Transmission Systems and the Telephone Network

Leon-Garcia & Widjaja: Communication NetworksCopyright ©2000 The McGraw Hill Companies

Transmission Systems and the Telephone Network

• Chapter 4 in Leon

• Skip in Chapter 3 Articles 3.8.7, 3.8.8 (polynomial math for CRC codes) I will ask you do to the long division in mod-2 arithmetic that we did last time

• Skip in Chapter 4 4.2.2 (SONET frame structure) 4.6 Signaling in POTS


B B

C C

A A

B

C

A

B

C

A

MUXMUX

(a) (b)

Trunkgroup

Figure 4.1

Sharing of an expensive channel by multiplexing (MUX)


A CBf

Cf

Bf

Af

W

W

W

0

0

0

(a) Individual signals occupy W Hz

(b) Combined signal fits into channel bandwidth

Figure 4.2

Frequency Division MUX (FDM)


(a) Each signal transmits 1 unit every 3T seconds

(b) Combined signal transmits 1 unit every T seconds

tA1 A2

tB1 B2

tC1 C2

3T0T 6T

3T0T 6T

3T0T 6T

tB1 C1 A2 C2B2A1

0T 1T 2T 3T 4T 5T 6T

Figure 4.3

Time Division MUX (TDM)


2

24

1

MUXMUX

1

2

24

24 b1 2 . . .b2322

frame

24 . . .

. . .

Figure 4.4

Standard T1 Carrier (TDM of 24 PCM voice channels)

(1+24channels*8bits/channel)*8000 frames/sec = 1.544 Mbps


North American Digital Hierarchy

PrimaryMultiplexEg. DigitalSwitch30 chan PCM

4th orderMultiplex

x4

2nd orderMultiplex

x4

3rd orderMultiplex

x4

34.368 Mbps2.048 Mbps 8.448 Mbps139.264 Mbps

CEPT 1CEPT 4

European Digital Hierarchy

28

M13Multiplex

M23Multiplex

x7

PrimaryMultiplexEg. DigitalSwitch24 chan PCM

M12Multiplex

x4

1

DS3 44.736 Mbps

DS1 1.544 Mbps DS2 6.312 Mbps DS3 44.736 Mbps

Figure 4.5


12345 12345

t

Figure 4.6


Figure 4.7 (Optical fiber network for long distance carrier in 1998) could not be reproduced well enough for inclusion.


Low-SpeedMappingFunction

MediumSpeed

MappingFunction

High-Speed

MappingFunction

DS3

44.736

DS1

DS2

CEPT-1

CEPT-4

139.264

ATM

150 Mbps

STS-1

STS-1

STS-1STS-1STS-1

STS-1STS-1STS-1

STS-3c

STS-3c

OC-n

Scrambler E/O

51.84 Mbps

High-Speed

MappingFunction

MuxSTS-n

Figure 4.8


MUX DEMUX MUX DEMUX

MUX DEMUX

(a) pre-SONET multiplexing

removetributary

inserttributary

ADM

removetributary

inserttributary

(b) SONET Add-Drop multiplexing

Figure 4.9


a

b

c

3 ADMs

physical loop net

OC-3nOC-3n

OC-3n

Figure 4.10


a

b c

logical fully-connected net

(a)

a

b

c

3 ADMs connected inphysical ring topology

OC-3nOC-3n

OC-3n

(b)

Figure 4.11


a

b

c

d

a

b

c

d

(a) Dual ring (b) Loop-around in response to fault

Figure 4.12


Inter-OfficeRings

MetroRing

RegionalRing

Figure 4.13


STE: Section Terminating Equipment, e.g. a repeaterLTE: Line Terminating Equipment, e.g. a STS-1 to STS-3 multiplexerPTE: Path Terminating Equipment, e.g. an STS-1 multiplexer

optical

section

optical

section

optical

section

optical

section

line

optical

section

line

optical

section

line

path

optical

section

line

path

(a)

(b)

STSPTE

LTESTE

STS-1 Path

STS Line

Section Section

Mux Muxreg reg regSONET

Terminal

STE STELTE

STSPTE

SONET Terminal

Figure 4.14


B BB 87B

InformationPayload

9 Rows

125 sTransportoverhead

90 bytes

SectionOverhead 3 rows

6 rowsLineOverhead

Figure 4.15


Pointer87 columns

9rows

first column is path overhead

SynchronousPayload

Envelope

framek

framek+1

Pointer

first octet

last octet

Figure 4.16


STS-1 STS-1

STS-1 STS-1

STS-1 STS-1

Map

Map

Map

STS-1 STS-1

STS-1 STS-1

STS-1 STS-1B

yteInterleave

STS-3

IncomingSTS-1 Frames

Synchronized NewSTS-1 Frames

Figure 4.17


1

2

m

OpticalMUX

1

2

m

OpticaldeMUX

1 2.m

Opticalfiber

Figure 4.18


Figure 4.19 (Optical signal in a WDM system) could not be reproduced well enough for inclusion.

Figure 4.19


(a) WDM chain network

ab c d

(b) WDM ring network

a

b

c

3 ADMs

Figure 4.20


User 1

SwitchLink

User n

User n-1

(a) Network

(b) Switch Control

123

N

123

N

Connectionof inputs to outputs

Figure 4.21


N

1 2

1

N

2

N-1

Figure 4.22


nxk

nxk

nxk

nxk

N/n x N/n

N/n x N/n

N/n x N/n

kxn1

2

N/n

Ninputs

1

2

3 3

N/n

Noutputs

1

2

k

2(N/n)nk + k (N/n)2 crosspoints

kxn

kxn

kxn

Figure 4.23


nxk

nxk

nxk

N/n x N/n

N/n x N/n

N/n x N/n

kxn1

N/n

Desiredinput

1

jm

N/n

Desiredoutput

1

2n-1

kxn

kxn

n-1

N/n x N/nn+1

N/n x N/n2n-2

free path freepath

n-1busy

n-1busy

Figure 4.24


12

24

12

24

FromTDM

DeMUX

ToTDMMUX

24 23 12

2 241 23

Read slots inpermuted order

Figure 4.25


nxk

nxk

nxk

nxk

N/n x N/n kxn1

2

N/n

Ninputs

1

3

1

12

n

input TDM frame with n slots

output TDM frame with k slots

Figure 4.26


nxk N/n x N/n

N/n x N/n

N/n x N/n

kxn1 1

2

N/n

1

2

k

kxn

kxn

nxk2

nxkN/n

first slot

kth slot

first slot

kth slot

Figure 4.27


nxk

nxk

nxk

nxk

N/n x N/nTime-Shared

SpaceSwitch

kxn1

2

N/n

Ninputs

1

2

3 3

N/n

Noutputs

TDMn slots

n slots

n slots

n slots

kxn

kxn

kxn

TDMk slots

TDMk slots

TSI Stage TSI StageSpace Stage

Figure 4.28


2x3

2x3

3x21

2

1

23x2D1

B1 A1B2 A2

C1D2 C2

B1 A1

C1D1

A1

B1

C1

D1

A1 C1

B1 D1

Figure 4.29

Leon-Garcia & Widjaja: Communication NetworksCopyright ©2000 The McGraw Hill Companies Figure 4.30


Signal

Source

Signal

Release

Signal

Destination

GoAhead Message

Figure 4.31


(a) Routing in a typical metropolitan area

(b) Routing between two LATAs

1

2 3

4

5

LATA 1 LATA 2

net 1

net 2

A B

C D

Figure 4.32


local telephone office

Dis

trib

utio

n F

ram

e

Serving Area I/f

Serving Area I/f

Pedestal

feeder cable

Switch

distribution cable

Figure 4.33


Original signal

Hybrid transformer

Received signal

Echoed signal

Receive pair

Transmit pair

Figure 4.34


Localanalog

Localdigital

Digitaltrunks

LocalSwitch

Tie lines

Foreign exchange

Channel-switched traffic (digital leased lines)

Circuit-switched traffic

Digitalcross-connect

System

Figure 4.35


Physical SONET

Topology usingADMs and DCCs

Logical Topology

Switches see thistopology

DCC

Figure 4.36

ADM

ADM

ADM

ADM

ADM

ADM


Basic Rate Interface (BRI): 2B+D

Primary Rate Interface (PRI): 23B+D

BRI

PRI

BRI

PRI

CircuitSwitched Network

ChannelSwitched NetworkPrivate

SignalingNetwork

PacketSwitched Networks

Figure 4.37


SPC

Control Signaling Message

Figure 4.39


Switch

Processor

Office B

Switch

Office A

ProcessorSignaling

ModemModem

Trunks

Figure 4.39


STP

STP

STP

STP

SSP SSP

Transport Network

Signaling Network

SSP = Service switching point (signal to message)STP = Signal transfer point (message transfer)SCP = Service control point (processing)

SCP

Figure 4.40


SSP

SSP

Transport Network

ExternalDatabase

SignalingNetwork Intelligent

Peripheral

Figure 4.40


Application Layer

Transport Layer

Network Layer

Data Link Layer

Physical Layer

Presentation Layer

Session Layer

SCCP

MTP Level 3

MTP Level 2

MTP Level 1

ISUPTCAPTUP

Figure 4.42


FewerTrunks

ManyLines

Figure 4.43


N(t)

t

1

2

3

4

5

6

7

all trunks busytr

unk

#

Figure 4.44


0.0001

0.001

0.01

0.1

1

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19

# trunks

Blo

ckin

g Pr

obab

ilit

y

1 2 3 4 5 6 7

8

9

10

offered load

Figure 4.45


Tandem Switch 2

Tandem Switch 1

B CA

(b) Trunkgroup

10 Erlangs between each pair90 Erlangs

E

F

D

B

C

A(a)

E FD

Figure 4.46


Switch SwitchHigh Usage Route

Tandem Switch

Alternate Route

Figure 4.47


High Usage Route B-E

Tandem Switch 1

Alternate Routes for B-E, C-F

High Usage Route C-F

Switch ASwitch B

Switch C

Switch E

Switch D

Switch F

Tandem Switch 2

Figure 4.48


High Usage Route

Alternate Routes

Tandem Switch 3

Tandem Switch 1

Tandem Switch 2

Switch A Switch B

Figure 4.49


Car

ried

Loa

d

Offered Load

Network Capacity

Figure 4.50


6

1

2

5

4

3

7

2

6

1

3

1

7

2

4 5

4

6

37

5

Figure 4.51


AC = authentication centerBSS = base station subsystemEIR = equipment identity registerHLR = home location register

wirelineterminal

MSC

PSTN

BSS BSS

STP SS#7HLRVLR

EIRAC

MSC = mobile switching center PSTN = public switched telephone networkSTP = signal transfer pointVLR = visitor location register

Figure 4.52


LAPDm

radio

RRM

MM

CM

radio

LAPDm

RRM

LAPD

64 kbps

SCCP

MTP Level 3

MTP Level 2

CM

MM

RRM

64 kbps

64 kbps

LAPD

RRM

64 kbps

MTP Level 3

MTP Level 2

SCCP

Um Abis A

mobile station base transceiver station

base station controller

MSC

Figure 4.53


satellitemotion

(a) (b)

Figure 4.54

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Transmission Systems and the Telephone Network