10-multiplexing-abinsediq-03feb2012

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MULTIPLEXERS, DIGITALHIERARCHY ANDCONCENTRATION

SYSC 4700 Telecommunications Engineering

David Falconer, Halim Yanikomeroglu, and Akram Bin SediqCarleton University

03 February 2012


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Multiplexing

Multiple signal

streams originatingat a common location

Multi-plexer (MUX)

Demulti-plexer (DEMUX)

Multiple streamscombined into onesignal on a singletransmission medium Separate

signal streams

restored

Examples:a central office, with many voice channels multiplexed onto anoptical fiber or copper pair.signals from a cellular base station to cellular subscribers

sharing a common radio channel.


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Multiple Access

Demulti-plexer (DEMUX)

Separatesignal streams

restored

Multiple information streams

all originate at separate locations,but are destined for a commonlocation.

Examples:Uplink signals from cellular radios to a base stationSignals from cable subscribers to a head end.


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Types of Multiplexing and Multiple Access for Constant-Rate

CommunicationsMultiplexing: Frequency division

(FDM) Time division (TDM) Code division (CDM)

Multiple Access: FDMA

TDMA CDMA


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FDM (Frequency Division Multiplex)

and FDMA

Bandwidth per channel =b.

Requires accurate frequency control and carefulfiltering, especially on uplink. A narrow guard band usually separates channel

spectra.

Frequency

user

1

user

2user N

Total bandwidth=Nbb


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Hybrid FDM/TDM and FDMA/TDMA

Time

Frequency

1 M

N

1

N time slots in each of M frequency channels NM channels


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CDM (Code Division Multiplex) and

CDMA

Unique User Spreading code #1 Spreading code #1

Low passfilter

Unique User Spreading code #2 Spreading code #2

Low passfilter

Channel


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Uplink/Downlink Duplexing: FDD and

TDD FDD (Frequency Division Duplexing):

Uplink and downlink use separate frequency bandssimultaneously.

Frequency

user 1 downlink user 1 uplink

Downlink band Uplink band


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Digital Multiplexing Most digital transmission and switching

facilities are now digital. Fibre optic transmission systems have high

(digital) capacity. New services (video, data, etc.), made

possible by high capacity digital technology,will have a wide range of bit rates; eg. 64Kb/s up to 10s or 100s of Mb/s.

Multiplex hierarchies: multiplexed signals arethemselves multiplexed.


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DS1 Frame Format ( -law

countries)

1 2 3 4 24

1 2 3 4 5 6 7 8

S bit

24 PCM code words, each representing 1 sample

8 bits per code word

193 bits in 125 s(1.544 Mb/s)


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North American

Plesiochronous Digital Hierarchy (PDH)

before SONET/SDH (Synchronous Optical Networking / SynchronousOptical Hierarchy)

24DS0s

DS1

4 DS1s

DS2

DS3

DS0 = 64 Kb/s [ 1 channel ]DS1 = 1.544 Mb/s T1 [24 ch ]

(European system E1 @ 2.048 Mb/s) DS2 = 6.312 Mb/s [ 96 ch ]DS3 = 44.736 Mb/s [ 672 ch ]DS4 = 274.176 Mb/s [ 4032 ch ]

DS5 = 400.352 Mb/s [ 5760 ch ]


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SONET/SDH

Synchronous Optical Networking / Synchronous

Optical Hierarchy

OC: optical carrier OC-1= 51.840 Mb/sOC-3 = 155.520 Mb/s OC-12= 622.080 Mb/sOC-24= 1.244160 Gb/sOC-48 = 2.488320 Gb/sOC-192 = 9.953280 Gb/sOC-768 = 39.813120 Gb/sOC-3072 =159.252480 GB/s

Multiple SONET signals can be transported over multiple wavelengths over a singlefiber by means of wave-division multiplexing (WDM) .

Gigabit Ethernet (GbE): an alternative protocol


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Four DS1s to One DS2 (M12

Multiplex) A1 A2 A3 A4 A5 A6 A7 A8

B1 B2 B3 B4 B5 B6 B7 B8

C1 C2 C3 C4 C5 C6 C7 C8

D1 D2 D3 D4 D5 D6 D7 D8

A1 B1 C1 D1 A2 B2 C2 D2 ...

4 X 1.544 Mb/s

6.312 Mb/s

4 DS1s DS2


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Pulse Stuffing in Older Digital

Multiplexers To accommodate slightly different clock

frequencies on different facilities, pulse

stuffing has been used:e.g. DS2 rate=6.312 Mb/s=4X1.544Mb/s+136 Kb/s;

Multiplexer adds as many extra stuff bits asare necessary to bring total bit rate to 6.312Mb/s.


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Concentration

Multiplexonly the

M activechannelsN channels,

of which onlyM < N are active

Switch(N inputs,M outputs)

Demult-

iplex

Switch(M inputs,N outputs)

M inputs to MUX


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Statistical Multiplexing - For Bursty,

Non-uniform Rate Digital SignalsSource #1:

Source #2:

Source #3:

Source #4:

Statisticalmultiplexer

output:Time


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Summary

Principles and definitions of multiplexing and multipleaccess

FDM, FDMA, TDM, TDMA, FDMA/TDMA, CDM,CDMA

Duplexing: FDD and TDD Digital multiplexing and the digital multiplex hierarchy:

pulse-stuffing systems synchronous digitalhierarchy (SONET)

Concentration Statistical multiplexing

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