J.Tiberghien - VUB 10-05-K.Steenhaut & J.Tiberghien

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30 Οκτ 2013 (πριν από 3 χρόνια και 10 μήνες)

106 εμφανίσεις

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

1

Telecommunications

Concepts

Chapter 2.1

The Circuit Switched
Telephone Network

J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

2

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

3

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

4

The Telephone Network

Analog

/
Digital

PABX

SW

SW

SW

SW

SW

PABX

SW

SW

J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

5

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

6

The Fixed Access Network

Analog phone on analog switch

Line

circuit

Analog

switch

twisted pair, average length 2.5 Km


Signaling (DTMF or pulse)

and voice multiplexed

In Belgium : last one went out of service in 2002

J.Tiberghien
-

VUB

10
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05
-
K.Steenhaut & J.Tiberghien
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VUB

7

The Fixed Access Network

Analog phone on digital switch

Line

circuit

Digital

switch

Digital

Analog

twisted pair, average length 2.5 Km


Signaling (DTMF or pulse)

and voice multiplexed

In Belgium : the most common situation

J.Tiberghien
-

VUB

10
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05
-
K.Steenhaut & J.Tiberghien
-

VUB

8

The Fixed Access Network

The ISDN Basic Access

twisted pair, average length 2.5 Km

144Kb/s

modem

Digital

switch

144Kb/s

modem

S bus

2 * 64 Kb/s + 16 Kb/s TDM

In Belgium : e.g. the Belgacom TWIN

J.Tiberghien
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VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

9

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

10

The
Mobile

Access Network

Mobility Management

NSS

HLR

VLR

PSTN

MSC

NSS

BSS

16 Kb/s

13 Kb/s

64 Kb/s

BSS : Base Station Subsystem

NSS : Network & Switching Subsystem

HLR :

Home Location Register

VLR :

Visitors Location Register

MSC :

Mobile Switching Center

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

11

The
Mobile

Access Network

Mobility Management


Mobile terminal identification


SIM card with unique id.


Data about SIM stored in HLR of operator who owns SIM


Phone calls directed to HLR of operator


Mobile terminal localization


BSS regularly makes broadcasts in its cells


Mobile selects best cell and sends its SIM id.


Presence of mobile recorded in local VLR


SIM’s owner HLR updated with applicable VLR


Handover


When location of mobile changes during conversation


Circuit routing modified “on the fly”


Sound quality briefly degraded


Handover not available between different operators

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

12

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

13

The
Mobile

Access Network

GSM radio system

time

frequency

15/26 ms

200 KHz

45 MHz

Tx

Rx

3 radio slots



A combination of FDM and TDM



Two separate frequency bands used for Tx and Rx



Slow frequency hopping for propagation diversity



Sender and receiver sequences shifted by 45MHz and 3 slots



Predefined time slot for signaling channel

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

14

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

15

The
Mobile

Access Network

Wireless interference margins

cause considerable loss in transmission capacity


Considerable room for
improvements by
controlling interferences :
Fast frequency hopping
spread spectrum radio
with
C
ode
D
omain
M
ultiple
A
ccess

=
Third generation mobile
networks (UMTS)

Frequency

Space

Time

J.Tiberghien
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VUB

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05
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K.Steenhaut & J.Tiberghien
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16

The
Mobile

Access Network


Data combined with
known

higher frequency pseudo random
sequence


Resulting modulated radio signal has high bandwidth


Shannon : low data rate combined with high bandwidth =
excellent noise margins!


Fast hopping Spread Spectrum

n b/s

Data

Pseudo
-
random
sequence

m * n b/s

xor

HF carrier

Modulated signal

Large bandwidth



m times bandwidth

needed for data

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
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VUB

17

The
Mobile

Access Network

Spread Spectrum and CDMA

D
1

S
1

xor

HF

Tx1

D
2

S
2

xor

HF

Tx2

D
2

S
2

HF

Correl

-
ator

Rx2

D
1

S
1

HF

Correl

-
ator

Rx1

For radio link Tx1
-
Rx1, emission by Tx2 is just
another source of noise

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
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VUB

18

The
Mobile

Access Network


Multi
-
path Interference

GSM : interference = noise

UMTS : correlator adds similar input signals with
appropriate delays so that they reinforce each other

Different paths have different

lengths and different delays

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

19

The
Mobile

Access Network

Third Generation Handover

When a receiver is between two cells, both
transmitters send the same signal. These two signals
reinforce each other, as multipath propagation does.

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

20

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network


»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

21

Time Domain Multiplexing

Synchronous

multiplexing

Unique bit pattern to
delimit frames

1

0

0

1

0

1

0

1

1

0

0

1

0

1

0

1

XX

J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

22

Primary Multiplexing

Trunk Network (E1 = CEPT30)

Digital

switch

Digital

switch

n*30*64 Kb/s

n*2048 Kb/s

J.Tiberghien
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VUB

10
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05
-
K.Steenhaut & J.Tiberghien
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VUB

23

Primary Multiplexing

Trunk Network (T1 = Bell D2)

Digital

switch

Digital

switch

n*23*64 Kb/s

n*1544 Kb/s

J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

24

The ISDN Primary Rate

for connecting Private Branch Exchanges

Digital

switch

2048 Kb/s (CEPT30)

E1 Optical Fiber or Microwave Link

PABX

pabx


e.g: VUB : 4 E1 lines = 120 simultaneous calls

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

25

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

26

Higher Order Multiplexing

Optical Fiber or Microwave Link

Digital

switch

Digital

switch

J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

27

Synchronous Multiplexing


of almost synchronous data flows


D

C

B

A

E

S

R

Q

P

T

F

E

S

T

D

C

B

A

R

Q

P

0

1

F

1 Frame

S

C

f
out

> n * MAX(f
in
)

Primary rate dataflows to be multiplexed

can be derived from independent clocks !

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

28

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network


»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

29


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 !


J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

30

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network


»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

31

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


frames


Different channels can each have their own
asynchronous clock.


Add
-
drop multiplexers


J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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32

Synchronous Digital Hierarchy

SDH
-

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

...

...

...

...

J.Tiberghien
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VUB

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05
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K.Steenhaut & J.Tiberghien
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33

SDH Rings

34 Mb/s

2 Mb/s

J.Tiberghien
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VUB

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K.Steenhaut & J.Tiberghien
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SDH Rings

J.Tiberghien
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VUB

10
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05
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K.Steenhaut & J.Tiberghien
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SDH Rings

J.Tiberghien
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VUB

10
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05
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K.Steenhaut & J.Tiberghien
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SDH Rings

The MCI Belgian Network

J.Tiberghien
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VUB

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05
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K.Steenhaut & J.Tiberghien
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37

SDH Rings

CUT !

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
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VUB

38

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

39

Telephone Exchange

(Conceptual Model)

Switching

Matrix

Line Circuit

Line Circuit

Line Circuit

Line Circuit

Line Circuit

Control Computer

trunk lines +

Inter
-
office

signaling

Register

Register

Register

Register

J.Tiberghien
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VUB

10
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K.Steenhaut & J.Tiberghien
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40

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 link, 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 ???


J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

41

The Telephone Network

629

62X

477

538

64X

643

673

Non
-
geographic Numbering

6234567

6292905

6433180

0800 12345

4776970

6736476

database

0800

J.Tiberghien
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VUB

10
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05
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K.Steenhaut & J.Tiberghien
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42

The Telephone Network

Number portability

Ported

numbers

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
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VUB

43

Contents


Traditional Overall structure



Access network

»
Fixed lines

»
Wireless access


GSM


UMTS


Trunk network

»
Primary multiplexing : E1 / T1 lines

»
Higher order multiplexing


Plesiochronous Data Hierarchy


Synchronous Data Hierarchy


Exchanges and signaling


General purpose SDH networks

J.Tiberghien
-

VUB

10
-
05
-
K.Steenhaut & J.Tiberghien
-

VUB

44

General Purpose SDH Networks

PABX

PABX

J.Tiberghien
-

VUB

10
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05
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K.Steenhaut & J.Tiberghien
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VUB

45

Bibliography

To know More about Telephony

Recommended for this chapter

John C. BELLAMY

Digital Telephony

Third edition

John Wiley, 2000.

ISBN : 0
-
471
-
34571
-
7