Amato, 1999 Cisco Press, ISBN 1-57870-126-0, 438pp. Textbook supporting a year-long course on networking technologies for aspiring LAN/WAN (and 3G) technicians and engineers. It covers every popular networking technology (including all its elements and devices) in deep and practical detail. Excellent real-world understanding of TCP/IP, as well as the nuts-and-bolts of everything from physical components to protocols to actual devices such as routers, switches, etc. You might even want to take the evening courses at a local community college near you.

“Cisco Networking Academy Program: Engineering Journal and Workbook, Volume I” edited by Vito Amato, 1999 Cisco Press, ISBN 1-57870-126-x, 291pp. The workbook for the First Year Companion Guide above. If you want some external structure in your self-study, this workbook will hold your hand as you climb every step of the ladder, and will lead you step by step through the sister textbook, ensuring you absorb everything you need to know.


Bibliography - General CDMA“IS-95 CDMA and CDMA2000: Cellular/PCS Systems Implementation” by Vijay K. Garg. 422 pp.

2000 Prentice Hall, ISBN 0-13-087112-5, $90. IS-95 and CDMA2000 Access technologies, DSSS, IS-95 air interface, channels, call processing, power control, signaling, soft handoff, netw. planning, capacity, data. CDMA2000 layers, channels, coding, comparison w/ WCDMA.

“CDMA Systems Engineering Handbook” by Jhong Sam Lee and Leonard E. Miller, 1998 ArtechHouse, ISBN 0-89006-990-5. Excellent treatment of CDMA basics and deeper theory, cell and system design principles, system performance optimization, capacity issues. Recommended.

“CDMA RF System Engineering” by Samuel C. Yang, 1998 Artech House, ISBN 0-89006-991-3. Good general treatment of CDMA capacity considerations from mathematical viewpoint.

“CDMA Internetworking: Deploying the Open A-Interface” by Low and Schneider. 616 pp. 2000 Prentice Hall, ISBN 0-13-088922-9, $75. A tour-de-force exposition of the networking between the CDMA BSC, BTS, and mobile, including messaging and protocols of IS-634. Chapters on SS7, Call Processing, Mobility Management, Supplementary Services, Authentication, Resource Management (both radio and terrestrial), 3G A-Interface details. One-of-a-kind work!

"CDMA: Principles of Spread Spectrum Communication" by Andrew J. Viterbi. 245 p. Addison-Wesley 1995. ISBN 0-201-63374-4, $65. Very deep CDMA Theory. Prestige collector’s item.


Bibliography - General Wireless

“Mobile and Personal Communication Services and Systems” by Raj Pandya, 334 pp. 2000 IEEE Press, $60. IEEE order #PC5395, ISBN 0-7803-4708-0. Good technical overview of AMPS, TACS< NMT, NTT, GSM, IS-136, PDC, IS-95, CT2, DECT, PACS, PHS, mobile data, wireless LANs, mobile IP, WATM, IMT2000 initiatives by region, global mobile satellite systems, UPT, numbers and identities, performance benchmarks.

“Wireless Telecom FAQs” by Clint Smith, 2001 McGraw Hill, ISBN 0-07-134102-1. Succint, lucid explanations of telecom terms in both wireless and landline technologies. Includes cellular architecture, AMPS, GSM, TDMA, iDEN, CDMA. Very thorough coverage; an excellent reference for new technical people or anyone wishing for clear explanations of wireless terms.

"Mobile Communications Engineering" 2nd. Edition by William C. Y. Lee. 689 pp. McGraw Hill 1998 $65. ISBN 0-07-037103-2 Lee’s latest/greatest reference work on all of wireless; well done.


Web Links and Downloadable Resources

Scott Baxter: http://www.howcdmaworks.comLatest versions of all courses are downloadable. Category - Username - PasswordIntro - (none required) - (none required)RF/CDMA/Performance - shannon - hertz3G - generation - thirdGrayson - telecom - allenAgilent - nitro - viper

Dr. Ernest Simo’s Space2000: http://www.cdmaonline.com/ and http://www.3Gonline.com/

CDG: http://www.cdg.org (check out the digivents multimedia viewable sessions)The IS-95 and IS-2000 CDMA trade marketing webside, CDMA cheerleaders.

GSM: http://www.gsmworld.comThe GSM Association website. Worldwide GSM marketing cheerleaders but also includes some excellent GSM and GPRS technical overview whitepapers and documents; latest user figures.

UWCC: http://www.uwcc.comThe IS-136 TDMA trade marketing website, TDMA cheerleaders.

RCR News: http://www.rcrnews.comWireless Industry trade publication - regulatory, technical, business, marketing news.Subscribers can access text archives of past articles; very handy in researching events.

Wireless Week: http://www.wirelessweek.comWireless Industry trade publication - regulatory, technical, business, marketing news.


More Web Links

3GPP: http://www.3gpp.org/The operators’ harmonization group concerned mainly with ETSI-related standards

3GPP2: http://www.3gpp2.org/The operators’ harmonization group concerned mainly with IS-95-derived CDMA standards

ITU: http://www.itu.int/imt/

ETSI: http://www.etsi.fr/

UMTS forum: http://www.umts-forum.org/

GSM MoU: http://www.gsmworld.com/

TIA: http://www.tiaonline.org/

T1: http://www.t1.org/

ARIB: http://www.arib.or.jp/arib/english/index.html

TTC: http://www.ttc.or.jp/

TTA: http://www.tta.or.kr/

ETRI: http://www.etri.re.kr/

RAST: http://www.rast.etsi.fi/

February, 2005 Supplement - 1RF100 v2.0 (c) 2005 Scott Baxter

Course RF100 SupplementCourse RF100 Supplement


Supplemental Topics

Link BudgetsHard Handoff StrategiesReradiatorsSome Operational Measurements and Capacity Considerations3G Systems


Section A

Link BudgetsLink Budgets


Link Budget Example: Usage Model and Service Assumptions

This section outlines the number of subscribers and amount of traffic by yearThis section shows the variability of outdoor and indoor signals, and the building penetration loss

Interactive Initial System Design Example v1.2fill in GREEN fieldsYELLOW fields calculate automatically

Step 1. Basic Business Plan Details

Year Launch 1 2 3 4 5Population 3,886,000 3,949,350 4,012,700 4,076,050 4,139,400 4,202,750Penetration, % 0.05% 1.85% 3.72% 5.64% 7.60% 9.57%#Customers 1,781 72,933 149,453 229,941 314,451 402,360BH Erl/Cust 0.1 0.05 0.045 0.05 0.05 0.05Total BH erl 178.1 3,646.7 6,725.4 11,497.0 15,722.6 20,118.0

2. Enter building penetration loss and standard deviations from measurements.

Composite Probability Of Service & Required Fade MarginEnvironment

Type ("morphology")

Building Median

Loss, dB

Building Std. Dev,

dB

Outdoor Std. Dev,

dB.

Composite Standard Deviation

Desired Reliability at Cell Edge, %

Fade Margin,

dB.Dense Urban 20 8 8 11.31 75.0% 7.63Urban 15 8 8 11.31 75.0% 7.63Suburban 15 8 8 11.31 75.0% 7.63Rural 10 8 8 11.31 75.0% 7.63Highway 8 6 8 10.00 75.0% 6.74


Reverse Link Budget Example

The Reverse Link Budget describes how the energy from the phone is distributed to the base station, including the major components of loss and gain within the system

3. Construct Link Budgets

Reverse Link Budget

Term or Factor GivenDense Urb. Urban Suburban Rural Highway Formula

MS TX Power (dbm) (+) 23MS antenna gain and body loss (+/-) 0MS EIRP (dBm) (+) 23.00 23.00 23.00 23.00 23.00 AFade Margin, (dB) (-) -7.63 -7.63 -7.63 -7.63 -6.74 BSoft Handoff Gain (dB) (+) 4 4 4 4 4 CReceiver Interf. Margin (dB) (-) -3 -3 -3 -3 -3 DBuilding Penetration Loss (dB) (-) -20.00 -15.00 -15.00 -10.00 -8.00 EBTS RX antenna gain (dBi) (+) 17 17 17 17 17 FBTS cable loss (dB) (-) -3 -3 -3 -3 -3 G

kTB (dBm/14.4 KHz.) -132.4 HBTS noise figure (dB) 6.5 I

Eb/Nt (dB) 5.9 JBTS RX sensitivity (dBm) (-) -120.0 -120.0 -120.0 -120.0 -120.0 H+I+J

Survivable Uplink Path Loss (dB) (+) 130.4 135.4 135.4 140.4 143.3

A+B+C+D+E+F+G-(H+I+J)


Forward Link Budget Example

This section shows the forward link power distribution, and compares the relative balance of the forward and reverse links

Forward Link Budget

Term or Factor GivenDense Urb. Urban Suburban Rural Highway Formula

BTS TX power (dBm) (+) 45 45 45 45 45BTS TX power (watts) 31.62 31.62 31.62 31.62 31.62% Power for traffic channels 74.0% 74.0% 74.0% 74.0% 74.0%Number of Traffic Channels in use 19 19 19 19 19BTS cable loss (dB) (-) -3 -3 -3 -3 -3BTS TX antenna gain (dBi) (+) 17 17 17 17 17BTS EIRP/traffic channel (dBm) (+,-) 44.9 44.9 44.9 44.9 44.9 AFade margin (dB) (-) -7.63 -7.63 -7.63 -7.63 -6.74 BReceiver interference margin (db) (-) -3 -3 -3 -3 -3 CBuilding Penetration Loss (dB) (-) -20.0 -15.0 -15.0 -10.0 -8.0 DMS antenna gain & body loss (dB) (+,-) 0 0 0 0 0 E

kTB (dBm/14.4 KHz.) -132.4Subscriber RX noise figure (dB) 10.5

Eb/Nt (dB) 6Subscriber RX sensitivity (dBm) (-) -115.9 -115.9 -115.9 -115.9 -115.9 F

Survivable Downlink Path Loss, dB (+) 130.2 135.2 135.2 140.2 143.1A+B+C+D

+E-F

Forward/Reverse Link Balance DenseUrban Urban Suburban Rural Highway

Which link is dominant? Reverse Reverse Reverse Reverse ReverseWhat advantage, dB? 0.2 0.2 0.2 0.2 0.2


Link Budgets: What is the Radius of a Cell?

This section uses the Okumura-Hata/Cost-231 model to describe the frequency, antenna heights, and environmental factors, and their relationship on the cell’s coverage distance

4. Explore propagation model to figure coverage radius of cell.

Frequency, MHz. 870Subscriber Antenna Height, M 1.5

DenseUrban Urban Suburban Rural Highway

Base Station Antenna Height, M 20 20 30 50 50

DenseUrban Urban Suburban Rural Highway

Environmental Correction, dB -2 -5 -10 -17 -17Coverage Radius, kM 1.30 2.17 6.87 20.86 25.40

Coverage Radius, Miles 0.81 1.35 4.27 12.96 15.78


Link Budgets: Putting It All Together

Step 4 estimates the number of cells required to serve each distinct environment within the systemSteps 5, 6, and 7 estimate the RF coverage from each cell, and the number of cells required

5. Calculate number of cells required for coverage, ignoring traffic considerations.

Dense TotalUrban Urban Suburban Rural Highway # Cells

Covered Area of this type, kM 2 55 450 1700 3400 1400 RequiredOne cell's coverage in this zone, kM 2 5.35 14.73 148.46 1367.34 2026.72 for System

# Cells required to cover zone 10.3 30.6 11.5 2.5 0.7 55.5

6. What is the traffic capacity (in erlangs) of your chosen BTS configuration, year-by-year?

Year Launch 1 2 3 4 5Erlangs which one BTS can carry 18.3 18.3 90 90 450 450

7, 8. What is the total busy-hour erlang traffic on your system? How many BTS are required?

Year Launch 1 2 3 4 5Total System Busy-Hour Erlangs 178.1 3,646.7 6,725.4 11,497.0 15,722.6 20,118.0

Capacity of One BTS, erlangs 18.3 18.3 90 90 450 450# BTS required to handle all the traffic 9.7 199.3 74.7 127.7 34.9 44.7

9. Examine your market, #BTS required for coverage and capacity; estimate totalnumber of BTS required.

Year Launch 1 2 3 4 5#BTS req'd just to achieve coverage 55.5 55.5 55.5 55.5 55.5 55.5

#BTS required just to carry traffic 9.7 199.3 74.7 127.7 34.9 44.7

Estimated total #BTS required 56.3 206.8 206.8 206.8 206.8 206.8


Section B

Hard Handoff StrategiesHard Handoff Strategies


Co-Channel CDMA Intersystem Handoff IssuesCochannel Hard Handoff Border Interference Problems

Consider two adjacent CDMA systems:• Same frequency• Not yet equipped for intersystem soft handoff, so only hard handoff is

possible between them; “dragged” handoffs become a big problemHandoff Performance Results:

• Mobiles CAN see pilots from adjoining system, so mobile-directed handoff is possible

• However, the handoff will be hard and mobiles can use only one system or the other, not both

• “dragging” mobiles cause severe interference in border cells• capacity, access failures, dropped calls, all will be poor in border area

BSC1 SW1

SW2 BSC2

Frequency 1

DallasFort Worth

Interference


Use Intersystem Soft Handoff:Avoid Border Area Interference Problems

Consider two adjacent CDMA systems:• Same frequency• ATM connection between BSCs allows soft handoff

Handoff Performance Results:• Mobiles CAN see pilots from adjoining system, so mobile-directed

handoff is possible• Intersystem soft handoff is possible, so simultaneous power control is

possible for mobiles in border area• Border RF environment is the same as internal RF environment, no

special problems

BSC1 SW1

SW2 BSC2

Frequency 1

DallasFort Worth

Intersystem Soft HandoffATM link

no problems


Avoid Interference, Use Different Frequencies?Hard Handoff Logistical Problems

Consider two adjacent CDMA systems:• Suppose intersystem soft handoff is not available• Systems are deliberately on different frequencies. This definitely

avoids interference in the border area, but causes other complicationsHandoff Logistical Problems:

• Mobiles on one system can’t see the pilots of adjoining cells on the other system! So, the mobiles will never request trans-border handoff

• Some method must be employed to force unsuspecting mobiles into transborder handoffs

• Common solutions: 1) implement intersystem soft handoff, 2) Pilot beacon cells, 3) auxiliary trigger mechanisms (Ec/Io, RTD, etc.)

Frequency 1

Frequency 2

BSC1 SW1

SW2 BSC2Dallas

Fort Worth

F2 Mobiles can’t see F1 pilots!

F1 Mobiles can’t see F2 pilots!


One Solution to the Multi-Frequency Problem2-Frequency Trigger Method: Beacon Cells

The Beacon Solution• A pilot beacon cell is a “mannequin” -- a signal which can be seen by

arriving mobiles from the other system on their own frequency, inducing them to request handoff as soon as it is appropriate

• When mobiles request soft handoff with the beacon, the old system steps in and instructs the mobiles to do intersystem hard handoff to the real cell which the mobiles are approaching on the other system

Special Logistical Concerns with Beacons• Of course, it’s possible for mobiles of one system to “wake up” looking

at the pilot of a beacon cell in the border area, rather than a real cell.• Therefore, a beacon cell must transmit not only its pilot, but also a

sync channel and a paging channel with global service redirection

Frequency 1

Frequency 2

BSC1 SW1

SW2 BSC2Dallas

Fort Worth

F2 Mobiles can see F2 beacon

F1 Mobiles can see F1 beacon


Another Solution for Multi-Frequency HandoffsBridge Cells, RTD Trigger in Boundary Sectors

All along the intersystem border, a one-cell-thick “transition zone” is created. The “bridge” cells in this zone are equipped with dual equipment, one set operating on each system.

• The outlooking sector of each bridge cell is tagged in the site database as a “boundary sector”. Whenever a mobile is served exclusively by a boundary sector, the system continuously monitors that mobile’s round trip delay (RTD).

• When the mobile’s RTD passes upward through a datafilled threshold, the system steps in and orders a hard handoff to the matching sector of the bridge cell on the other system

– this ensures the handoffs happen in clean environments with highprobability of success

– disadvantage: more BTS hardware needed than otherwise

Frequency 1

Frequency 2

BSC1 SW1

SW2 BSC2

DallasFort WorthBoundary Sector

Boundary Sector


Another Solution for Multi-Frequency HandoffsArbitrary Ec/Io Trigger Mechanisms

Outlooking sectors of border cells are tagged as “boundary sectors” in the system database

• Whenever a mobile is served exclusively by a boundary sector, the system frequently interrogates the mobile with pilot measurementrequest messages

• When the mobile’s reports the boundary sector’s Ec/Io is below a preset threshold, the system immediately commands a hard handoffto a previously defined sector on the other system. Everyone hopes (prays?) that sector is able to hear the mobile for a successful handoff.

– The Ec/Io trigger threshold is sometimes a fixed value (usually 11 db above the T_Drop in the serving sector, although some networks’ later software allows an arbitrary trigger level to be set

Frequency 1

Frequency 2

BSC1 SW1

SW2 BSC2

DallasFort WorthBoundary Sector

Boundary Sector


CDMA/AMPS Overlay Systems: Handdown

CDMA mobiles approaching the edge of CDMA coverage must hand down to AMPS

• however, CDMA mobiles cannot see AMPS signals during CDMA calls, and therefore will not request handoff

Methods for triggering CDMA-to-AMPS Handdown: the same ones we considered for CDMA-CDMA intersystem handoff

• beacon cells• bridge cells with RTD trigger• arbitrary Ec/Io thresholds on boundary sectors

Once a CDMA phone hands down to analog, it cannot be handed back up during the same call (due to long CDMA acquisition time)

CDMA Overlay

AMPS Existing System


CDMA/AMPS Overlays: CDMA Acquisition

System acquisition is primarily controlled by the mobile• dual-mode mobiles look for CDMA first, then AMPS if needed

Distant mobiles may find unreliable CDMA signals beyond the edge of CDMA coverage, originate calls likely to drop

• most systems transmit Global Service Redirection Messages on all out-looking sectors to immediately force any distant mobiles to reacquire on AMPS

– hence no CDMA originations on outermost CDMA sectors!– However, still possible to soft-handoff into outer sectors

Many operators request handset manufacturers to add feature of periodic rechecking by idle handsets seeking to acquire CDMA

CDMA Overlay

AMPS Existing System


Section C

ReradiatorsReradiators


Cell RR

Wireless Reradiators

Reradiators (also called “boosters”, “repeaters”, “cell enhancers”) are amplifying devices intended to add coverage to a cell site Reradiators are transparent to the host Wireless system

• A reradiator amplifies RF signals in both directions, uplink and downlink

• The system does not control reradiators and has no knowledge of anything they do to the signals they amplify, on either uplink or downlink

Careful attention is required when using reradiators to solve coverage problems

• to achieve the desired coverage improvement

• to avoid creating interference• to ensure the active search window is large

enough to accommodate both donor signal and reradiator signal as seen by mobiles

Reradiators are a ‘“crutch” with definite application restrictions. Many operators prefer not to use re-radiators at all. However, reradiators are a cost-effective solution for some problems.


Wireless Reradiators

Two types of Reradiators commonly are applied to solve two types of situations:

• “filling in” holes within the coverage area of a cell site -- valleys and other obstructed locations, convention centers, etc.

– Low-Power broadbandreradiators are used for this purpose (AMPS, TDMA, GSM, CDMA)

• expanding the service area of a cell to large areas beyond its natural coverage area

– High-Power, channelized frequency-translating reradiatorsare used for this purpose

– Only used in AMPS, TDMA; not currently feasible for CDMA

CellRR

Cell RR


Wireless ReradiatorsPropagation Path Loss Considerations

To solve a coverage problem using a reradiator, path loss and link budget must be considered

• how much reradiator gain is required?• how much reradiator output power is required?• what type of antennas would be best? • how much antenna isolation is needed?• how big will the reradiator footprint be?• how far can the reradiator be from the cell?• will the reradiator interfere with the cell in other areas?• What is the propagation delay through the reradiator, in chips?• Will search windows need to be adjusted for compensation?

CellRR

ERP

GainPath Loss

Path Loss (free space??)

Gain

RRGain

Line Loss

Signal Levelin target area

(free spaceusually applies)


Wireless ReradiatorsSearch Window Considerations

A reradiator introduces additional PN delay• typically 5 to 30 chips • the energy seen by the mobile and by the base station is

spread out over a wider range of delays

DonorCell

RR

ReradiatorSignal

Direct Signal fromDonor Cell

Delay = ? chips

DON’T FORGET THE WINDOWS!Search Windows must be widened byapproximately 2 x reradiator delay toensure capture of both donor and reradenergy by mobile and base station.•Srch_Win_A, Srch_Win_R, Srch_Win_N•Base station Acquisition & Demodulationsearch windows

Reference PNDonor Energy Reradiator Energy


In a few special cases, it is possible to reradiate useful Wireless coverage without any amplifiers involved!Link budget is marginal

• donor cell must be nearby• high-gain antenna required toward

donor cell• distance from RR to user must be

small– ≅100 feet feasible w/omni

antenna– ≅500 feet w/directional antenna

Passive Wireless ReradiatorsTypical Link Budget

Donor cell EIRPPath Loss Donor<>RR

RR Donor Ant. GainSignal Level into Line

RR Line LossRR Serving Ant. GainPath Loss RR<>UserSignal Level @ User

+52-102+22-28-6

+12-69-91

dBmdBdBidBmdBdBidBdBm

Passive ReradiatorLink Budget Example

DonorCell

ERP

Path Loss

Path Loss (250 ft., free space)

(2.1 miles,free space) Basement Auditorium, etc.

Line Loss-6 db


Broadband Low-Power Wireless Reradiators

Used mainly for filling small “holes” in coverage area of a cellInput and output on same frequency

• usable gain: must be less than isolation between antennas, or oscillation occurs

• this gain restriction seriously limits available coverage

• Typically achievable isolations: 70-95 dB

• Good point: every channel in donor cell is re-radiated

BPF:Uplink

BPF:Downlink

Wireless Spectrum

Frequency

Cell

BroadbandReradiator

UnavoidableCoupling

Combiner

Combiner


Broadband low-power reradiators can deliver useful signal levels over footprints up to roughly 1 mile using nearby donor cellsLink budget is usually very “tight”

• paths can’t be seriously obstructed• antenna isolation must be at least

10 db more than desired RR gain• can’t overdrive reradiator 3rd.

order IM

Broadband Low-Power Wireless ReradiatorsTypical Link Budget

DonorCell RR

ERP

GainPath Loss

Path Loss (1/2 mile,

free space)

Gain

RRGain

Line Loss

Signal Levelin target area

(6 miles,free space)

Donor cell EIRPPath Loss Donor<>RR

RR Donor Ant. GainRR Line Loss

Signal Level into RRRR Gain

RR Power OutputRR Line Loss

RR Serving Ant. GainPath Loss RR<>UserSignal Level @ User

+52-111+12

-3-50+50+0-3

+12-89.4-80.4

dBmdBdBidBdBmdBdBmdBdBidBdBm

Broadband ReradiatorLink Budget Example


Other Reradiator Issues

Amplification of Undesired Signals• The reradiator is a broadband device capable of amplifying

other signals near the intended CDMA carrier, both on uplink and downlink. Will these signals capture unwanted traffic, cause unwanted interference, or overdrive CDMA handsets or the base station?

Linearity• CDMA reradiators must be carefully adjusted to ensure they

are not overdriven. Overdriving would produce clipping or other nonlinearities, resulting in code interference

Traffic Capacity• Re-radiators may introduce enough new traffic to create

overloads in the donor cellAlarms

• Separate arrangements must be made for integrating alarms and surveillance reports from reradiators into the system


Section D

Operational MeasurementsSome Capacity ConsiderationOperational Measurements

Some Capacity Consideration


Total Blocked Call Percentage Example

This is an example of a cumulative system-wide total blocked call percentage chart maintained by one PCS customer

Total Block Call Percentage

1.0%1.5%2.0%2.5%3.0%3.5%4.0%4.5%5.0%5.5%6.0%6.5%7.0%7.5%8.0%

Date

Perc

ent

Blkd


Dropped Call Percentage Tracking Example

Dropped call percentage tracking by a PCS customer.

Total Drop Call Percentage

0.0%

0.5%

1.0%

1.5%

2.0%

2.5%

3.0%

3.5%

4.0%

4.5%

5.0%

Date

Perc

ent

%Drops


Total System Daily MOU Example

Total system daily MOU plotted by a PCS customer

Daily Total System MOU

0

50000

100000

150000

200000

250000

300000

Date

MO

U

Daily Total System MOU


“Top Ten” Performance Tracking Example

Many operators use scripts or spreadsheet macros to produce ranked lists of sites with heavy traffic, performance problems, etc.

Call Attempts

Eng Site

MSC Site Call Att

Call Succ

%Call Succ

Block Calls

%Blck Calls

Acc Fail

%Acc Fail

Drop Calls

%Drop Calls Call Attempts

6.1 13X 2561 2234 87.2 130 5.1 130 5.1 145 5.72.1 2X 2244 2017 89.9 101 4.5 101 4.5 93 4.11.2 1Y 1922 1743 90.7 83 4.3 83 4.3 66 3.464.3 93Z 1833 1549 84.5 137 7.5 136 7.4 110 6.0108.2 30Y 1740 1589 91.3 46 2.6 45 2.6 83 4.81.3 1Z 1630 1495 91.7 31 1.9 31 1.9 81 5.063.2 57Y 1623 1486 91.6 49 3.0 49 3.0 66 4.1102.2 4Y 1615 1495 92.6 18 1.1 18 1.1 70 4.3108.1 30X 1490 1387 93.1 27 1.8 27 1.8 54 3.643.3 42Z 1488 1410 94.8 4 0.3 4 0.3 53 3.6

0

500

1000

1500

2000

2500

3000

6.1

2.1

1.2

64.3

108.

2

1.3

63.2

102.

2

108.

1

43.3

Sector

Cal

ls

% Blocked Calls September 5, 1997Eng Site

MSC Site Call Att

Call Succ

%Call Succ

Block Calls

%Blck Calls

Acc Fail

%Acc Fail

Drop Calls

%Drop Calls % Blocked Calls

64.3 93Z 1833 1549 84.5 137 7.5 136 7.4 110 6.06.1 13X 2561 2234 87.2 130 5.1 130 5.1 145 5.763.3 57Z 1282 1098 85.7 65 5.1 65 5.1 90 7.02.1 2X 2244 2017 89.9 101 4.5 101 4.5 93 4.11.2 1Y 1922 1743 90.7 83 4.3 83 4.3 66 3.463.2 57Y 1623 1486 91.6 49 3.0 49 3.0 66 4.164.1 93X 1027 926 90.2 30 2.9 30 2.9 58 5.726.3 35Z 855 698 81.6 24 2.8 24 2.8 112 13.1108.2 30Y 1740 1589 91.3 46 2.6 45 2.6 83 4.81.3 1Z 1630 1495 91.7 31 1.9 31 1.9 81 5.0

0.01.02.03.04.05.06.07.08.0

64.3 6.1

63.3 2.1

1.2

63.2

64.1

26.3

108.

2

1.3

Sector%


Lucent Reports

This figure shows various operating statistics available throughAutoPace from Lucent systems

• forward power control status• origination failures and dropped calls

Highlight by CDMA_Acs Chn_Oc (2,1,0, ) Mean: 28.2 Std Dev: 27.83 Sort by Sys/ECP/Ce ll/Name /Antenna ID /Ant_Name

Sys/ECP/Ce ll/Name /Antenna ID /Ant_Name CDMA_Acs CDMA_Avg CDMA_Fwd CDMA_Fwd CDMA CDMA_Pg CDMA_Pk CDMA_Pk CDMA_Rev CDMA_RevChn_Oc Sq_DG PCOLdur PCOLcnt Intcpt_Msg Ch_Ocpn Acs_ChOc Pg_ChOc PCOLdur PCOLcnt

TOTALS 5,921.00 1,123,466 581.00 339.00 0.00 489,506 91,989 555,984 305.00 6.00 179 2 1 JACKSON 1 Antenna:1 30.00 6,187.00 12.00 4.00 0.00 2,771.00 985.00 3,264.00 0.00 0.00 179 2 1 JACKSON 2 Antenna:2 28.00 6,157.00 4.00 4.00 0.00 2,763.00 563.00 3,140.00 0.00 0.00 179 2 1 JACKSON 3 Antenna:3 10.00 6,088.00 2.00 1.00 0.00 2,754.00 281.00 3,197.00 0.00 0.00 179 2 2 WILDER 1 Antenna:1 27.00 6,168.00 0.00 0.00 0.00 2,795.00 563.00 3,125.00 0.00 0.00 179 2 2 WILDER 2 Antenna:2 13.00 5,016.00 0.00 0.00 0.00 2,756.00 422.00 3,120.00 0.00 0.00 179 2 2 WILDER 3 Antenna:3 13.00 4,818.00 0.00 0.00 0.00 2,766.00 281.00 3,155.00 0.00 0.00 179 2 3 MARKET 1 Antenna:1 4.00 6,200.00 0.00 0.00 0.00 2,760.00 140.00 3,100.00 0.00 0.00 179 2 3 MARKET 2 Antenna:2 10.00 6,073.00 0.00 0.00 0.00 2,731.00 422.00 3,195.00 0.00 0.00 179 2 3 MARKET 3 Antenna:3 55.00 6,580.00 5.00 3.00 0.00 2,809.00 845.00 3,391.00 0.00 0.00

Highlight by %CDMA Est Ca lls (2,1,0, ) Mean: 96.71 Std Dev: 1.22 Sort by %CDMA Est Ca lls

Sys/ECP/Ce ll/Name /Labe l %CDMA ReAcquir CCE CDMA_CE Prim_CS %Prim_CS Sec_CS %CDMA %CDMA CDMA %CDMA T otCDMA CDMAT otlEst Ca lls ed_Ca lls e rlangs Usage CE_Use CE_Use CE_Use SoftHO Use SUFa il Lost_Ca ll Lost Ca lls Fa ilures Origins

TOTALS 96.83 2.84 6,580 2,368,959 1,451,816 61.28 917,143 38.72 2.79 1,722.00 1.17 7,856.00 5,069.00 179 2 67 MARSHALL 93.55 3.22 62.60 22,535.00 9,300.00 41.27 13,235.00 58.73 6.14 15.00 1.67 95.00 65.00

179 2 10 TIGER 93.58 2.61 128.68 46,323.00 19,788.00 42.72 26,535.00 57.28 5.68 42.00 2.18 208.00 143.00 179 2 28 LEATHERWOOD 94.18 3.89 71.45 25,722.00 13,689.00 53.22 12,033.00 46.78 5.44 20.00 1.18 143.00 89.00

179 2 30 SHEPHERDS 94.36 2.38 63.54 22,873.00 11,113.00 48.59 11,760.00 51.41 3.62 10.00 0.89 77.00 47.00 179 2 121 PENTAGON 94.44 5.26 36.16 13,016.00 8,448.00 64.90 4,568.00 35.10 3.68 64.00 5.98 108.00 73.00

179 2 1 COLLEGE 94.67 2.65 76.37 27,494.00 15,965.00 58.07 11,529.00 41.93 4.64 15.00 0.98 102.00 67.00 179 2 45 MARYLAND 94.73 2.06 115.21 41,476.00 23,219.00 55.98 18,257.00 44.02 5.04 35.00 1.44 206.00 141.00 179 2 16 AVONDALE 94.90 2.99 98.26 35,372.00 20,059.00 56.71 15,313.00 43.29 4.47 41.00 1.78 178.00 130.00


BTSC MO Attributes

Attribute Name DataType

Seq.Number

Access,Range Description

BlockedOriginationsNoTCE word16 0x0002A42

Pfull

Number of originations blocked because no idle channel elements were available

BlockedOriginationsNoFwdCap 0x0002B43

Number of originations blocked due to lack of BTS forward link excess capacity

BlockedOriginationsNoRevCap 0x0002C44

Number of originations blocked due to lack of reverse link capacity

BlockedHandoffsNoTCE 0x0002D45

Number of handoffs blocked because no idle channel elements were available

BlockedHandoffsNoFwdCap 0x0002E46

Number of handoffs blocked due to lack of BTS forward link excess capacity

BlockedHandoffsNoRevCap 0x0002F47

Number of handoffs blocked due to lack of reverse link capaicty

SuccessfulOriginations 0x0003048 Number of successful originations

SuccessfulHandoffs 0x0003149 Number of successful handoffs

word16

word16

word16

word16

word16

word16

word16

Pfull

Pfull

Pfull

Pfull

Pfull

Pfull

Pfull

Each attribute is a periodic counter maintained during the 15-minute automatic logging period.


Nortel FA MO AttributesEach attribute is a periodic counter maintained during the 15-minute automatic logging period.

FA MO Sequence Number OM name

FA MO Sequence Number OM name

16 TCEUtilMaximum 2D soft4softer1Alpha17 NumOfTCsConfigured 2E soft4softer1Beta18 soft1softer1Alpha 2F soft4softer1Gamma19 soft1softer1Beta 30 soft4softer2AlphaBeta1A soft1softer1Gamma 31 soft4softer2BetaGamma1B soft1softer2AlphaBeta 32 soft4softer2GammaAlpha1C soft1softer2BetaGamma 33 soft4softer31D soft1softer2GammaAlpha 34 soft5softer1Alpha1E soft1softer3 35 soft5softer1Beta1F soft2softer1Alpha 36 soft5softer1Gamma20 soft2softer1Beta 37 soft5softer2AlphaBeta21 soft2softer1Gamma 38 soft5softer2BetaGamma22 soft2softer2AlphaBeta 39 soft5softer2GammaAlpha23 soft2softer2BetaGamma 3A soft6softer1Alpha24 soft2softer2GammaAlpha 3B soft6softer1Beta25 soft2softer3 3C soft6softer1Gamma26 soft3softer1Alpha 3D TimeNotInUse27 soft3softer1Beta28 soft3softer1Gamma29 soft3softer2AlphaBeta2A soft3softer2BetaGamma2B soft3softer2GammaAlpha2C soft3softer3


Nortel BTSC MO Events

Event Report Name TypeEvent Report

Seq.Number Description

Each event counter is maintained during the 15-minute automatic logging period.

BTSCPerformanceData PerformanceData 0x000?0?

Includes as parameters all attributes with P access documented in the attribute table for

this MO.

FA MO Events

Event Report Name TypeEvent Report

Seq.Number Description

Each event counter is maintained during the 15-minute automatic logging period.

FAPerformanceData PerformanceData 0x000?0?

Includes as parameters all attributes with P access documented in the attribute table for

this MO.


Nortel BTSC MO Report Example

XYZ 19971120 BTSC MO Report+----+----------------------------+------+------+------+------+------+------+------+------+|BTS | Start Date/Time - |OBlock|OBlock|OBlock|HBlock|HBlock|HBlock| Succ | Succ || | End Date/Time |No TCE|No Fwd|No Rev|No TCE|No Fwd|No Rev| Origs|Handof|+----+----------------------------+------+------+------+------+------+------+------+------+| 1|1997/11/20 01:30:00-02:00:00| 0| 0| 0| 0| 0| 0| 3| 5|| 1|1997/11/20 12:00:00-12:30:00| 0| 0| 0| 0| 0| 0| 46| 314|| 1|1997/11/20 12:30:00-13:00:00| 0| 0| 0| 0| 0| 0| 76| 470|| 1|1997/11/20 13:00:00-13:30:00| 0| 0| 0| 0| 0| 0| 45| 414|| 1|1997/11/20 13:30:00-14:00:00| 0| 0| 0| 0| 0| 0| 55| 375|| 1|1997/11/20 14:00:00-14:30:00| 0| 0| 0| 0| 0| 0| 50| 525|| 1|1997/11/20 14:30:00-15:00:00| 0| 0| 0| 0| 0| 0| 72| 433|| 1|1997/11/20 15:00:00-15:30:00| 0| 0| 0| 0| 0| 0| 66| 412|| 1|1997/11/20 15:30:00-16:00:00| 0| 0| 0| 0| 0| 0| 53| 323|| 1|1997/11/20 16:00:00-16:30:00| 0| 0| 0| 0| 0| 0| 63| 342|| 1|1997/11/20 16:30:00-17:00:00| 0| 0| 0| 0| 0| 0| 51| 331|| 1|1997/11/20 17:00:00-17:30:00| 0| 0| 0| 0| 0| 0| 39| 323|| 1|1997/11/20 17:30:00-18:00:00| 0| 0| 0| 0| 0| 0| 51| 310|| 1|1997/11/20 18:00:00-18:30:00| 0| 0| 0| 0| 0| 0| 45| 237|| 1|1997/11/20 18:30:00-19:00:00| 0| 0| 0| 0| 0| 0| 31| 299|| 1|1997/11/20 19:00:00-19:30:00| 0| 0| 0| 0| 0| 0| 37| 282|| 1|1997/11/20 19:30:00-20:00:00| 0| 0| 0| 0| 0| 0| 19| 143|| 1|1997/11/20 20:00:00-20:30:00| 0| 0| 0| 0| 0| 0| 18| 96|| 1|1997/11/20 20:30:00-21:00:00| 0| 0| 0| 0| 0| 0| 33| 192|| 1|1997/11/20 21:00:00-21:30:00| 0| 0| 0| 0| 0| 0| 25| 226|| 1|1997/11/20 21:30:00-22:00:00| 0| 0| 0| 0| 0| 0| 15| 235|| 1|1997/11/20 22:00:00-22:30:00| 0| 0| 0| 0| 0| 0| 15| 216|| 1|1997/11/20 22:30:00-23:00:00| 0| 0| 0| 0| 0| 0| 9| 162|| 1|1997/11/20 23:00:00-23:30:00| 0| 0| 0| 0| 0| 0| 3| 40|| |Totals for BTS 1 | 0| 0| 0| 0| 0| 0| 1235| 8895|


Nortel FAMO Report Example

XYZ 19971120 FA MO Report+----+----------------------------+---------+---------+-----+-------+-------+-------+-----+---+|BTS | Start Date/Time - | MOU | MOU | CE/ | MOU | MOU | MOU |%Soft|Max|| | End Date/Time | CE | Traffic | User| Alpha | Beta | Gamma | HO |TCE|+----+----------------------------+---------+---------+-----+-------+-------+-------+-----+---+| 1|1997/11/20 07:00:00-07:30:00| 41.99| 33.35| 1.26| 11.77| 4.62| 16.96|20.58| 15|| 1|1997/11/20 07:00:00-07:30:00| 73.06| 46.22| 1.58| 17.72| 14.10| 14.39|36.75| 15|| 1|1997/11/20 08:00:00-08:30:00| 109.87| 66.05| 1.66| 24.78| 20.21| 21.06|39.88| 15|| 1|1997/11/20 10:00:00-10:30:00| 153.79| 89.81| 1.71| 41.85| 32.19| 15.77|41.60| 15|| 1|1997/11/20 10:30:00-11:00:00| 181.09| 102.19| 1.77| 43.60| 28.22| 30.38|43.57| 15|| 1|1997/11/20 11:00:00-11:30:00| 152.59| 84.73| 1.80| 37.61| 18.51| 28.61|44.47| 15|| 1|1997/11/20 11:30:00-12:00:00| 143.70| 89.16| 1.61| 39.66| 24.78| 24.72|37.95| 15|| 1|1997/11/20 12:00:00-12:30:00| 156.58| 89.52| 1.75| 25.51| 21.91| 42.10|42.83| 15|| 1|1997/11/20 12:30:00-13:00:00| 165.54| 89.97| 1.84| 44.41| 22.89| 22.67|45.65| 15|| 1|1997/11/20 13:00:00-13:30:00| 170.36| 99.19| 1.72| 52.81| 24.58| 21.79|41.78| 15|| 1|1997/11/20 13:30:00-14:00:00| 145.34| 93.71| 1.55| 41.88| 24.05| 27.77|35.53| 15|| 1|1997/11/20 14:00:00-14:30:00| 189.61| 121.49| 1.56| 52.43| 30.99| 38.06|35.93| 15|| 1|1997/11/20 14:30:00-15:00:00| 153.65| 108.08| 1.42| 47.58| 37.52| 22.99|29.65| 15|| 1|1997/11/20 15:00:00-15:30:00| 165.08| 106.66| 1.55| 49.00| 29.69| 27.97|35.39| 15|| 1|1997/11/20 15:30:00-16:00:00| 159.27| 94.72| 1.68| 42.04| 28.43| 24.25|40.53| 15|| 1|1997/11/20 16:00:00-16:30:00| 172.52| 114.62| 1.51| 56.57| 28.50| 29.55|33.56| 15|| 1|1997/11/20 16:30:00-17:00:00| 156.83| 105.46| 1.49| 53.29| 30.38| 21.80|32.76| 15|| 1|1997/11/20 17:00:00-17:30:00| 129.13| 82.52| 1.56| 31.50| 24.28| 26.73|36.10| 15|| 1|1997/11/20 17:30:00-18:00:00| 134.80| 81.76| 1.65| 35.80| 30.20| 15.77|39.35| 15|| 1|1997/11/20 18:00:00-18:30:00| 96.91| 60.49| 1.60| 27.80| 15.38| 17.31|37.58| 15|| 1|1997/11/20 18:30:00-19:00:00| 124.25| 73.62| 1.69| 22.37| 30.93| 20.33|40.75| 15|| 1|1997/11/20 19:00:00-19:30:00| 75.50| 41.14| 1.83| 18.03| 14.88| 8.24|45.50| 15|| 1|1997/11/20 19:30:00-20:00:00| 40.58| 23.56| 1.72| 12.50| 5.72| 5.33|41.95| 15|| 1|1997/11/20 20:00:00-20:30:00| 51.14| 29.81| 1.72| 13.26| 10.37| 6.19|41.71| 15|| 1|1997/11/20 20:30:00-21:00:00| 102.45| 55.26| 1.85| 16.36| 18.49| 20.41|46.07| 15|| 1|1997/11/20 21:00:00-21:30:00| 108.48| 74.86| 1.45| 28.32| 17.26| 29.27|30.99| 15|| 1|1997/11/20 21:30:00-22:00:00| 109.92| 68.50| 1.60| 26.53| 19.22| 22.75|37.68| 15|| 1|1997/11/20 22:00:00-22:30:00| 86.58| 59.36| 1.46| 26.09| 15.11| 18.15|31.45| 15|| 1|1997/11/20 22:30:00-23:00:00| 94.96| 63.48| 1.50| 27.73| 20.85| 14.90|33.15| 15|| 1|1997/11/20 23:00:00-23:30:00| 28.07| 20.76| 1.35| 9.06| 8.14| 3.55|26.04| 15|| |Totals for BTS 1 | 3690.90| 2280.64| 1.62| 980.80| 655.61| 644.22|38.21| 15|


Section E

Basics of Interference, Noise and CDMA Capacity

Basics of Interference, Noise and CDMA Capacity


The Noise Floor

Even when no interference, a received signal must compete with the always-present noise in the receiver itselfAmbient heat causes electrons everywhere to move around, producing “thermal noise” in every electronic circuitThe noise power is proportional to absolute temperature and the receiving bandwidth; see equation at rightWhat this means for a CDMA receiver:

• There is an unavoidable noise of -113.1 dbm in the bandwidth of a CDMA signal, 1.2288 MHz.

See the spreadsheet “Noise.xls” below

THERMAL NOISE

Nt = kTBwhere:Nt = thermal noise powerK = Boltzmann’s Constant

= 1.3806 x 10-23

T = Temperature (Kelvin)= 290ºK room temperature

B = bandwidth

T, deg K BW, Hz Noise, dbm RX NF RX Sens. Remarks290 1 -174.0 0.0 -174.0 Theoretical Baseline290 1,228,800 -113.1 5.0 -108.1 Typical CDMA Uplink at BTS receiver290 1,228,800 -113.1 8.0 -105.1 Typical CDMA Downlink at Mobile Receiver

Thermal Noise Floor, Bandwidth, and Receiver Sensitivity

This noise is sometimes called “Johnson Noise”,

“White Noise”, and “Background Noise”


Reverse Link Noise Floor Rise Due To TrafficThe first user on a sector must satisfy:

• User’s signal + CDMA processing gain must equal BTS thermal noise + BTS noise figure + desired Eb/No

The second user on a sector must satisfy• all the above PLUS first user’s energy• and the first user must also slightly

increase to match, maintaining its qualityEach additional user faces more interfering power from existing users, etc., etc.For given starting conditions, there is a number of users that drives the situation out of control – users must transmit more power than a CDMA mobile can produce

• This number of users is the “Pole Point”; this is the “Pole Capacity” of the sector

V = Voice Activity FactorW = Spreading BandwidthNo= P.S.D. of Thermal NoisePt = Mobile TxR = Vocoder Rate


Loading and the Noise Floor

For two standard cell configurations, the spreadsheet shows the calculated pole point capacity and the intended operating limit at 50% of pole capacityThe graph shows the calculated receive power at a BTS for zero to 42 users under typical conditions

• notice a 10 db rise occurs with just 12 users• a 15 db rise occurs with just 15 users• this cell’s capacity needs optimization!

Explore the Noise Floor Rise spreadsheet to see the effects of target Eb/No, BTS noise figure, and other parameters on the results

3-Sector BTS Pole Capacity

Per Sector

6-Sector BTS Pole Capacity

Per SectorOperating Limit: 50% Pole 20.9 18.5

100% Pole Point #Users 41.8 37.0Processing Gain 128.00 128.00

#Sectors 3 6Sectorization Gain 2.55 4.50

Voice Activity Factor 0.40 0.40Adjacent Cell Interference 0.60 0.60

Target Eb/No, ratio 4.17 4.17Radio Configuration RC1 RC1

Vocoder EVRC EVRCChip Rate 1,228,800 1,228,800 Data Rate 9,600 9,600

Required Eb/No, db 6.20 6.20

Noise Floor Rise Due To Loading

-120

-100

-80

-60

-40

-20

00 5 10 15 20 25 30 35 40 45

Number of Users

BTS

RX d

B


What’s So Important About Noise Floor?

In theory, the capacity of a sector isn’t affected by the noise floor• as long as they’re strong enough, the desired number of

mobiles can use the sector simultaneouslyBut the range of the sector is directly determined by the noise floor

• when the noise floor is elevated by interference, the usable range of the cell shrinks proportionally

• users at the cell edge may be unable to access, unable to keep a call from dropping, unable to achieve high data rates, unable to keep acceptable FER

The noise floor at the BTS receiver is the point in the CDMA system most vulnerable to external interference


Recognizing Interference: Do I have it?!!

Clues that you might have an interference problem:• Bad Stats: increased blocking, TCCFs, access failures, drops

worse than expected even in heavy traffic areas• clusters of several sectors with over 10% blocking• customer complaints of severe impairments, usually localized• increased noise floor in BTS statistics – both peak and average• depressed data throughput compared to healthy sectors

Field Observations• Visible non-CDMA signals on a spectrum analyzer • pockets in good-coverage areas where Ec/Io is poor due to

interference


Interference? Track It Down!

OK, so you’ve got some solid evidence that interference is going on. How can you identify the source of the interference, and dosomething about it?For Reverse Link Interference:Identify the affected sectors to recognize affected areaField Investigation Normally Will Be Required

• look into BTS multicoupler outputs to identify interferer• spectrum analyzer and yagi antenna

– direction toward interferer from surrounding high sites –remember to use BP filter if needed to suppress strong fundamental so you can see true interference only

– triangulate to locate interferer– locate the source


Identifying and Handling Interference Sources

Source will usually be a communications-related or power-related device; at building entry, ask if anyone is doing communications activities in that buildingUse company procedures for dealing with the interferer owner to obtain short-term resolutionLong-term resolution

• is signal unauthorized or unintended?– repair equipment if defective– does suppression meet required specs? add filter if needed


Major Sources of Interference

Reverse Link• INTERNAL: maximum traffic loading is maximum acceptable

interference, just from “friendly fire”• Rogue Mobiles – a mobile needing handoff into the victim site but

unable to get it and transmitting high levels as it approaches• In-channel Narrowband Interferers

– military, land mobile, law enforcement, industrial• In-channel Unstable, parasitic, transmitters • In-band strong mobile signals of other operators on adjacent blocks• Broadband: welding shops, arcing signs and bulbs, utility transformers

and power lines with arcing insulators, dirty LANs• Oscillating or noisy in-building amplifiers, repeaters, and television

master antenna systems with booster amplifiers• sources can be very small, but near the BTS

Forward Link• symptom: localized interference, usually on one carrier (not all)• sources usually stronger than in reverse link case, easier to find


Triangulation

Triangulation is the process of locating a transmitting source by measuring radial distance or direction of the received signal from several different pointsTriangulation can be used to pinpoint the geographic position of a user or interfererThe drawing shows the basic principle of triangulation.

• The emitter’s location is found by measuring the relative direction of the signal from three different locations.

• The area where the radials overlap becomes search area for the emitter’s exact location.

1


Triangulation – Rounds Two and Up

The first round of triangulation will identify the vicinity of the emitter. However, the search area may still be impractically large.Another round of triangulation from closer points surrounding the search area may be required.When completed you should have 3 new intersecting lines which reveal the approximate location of the interferer within a triangle of uncertainty. This method can also be used to find interferers inside a large building.

1


Site Configuration Principles

Antenna Isolation• Vertical separation highly effective

vs other operators but not desirable among our own antennas due to F/R imbalance

• Horizontal IsolationEstimating Isolation

• assume free space loss and published antenna patterns for “worst-case” maximum coupling scenario

Each operator should set minimum separation guidelines for general construction, based on intermodconsiderations of their own and their neighbors’ frequency bands and signal characteristics

Isolation

A widely-accepted general principle is to do whatever is required to achieve 40 db or better isolation between all antennas.


Observed Isolations between PCS Antennas

Typical observed isolations between commonly-used PCS antennas at various horizontal and vertical separations

• thanks to Don Button and EMS Wireless


IntermodulationIntermodulation

Section F


Modulation and Mixing vs. Intermodulation

When two signals are intentionally combined in a non-linear device we call the effect modulation

• Amplitude modulator, or quad phase modulator• Mixer, down or up converter in superheterodyne

When two (or more) signals are unintentionally combined in a non-linear device, we call the effect intermodulation (a pejorative term)

An analogy: Botanists use soil to grow plants. But on your living room carpet, soil is just dirt.IM signals increase system noise, or cause distinctive recognizable interference signals


Intermod Basics

Definition: Intermodulation (“IM”) is the unintended mixing of legitimate RF signals, producing undesired signals (‘intermodulation products’) on unrelated frequencies possibly already being used for other services

• IM can devastate reception on certain frequencies at base stations and other communication facilities

Intermodulation occurs because signals are passing through a nonlinear device, allowing each signal to alter the waveshape of the others

• the frequencies of the intermodproducts are sums and differences of multiples of the original signal frequencies, and can be calculated exactly

• the strength of the intermodproducts depends on the degree of nonlinearity of the circuits involved, and can be predicted with good accuracy using measured “intercept” levels

Power transfer characteristicsof typical amplifier or other device

Noise floor

Input power (dBm)

Outputpower(dBm)

Third orderintercept

point

Third orderintermodulation

products

Predictedpower

ff1 f2

Non-linear deviceInput Output

f3f1-2f2 3f2-2f1f1 f2

2f2-f12f1-f2

rf100

Documents

wireless radio telegraph

cdma principles

radio milestones1888

radio frequencies

scott baxter v2

public marriage of radio

radio guglielmo marconi

optimization principles