Lecture 1 - Introductionlecture1_2013

KT6124

Rosdiadee Nordin

M.Eng. (Communication & Computer)

TelecommunicationNetwork

Course BriefingSemester I, 2012-2013

Ir. Dr. Rosdiadee Nordin Maxis (2002-2006)

Electrical: DC system (rectifier & battery bank) and AC system (generator, power protection; lightning, DB)

Core Switching: MSC, HLR, VLR, Switch Commander & regional E1 expansion

Tutor (2006), Lecturer (2011), P.Eng. & SMIEEE (2012) BSc. – UKM (Electronics & Electrical), Malaysia, 2001 Ph.D. – Univ. of Bristol, Wireless Engineering, 2011 Research Area – Wireless Communications

Pre-4G (LTE): MIMO, OFDMA 4G and beyond (LTE-A & ??): Carrier Aggregation, Coordinated Multipoint,

Energy Efficient Communications, TV White Space Applied: Wireless Indoor Localization and Wireless Sensor for Bicycle

Performance Monitoring Email: [email protected] Telephone: 03-892118402

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Synopsis – Program Booklet

KT6124 – TELECOMMUNICATION NETWORKThis course give an introduction to telecommunication system and network.The discussion will cover various aspect of telecommunication such asstandards, transmission and planning, multiplexing and hierarchy, switching,signalling, telecommunication traffics and services.

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Syllabus – Program Booklet

KT6124 – TELECOMMUNICATION NETWORKSwitching system engineering: Types of public switched network. Switchingsystem: circuit, store and forward, packet. Numbering, routing system andcharging. Subscriber function. Telephone system basic requirement.Telephone equipment characteristics. Local circuit and hybrid transformation.Dialing system: decadic and DTMF. Subscriber and group switching. Analogand digital switching. Switching: Strowger, cross-bar and time and space.Digital analysis. Controlling sections. Stored Programmable Controlledexchange. Signaling: subscriber, line and register. Transmission system: FDMand PCM 30/32 channel. CCITT, CCIR function in switching planning. DigitalNetwork: ISDN, SDH. Teletraffic Engineering: telephone traffic performance.Teletraffic and queuing theory. Delay and loss system, Grade of service.Erlang and Bernoulli distribution. Broadband network: ATM and B-ISDN.Intelligent network.

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Course Outline

Introduction Transmission Multiplexing and Hierarchy Switching Telecommunication Traffics Switching Network Signaling Services

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References1. J.E.Flood, Telecommunications Switching, Traffic and Networks, Prentice

Hall, 19942. Roger L. Freeman, Fundamentals of Telecommunications, 2nd Edn., John

Wiley & Sons, 20053. Clarke, M.P., Network & Telecommunications: Design & Operation, Wiley4. Harry G. Perros, Connection-Oriented Networks, Wiley, 2005.

Softcopy Softcopy Softcopy Softcopy

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References1. G. Gananasiwam, Telecommunications Switching and Networks, New

Edge International Publisher, 20062. T. Viswanathan, Telecommunication Switching System And Networks, PHI,

2006

Softcopy

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Evaluation

Assignments (3) 20-30% Midterm exam 20-30% Quiz 10% Final exam 40-50%

Previous Performance (Sem. 1, 2011-2012)

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Previous Performance (Sem. 1, 2010-2011)

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TELECOMMUNICATIONNETWORK

IntroductionSemester 1, 2012/2013

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Introduction Tele/communications

- The process of transmitting a message between two remotelocations.

- Message - could be Voice, Music, Textual, Pictorial (graph,diagram, image, etc.) or moving image (video).

Better proportion of data communications links and speech is beingconverted into digital forms, as well as “data” will eventually beconveyed more naturally in these digital forms.

The purpose of telecommunications is to convey information from onelocation to another. Data : Precise communication Voice : More convenient to convey information, that’s why voice

communication has predominated for over a century

The telephone network, until the last three decades, was almost entirelyanalog

Introduction

Narrowband vs. wideband Baseband vs. Broadband

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Communication

Telecommunication

14

Introduction

Narrowband vs. wideband – wired/wireless datarate

Introduction Baseband :

a single data signal is transmitted directly on a wire. The data istransmitted directly on the wire using positive and negativevoltages. RS-232 interface is an example of basebandtransmission.

A baseband signal is an information signal that has not undergone the modulation

process. represents voice, data, or video information signal. must be band-limited before being used to modulate a carrier

signal.

Broadband : is a technique where the data to be transmitted is sent using a

carrier signal, such as a sinusoidal wave. Many differentfrequency carrier signal can be transmitted simultaneously, morethan one signal can be sent on the same wire.

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Introduction

When data (or any other signal) is to be conveyed outside one’splace, this involves the modulation of the broadband signal onto acarrier frequency, either by Amplitude Shift Keying (ASK) Frequency Shift Keying (FSK) Phase Shift Keying (PSK) or Combination of the ASK and PSK (QPSK, /4-PSK, DQPSK)

In baseband signal, speech is being conveyed by Pulse CodeModulation (PCM)

The standard digital voice channel that available in today has acapacity of 64 Kbps, or a multiplexed of 1.544Mbps [T1],2.048Mbps [E1]

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Telecommunication System

ReceiverTransmission ChannelTransmitter

Input TransducerEncoderModulatorAmplifier

Air, Free SpaceCopper CableOptical Fiber

Output TransducerDecoderDemodulatorAmplifier

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Encoder DecoderModulator/Transmitter

Demodulator/Receiver

Transmission Channel

Information signal input

Information signal output

Free-space lossReflectionRefractionScatteringMultipathDiffractionShadowingNoiseInterference

Telecommunication System

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Telecommunication System

Sensor/Transducer : transform one form of energy into another eg. Sound Electrical

Transmitter: amplifies and processes the electrical replica of message for transmission

Receiver: amplifies and processes the received electrical signal in reverse manner to recover the original message

Transmission Channel : a path connecting Transmitter [Tx] to Receiver [Rx], which is characterized by attenuation, etc

Factors involve in a communication system: Type of information (data, text, graphic, voice, music, multimedia, etc.) Information format (analog, discrete, digital, random, deterministic, periodic

etc.) Transmission speed (low, medium, high, etc.) Transmission medium (wired, wireless) Transmission distance (short, medium, long) Modulation techniques (AM, PM, ASK, PSK, PCM, QAM, OFDM, etc.) Error control (BCD, Gray, Morse, ASCII, FEC, cyclic, etc.)

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Telecommunication System

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Telecommunication System

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Telecommunication Services

Teleservice Bearer services Supplementary services Services capabilities (supports for VAS)

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PSTN

Public Switch Telephone Network

POTS

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CCITT, from French: Comité Consultatif International Téléphonique et Télégraphique

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PSTN Topology

A star network

higher-order or multiple-star network

27

Transmission Topology

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Transmission Topology

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Transmission Topology

As the area covered by a star networkand the number of stations served byit grow, line costs increase and it theneconomic to divide the network intoseveral smaller network served by itsown exchange

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PSTN Topology

North America British

Customer’s loop Local/Access NetworkCentral Office ExchangeEnd office Local ExchangeClass 5 officeInter-office trunk JunctionJunctor TrunkToll office Trunk exchangeToll network Trunk network

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PSTN

Transmission links/nodes Customer nodes Switching nodes Transmission nodes Service nodes

Subsystem Transmission systems Switching systems Signalling system

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Telecommunication Standard

COMMUNICATION STANDARDS

A set of rules that must be followed by communication devices to allow for interoperability between equipment from different manufacturer

Example rules Which voltage used to represent ‘0’, which voltage used to represent ‘1’ How many start bits, how many stop bits Which voltage(s) used for start bits, which voltage(s) used for stop bits How many bits in one frame (7 bits, 8 bits, 10 bits, …) The format of control signals, how many control pins

Advantages Ensures a large market for equipment and software Allows products from different vendors to communicate

Disadvantages Freeze technology May be multiple standards for the same thing

Example standards RS232, IEEE 802.11 (WiFi), etc.

PROTOCOL & STANDARD: MAN vs MACHINE

PROTOCOL & STANDARD: MAN VSMACHINE

Definition:

Standards are documented agreements containing technical specifications or other precise criteria to be used consistently as rules, guidelines, or definitions of characteristics, to ensure that materials, products, processes and services are fitted for their purpose.

Telecommunication Standard

Goal: Technological coordination by providing...

Compatibility=> determination of interfaces between cooperating technical units

(e.g. cellular phone and radio network) Portability

=> easy exchange/replacement of components and/or data of atechnical system (e.g. exchangeable memory devices)

Interoperability=> joint operation of different systems

(e.g. communication of different computers via the Internet)

single company=> de facto standards

associations of a plurality of companies, consortia=> multi-company commercial standard

formal commercial standards bodies=> multi-company official/commercial standard

government standards bodies=> multi-company official standard

Telecommunication Standard

ITU-T(CCITT)

telecommunications information technology

glob

al fu

nctio

nre

gion

al fu

nctio

n

ISO

ECMA

GSC

T1 TTC

Isoc

IECJTC 1

IEEE

ITSTC

CEN

RW-CC

WS1

WG2 WG4

WG5

WS3WS2

WG3

WG1 WG6

Forum

ANSI

ARIB

CWTS Org2Org1

W3C

ITU

Telecommunication Standard

APT

ETSI

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Bearer Serviceprovides a "transport system" for exchanging information

Tele-servicesincludes functions for connection, and a uniform "language" for communication and for shaping the messages conveyed

Example: two telephones talk to eachother via telephone network

Also, Voice/Data/Text/Image etc

Telecommunication Network

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Typical Network Services

PSTN(Public Switched Telephone Network) PLMN(Public Land Mobile Network) PSPDN(Packet Switched Public Data Network) ISDN(Integrated Services Digital Network) Frame Relay Signaling Network(CAS/CCS) Internet IN(Intelligent Network)

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Network Services

Teleservices – depend on particular terminal apparatus e.g. telephone, teleprinter

Bearer Services – transmission capacity that can be used for any desired function e.g. private circuit

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Network Services

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More About WANs Virtual private networks (VPNs):

A private network configured within a public network Can be built on top of the Internet Service offered by the telephone companies and ISPs

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Value added networks (VANs): Public data networks that “add value” by transmitting data

and by providing access to commercial databases and software

Use packet switching Subscription based Often used in electronic data interchange (EDI) systems

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Public switched data network technologies (PSDN) Data flows through a public network managed by a

telecommunications carrier Most common technologies:

ISDN (integrated service digital network) X.25 Frame relay Asynchronous transfer mode (ATM)

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example of modulation

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ASK/FSK/PSK

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Sending Multiple Bits Simultaneously Each of the three modulation techniques can be

refined to send more than one bit at a time. It ispossible to send two bits on one wave by definingfour different amplitudes.

This technique could be further refined to send threebits at the same time by defining 8 different amplitudelevels or four bits by defining 16, etc.

The same approach can be used for frequency andphase modulation.

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Sending Multiple Bits Simultaneously

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Hybrid Amplitude and Phase modulation QAM : Quadrature Amplitude Modulation

represents 4 bits per baud (I.e. V = 16)

45o

0o

315o

270o

225o

180o

135o90o

8 phase changes2 different amplitude

levelsTherefore V = 16

Used in ITU V.32 modems

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Digital Encoding of Analog Signals (PCM) Concept:

Take samples of analog signal. To each sample - assign acode. Then transmit that code (digital signal).

If we sample at the rate of twice the bandwidth of thechannel then the resulting digital signal contains all theinformation in the original analog signal - Nyquist’s theorem(1924)

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PCM - Pulse Code Modulation

Each is assigned a n-bit binary code

time

Samples

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PCM

Transmitting an analog signal over a digital network (e.g. Voice on telephone n/w) Each signal is sampled 8000 times per second Each sample is converted to a 7 bit code 1 bit is added for control information there are 128 different such codes (27) The digital signal is then transmitted at 64,000 = 64 Kbps =

8*8000

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Differential PCM Voice signals do not change extremely/rapidly Changes of more than +/- 16 levels between samples is

very rare Hence use just 5 bits instead of 7 to represent each

sample If signal jumps very widely then several samples are

needed to “catch up”

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Delta Modulation Voice signals do not change very rapidly Transmit only one bit at each sample (indicating a +1 or -

1) to indicate whether the signal is increasing or decreasing.

Amplitude of next sample differs from previous one by 1 unit (either +1 or -1).

If very rapid changes take place then the coding takes a while to “catch up”

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Problems (Delta Modulation)

time

Samples cannot keep up with rapidlychanging signal

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Predictive Encoding

Both sender and receiver extrapolate from the last few values received to predict what the next value would be.

The transmitter sends a value only if it were different from what is predicted

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Data transfer in the presence of noise Shannons Law:

C = B * log2 (1 + S/N) where: C = achievable channel capacity B= Bandwidth of line (in Hz) S = Average signal power N = Average Noise power S/N = Signal to Noise Ratio

this is usually measured in decibels (dB) where dB = 10 * log10 (S/N)

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Telephone Channel Capacity

Voice Channel0-4,000 Hz

Frequency (Hertz)

Voice Bandwidth 300-3,300 Hz

GuardBand

GuardBand

0 300 3,300 4,000

Volta

ge

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Example: Channel capacity of a telephone line (voice grade):

typical signal to noise ratio of a voice grade line = 30 decibels i.e. 30 = 10* log10(S/N) => S/N = 1,000 Bandwidth = 3,000 Hz Thus C = 3,000 * log2 (1+1,000) C = 30, 894 bits per second = 30 Kbps (approx) This is the extreme limit though, hardly ever reached

since ideal conditions are not present.

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Converting Voice (analog) to digital : Use PCM Sample 8,000 times in each second Time between each sample = 1/8,000 = 125 µs (not

perceptible to the human ear) Voice signals lie between 300 – 3,300 Hz hence we

are sampling at twice the frequency What does Nyquist’s theorem imply ?

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Quantization

Linear and Non-Linear (logarithmic)

A-law and -law

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Quantization

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Data Encoding

Data needs to be encoded in a format that computers can understand : ASCII (8 bits), 128 characters, 1 bit used for error detection EBCDIC (8 bits), 256 characters Baudot (5 bits) Morse

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Digital Signal Encoding

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Transmitting Data

In order for data to be transmitted and received in a legible form The receiver must know where

a character starts a character ends

in the stream of bits that is received from a transmitter

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Transmitting Data

Flow Control Hardware flow control RTS/CTS Software flow control XON/XOFF

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Flow Control

Necessary when data is being sent faster than it can be processed by receiver

Computer to printer is typical setting Can also be from computer to computer, when a

processing program is limited in capacity

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Stop-and-Wait Flow Control

Simplest form Source may not send new frame until receiver

acknowledges the frame already sent Very inefficient, especially when a single message is

broken into separate frames

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Stop-and-Wait Flow Control

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Transmission Mode Simplex transmission

Only one way communication

Half duplex transmission Two ways communication, but one at a time; not

simultaneously

Full duplex transmission

Simultaneously in both directions

Unicast, Multicast, Anycast, Broadcast

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Local PC transmits

Local PC to remote PC transmissionRemote PC

receives

Local PC receives

Remote PC to local PC transmission

Remote PC transmits

Turnaround time

Half-duplex: Modems transmit in both directions, only one direction at a time.

Local PC transmits

and receives

Local PC to remote PC transmissionRemote PC

receives and

transmits

Full-duplex: Modems transmit in both directions simultaneously

Remote PC to local PC transmission

Half Duplex versus Full-Duplex

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Modes of transmission

Asynchronous Each character is considered a unit of information All timing and error checking is included within

Synchronous Information is sent as a block of data Control and error checking information is added to each

block

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Asynchronous Transmission Each character is sent independent of the next (or

previous character sent) Before each character is a START bit Time between each character is not constant Requires control bits for each character sent (for

error checking) At the end of each character is a STOP bit At least 3 of 9 bits (for a 7 bit code) sent are not

information but overhead. Hence this is inefficient

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Synchronous Transmission Information is transmitted in a block of bits Each block is preceded by a sequence of bits called

a preamble Each block ends with a sequence of bits called a

postamble Control bits are added to allow error checking The data plus preamble plus postamble plus control

information is called a Frame. Much more efficient as compared to Asynchronous

transmission More complex and expensive to implement than

Asynchronous

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Characteristics:

Data is sent as a block of uninterrupted characters Synchronization characters precede and follow the

data block The data block may be 1000 uninterrupted characters Synchronization is maintained whether data is

actually being sent and detected or not Modems remain synchronized during idle time

Efficiency (1000 character transmission)

Control / overhead bits: 48 total control bits per block using HDLC

48 control bits per block x 1 block = 48 control bits 7000 data bits / 7048 total bits = 99.3% efficient

Synchronous transmission

Characteristics:

Data is sent one character at a time Each character has a start and 1, 1.5, or 2 stop bits Synchronization is reestablished for each character Time between character is unsynchronized and of

random length

Efficiency (1000 character transmission)

Control / overhead bits: 1 start and stop bits per character

2 control bits per character x 1000 characters = 2000 control bits

7000 data bits / 9000 total bits = 77.7% efficient

Asynchronous transmission

modem modem

modemmodem

Stop bit Start bit

Synchronization character

1 1 1 11 1 1 1 1 1 1 1 1 000000000000000

1 1 1 11 1 1 1 1 1 1 1 1 000000000000000

Asynchronous versus Synchronous

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Serial versus Parallel Transmission Serial mode

Message is sent one bit at a time

Parallel mode Each character is sent over

a different wire, simultaneously The size of messages depends on its context

Credit card authorization = 1000 bits One page typed memo = 15000 bits One second of digital voice = 56000 bits One second of Full motion video = 100 million bits

UART vs. USART

|0|1|0|1|1|0|1|1|Sender Receiver

|0|1|0|1|1|0|1|1|Sender

Receiver

Type of Comms Protocols

PARALLEL DATA TRANSMISSION

IEEE-488 Parallel (HPIB or GPIB )

Centronics Parallel Protocol (Printer )

SCSI IDE ISA (Industrial Standard

Architecture, 16 bit) PCI (Referral Component

Interconnect, 32 bit) AGP

SERIAL DATA TRANSMISSION

RS 232, RS 422, RS 485 UART (Universal Asynchronous

receiver-transmitter) USART (Universal Synchronous-

Asynchronous receiver-transmitter) MIDI IEEE1394, also called "FireWire" CAN (Controller Area Network) USB (Universal Serial Bus) I2C (Inter Integrated Circuit) --

Philips SPI (Serial Peripheral Interface bus) Micro-wire Ethernet Fiber optics Bluetooth WiFiDifferent type of media

SERIAL COMMUNICATIONS

RS232 The most popular serial communication standard developed by

Electronics Industries Association (EIA) in the 1960s’

DTE v.s. DCE DTE: Data Terminal Equipment (e.g. PC) DCE: Data Communication Equipment or Data Circuit-

Terminating Equipment (e.g. modem, switch, router, and other communication device)

DTE and DCE have different pin definitions

INTERFACES/CONNECTORS

RS-232 DB-25 25-pin connector DB-9 9-pin connector Pin definition for DTE

We can either use all 9 pins, or just use 3 pins: TxD, RxD, GND TxD: transmit data RxD: receive data GND: signal ground

The remaining pins are for more sophisticated controls

DB-25 FemaleDB-25 Male

INTERFACES/CONNECTORS

RS-232 (DB9 and DB25)

SERIAL COMMUNICATIONS

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Basic data communications H/W

Modem - MOdulator/DEModulator used to convert digital signals from a computer to analog

signals via modulation so as to transmit over telephone networks

Old modem (voice-graded telephone line) - ASK Modern modem – FSKSophisticated modem - PSK

Local PC

modem modem

Remote PC

Phone network

1000001 1000001

Input Digital data

Processing Transform digital data input to analog data output (modulation)

Output - Input Analog

Processing Transform analog data input to digital data output (demodulation)

Output Digital data

PSTN

CODEC’s

MODEM STANDARDS

V.29 2400 bauds 9600 bps

16-QAM, 4-QAM

MODEM STANDARDS

MODEM OPERATION – 56k

MODEM STANDARDS – 56k

Asymmetrical Stream

Dial Up Operation (1)

Dial Up Operation (2)

Dial Up Operation (3)

HARDWARE & INTERFACES

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Modem Standards

V.22bis transmission rate 2400 bps baud rate 600 bauds data compression V.42bis Error correction V.42 Modulation method 4QAM and TCM

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Modem Standards V.32

transmission rate 9.6 Kbps Baud rate 2400 bauds Data compression/error correction same Modulation method 4-QAM and TCM

V.32bis same as above except uses 6-QAM and TCM

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