Circuit switch telecommunication network

J.Tiberghien - VUBJ.Tiberghien - VUB

TelecommunicationsConcepts

Chapter 2.1

The Circuit Switched

Telephone Network


Contents

• The traditional Telephone Network

–Overall structure

–Trunk lines

»Plesiochronous Data Hierarchy

»Synchronous Data Hierarchy

–Exchanges and signaling

–General purpose SDH networks


The Telephone Network

PABX

SW

SW

SW

SW

SW

PABX

SW

SW

Analog / Digital



Some details : Analog telephones on analog switch

twisted pair, average length 2.5 Km Linecircuit

Analogswitch



Some details : Analog telephone on digital switch

twisted pair, average length 2.5 Km Linecircuit

Digitalswitch

DigitalAnalog



Some details : ISDN Basic Access

twisted pair, average length 2.5 Km 144Kb/smodem

Digitalswitch

144Kb/smodem

S bus

2 * 64 Kb/s + 16 Kb/s


Contents



–Trunk lines






Time Domain Multiplexing

1 0 0 1

0 1 0 1

1 0 0 10 1 0 1

Synchronous multiplexing



Trunk Network (CEPT30)

Optical Fiber or Microwave Link

Digitalswitch

Digitalswitch

n*30*64 Kb/s

n*2048 Kb/s



Trunk Network (Bell D2)

Digitalswitch

Digitalswitch

n*23*64 Kb/s

n* 1544 Kb/s




Some details : ISDN Primary Rate

Digitalswitch

2048 Kb/s (CEPT30)

Optical Fiber or Microwave LinkPABX


The Telephone NetworkTrunk Network


n*30*64 Kb/s

n*2048 Kb/s

Analogswitch

AnalogDigital


The Telephone NetworkTrunk Network

Digitalswitch

Digitalswitch



Contents



–Trunk lines






Synchronous Multiplexing

of almost synchronous data

flows

D C B AE

S R Q PT

F

EST D C B AR Q P01F

1 Frame

S C

fout > n * MAX(fin)


Plesiochronous Digital Hierarchy–Each multiplexed section has its own clock

–Each level of multiplexing has its own clock

– Frame structure from multiplexed signals is not explicitly present in the multiplexed stream

>Full demultiplexing required at each node !


Contents



–Trunk lines






Synchronous Digital Hierarchy

STM-1 STM-1

Up to 63 channels at 2 Mb/s

– The entire trunk network has one clock

–Multiplexed stream based on 125 S frames

–Different channels can each have their own asynchronous clock.

–Add-drop multiplexers


Synchronous Digital HierarchySDH - SONET

Data rate CCITT USA-Elec. USA-Opt.

51.84 STS-1 OC-1

155.52 STM-1 STS-3 OC-3

466.56 STM-3 STS-9 OC-9

622.08 STM-4 STS-12 OC-12

933.12 STM-6 STS-18 OC-18

1244.16 STM-8 STS-24 OC-24

1866.24 STM-12 STS-36 OC-36

2488.32 STM-16 STS-48 OC-48


SDH Rings

34 Mb/s 2 Mb/s


SDH Rings


SDH RingsThe Worldcom Belgian

Network

065

060

064

071

057

069

056

051

058

059 050

068

055054

053

067

02

09 052

03

061

082084

083

085

063

086 080

010

081

016

019

011015

014

04

012

087

089013WCOM POP

WCOM POP

WCOM POP

WCOM POP

WCOM POP

WCOM POP

WCOM POPWCOM POP

WCOM POP

WCOM POPLUXEMBOURG


SDH Rings

CUT !


Contents



–Trunk lines






Telephone Exchange

(Conceptual Model)

SwitchingMatrix

Line Circuit

Line Circuit

Line Circuit

Line Circuit

Line Circuit

Control Computer

trunk lines +Inter-office

signaling

Register

Register

Register

Register


Signaling system generations

• SS1 - SS5 : Analog call forwarding between exchanges• SS6 : First digital signaling system

– monolithic communications system (no layers)– Full mesh of virtual circuits, based on 2400 b/s links

• SS7 : Signaling system for the intelligent network– uses any digital links, satellites included– layered, OSI inspired, network architecture – supports "intelligent network" applications

» Non-geographic numbers (800)» CLIP, Call forwarding, Conference calls, etc...» Number portability» Carrier selection» Mobility & roaming

• IP ???



629

62X

477

538

64X

643

673

Non-geographic Numbering

6234567

62929056433180

0800 12345

4776970

6736476

database0800


The Telephone NetworkNumber portability

Ported numbers


The Telephone NetworkCarrier selection

• through prefix• through preselection


Contents



–Trunk lines




• General purpose SDH networks


General Purpose SDH Networks

PABXPABX


BibliographyTo know More about

Telephony

Recommended for this chapter

John BELLAMY

Digital Telephony

Second edition

John Wiley, 1991.

ISBN : 0-471-62056-4


BibliographyTo know More about

SDH

Recommended for this chapter

Mike SEXTON, Andy REID

Transmission Networking:

SONET and the Synchronous Digital Hierarchy

Artech House, 1992.

ISBN : 0-89006-551-9

Circuit switch telecommunication network

Technology

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