SDH Transmission Network Layout

23/4/8 NO.1

SDH Transmission Network Layout

23/4/8 NO.2

Transmission Network Overview

23/4/8 NO.3

TransportTransportnetworknetwork

TransportTransportnetworknetwork

Exchange

ATM EX

IP Router

AN

Video Conference

VoiceVoiceVoiceVoice

DataDataDataData

ImageImageImageImage

Transmission Network Function OverviewTransmission Network Function OverviewTransmission Network Function OverviewTransmission Network Function Overview

23/4/8 NO.4

For convenience of network layout,we defined two concept about transmission network.

Delaminating---To delaminate transmission network into several layers on upright direction,border upon layers is client/server relationship.

Division---To divide layer network into different part on level direction ,generally divide on geographic.

Delaminating And DivisionDelaminating And DivisionDelaminating And DivisionDelaminating And Division

23/4/8 NO.5

IP

SDLPPP

AAL5GE Vision

RobustPacket over

Fiber

RobustPacket over

SONET/SDHPOS Mapping

(today’s IP/DWDM)

ATM 1/10GE MAC

StandardATM Mapping

ATM Vision

SONET/SDHCell PL 1/10 GE

PHY

Common Vehicle: Digital Wrapper

DWDM

Delaminating And DivisionDelaminating And DivisionDelaminating And DivisionDelaminating And Division

23/4/8 NO.6

Nation and province backbone

Regional and metro junction

Access layer

OXCOADM

OADMOADM

OLA

OLA

OTM

OTM

OTM

ZXWM-32

ZXSM-10G

ZXSM-2.5G

ZXSM-150/600/2500

ZXSM-150(V2) ZXSM-600(V2)

ZXSM-10

ADM

ADM ADM

ADM

ADM TM

REGADM

ADM

ADM

ADM

ADM

E110Base-T

V.282B+DX.21

ZXSM-10ZXSM-10

V.35

V.28

STM-1

EM

TRK

LEZXSM-10ZXSM-10

LEV.11G.703

ZXWM-32

ZXSM-10G

ZXSM-2500

ZXSM-150/600/2500V10.0

ZTE’s Total Solutions for Transmission NetworkZTE’s Total Solutions for Transmission Network ZTE’s Total Solutions for Transmission NetworkZTE’s Total Solutions for Transmission Network

23/4/8 NO.7

Basis of Network Layout

23/4/8 NO.8

Essential of network layoutEssential of network layoutEssential of network layoutEssential of network layout

Network structure designNetwork structure design

Network protectionNetwork protection

Network service schemeNetwork service scheme

Network synchronous method Network synchronous method

Network management systemNetwork management system

23/4/8 NO.9

Structure Design of networkStructure Design of networkStructure Design of networkStructure Design of network

Point to point

Chain

Ring Tree

Star Mesh

And other topology

Principle ： ring is the main topology structure

23/4/8 NO.10

Transmission medium--- FiberTransmission medium--- FiberTransmission medium--- FiberTransmission medium--- Fiber

There are 4 kinds of single mode fiber defined by ITU-T recommendation ：

G.652---single mode fiber

G.653---dispersion shift single mode fiber

G.654---cut-off wavelength shift fiber ， main use for seabed communications

G.655---none zero dispersion shift single mode fiber

23/4/8 NO.11

Absorb lossIntrinsic absorb:--- Ultraviolet absorb\ Infrared absorbExtrinsic absorb:---impurity absorb

Scatter lossRayl scatter:

Loss


23/4/8 NO.12

Dispersion

pulse width disperse

TThe optical pulse has different spectrum.when the pulse spread in fiber,the spectrum components have different speed. It induce pulse width broad or dispersion with distance increase.


23/4/8 NO.13

Loss and Dispersion

EDFA bandwidth

1.2 1.3 1.4 1.5 1.6 1.7wavelengh (mm)

Lo

ss (

dB

/km

)

0.1

0.2

0.4

0.81.0

0

-20

-10

10

20

Disp

ersi

on (p

s/n

m-k

m)

Loss bandy

SMF

DSF

G.652

G.653

NZDF+G.655+

NZDF-G.655-


23/4/8 NO.14

ScatteringStimulated Raman Scattering （ SRS ）Stimulated Brillouin Scattering （ SBS ）

Kerr (refractive index) domino effectSelf-phase modulation （ SPM ）Cross-phase modulation （ XPM ）Four wave mixing （ FWM ）

Fiber nonlinearity


23/4/8 NO.15

cause by dual-refraction of fiber, introduced randomly by pressure 、 bend 、 wring 、 temperature and so on

Polarization mode dispersion -PMD


cause disturbing between signals One of the solution is to improve craft of fiber

manufacture or insert polarization controllers at input and output of system.

23/4/8 NO.16

factors of restricting

transmission distance

factors of restricting

transmission distance

Power Budget---include fiber loss 、 tie-in 、 dispersion 、

margin of power 、 margin of equipment

Dispersion Budget---light source chirp 、 dispersion

Polarisation mode dispersion---PMD

Fiber nonlinearity ---Stimulated Scattering (SRS\SBS) 、

Kerr (refractive index) domino

effect(SPM\XPM\FWM)


23/4/8 NO.17

System transmission solution of ultra-long distance

System transmission solution of ultra-long distance

Fiber Loss => amplify,use optical amplifier;

Fiber dispersion => dispersion compensating;

Nonlinearity => decrease transmitter power;

PMD => no effective compensational method.


23/4/8 NO.18

Method of system designMethod of system design

TThe worst value arithmetic he worst value arithmetic

complying with ITU-Tcomplying with ITU-T


23/4/8 NO.19

The worst value arithmetic-------

Before end of live , all margins of optical cable and equipment use up . At this time system can work normally.

this is the most normal method of system design. It is basis design method for SDH.


23/4/8 NO.20

L=(Ps － Pr － Pp―C―Mc)/( f+

s)

The power calculation is made according to the following formula:

L — transmit distance of regenerator section

Ps — minimum transmit power of S point at end of life

Pr — worst input sensitivity of R point at end of life

(BER≤10-12);

Pp —optical path penalty, L16.2 equal to 2dB,others equal

to 1dB; （ total dispersion penalty ）


23/4/8 NO.21


C — attenuation sum of all optical connectors,

0.5dB/connector

Mc — margin of optical cable, generally in 3dB

f — attenuation coefficient of optical cable;

(generally in 0.20dB/Km or 0.22dB/Km)

s — attenuation coefficient of optical cable melt

connection (generally in 0.025dB/Km)

L=(Ps － Pr － Pp―C―Mc)/( f+

s)

23/4/8 NO.22

The worst value at EOL means take into account initial transmit

power and aging margin-ML (generally in 1.5dB) at transmitter ;

and take into account initial input sensitivity and aging margin-Me

(generally in 3 dB) .


Speed（ Mb/

s ）

Transmitter Receptor

Type

RXMM930

ML

dBEOL(dB

m)Type

TXSSS331

Factory inspection and project acceptance(dBm)

MedB

EOL(dBm)

2488.320 (1550nm) 0 1.5 -1.5 -31.5 3 -28.5

Factory inspection and project acceptance(dBm)

23/4/8 NO.23

ZXSM-600 ： initial transmit power is 0dBm,initial input sensitivity is –31.5dBm

ZXSM-2500: initial transmit power is 0dBm,initial input sensitivity is –31.5dBm

Mc — optical cable margin(generally in 3dB) ；

f + s— equal to 0.27dB;

example:example:

result:result: ZXSM-600 ： L=81.48km

ZXSM-2500:L=77.78km

generally: ZXSM-600 ： when L>=90km ；

ZXSM-2500 ： when L >=85km ， advisement EDFA


23/4/8 NO.24

Transmission solution of ultra-long distanceTransmission solution of ultra-long distance

Transmitting power budget solution

of ultra-long distance——

Erbium doped fiber amplifier （ EDFA ）


23/4/8 NO.25

Location and function Characteri sti c

BA Booster Amplifier

After transmi tter Improve output power

Input power l arge Saturation output power

l arge

PA Pre-amplifier

Before receptor Improve input sensi ti vi ty

Input power smal l Saturation output power

l arge

LA Line amplifier

In l i ne Compensating l i ne l oss

Input power smal l High requi rement on SNR

Basic applications of EDFA


23/4/8 NO.26

Basic structure of EDFA

pump wavelength ： 980nm or 1480nm


isolator

coupler

isolator

Erbium doped fiber

Input signal

Output signal

980nm pump l

aser

1530 ~1565nm

23/4/8 NO.27

Amplified principle of EDFA

working bandwidth ： 1530 ～ 1565nm


980 nm 1480 nm

N1

N3

N2

1550 nm

1550 nm

stimulated emission

signal

Pump source

Input signal

23/4/8 NO.28

Transmission solution of ultra-long distance


Forward Error Correction technique (FEC)Forward Error Correction technique (FEC)

Equivalent improve OSNR

out-band FEC ： improve OSNR about 5-6dB ， generally in 5.5dB

in-band FEC ： improve OSNR about 2-3dB

out-band FEC+in-band FEC ： improve OSNR about5.6dB

Adapt to high-speed system and DWDM

Problem of using EDFA:lead in noise =>OSNR become worse=>bit error


23/4/8 NO.29

L = DA/D km Dispersion accommodation of optical source---DA ps/nm Dispersion coefficient of fiber ---D ps/(nm.km ) G.652 1550nm D= 17~20 ps/(nm.km)

1310nm D= 3.5~5 ps/(nm.km)

G.655 1550nm D= 2~6 ps/(nm.km)

Calculating method of dispersion limit distance


23/4/8 NO.30

Solution of dispersionSolution of dispersion

Dispersion compensating fiber(DCF)

Localization ： insert loss,need compensate by EDFA

Choose lower dispersion fiber(for example:G.655)




Usual External Modulator ： ----Electric Absorb (EA)

----LiNbO3

----MZ(III-V)

External modulator

23/4/8 NO.31

Type DCM-20

DCM-40 DCM-60 DCM-80

Dispersion compensating range (ps/nm) -329±15 -680±21 -1020±31 -1360±41

Insertion loss (dB)(typical value)

＜ =4.1(3.2)

＜ =5.1(4.4)

＜ =7.0(6.0)

＜ =8.9(7.7)


Dispersion compensating module and technical parameter

23/4/8 NO.32

Solution of optical source chirp——Solution of optical source chirp——

improve optical sourceimprove optical source

Such as ：

adopt External modulate source

adopt Pre-chirp source




23/4/8 NO.33

＜85km L16.2 OI16

85~100 km L16.2 OI16+BA（14dB）

100~140 km Ultra-long distence（EA）OI16+BA（14dB）

140~150 km Ultra-long distence（EA）OI16+BA（17dB）

150~175 km Ultra-long distence（EA）OI16+BA（14dB）+PA

175~185 km Ultra-long distence（EA）OI16+BA（17dB）+PA

Referenced Configuration

Referenced Configuration


23/4/8 NO.34

Network self-healing protect and switchNetwork self-healing protect and switchNetwork self-healing protect and switchNetwork self-healing protect and switch

Time requirements of service restore

Time requirements of service restore

Two time threshold value of service break offTwo time threshold value of service break off ：：

(1)(1)50ms50ms ：：When interrupting time is less than 50ms ， it could meet requirements of the most service.It takes no effect to PSTN and low speed data service.

(1)2s(1)2s ：： When interrupting time is less than 2s ， it could ensure stability of transmission network and signaling network. We regard it as the target value of network restore （ we call it Connection Drop out Time---CDT ）。

23/4/8 NO.35

Calculation of multi-section switching time

Calculation of multi-section switching time

T =T1+ (N-2)×T2 + T3 ×2 + L/c Total switching time ：T1 ： time interval of checking alarm signal （ 0.4ms ）

T2 ： passing through time of transporting K1 、 K2 bytes in ADM(1.5ms/2F ， 3ms/4F ）

T3 ： time of bridge and switch （≤ 8ms ）

T4: time interval of signal transmitting in fiber, include transporting K bytes in REG stations.

N ： number of ADM station on ring

L ： perimeter of ring

C ： velocity of light in fiber （ 200KM/ms)

Network self-healing protect and switchNetwork self-healing protect and switchNetwork self-healing protect and switchNetwork self-healing protect and switch

23/4/8 NO.36

ZXSM-2500ADM

ZXSM-2500ADM

ZXSM-2500ADM

ZXSM-2500ADM

ZXSM-2500ADM

A BH

G

EF D

ZXSM-2500ADM

ZXSM-2500ADM

C

ZXSM-NMS

Manager center2

ZXSM-NMS

Manager center1

ADA

ASM-40

ROUTER

1601

ADA

ASM-40

ROUTER

1601

E1

Collecting south ring: N=8, L=5110km (Didn't’t consider processing time of DWDM)

ZXSM-2500ADM

23/4/8 NO.37

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500ADM

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500ADM

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500ADM

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500ADM

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500ADM

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

ZXSM-2500REG

AA R R R R R R

R

R

R

R

R R R RR

A

R

R

R

R

R

R

R

R

R

R

R

R

R

R

A RR R R R R R R R R R A

R

R

ZXSM-NMS

Manager center2

ADA

ASM-40

ROUTER

1601

ADA

ASM-40

ROUTER

1601

E1

ZXSM-NMS

Manager center1

ADA

ASM-40

ROUTER

1601

ADA

ASM-40

ROUTER

1601

E1

R:REG A:ADM

Southwest ring: N=5, L=4266km

23/4/8 NO.38

calculating resultSouthwest ring: N=5, L=4266km

switching time=0.4+(5-2)×1.5+2×4+4266/200=34.23ms

Collection South ring: N=8, L=5110km

switch time=0.4+(8-2) × 1.5+2 × 4+5110/200=42.95ms

23/4/8 NO.39

Network service distribution Network service distribution Network service distribution Network service distribution

D B

C

A

STM-16 环

For example two fiber bi-directional multi-section shared protection ring

23/4/8 NO.40

Service matrix listService matrix list

A

A

B C D

B

C

D

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M

1*STM-1 63*2M


23/4/8 NO.41

Sketch of time slot distributionSketch of time slot distribution

NO.1

NO.2

NO.3

NO.4

NO.5

NO.6

NO.7

NO.8

A B C D A

63*2M63*2M

63*2M63*2M

63*2M

63*2M

1*STM-1 1*STM-1 1*STM-1 1*STM-1

1*STM-1

1*STM-1

Red: 63*2M Black:1*STM-1


23/4/8 NO.42

Synchronous method of network clockSynchronous method of network clockSynchronous method of network clockSynchronous method of network clock

Basic Synchronous ModeBasic Synchronous Mode

Slave clock

Master clock

Master-Slave synchronous mode

Mutual synchronous mode

23/4/8 NO.43

Clock levelClock level

Primary reference clock

Slave clock of tie station

Slave clock of end station

SDH clock

G.811

G.812

G.812

G.813


23/4/8 NO.44

Clock typeClock type

•Cesium atomic clock

•Quartz crystal oscillation

•Rubidium atomic clock

Working modeWorking mode

•Locked mode

•Hold over mode

•Free running mode


23/4/8 NO.45

SDH network synchronous mode(according to work principle )

SDH network synchronous mode(according to work principle )

synchronous mode

pseudo synchronous mode

plesiochronous mode

Asynchronous mode

all clock in network lock on one primary reference clock

There are several G.811 clocks. They have same nominal frequency ,but their precise frequency is difference.

Some NEs’ clock become holdover or free mode after one or more synchronous route and backup route are all fault.

There is much frequency difference between NEs’ clock ，clock precision can’t meet G.813 ， it will produce AIS, SDH network can’t work in this mode 。


23/4/8 NO.46

G.811

PRC

G.812

Tie station

G.812

Tic stationN*G.813 N*G.813 N*G.813

1 K

Require:

1 ） total number of G.813 less than 60

2 ） K less than 10

3 ） N less than 20

Synchronous network timing reference chain

Principle :

for network reliability, the number of NE is as less as possible on timing chain.


23/4/8 NO.47

Timing method of SDH NE

Timing method of SDH NE

external synchronization timing

extract timing source from line

SDH equipment clock

In this manner,timing source of NE is provided by external timing clock, 2Mb/s and 2MHz/s from PDH network are often used 。subdivided to overpass timing(REG) 、 loop timing(TM) and line timing(ADM)

Equipment clock accuracy of TM and ADM must be less than or equal to ±4.6×10-6


23/4/8 NO.48

Timing of SDH NETiming of SDH NE

The reliability of synchronization network must be high, normally,NE or node require there must be two or more synchronization direction to get timing signal, thus, if original timing source is unavailable, it can get the timing signal from backup direction.

In SDH network ， timing reference between Nes is often transported by lower level Nes’ clock ， so something is needed to indicate the quality of timing signal, according to this, we can get the best timing direction to insure the performance of synchronization network. At present ， the SSM byte is recommended by ITU-T to indicate timing signal’s quality 。


23/4/8 NO.49

b 0b 0 b 1b 1 b 2b 2 b 3b 3 b 7b 7b 6b 6b 5b 5b 4b 4Recommended by ITU-TRecommended by ITU-T ：：

Signal QualitySignal QualityNot defined Not defined

Perfect synchronizationPerfect synchronization

not achievednot achieved


23/4/8 NO.50

Definition of S1 by ITU-TDefinition of S1 by ITU-T


S1(b5—b7) Synchronization status message

0000

0010

0100

1000

1011

1111

Message unknown

G.811 clock

G.812 clock for tandem station

G.812 clock for end station

G.813 clock for SDH equipment

Message unused

23/4/8 NO.51

b 0b 0 b 1b 1 b 2b 2 b 3b 3 b 7b 7b 6b 6b 5b 5b 4b 4

ZTE Redefines S1 Byte Based on ITU-T ZTE Redefines S1 Byte Based on ITU-T RecommendationsRecommendations

Signal QualitySignal Quality

Perfect synchronization achievedPerfect synchronization achieved

Patented technologyPatented technology

Best Timing Source Best Timing Source Selection Realized, Selection Realized,

Timing Ring AvoidedTiming Ring Avoided

Patented S1 byte handling


23/4/8 NO.52

Questions : （ network layout ） :

1. simply describe conception of Delaminating and Division to transport

network, give a sketch of SDH network structure.

2. Transmission loss of fiber means ， the main reas

on is and ， also lead by the shortage of fiber structure.

3. In calculating formulae of protection and switching ， T=Talarm+Tpass*(N-2)+Tswitch*N+L/c ， ‘N’ means the number of stations on the ring, stations point to the quant

ity of on the ring.

A. ADM B. REG C. ADM+REG

4. Give a sketch of SDH timing link model and describe.

5. Introduce method of overcoming dispersion limit in simple words.

23/4/8 NO.53

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SDH Transmission Network Layout

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