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Mobile WiMAX Technologies & Measeurement
Mobile WiMAX Technologies & Measeurement
© Copyright 2005 Agilent Technologies, Inc.
May, 2006presented by:
Brian Su
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Agenda
• Overview for Broadband Wireless Access• WiMAX-OFDMA Technologies• WiMAX-OFDMA Signal Meas. & Analysis• 802.16e WiMAX-OFDMA RF Measurement• Resource
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Wireless ConnectivityComplementary Technologies
PAN
LANMANWAN
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Wireless Connectivity ApplicationsBluetooth 802.15.1 (WPAN)• Cable Replacement• Application: Headset, PC
Peripheral: Mouse, Keyboard HotSync cradle, Scanner, Printer, External FLASH memory, CD drives, etc.
WLAN 802.11a/b/g• Wireless extension of
Ethernet • Application: Laptop LAN
(High data rate) data line
802.11n• Improved 802.11a/g
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Wireless Connectivity ApplicationsWiMAX 802.16-2004 (802.16d)• Wireless broadband • Application: Last mile
connectivity, backhaul for hotspots
WiMAX 802.16 OFDMA (802.16e)• Mobile wireless broadband • Application: Provide Mobile
Wireless broadband to devices, such as PDA’s, computer, cell phones.
UWB• High-speed cable replacement• Application: Wireless USB
Home Theater, video streaming, portable devices
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Mobility
802.11/802.16
(Roam Between Service Areas)
Consolidate 802.16/802.16a/ 802.16c Modifications and Interoperability
2-11 GHz
Non Line of Sight
Up to 75 Mbps
(20 MHz Chan)
802.16
System profiles
Interoperability
10-66 GHz
Line of Sight
Up to 134 Mbps (28 MHz Chan)
Fixed Wireless
IEEE 802.16e
(802.16-2005)
IEEE 802.16d
(802.16-2004)
Rev. 5
IEEE 802.16a
January 2003
IEEE 802.16c
December 2002
IEEE 802.16
December 2001
IEEE 802.16 WirelessMAN Evolution
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What are WiMAX and 802.16? (I)• IEEE 802.16: An IEEE sponsored specification targeted at a
variety of Broadband Wireless Access opportunities not addressed by others like 802.11 (WLAN). Below is the IEEE802.16 document structure specific to 802.16e:
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802.16 standards802.16-2004 (Released)
802.16e related standards
802.16e MobileBWA < 6 GHz 512 to 2048 FFT
OFDMA w/64 QAM 5, 10, 20 MHz
Air Interface Application Frequency Modulation Bandwidth /Max bit rate
WirelessMAN - SC Line of Sight, Pt-Pt Microwave 10-66 GHz Single Carrier
w/64 QAM20 -28 MHz /134.4 Mbps
WirelessMAN - SCa NLOS,Fixed BWA < 11 GHz Single Carrier
w/64 QAM 1.25 to >20 MHz
WirelessMAN - OFDM NLOS,Fixed BWA < 11 GHz 256 FFT OFDM
w/64 QAM1.25 to 20 MHz /
~75 MbpsWirelessMAN -
OFDMANLOS,
Fixed BWA < 11 GHz up to 2048 FFTOFDMA w/64 QAM 1.25 to 20 MHz
WirelessHUMAN NLOS,Fixed BWA
< 11 GHzunlicensed
256 FFT OFDMw/64 QAM
1.25 to 20 MHz /~75 Mbps
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What are WiMAX and 802.16? (II)• WiMAX Forum: An industry organization to promote the
IEEE 802.16 standard for Broadband Wireless Access (BWA)
• Has established a series of Radio Conformance Tests (RCT) to prove conformance and interoperability (like the WiFi Alliance for WLAN).
• “Profiles” are used to define a subset of applications and the tests required
• Mobile WiMAX certification profiles under discussion now• Radio Conformance Tests (RCT) targeted for completion
by end of May 2006• Certification lab setup in Q3/Q4 2006. Wave 1
Certification testing targeted to start at end of October 2006
• Agilent is a member of the WiMAX forum, and our equipment is used in the certification process
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802.16e, WiBro, and OFDMA• Technologies for addressing the application of mobile broadband
wireless access (portable Internet)• 802.16e – an amendment to the 802.16-2004 standard focusing on the
OFDMA physical layer• Allows 128, 512, 1024, or 2048 sub-carriers in 1.25, 5, 10, or 20 MHz
BWs respectively. Additional BWs (e.g. 3.5, 5.5, 7 MHz) may be used for Europe.
• Focus on licensed frequencies < 4 GHz (standard allows 2-6 GHz)
• WiBro (Wireless Broadband) - began a few years ago as a proprietary TTA standard for Korea, formerly called HPI (High-speed Portable Internet)
• Now mostly merged into 802.16e standard as one of the system profiles• 1024 sub-carriers in 8.75 MHz BW in 2.3-2.4 GHz band only• Development is more advanced than 802.16e: tested at speeds up to 120
km/hr• Commercial service expected to be launched in April 2006
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Agenda
• Overview for Broadband Wireless Access• WiMAX-OFDMA Technologies• WiMAX-OFDMA Signal Meas. & Analysis• 802.16e WiMAX-OFDMA RF Measurement• Resource
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Contrasting OFDMs – WLAN 802.11a/g
Carriers: 52Spacing: 312.5 kHz
802.11a (18 MHz)
4 BPSK Pilots, fixed locations
BPSK, QPSK, 16QAM, 64QAM
802.11a/g = Freq range: 2.4/5.8GHz Data rate: ≤ 54 Mbps Mobile/Fixed: Fixed
Short Training Data NSig Symbol Data 1 Data 2Chan. Estimation . . .Preamble Payload
2 sym 1 sym 1 sym 1 sym 1 sym 2 sym
Payload – multi-symbol, one mod type, no overlap
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Contrasting OFDMs – 802.16d WiMax Fixed
.
.
.
802.16d (1.25 MHz)
8 BPSK Pilots, fixed location
802.16d (20 MHz)
BPSK, QPSK, 16QAM, 64QAM
.
.
.:
10 MHz7.0 MHz3.5 MHz
:
Carriers: 200Spacing: 90 kHz
Carriers: 200Spacing: 5.6 kHz
802.16d = Freq range: 2 - 11GHz Data rate: ≤ 70 Mbps Mobile/Fixed: Fixed
Data NFCH Data 1 Data 2Chan est. . . .Preamble Payload
1 sym N sym N sym N sym 1 sym
Long synch
1 sym
Payload – multi-symbol, multi-mod type, no overlap
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Contrasting OFDMs--802.11a vs. 802.16 WiMAX
802.11a 52 carriers,312.5 kHzspacing
802.16 200 carriers,
90 kHzspacing .
.
.
200 carriers,6.7 kHzspacing
802.11a (18 MHz)
802.16 (1.5 MHz)
4 BPSK Pilots
8 BPSK Pilots
802.16 (20 MHz)
BPSK, QPSK, 16QAM, 64QAM
BPSK, QPSK, 16QAM, 64QAM
.
.:
10 MHz7.0 MHz3.5 MHz
:A smaller sub-carrier spacing gives greater immunity to multipath fading
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Contrasting OFDMs – 802.16e WiMax Mobile
83-120 Pilots
802.16e: Freq range: 2- 6 GHz Data rate: ≤ 70Mbps Mobile/Fixed: Mobile (60~100kph)
FFT: 2048Carriers: 1680Spacing: ~11kHz
FFT: 1024Carriers: 840Spacing: ~11kHz
FFT: 512Carriers: 408Spacing: ~11kHz
42-60 Pilots
802.16e (5 MHz)
166-240 BPSK Pilots, variable
location
802.16e (20 MHz)
QPSK, 16QAM, 64QAM
OFDMA Symbol Number
time
802.16e (10 MHz)
Payload – multi-symbol, multi-mod type, overlap
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802.16 OFDMA Concepts: SlotsIn OFDMA, the minimum possible data unit is a “Slot”A slot has 2 dimensions, one dimension is time, the other is subchannel number3 most common slot sizes
•1 Subchannel and 1 OFDMA Symbol•1 Subchannel and 2 OFDMA Symbols•1 Subchannel and 3 OFDMA Symbols
Different “Zones” will use different slot sizes
1 subchannel SLOT
1 subchannel
1 subchannel
Symbol 1Symbol 2Symbol 3
SLOT
SLOT
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802.16e OFDMA ConceptsSub-channelization – Sharing the bandwidth
• The carriers are organized into “logical sub-channels” consisting of ~28 subcarriers each.
• MAC layer assigns user data to 1 or more logical sub-channels for enough symbol times to carry the required no. of bits.
34 logical sub-channels,
24.7 carriers/sub-channel (10MHz)
• Subchannel-to-subcarrier assignment changes for every symbol, based on permutation formula seeded by variables such as Cell-ID, sector number, etc.
Logical Subchannels
0-2
Logical Subchannels 3-8
User 1User 2
User 4User 3
. . .
. . .
. . .
. . .
Carrier -420 . . . . . . . 0 . . . . . . .. . .+420
10MHz Example
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802.16 OFDMA ConceptsExample of a ‘data burst’ allocated to a user
0123456789
k k+1 k+ 2 k+3 k+4 k+5 k+6
n+6 n+7 n+8
n n+1 n+2n+3 n+4 n+5
• A data burst is a group of contiguous sub channels and symbols
• The base station assigns a data burst/region to a user to use to receive or transmit data.
LogicalSubchannels
perm
utat
ion
Physical Subcarriers
Symbol number
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802.16 OFDMA Concepts: ZonesThere are currently more than 7 zones that have been defined
PUSC (partial usage of subchannels)
FUSC (full usage of subchannels)
PUSC with all subchannels
Optional FUSC
AAS (Adaptive Antenna System)
AMC (Adaptive Modulation and Coding)
Option FUSC with all subchannels
Zones are used to help implement basestation functionality such as beamforming, assigning subchannels to different sectors of a single cell, and to define subchannelization that reduces basestation to basestation interference
Prea
mbl
e
FCH
and
DL
Map
PUSC
FUSC
Opt
iona
l FU
SC
AMC
DL Subframe
(A subframe can contain multiple zone types)
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Fixed WiMAX vs. 802.16e Summary
• OFDM, 256 carriers, 17 BW options from 1.25-20 MHz (variable sub-carrier spacing)
• Coding: CC only mandatory one• Two basic types of preambles:
Long and Short• All carriers have same
modulation in one symbol• Sub-channelization optional• Space Time Coding (STC)
optional
• OFDMA with 128, 512, 1024, or 2048 carriers in 1.25, 5, 10, or 20 MHz BW respectively. Some requests for additional BWs for European market. • Coding: CC mandatory; CTC and STC optional but popular (CTC required for WiBro)• Many preambles, with 114 preamble modulation series based on segment and IDCell
• New features:• Permutation zones: PUSC, FUSC,
OPUSC, AMC, OFUSC, TUSC1, TUSC2• Bursts and zones allocated by sub-
channels and symbols• Sub-channels divided into segments
(BTS sectors)• Physical sub-channels renumbered to
logical sub-channels• Hybrid automatic repeat request (HARQ)• Adaptive antenna system (AAS) for
beamforming• Repetition coding• Power boosting
This is just a partial list. 802.16e is MUCH more complex than the 256-carrier OFDM PHY!
Fixed WiMAX (OFDM)802.16e OFDMA
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802.16 OFDMA ConceptsDrawing of ‘data region’ or ‘data bursts’
• In OFDMA, data bursts overlap in time
• Maximizes data flow in complex environment
OFDMA
OFDM
• In 802.16-2004 OFDM user data DO NOT overlap in time.
OFDMA Symbol Number
time
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802.16e 10MHz BW “Basics”
QPSKQPSKModulation format1 sym (115.2 µs) 1 sym (100.8µs)Length
8528.310 MHz9.498 MHzActual bandwidth
115.2 µs102.8571 µsSymbol time1/81/8Guard Interval
1,4,7…/ 2,5,8…/ 3,6,9…
1,4,7…/ 2,5,8…/ 3,6,9…
Carrier sequence29.297 kHz33.48 kHzCarrier spacing
Preamble
9.7656 kHz10.9375 kHzCarrier spacing8658.437 MHz9.643 MHzDL-OFUSC, UL-OPUSC8518.300 MHz9.487 MHzDL-FUSC8418.203 MHz9.375 MHzUL/DL-PUSC
Actual BW8.75 MHz10MHzNominal BW
Total bins
Korea (WiBro)802.16e802.16 OFDMA Concepts: 1024 FFT Example
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Frame Structure for 802.16e OFDMAEach subframe is divided into zones
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Detailed OFDMA Frame Structure
Symbol #
•UL Burst 2
•UL Burst 1
•DL Burst 3 •DL Burst 7
•DL B
urst
10
•DL B
urst
9
•DL Burst 6•DL Burst 2
•DL Burst 8•DL Burst 5•DL Burst 4
•DL B
urst
1
•Pream
ble
DL Zone 1(PUSC) DL Zone 3DL Zone 2
1st DLzone only
•FCH
•DL-M
AP
Logi
cal S
ubch
anne
ls
UL Zone 1(PUSC)
•UL Burst 3
Ranging Subchannel
•UL Burst 4
timeTTG
•Pream
ble•FC
H•D
L-MA
P
RTG
Frame 1 (2 to 20 ms) Frame 2
In OFDMA, data bursts overlap in time. This maximizes data flow in a complex environment
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Agenda
• Overview for Broadband Wireless Access• WiMAX-OFDMA Technologies• WiMAX-OFDMA Signal Meas. & Analysis• 802.16e WiMAX-OFDMA RF Measurement• Resource
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802.16 Test ParametersTransmitterPower, Frequency & TimeSpectrum Mask, ACP, harmonics & spuriousModulation & timing errorsReceiverBER, FERImpairmentsInterference
FunctionalThroughputOther
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802.16e Test Modes: What does your device support
RF translation ADC Baseband
/ MAC
What is controlling the Device Under Test?
What modes can be used to increase throughput of the test procedure?
Device configuration software
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Signal Generation/Analysis: Two Major Types of Testing• Creating & Measuring Spectrally and Statistically
Correct Signals• Component & subsystem testing
• RCE/EVM interpretation of performance (compression, CFR, distortion, phase noise, etc.)
• Creating & Measuring Fully Compliant Signals• Configuring & verifying DSP
• Complete transmitter & receiver testing
• Compatibility/interoperability testing
• Margin testing
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Agilent’s 802.16e WiMAX Product Portfolio
DUT
E4438C Signal Generator
PSA-series Signal Analyzer orInfiniium-series Oscilloscopes or89600-series VXI modules or16900-series Logic Analyzers
LAN,GPIB
89601A VSA Software, Opt B7Y 802.16e OFDMA analysis
N7615A Signal Studio for802.16e OFDMA signal creation
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Physical Layer Signal Source Solution
• Not just RF: Highly Flexible signal generation, with RF, Differential IQ and Digital Outputs (option 003)
• Generates WiBro and 802.16e arbitrary waveform files
• Two Channel RF Phase Coherence possible with simple external frequency mixing
E4438C Series Vector Signal Generator with N7615A Signal Studio for 802.16 OFDMA
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Signal Generation: RF, Digital & Analog Baseband
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802.16e OFDMA Signal Generation N7615A• Supports OFDMA PHY in IEEE 802.16-2004 and
802.16e standards
• Generates up to 16 frames (same config. with incrementing frame number and continuing data in MAC PDUs
• Fixed data patterns, PN9 or PN15 sequences, or user data files
• Supports 512, 1024, and 2048 FFTs with variable bandwidths
• Automatically generates FCH, DL-MAP, UL-MAP for receiver test
• Create downlink or uplink subframes, TDD or FDD
• Zone types: DL-PUSC, DL-FUSC, UL-PUSC, UL-OPUSC
• Flexible configuration of zones, bursts, and MAC PDUs
• Add real-time AWGN when used with E4438C option 403
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N7615A User Interface: Downlink
Add multiplezones
Flexible burstconfiguration
(auto or manual)
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N7615A User Interface: Uplink
Automatic or manual burst allocation
Add one or more MAC PDUs in each burst
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Physical Layer Measurement in the Standard:Receiver Sensitivity (16e example)• A BER measurement with unique
spec for each Channel BW, Mod type, and coding gain.
• Must have BER less than 10e-6 for the specified power levels
• Test messages are specially defined patterns: SBPSK, SQPSK, S16QAM, and S64QAM
RF
Radio Receiver
Radio Control and
BER Software
Radio Control and payload data
Test messages are specially defined patterns: SBPSK, SQPSK, S16QAM, and S64QAM. UI from N7615A shown here
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N7615A User Interface: Waveform Generation Log Displays raw data generated, including
contents of DLFP (FCH), DL-MAP, UL-MAP, and data bursts with MAC headers and CRC.
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Signal Analysis: RF, Digital & Analog Baseband
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WiMAX RF Signal Analysis
ESA(opt.H70)/PSA(opt.H70) +89611A
DC to 26.5 GHz(36MHz BW)
ESA/PSA+InfiniiumDC to 26.5 GHz
89641A: DC to 6.0 GHz (36 MHz BW)
89610A: DC to 40MHz(I/Q input)
OPTION 1 OPTION 2 OPTION 3
PSA option 140/122(40MHz/80MHz BW)
PSA
• All HWs need link with S/W 89601a+option B7S/B7Y
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89601A Optional Measurement Software• Option AYA(Digital Demodulation): Vector Modulation Analysis (also called
Digital Demodulation).
• Option B7N(3G Application): Extends Option AYA Vector Modulation Analysis capabilities to include W-CDMA (3GPP),cdma2000, cdma20001xEV-DO and TD-SCDMA vector modulation analysis.
• Option B7R(WLAN Application): Vector Modulation Analysis capabilities for WLAN DSSS/CCK/PBCC/OFDM Signal.(89607 WLAN Test Suite license is included inside)
• Option B7S(802.16-2004 modulation analysis): Vector Modulation Analysis capabilities for IEEE-802.16-2004(WiMax) Signals.
• Option B7Y(802.16 OFDMA modulation analysis): Vector Modulation Analysis capabilities for IEEE-802.16 OFDMA Signals.
• Option B7Z(802.11n MIMO modulation analysis): Vector Modulation Analysis capabilities for IEEE-802.11n MIMO Signals.
• Option 105(Dynamic Link to EESof/ADS): Allows you to connect your 89600-Series VSA software to Agilent's EESof Advanced Design System
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A Meas. & Troubleshooting Sequence
Get basics right,find major problems
Signal qualitynumbers, constellation,
basic error vector measurements
Find specificproblems & causes
Frequency,
Frequency & Time
Basic
Digital Demod
Advanced &
Specific Demod
One suggested sequence, especially for signals that are not fully understood
As signals become more complex, vectormeasurements are even MORE useful prior to digital demodulation
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Meas. & Troubleshooting Sequence
Wideband spectrumNarrowband spectrumFrequency & TimeTriggering, timing
Gated SpectrumGated power, CCDFTime captureSpectrogram
Get basics right,find major problems
Signal qualitynumbers, constellation,
basic error vector measurements
Find specificproblems & causes
Frequency,
Frequency & Time
Basic
Digital Demod
Advanced &
Specific Demod
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Simultaneous Frequency & Time Measurements
FFT based spectrum analysis |Arb Spans/RBWs |Full markers
Power vs. Time
Rise Time & zoom
Spectrum & Occupied
BW
Band power (dBm, RMS (sqrt), C/N,
C/No)
Trigger level
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Downlink Preamble• 1 Symbol of QPSK• Every third carrier, 1/3
of 852 active carriers• No Pilots
284 active QPSK carriers
1 Symbol
•Gate Length = 1 Symbol Time•Uniform Window for Maximum Frequency Resolution
OFDMA
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Resolving All Carriers in Preamble OFDMA
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Amplification Problems--Gain Compress.
Before Amplification After Amplification
Use Time-Gated CCDF to Investigate Different Modulation Types
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Spectrogram enhancements—Delta Marker
• Spectrogram marker enhancements • Height can now be
described in time as well as scans
• Offset and delta markers let you position two independent lines to read absolute position of marker and delta between the two points
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Other Meas. Before Digital Demodulation• Time Capture
• Reduce uncertainty by analyzing known signal (useful during transition to digital demodulation)
• Provides for “real-time” & overlapped analysis
• Identify patterns not otherwise seen
• Capture 2-10 bursts (generally avoid very large captures)
• Spectrogram• See entire burst in frequency and time on one display
• Find subtle patterns, errors (data portion of burst should not have repeated patterns
• Find Problems Even if Demod. not yet Possible• Example: Power problem could be seen in demodulation mode, but
malformed pilots prevent demodulation--measure in vector mode
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Meas. & Troubleshooting Sequence
Set up demod & displaysConstellationError SummaryError vector spectrumError vector time
Cross-domain &cross-measurement links
Parameter adjustmentMore time capture
Get basics right,find major problems
Signal qualitynumbers, constellation,
basic error vector measurements
Find specificproblems & causes
Frequency,
Frequency & Time
Basic
Digital Demod
Advanced &
Specific Demod
2
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Two Types of Demod Measurements• Two types of measurements
• “Uniform zone” similar to traditional OFDM, one modulation format and power level used over the entire permutation zone.
• “Data burst” uses definitions made by the user through the subchannel-by-symbol grid on the “Zone definition” tab.
• Results are the same, except “Data Burst” mode also provides “Data Burst Summary” results
• Uses:• Uniform zone analysis for component manufacturers
(Amps, Repeaters, Antennas, etc.) and anyone not dealing with the baseband DSP
• Data Burst analysis for others
OFDMA
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Initial Demodulation Results• Constellation
• Successful demodulation?
• Expected modulation type(s)?
• Indications of error?
• Symbols/Errors Table• Relative constellation error (RCE) = EVM of data and
pilot carriers
• Pilot & common pilot errors (CPE)
• I/Q errors including gain imbalance, quadrature error, delay mismatch
• Carrier frequency error, symbol clock error
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Digital Demodulation--Basic Setup
• Uniform ZoneMeasurement
Data BurstAnalysisNot Used
OFDMA
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Troubleshooting 802.16-2005 Radios: Basic Demodulation Results
OFDMA
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Basic Demodulation: Manual Selection of Demod Type• The result is incorrect, but successfully locked to Pilots
OFDMA
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Data Burst AnalysisManually Defineand Select Zonesor use Map File
Select any Zoneor Combination,with or withoutFCH
OFDMA
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Linking Vector and Demod Measurements OFDMA
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Color Coding Reveals Signal Structure OFDMA
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Initial Demodulation Results (cont.)• Error Vector Spectrum
• All symbols shown on Y-axis for each carrier on X-axis
• All-symbol average for each carrier is shown
• Examine for patterns/trends by carrier, differences between carriers & pilots
• Spurs will affect individual or few carriers, for all symbols
• Error Vector Time• All carriers shown on Y-axis for each symbol on X-axis
• All-carrier average for each symbol is shown
• Examine for patterns or changes according to symbol (time)
• Impulsive errors (DSP, interference, clocks, power) will affect all carriers for an individual symbol or group of symbols
OFDMA
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Error Vector Spectrum
Zoomed
All Carriers, 2 Data Bursts
OFDMA
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Initial Demodulation Results (cont.)• Coupled Markers
• Identify a symbol by time or frequency or error magnitude
• Link a symbol across time and frequency domains, and between different display types
• Link error peaks to constellation points, amplitude values, specific carriers, time points in a burst, as a way to pinpoint error mechanism
• Identify specific time instant or frequency to examine with advanced & specific demodulation techniques (next)
• Change Measurement & Display Parameters Without Taking New Data
• Use Time Capture to Provide Consistent Signal & Error Behavior
OFDMA
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Meas. & Troubleshooting Sequence
Demod by carrieror symbol or both
Select pilot tracking typesSelect carrier, timingPreamble (equalization) analysis
Cross-domain &cross-measurement links
Demod parameter adjustmentsMore time capture
Get basics right,find major problems
Signal qualitynumbers, constellation,
basic error vector measurements
Find specificproblems & causes
Frequency,
Frequency & Time
Basic
Digital Demod
Advanced &
Specific Demod
3
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Burst by Burst Signal Analysis
Validate mod. formats
Validate boosting levels
Validate permutationalgorithms
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Uplink Analysis of Singe Data Burst• Non-Uniform Signal, Single Data Burst
DL-PUSC burstsare rectangularUL-PUSC burstsare wrapped
OFDMA
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Pilot Tracking• In OFDMA, Pilots Change Location and are Not Present for All
Symbols
• In OFDMA, Pilot Tracking can “Break” Demod
• Demod relative to incorrect (data) carriers
• Demodulation Is Adjusted During A Subframe
• Demod is Performed Relative to the BPSK Pilots
• Some Errors are “Tracked Out” as Demod Follows Pilots
• Tracking Types can be Enabled/Disabled Independently
• Amplitude (default is off)
• Phase (default is on)
• Timing (default is off)
• Pilot Tracking Reduces Close-In Phase Noise
OFDMA
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Advanced Demodulation Results
• Common Pilot Error
• Pilot carriers provide continuous amplitude & phase reference to receiver
• Difference between the measured and ideal pilot subcarrier symbols
• Reveals signal changes during burst
OFDMA
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• Channel Frequency & Impulse Response. Derived From Preamble or Preamble + Data
Channel Response from Equalizer OFDMA
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Relative Subcarrier Power• New Data Type: Channel Frequency Response Adjacent
Difference• Adjacent subcarrier power difference
• Measured from preamble, every 3rd physical subcarrier, or from selected data, with interpolation
OFDMA
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Agenda
• Overview for Broadband Wireless Access• WiMAX-OFDMA Technologies• WiMAX-OFDMA Signal Meas. & Analysis• 802.16e WiMAX-OFDMA RF Measurement• Resource
Mobile WiMAX 802.16e RF Measurement
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WiMAX & Mobile WiMAX Transmitter Testing
Base-band Stduio
Digital Interface
RF/Analog BB VSA/89601A SW
Analog I/Q
Digital I/Q
89601A-B7S WiMAX
89601A-B7Y Mobile WiMAX
RFTx
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IEEE 802.16e OFDMA Tx Specifications Overview
8.4.12.1 – Transmit power level control8.4.12.2 – Transmitter Spectral Flatness8.4.12.3 – Transmitter Constellation Error (RCE)8.4.14.1 – Center Frequency and Symbol Clock Frequency Tolerance
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8.4.12 Transmitter requirements
• 8.4.12.1 Transmit power level control• The transmitter shall support monotonic
power level control of 45dB minimum (30 dB for license-exempt bands)
• Minimum step size of 1 dB
• Relative accuracy of ± 0.5 dB.
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8.4.12 Transmitter requirements• 8.4.12.2 Transmitter spectral flatness
• The average energy of the constellations in each of the n spectral lines shall deviate no more than indicated in follow table.
• The absolute difference between adjacent subcarriers shall not exceed 0.1 dB.
• The power transmitted at spectral line 0 shall not exceed -15 dB relative to total transmitted power
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Physical Layer Measurement in the Standard: Transmitter Spectral Flatness• The absolute difference
between each adjacent sub-carrier shall be no more than 0.1dB
• +/-2dB difference from average energy allowed for carriers closer to center
• +2/-4dB difference from average energy allowed for carriers furthest from center
• There are several different methods of measurement
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8.4.12 Transmitter requirements• 8.4.12.2.3 Transmitter constellation error
• To ensure that the receiver SNR does not degrade more than 0.5 dB due to the transmitter SNR, the relative constellation RMS error, averaged over subcarriers, OFDMA frames, and packets, shall not exceed a burst profile dependent value according to Table
-26-2664-QAM-1/2
-30-28
-24-20.5-18-15
Relative constellation error for SS (dB)
–30–28
–24–20–18–15
Relative constellation error for BS(dB)
Burst Type
64-QAM-3/464-QAM-2/3
16-QAM-3/416-QAM-1/2QPSK-3/4QPSK-1/2
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8.4.14 Frequency control• 8.4.14.1 Center Frequency and symbol clock frequency tolerance• For BS
• The transmitted center frequency, receive center frequency, and the symbol clock frequency shall be derived from the same reference oscillator.
• The reference frequency accuracy shall be better than ±2*10–6.• For SS
• Both the transmitted center frequency and the sampling frequencyshall be derived from the same reference oscillator.
• The center frequency shall deviate no more than 2% of the subcarrier spacing.
Agilent Restricted
IEEE 802.16e OFDMA Rx Specifications Overview
8.3.13.1.1 – Receiver Sensitivity8.3.13.1.2 – MS uplink transmit time tracking accuracy8.3.13.1.3 – MS aotonomous neighbor cell scanning8.3.13.2 – Receiver Adjacent and Non-adjacent channel Rejection8.3.13.3 – Receiver Maximum Input Signal8.3.13.4 – Receiver Maximum Tolerable Signal
39
Agilent Restricted
Agilent’s WiMAX Receiver Test BER/PER Testing
Rx
E4438C ESG Vector Signal Generator
Chipset Vendor-supplied SW will perform BER/PER
testing
WiMAX Signal Studio Software
Agilent Restricted
DUT
Digital I/Q or IF Signal Generation:Signal Generators with Digital Outputs
• Pre-Configured and Proprietary Signals using Arbitrary Waveform Generator
• Solutions Optimized for Digital I/Q and IF
Signal Generator with Digital Outputs
Digital SignalInterface Module
40
Agilent Restricted
8.3.13 Receiver requirements• 8.3.13.1 Receiver sensitivity
• The BER measured after FEC shall be less than 10–6
• Using the defined standardized message packet formats
• Using an AWGN channel.
161/2
3/42/3
3/41/23/41/2
Coding Rate
2018
1410.5
85
Relativer SNR (dB)Modulation
64-QAM
16-QAM
QPSK
NFpLossN
NFRSNRRFFT
UsedSRxss ++⎟⎟
⎠
⎞⎜⎜⎝
⎛ ××+×−+−= Im10log10)(10log10114
Agilent Restricted
8.3.13 Receiver requirements• 8.3.13.2 Receiver adjacent and non-adjacent channel rejectio
• 8.3.13.3 Receiver maximum input signal• For SS, the receiver shall be capable of decoding a maximum on-
channel signal of –30 dBm.• For BS, the receiver shall be capable of decoding a maximum on-
channel signal of –45 dBm.• 8.3.13.4 Receiver maximum tolerable signal
• The receiver shall tolerate a maximum signal of 0 dBm without damage.
-23-4
-11
Adjacent Channel Rejection C/I (dB)
-30
Non-Adjacent Channel Rejection (dB)Modulation/Coding
64-QAM-3/4
16-QAM-3/4
41
Agilent Restricted
Access to all test points…
Agilent Restricted
CONCLUSION: Structured Measurement Approach
• An Orderly Approach Will• Reduce setup and measurement errors (correct center frequency, span,
pulse/burst parameters)
• Find problems at the earliest stages of analysis
• Provide more understandable and useful measurement results
• Help avoid missing certain signal problems or impairments (some impairments are most clearly seen in vector measurements)
• Provide the fastest path to complete troubleshooting
• Agilent's 16e solution is >1 year old, and is in its 5th release!
• Mature, fully-validated analysis solution with a deep feature set
42
Agilent Restricted
Resources• Agilent WiMAX Portal
www.agilent.com/find/wimax• WiMAX Ap-Notes (3)
• New OFDMA Ap-Note (available soon)
• Analysis: 89600 opt. B7Y technical overview & demonstration guide
• Signal Generation: N7615A technical overview
• Trial Version Software• 89601A VSA Software - CD Trial: Order 5980-1989E
• N7615A Signal Studio for 802.16 OFDMAwww.agilent.com/find/esg
Agilent Restricted
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