SDH Principle(Chapter1~4)

8/12/2019 SDH Principle(Chapter1~4)

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SDH Principle Issue 3.0 Table of Contents

Table of ContentsChapter 1 SDH Overview...........................................................................................................1

1.1 Technical Background of SDH !h" did SDH trans#ission s"ste# e#erge$.......................11.% &d'antages of SDH o'er PDH......................................................................................................(1.3 Disad'antages of SDH................................................................................................................. .)Su##ar"............................................................................................................................................10*+ercises............................................................................................................................................10

Chapter 2 The Frame Structure and Multiple in! Method of SDH Si!nals................................1%.1 ST, - ra#e Structure................................................................................................................1%.% ,ultiple+ing Structure and Procedures of SDH...........................................................................(

%.%.1 ,ultiple+ing of 1/0,b s signals into ST, - signals..................................................... .%.%.%,ultiple+ing of 3/,b s signals into ST, - signals.......................................................11%.%.3,ultiple+ing of %,b s signals into ST, - signals.........................................................13

%.3 Concepts of ,apping2 &ligning and ,ultiple+ing.....................................................................1)Su##ar"............................................................................................................................................%0*+ercises............................................................................................................................................%0

Chapter " Overhead and #ointer................................................................................................13.1 'erhead........................................................................................................................................1

3.1.1 Section 'erhead............................................................................................................. ..13.1.% Path 'erhead..................................................................................................................1/

3.% Pointers........................................................................................................................................%%3.%.1 &d#inistrati'e 4nit Pointer &4 PT5...........................................................................%33.%.% &4 / concatenation..........................................................................................................%63.%.3 Tributar" 4nit Pointer T4 PT5..................................................................................%7

Su##ar"............................................................................................................................................3(*+ercises............................................................................................................................................3(

Chapter $ %o!ic Composition of SDH &'uipment......................................................................1/.1 Co##on -* of SDH net8ork......................................................................................................1/.% 9ogic functional block of SDH e:uip#ent.................................................................................../Su##ar"............................................................................................................................................%(

*+ercises............................................................................................................................................%(

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Chapter 1 SDH Overview

Objectives:

To understand the background of SDH !h" did SDH trans#ission s"ste#e#erge$

To understand the ad'antages and disad'antages of SDH s"ste#.

To understand the general concept of SDH for future further stud".

1.1 Technical (ac)!round of SDH **** +h, did SDH transmissions,stem emer!e-

Before learning SDH trans#ission s"ste#2 8e #ust understand the concept ofSDH. !hat is SDH$ SDH is the abbre'iation of S"nchronous Digital Hierarch".9ike PDH plesiochronous digital hierarch"2 SDH is a trans#ission s"ste#;protocol< 8hich defines the characteristic of digital signals2 including fra#estructure2 #ultiple+ing #ethod2 digital rates hierarch"2 and interface code pattern2and so on.

!hat is the technical background for the e#ergence of SDH$

&s 8e kno82 this is a societ" of infor#aton. & highl" de'eloped infor#ationsociet" de#ands a teleco##unication net8ork 8hich can pro'ide a 'ariet" ofteleco##unication ser'ices. The infor#ation trans#itted2 s8itched and processed'ia the teleco##unication net8ork 8ill steadil" increase. This re:uires #odernteleco##unication net8orks to be digital2 integrate2 intelligent and personal.

&s an i#portant part of the teleco##unication net8ork2 the trans#ission s"ste#directl" affects the de'elop#ent of the net8ork. Countries all o'er the 8orld areno8 #aking great efforts in building infor#ation high8a"s. ne of the ke"

pro=ects of the infor#ation high8a" is to establish high capacit" optical fiber

trans#ission net8orks and to broaden the band8idth so as to increase signal ratesin the trans#ission lines. This like e+panding high8a"s for large traffic flo8s.,ean8hile2 subscribers e+pect a uni'ersal interface standard forteleco##unication net8orks so that each subscriber in our >global 'illage> caneasil" co##unicate at an" ti#e and an" place.

&s the #ultiple+ing #ethod of the trans#ission net8ork established on thetraditional PDH s"ste# can not satisf" the re:uire#ents of high capacit"transi#ission and regional standards of the PDH s"ste# #ake it difficult fornet8orks interconnection2 PDH s"ste# is beco#ing a #ore and #ore serious

>bottleneck> of #odern teleco##unication net8ork 8hich restrains the rapid

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de'elop#ent of the net8ork to8ards large capacit" and standardi?ation.

The disad'antages of traditional PDH trans#ission s"ste# are as follo8s@

1. nterface

1< There are onl" so#e regional pro'isions2 instead of uni'ersal standards forelectrical interface. The present PDH digital signal hierarch" has three ratele'els@ *uropean Series2 -orth erican Series and Aapanese Series. *ach ofthe# has different electrical interface rate le'els2 fra#e structures and#ultiple+ing #ethods. This #akes it difficult for international interconnectionand is far behind the de'elop#ent trend of con'enient co##unication at an"ti#e and place. The rate le'els of electrical interface of these three signals aresho8n in igure 1 1.

/0/Mb s

1" Mb s

"$Mb s

3Mb s

2Mb s

1.04b s

$55Mb s

155Mb s

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&uropean Series 7apanese Series 8orth 9merican Series

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igure 1 1 the rate hierarch" diagra# of electrical interfaces

%< -o uni'ersal standards for optical interfaces. &ll PDH e:uip#ent#anufacturers use their o8n line codes to #onitor the trans#ission

perfor#ance in the optical links. & t"pical e+a#ple is #BnB code2 of 8hich#B is the infor#ation code and nB is the redundanc" code. The function of theredundanc" code is to reali?e the #onitoring function of the e:uip#ent o'erthe trans#ission perfor#ances of the links. Due to the insertion of redundanc"codes2 the signal rate of optical interface is higher than the standard signal rateof electrical interface of the sa#e rate le'el. This not onl" increases the po8er

penalt" of the trans#itter2 but also results in inco#patibilit" of e:uip#ent pro'ided b" different 'endors. Because #anufactures add different redundanc"codes ne+t to the infor#ation codes during line coding in order to achie'e line#onitoring functions2 the optical interface code patterns and rates of the sa#erate le'els e#plo"ed b" different #anufactures are different. So e:uip#ent at

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the t8o ends of a trans#ission link #ust be pro'ided b" the sa#e 'endor. Thiscauses #an" difficulties for net8ork structuring2 #anage#ent and net8orkinterconnection.

2. Multiple in! method

In the present PDH s"ste#2 onl" 1.(,b s and %,b s rate signals ;includingAapanese Series .3,b s rate signal< are s"nchronous. &ll other signals areas"nchronous and re:uire code rate =ustification for #atching and accepting clockdifference. &s PDH adopts as"nchronous #ultiple+ing #ethod2 the locations of thelo8 rate signals are not regular nor fi+ed 8hen the" are #ultiple+ed into higherrate signals. That is to sa"2 the locations of the lo8er signals are unable to beidentified fro# the higher speed signals. But this is the ke" to directl" add droplo8er speed signals fro# the higher speed signals. This is the sa#e 8hen lookingfor a stranger in a cro8d. ou can easil" find hi# if "ou kno8 8hich line and8hich ro8 he sta"s in 8hen the cro8d is arranged in an specific order. But if thecro8d is in a #ess2 "ou ha'e to co#pare each person 8ith the photo to locate the#an.

Since PDH adopts as"nchronous #ultiple+ing #ethod2 lo8 rate signals can not bedirectl" added dropped fro# PDH high rate signals. or e+a#ple2 %,b s signalscan not be directl" added droped fro# 1/0,b s signals. Here arise t8o proble#s@

1< &dding dropping lo8 rate signals fro# high rate signals #ust be conductedle'el b" le'el. or e+a#ple2 to add drop %,b s lo8 rate signals fro# 1/0,b ssignals2 the follo8ing procedures #ust be conducted. ; igure 1 %back to back> e:uip#ent is used during the processof adding dropping %,b s signals fro# 1/0,b s signals. Three stages of de#ultiple+ing e:uip#ent are used to drop %,b s lo8 rate signals fro# 1/0,b ssignals and then three stages of #ultiple+ing e:uip#ent are used to add %,b s lo8rate signals into 1/0,b s signals. ne 1/0,b s signal can be #ultiple+ed into /%,b s lo8 rate signals. ,ultiple+ing and de #ultiple+ing e:uip#ent in all threestages are re:uired to add drop e'en one %,b s signal fro# 1/0,b s signals. Thisnot onl" enlarges the si?e and increases cost2 po8er consu#ption and co#ple+it"

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of e:uip#ent2 but also decreases the reliabilit" of the e:uip#ent.

%< Since adding dropping lo8 rate signals to high rate ones #ust go through#an" stages of #ultiple+ing and de #ultiple+ing2 i#pair#ent to the signals

during #ultiple+ing de #ultiple+ing processes 8ill increase and trans#ission perfor#ance 8ill deteriorate. This is unbearable in large capacit" trans#ission.That s the reason 8h" the trans#ission rate of PDH s"ste# has not beingi#pro'ed further.

". Operation maintenance

In the fra#e structure of PDH signals2 there are fe8 o'erhead b"tes used foroperation2 ad#inistration and #aintenance ; &,


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1.2 9dvanta!es of SDH over #DH

Since SDH trans#ission s"ste# e'ol'es fro# PDH2 it has unparalleled ad'antageso'er PDH. Co#pared 8ith PDH2 it is a ne8 trans#ission s"ste# that has #aderadical re'olution in technical s"ste#.

irst2 8e 8ill discuss the basic concept of SDH. The core of this concept is2 in 'ie8of an integrated national teleco##unication net8ork and internationalinterco##unication2 to establish digital teleco##unication net8orks2 and to #akeup i#portant parts of integrated ser'ices digital net8orks ;ISD-


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Technical details:

!hat is b"te interlea'ed #ultiple+ing #ethod$

!e can e+plain it b" the follo8ing e+a#ple. There are three signals 8ith the fra#estructure of 3 b"tes in each fra#e.

9 91 92 9" (1 (2 (" C1 C2 C"

( C

If signal D is for#ed b" b"te interlea'ed #ultiple+ing #ethod2 it 8ill ha'e a fra#estructure of 7 b"tes in each fra#e and these 7 b"tes are arranged in the order assho8n in the follo8ing figure@

91 (1 (2C1 C2 C"("

D

92 9"

This #ultiple+ing #ethod is called b"te interlea'ed #ultiple+ing #ethod.

%< ptical Interface

9ine interfaces ;here refers to optical interface< adopt uni'ersal standards. 9inecoding of SDH signals is onl" scra#bling2 insteand of inserting redundanc" codes.

The standard for scra#bling is uni'ersal. Therefore the opposite ter#inal

e:uip#ent can be interconnected 8ith SDH e:uip#ent of different 'endors 'iastandard descra#bler alone. The purpose of scra#bling is to #ake the probabilit"of >1> bits and >0> bits occurence gets close to (0F so as to e+tract clock signalsfro# line signals. &s line signals are scra#bled onl"2 the line signal rates of SDHare the sa#e 8ith the standard signal rates of the SDH electrical interface. This 8illnot add e+tra optical po8er penalt" to the trans#itting laser2

2. Multiple in! method

&s lo8 rate SDH signals are #ultiple+ed into the fra#e structure of high rate SDHsignals 'ia b"te interlea'ed #ultiple+ing #ethod2 their locations in the fra#e ofhigh rate SDH signal are fi+ed and regular2 or sa"2 predictable. Therefore2 lo8 rateSDH signals2 e.g. 1((,b s2 ;ST, 1


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-ote that this is different fro# the abo'e process of directl" adding dropping lo8rate SDH signals to fro# high rate SDH signals. Here it refers to directadding dropping of lo8 rate tributar" signals2 such as %,b s2 3/,b s2 and1/0,b s2 to fro# SDH signals. This sa'es lots of #ultiple+ing de #ultiple+inge:uip#ent ;back to back e:uip#ent


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The abundant o'erheads in SDH signals account for 1 %0 of the total b"tes in afra#e. It greatl" enhances the &, function and reduces the cost of s"ste##aintenance that occupies #ost of the o'erall cost of teleco##unicatione:uip#ents. The o'erall cost of SDH s"ste# is less than that of PDH s"ste# andesti#ated to be onl" (.)F of that of the later.

$. Compatibilit,

SDH has high co#patibilit"2 8hich #eans that the SDH trans#ission net8ork andthe e+isting PDH trans#ission net8ork can 8ork together 8hile establishing SDHtransi#ission net8ork. SDH net8ork can be used for trans#itting PDH ser'ices2 as8ell as signals of other hierarchies2 such as as"nchronous transfer #ode ;&T,cargoes> in ST, - duringtrans#ission. The function of P H is to locate the certain i#paired cargo in casei#pair#ents occurred. S H i#ple#ents the o'erall #onitoring of cargoes 8hilethe P H #onitors a specific cargo. S H and P H also ha'e so#e ad#inistrationfunctions

The Section 'erhead is further classified into 5egenerator Section 'erhead;5S H< and ,ultiple+ Section 'erhead ;,S H


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SDH Principle Issue 3.0 Chapter % The ra#eStructure and ,ulltiple+ing ,ethod of SDH Signals

The &d#inistrati'e 4nit Pointer 8ithin colu#n 7

- of ro8 / of the ST, - fra#eis 7

- b"tes in total. !hat s the function of &4 PT5$ !e ha'e #entioned before

those lo8 rate tributaries ;e.g. %,b s< could be added dropped directl" fro# highrate SDH signals. Because the locations of lo8 rate signals 8ithin a high rate SDHfra#e structure are predictable2 i.e. regular. The predictabilit" can be achie'ed 'iathe pointer o'erhead b"tes function in the SDH fra#e structure. The &4 PT5indicates the e+act location of the first b"te of the infor#ation pa"load 8ithin theST, - fra#e so that the infor#ation pa"load can be properl" e+tracted at therecei'ing end according to the 'alue of this location indicator ;the 'alue of the

pointer ST, /

and /

ST, / --> ST, 1 . During the #ultiple+ing2 the fra#e fre:uenc" re#ains

unchanged ;)000 fra#e per second


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Through these routes2 digital signals of three PDH hierarchies can be #ultiple+edinto ST, - signals 'ia a 'ariet" of #ethods. The routes defined b" IT4 T areillustrated in igure % %.

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Multiple in! 9li!nin! ad=ustmen tMappin!

igure % % the #ultiple+ing #apping structure defined in 5ec. .607

&s illustrated in igure % %2 this #ultiple+ing structure includes so#e basic#ultiple+ing units@ C Container2 JC Jirtual Container2 T4 Tributar" 4nit2T4 Tributar" 4nit roup2 &4 &d#inistrati'e 4nit2 and &4 &d#inistrati'e4nit roup. The suffi+es of these #ultiple+ing units denote their correspondingsignal le'els. &s illustrated in the figure2 there are se'eral routes ;se'eral#ultiple+ing #ethods< through 8hich a 'alid pa"load can be #ultiple+ed intoST, - signals. or e+a#ple2 there are t8o #ultiple+ing routes for %,b s signals2i.e. t8o #ethods for #ultiple+ing %,b s signals into ST, - signals. ou #a"ha'e noted that ),b s PDH signals can t be #ultiple+ed into ST, - signals.

&lthough there are se'eral routes for a kind of signals to be #ultiple+ed into SDHST, - signals2 the #ultiple+ing route used in a countr" or an area #ust be uni:ue.In China2 the SDH optical trans#ission net8ork technological s"ste# stipulatesthat PDH signals based on %,b s signals shall be regarded as the 'alid pa"load ofSDH and the #ultiple+ing route of &4 / shall be e#plo"ed. This #ultiple+ingroute structure is illustrated in igure % 3.

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igure % 3 basic #ultiple+ing #apping structure e#plo"ed in China and so#e other countries

2.2.1 Multiple in! of 1$5Mb s si!nals into STM 8 si!nals

1< irst2 the 1/0,b s PDH signals are adapted 'ia bit rate =ustification ;bit


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stuffing #ethod< into C /2 8hich is a standard infor#ation structure used toacco##odate 1/0,b s PDH signals. &fter being processed 'ia bit rate

=ustification techni:ues2 ser'ice signals of 'arious rates in'ol'ed in SDH#ultiple+ing #ust be loaded into a standard container corresponding to the ratele'el of the signal@ %,b s C 1%2 3/,b s C 3 and 1/0,b s C /. The #ainfunction of a container is for bit rate =ustification. Putting 1/0,b s signals intoC / is si#ilar to signal packing. The rate of 1/0,b s signals thus is ad=usted tostandard C / rate. This is also si#ilar to the packing of */ signals in a si?ee:ual to standard C /. The fra#e structure of C / is block fra#e in unit of

b"tes2 8ith the fra#e fre:uenc" of )000 fra#e per second. That is to sa"2 the1/0,b s signals are s"nchroni?ed to SDH trans#ission net8ork after beingadapted into C / signals. This process is =ust like loading C / to as"nchronous1/0,b s signals. The fra#e structure of C / is illustrated in igure % /.

1" .20$Mb s

1 205

1$ .60Mb s

3555*frame second

igure % / C / fra#e structure

The fra#e of C / signals has % 0 colu#ns

7 ro8s ;the block fra#e of PDH signalsre#ains constantl" to be 7 ro8s 8hile #ultiple+ing into ST, -


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JC / is a standard 'irtual container corresponding to 1/0,b s PDH signals. This process is =ust like en'eloping the C / signals for the second ti#e2 so as to enclosethe o'erhead P H for path #onitoring and #anage#ent into the en'elope. Theo'erhead P H i#ple#ents real ti#e #onitoring o'er path signals.

The en'eloping rate of the 'irtual container ;JC< is also s"nchronous 8ith theSDH net8ork. Different JCs ;e.g. JC 1% for %,b s and JC 3 for 3/,b s< ares"nchronous 8ith each other. &s"nchronous pa"loads fro# different containers areallo8ed to load 8ithin the 'irtual containers. The 'irtual container2 a kind ofinfor#ation structure 8hose integrit" is al8a"s #aintained during trans#ission onthe SDH net8ork2 can be regarded as an independent unit ;cargo package


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%60 colu#ns2 onl" 8ithout S H. In fact2 this infor#ation structure can be regardedas an en'elope of &4 / JC / packet is en'eloped once #ore ;&4 PT5addedfloat> 8ithin theST, fra#e2 i.e. the fre:uenc" offsets and phase differences to a certain degree

bet8een JC / and &4 / are tolerable. r in other 8ords2 certain ti#e difference bet8een the loading speed of the cargo and the 8aiting ti#e of the truck is allo8ed2i.e. certain difference bet8een the rate of JC / and the packing rate ;loadingspeed< of &4 / is allo8ed. This difference 8ill not affect the correct locating anddisasse#bling of JC / at the recei'ing end. &lthough the package #a" >float> inthe co#part#ent ;the infor#ation pa"load area


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igure % 6 ,ultiple+ of &4 / 'ia &4

/< The last step is to add corresponding S H to &4 / to for# ST, - signals. Thearrange#ent of - &4 s #ultiple+ed into the ST, - is sho8n in igure % ). The&4 is a structure of 7 ro8s b" % 1 colu#ns plus 7 b"tes in ro8 / ;for the &4 n

pointers


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2.2.2 Multiple in! of "$Mb s si!nals into STM 8 si!nals

Si#ilarl"2 3/,b s signals are first adapted into the corresponding standardcontainer C 3 through bit rate =ustification. &fter adding corresponding P H2 theC 3 is packed into JC 3 8ith the fra#e structure of 7 ro8s

)( colu#ns. or the

con'enience of locating JC 3 at the recei'ing and separating it fro# the high ratesignals2 a three b"te pointer2 T4 PT5 ;Tributar" 4nit Pointer


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interlea'ed #ultiple+ing #ethod. The arrange#ent of three T4 3s#ultiple+ed in the JC / is sho8n in igure % 11. The T4 3 is a 7 ro8 b" )colu#n structure. The JC / consists of one colu#n of JC / P H2 t8ocolu#ns of fi+ed stuff and a %() colu#n pa"load structure. The three T4 3sare b"te interlea'ed into the 7 ro8 b" %() colu#n JC / pa"load structure andha'e a fi+ed phase 8ith respect to the JC /. &s described in igure % 62 the

phase of the JC / 8ith respect to the &4 / is gi'en b" the &4 / pointer.

9 9 ( C 9 ( C 9 ( C 9 ( C

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igure % 11 ,ultiple+ of three T4 3s into a JC /

Since the T4 3 is an infor#ation structure of 7 ro8s

) colu#ns2 the infor#ationstructure co#posed of three T4 3 'ia b"te interlea'ed #ultiple+ing is a blockfra#e structure of 7 ro8s

%() colu#ns. !hile C / is a block fra#e structure of 7

ro8s

% 0 colu#ns. T8o colu#ns of stuffed bits are added to the front of theco#posite structure of 3

T4 3 to for# a C / infor#ation structure. igure % 1%

sho8s the fra#e structure of one C /.

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igure % 1% the fra#e structure of C /

The last step is to #ultiple+ C / into ST, -. This is si#ilar to the process of#ultiple+ing 1/0,b s signals into ST, - signals@

C / KJC / K&4 / K&4 KST, -.

1%


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? Questions:

Do "ou undstand 8h" t8o pointers &4 PT5 and T4 PT5 are used here$ These

t8o pointers pro'ide aligning functions on t8o stages. The &4 PT5 pro'ides thefunction of correct aligning and separating of JC / at the recei'ing end. Since aJC / can acco##odate three JC 32 ;Can "ou figure out 8h" it is 3$


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! ! ! ! ! ! , - !

! ! ! ! ! ! ! ! ! ! ! ! ! ! ! !! The first C

1% basicfra#e

structure@ 7

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! ! The % nd C 1% basic fra#estructure@ 7

/%E3%!1 1

! ! The 3rd C 1% basic fra#estructure@ 7

/%E 3%!1 1

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structure@7

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!! ! ! ! ! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! !! ! ! ! ! ! ! !

*ach s:uare represents a b"te ;) bits


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fra#e 8ithin the #ulti fra#e 8hich basic fra#e it is in the #ulti fra#e.

%< To #onitor on a real ti#e basis the perfor#ance of each %,b s path signalduring trans#ission on SDH net8ork2 C 1% #ust be further packed addingcorresponding path o'erhead ;lo8er order o'erhead< to for# a JC 1%infor#ation structure. &s sho8n in the attached figure at the end of Section %2 the9P P H ;lo8er order path o'erhead< is added to the notch in the top left corner ofeach basic fra#e. *ach #ulti fra#e has a set of lo8er order path o'erheadco#posed of total / b"tes@ J(2 A%2 -% and /. Since the JC can be regarded as anindependent entit"2 dispatching of %,b s ser'ices later is conducted in unit of JC1%.

& set of path o'erhead #onitors the trans#ission status of the 8hole #ulti fra#e

on a net8ork. Ho8 #an" fra#es of %,b s signals does a C 1% #ulti fra#eacco##odate$ ne C 1% #ulti fra#e acco##odates / fra#es of PC,30 3%signals. Therefore a set of 9P P H #onitors the trans#ission status of / fra#es ofPC,30 3% signals.

3< or correct aligning of JC 1% fra#es in the recei'ing end2 a four b"te T4 PT5is added to the four notches of the JC 1% #ulti fra#e. Then the infor#ationstructure of the signal changes into T4 1% 8ith 7 ro8s

/ colu#ns. The T4 PT5

indicates the specific location of the start point of the first JC 1% 8ithin the #ultifra#e.

/< Three T4 1% for#s a T4 % 'ia b"te interlea'ed #ultiple+ing. The T4 % hasthe fra#e structure of 7 ro8s b" 1% colu#ns. The #ultiple+ing of three T4 1%sinto one T4 % is sho8n in igure % 1/.

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. . . . . . . . . . . . . . . .

>2?

T@*11 T@*12 T@*2

T@4*2

T@4*"

35 32 3$ 306 31 3" 3/

Fi ed stuff

igure % 1/ ,ultiple+ing of three T4 1% into one T4 %

(< Se'en T4 % can be #ultiple+ed into a T4 3 infor#ation structure 'ia b"teinterlea'ed #ultiple+ing. -ote that this infor#ation structure for#ed b" the 6

T4 % is 7 ro8 b" )/ colu#n. T8o ro8s of fi+ed stuff bits shall be added in frontof the structure2 as illustrated in igure % 1/. The #ultiple+ing structure for theT4 % 'ia the T4 3 is depicted in igure % 1/ and igure % 1(. The T4 3 is a7 ro8 b" ) colu#n structure 8ith the first t8o colu#ns of fi+ed stuff.

T1/13155* /

.

.

.

.

.

.

.

.

. . . . . . . .

T@4*2 T@4*2

#OH #OH

#OH

AC*2 AC*1

T@4*">6 G T@4*2?

" AC*12s or $ AC*11sin 1 G T@4*2

T@*2#T

T@*1#T s

30 Columns

#T #ointer

F i e

d s t u f f

F i e

d s t u f f

1


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igure % 1( ,ultiple+ of se'en T4 %s 'ia a T4 3

The arrange#ent of se'en T4 %s #ultiple+ed 'ia the T4 3 is depicted inigure % 1(. The T4 %s are one b"te interlea'ed in the T4 3. igure % 1

sho8s the fra#e structure of one T4 3.

1

1

3$

T@4"

igure % 1 T4 3 infor#ation structure

< The procedures of #ultiple+ing the T4 3 infor#ation structure into ST, -are the sa#e as #entioned before.

Technical details:

ro# the procedures of #ultiple+ing 1/0,b s signals into ST, - signals 8e cansee that one ST, - corresponds to -

1/0,b s2 i.e. one ST, 1 signal can onl" be

#ultiple+ed into one 1/0,b s. Therefore2 the capacit" of an ST, 1 signal e:ualsto that of / %,b s signals if 1/0,b s is #ultiple+ed into the ST, 1.

Si#ilarl"2 in the case of #ultiple+ing 3/,b s signals into ST, 1 signals2 theST, 1 can acco##odate three 3/,b s signals2 i.e. it has a capacit" of /)

%,b s.

In the case of #ultiple+ing %,b s signals into ST, 1 signals2 the ST, 1 canacco##odate 3

6

3E 3 %,b s signals

ro# abo'e anal"sis2 it can be concluded that in the cases of #ultiple+ing 1/0,b sand %,b s into SDH ST, -2 the utili?ation ratio of the signal is fairl" high.Ho8e'er2 in the case of #ultiple+ing 3/,b s into ST, -2 the utili?ation ratio isrelati'el" lo8.

&s sho8n in the procedures of #ultiple+ing %,b s signals into ST, - signals2 3T4 1%s can be #ultiple+ed into one T4 %2 6 T4 %s into one T4 32 3 T4 3sinto one JC / and one JC / into one ST, 12 i.e. the #ultiple+ing structure of%,b s is 3 6 3. Since the #ultiple+ing #ethod is b"te interlea'ed2 the 3 JC 1%s8ithin a JC / are not arranged in se:uence. The nu#ber difference bet8een t8oad=acent T4 1% is %1.

In order to pro'ide a si#ple and con'enient #eans of deter#ining the totaltributar" capacit"2 i.e. the nu#ber of lo8er order tributaries pro'ided2 the pa"loadcolu#ns are allocated a Ti#e Slot nu#ber. The nu#ber of Ti#e Slots per tributar"

in each fra#e is deter#ined b" the pa"load configuration.

16


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Ti#e Slots ;TS< are nu#bered fro# 0 to 3 in the JC / for *1 signals.

This is a for#ula for calculating the ti#e slot nu#ber of T4 1% at differentlocations 8ithin the sa#e JC /@

JC 1% ;T4 1%< ti#e slot nu#berET4 3 location nu#berN;T4 % locationnu#ber 11> is e'en. B is the result ofBIP ) parit" for the &1&%&3&/ block.

The #echanis# for B1 b"te is@ the trans#itting e:uip#ent processes BIP ) e'en parit" o'er all b"tes of the pre'ious fra#e ;1 ST, -< after scra#bling and placesthe result in b"te B1 of the current fra#e ;% ST, -< before scra#bling. Therecei'er processes BIP ) parit" o'er all bits of the current fra#e ;1 ST, -1>2 8e can #onitor the nu#ber of error blocks occurred in1 ST, - fra#e during trans#ission.

Technical details:

Since error perfor#ance of higher rate signals is reflected 'ia error blocks2 theerror status of ST, - signals is actuall" the status of error blocks. &s can be seenfro# the BIP ) parit" #ethod2 each bit of the parit" result is corresponding to a bit

block2 e.g. a colu#n in igure 3 . So a B1 b"te can at #ost #onitor ) error blocksfro# an ST, - fra#e that occur during trans#ission ;The result of BIP ) is ) bits8ith each bit corresponding to a colu#n of bits a block


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SDH Principle Issue 3.0 Chapter 3 'erhead and Pointer

e:uip#ent 8ill report corresponding alar#s.

!hen the error bit ratio ;*B5< is greater than 10* 2 the gi'en alar# is B1 SD.

!hen the error bit ratio ;*B5< is greater than 10* 32 B% *GC 8ill be gi'en.

(it nterleaved #arit, 8

2$ code >( #*8

2$? b,te (2

B% is si#ilar to B1 in operation #echanis# e+cept that it #onitors the error statusof the #ultiple+ section la"er. The B1 b"te #onitors the trans#ission error of theco#plete ST, - fra#e signal. There is onl" one B1 b"te in an ST, - fra#e;!h"$ ou ll get the ans8er 8hen 8e discuss the interlea'ed #ultiple+ing of thesection o'erhead during #ultiple+ing of ST, 1 into the ST, -


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Notes:

If the B% of the recei'e end has detected error blocks2 the nu#ber of error blocks

detected b" the B% 8ill be displa"ed in this end perfor#ance e'ent ,S BB*;,ultiple+ Section Background Block *rror


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of the s"nchroni?ation is unkno8n and the other to signal that the section shouldnot be used for s"nchroni?ation. The re#aining codes are reser'ed for :ualit"le'els defined b" indi'idual &d#inistrations.

Table 3-1 Assignment of bit patterns

1 bitsb!-b" #$ s%nchroni&ation 'ualit% level description

0000 ualit" unkno8n ;*+isting S"nc. -et8ork1> fro# old e:uip#ent2 ne8 e:uip#ent shallnot generate a Signal 9abel ,is#atch alar#.% In the case of a JC 1%2 the code >3> shall2 for back8ard co#patibilit" purposes2 continue to be

interpreted as pre'iousl" defined e'en if the bit s"nchronous #apping of %0/) kbit s signal is notdefined an"#ore.

3 &n" #apping defined in 5eco##endation .1)1 8hich does not correspond to a #apping defined in5eco##endation .606 falls in this categor".

/ nl" for net8orks supporting the transport of Tande# Connection signals.

igure 3 10 the structure of the JC 1% P H ;J(


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;9o8er rder Path Background Block *rror< and #ean8hile an 9P 5*I ;9o8errder Path 5e#ote *rror Indication< is sent back to the trans#itter 'ia the b3 of theJ( b"te. Thus the corresponding nu#ber of block errors can be displa"ed in thetrans#itter perfor#ance e'ent 9P *BB* ;9o8er rder Path ar *nd BackgroundBlock *rror


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72 AC*12 path trace b,te

The function of the A% is si#ilar to that of the A0 and A1. It is used to trans#itrepetiti'el" a 9o8er rder Path &ccess Point Identifier agreed #utuall" b" thetrans#itter and the recei'er so that the path recei'ing ter#inal can 'erif" itscontinued connection to the intended trans#itter.

82 8etwor) operator b,te

This b"te is allocated for specific #anage#ent purposes.

$ >b1*b$? 9utomatic #rotection Switchin! >9#S? channel

These bits are allocated for &PS signalling for protection at the lo8er order pathle'el

$ >b/*b6? eserved

Bit ( to 6 of / are reser'ed for an optional use described in JII.% of &ppendi+ JIIin .606. If this option is not used2 these bits shall be set to >000> or >111>. &recei'er is re:uired to be able to ignore the contents of these bits. The use of theoptional function is at the discretion of the o8ner of the trail ter#ination sourcegenerating the / b"te.

$ >b3? eserved

This bit is allocated for future use. This bit has no defined 'alue. The recei'er isre:uired to ignore its content.

Technical details:

&s described earlier2 bits 32 / and ) of b"te J( are allocated to con'e" back to aJC 1% trail ter#ination source the status and perfor#ance of the co#plete trail.Bits ( to 6 of b"te / #a" pro'ide a re#ote defect indication 8ith additionaldifferentiation bet8een the re#ote pa"load defect ;9CD


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Table 3-/ 7 4b!-b/5 coding and interpretation

b! b. b/ (eaning Triggers

0 0 0 -o re#ote defect -o re#ote



0 1 0 5e#ote pa"load defect

9CD;-ote 18DF?

Bits 1 / ;- bits< of the pointer 8ord carr" an -D 8hich allo8s an arbitrar"change of the pointer 'alue if that change is due to a change in the pa"load.

our bits are allocated to the flag to allo8 error correction. -or#al operation isindicated b" a >0110> code in the - bits. -D is indicated b" in'ersion of the -

bits to >1001>. &n -D should be interpreted as enabled 8hen three or #ore of thefour bits #atch the pattern >1001>. &n -D should be interpreted as disabled 8henthree or #ore of the four bits #atch the pattern >0110>. The re#aining 'alues ;i.e.>0000>2 >0011>2 >0101>2 >1010>2 >1100> and >1111>< should be interpreted asin'alid. The ne8 align#ent is indicated b" the pointer 'alue acco#pan"ing the

-D and takes effect at the offset indicated.

#ointer !eneration

The follo8ing su##ari?es the rules for generating the &4 / pointers.

1. During nor#al operation2 the pointer locates the start of the JC / 8ithin the&4 n fra#e. The -D is set to >0110>.

%. The pointer 'alue can onl" be changed b" operation 32 / or (.

3. If a positi'e =ustification is re:uired2 the current pointer 'alue is sent 8ith the

%


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I bits in'erted and the subse:uent positi'e =ustification opportunit" is filled8ith du##" infor#ation. Subse:uent pointers contain the pre'ious pointer'alue incre#ented b" one. If the pre'ious pointer is at its #a+i#u# 'alue2 thesubse:uent pointer is set to ?ero. -o subse:uent incre#ent or decre#entoperation is allo8ed for at least three fra#es follo8ing this operation.

/. If a negati'e =ustification is re:uired2 the current pointer 'alue is sent 8ith theD bits in'erted and the subse:uent negati'e =ustification opportunit" iso'er8ritten 8ith actual data. Subse:uent pointers contain the pre'ious pointer'alue decre#ented b" one. If the pre'ious pointer 'alue is ?ero2 the subse:uent

pointer is set to its #a+i#u# 'alue. -o subse:uent incre#ent or decre#entoperation is allo8ed for at least three fra#es follo8ing this operation.

(. If the align#ent of the JC n changes for an" reason other than rules 3 or /2 thene8 pointer 'alue shall be sent acco#panied b" -D set to >1001>. The -Donl" appears in the first fra#e that contains the ne8 'alues. The ne8 locationof the JC n begins at the first occurrence of the offset indicated b" the ne8

pointer. -o subse:uent incre#ent or decre#ent operation is allo8ed for at leastthree fra#es follo8ing this operation.

#ointer interpretation

The follo8ing su##ari?es the rules for interpreting the &4 n pointers.

1. During nor#al operation2 the pointer locates the start of the JC / 8ithin the

&4 / fra#e.

%. &n" 'ariation fro# the current pointer 'alue is ignored unless a consistent ne8'alue is recei'ed three ti#es consecuti'el" or it is preceded b" one of the rules32 / or (. &n" consistent ne8 'alue recei'ed three ti#es consecuti'el"o'errides ;i.e. takes priorit" o'er< rules 3 or /.

3. If the #a=orit" of the I bits of the pointer 8ord are in'erted2 a positi'e =ustification operation is indicated. Subse:uent pointer 'alues shall beincre#ented b" one.

/. If the #a=orit" of the D bits of the pointer 8ord are in'erted2 a negati'e =ustification operation is indicated. Subse:uent pointer 'alues shall bedecre#ented b" one.

(. If the -D is interpreted as enabled2 then the coincident pointer 'alue shallreplace the current one at the offset indicated b" the ne8 pointer 'alue unlessthe recei'er is in a state that corresponds to a loss of pointer.

".2.2 9@*$ concatenation

&4 /s can be concatenated together to for# an &4 / Gc ;G concatenated &4 /s0000>2 >0011>2 >0101>2>1010>2 >1100> and >1111>< should be interpreted as in'alid. The ne8 align#ent isindicated b" the pointer 'alue and si?e 'alue acco#pan"ing the -D and takeseffect at the offset indicated.

#ointer !eneration

The follo8ing su##ari?es the rules for generating the T4 1% pointers@

1. During nor#al operation2 the pointer locates the start of the JC 1% 8ithin theT4 1% fra#e. The -D is set to >0110>.

%. The pointer 'alue can onl" be changed b" operation 32 / or (.

3. If a positi'e =ustification is re:uired2 the current pointer 'alue is sent 8ith the

33


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I bits in'erted and the subse:uent positi'e =ustification opportunit" is filled8ith du##" infor#ation. Subse:uent pointers contain the pre'ious pointer'alue incre#ented b" one. If the pre'ious pointer is at its #a+i#u# 'alue2 thesubse:uent pointer is set to ?ero. -o subse:uent incre#ent or decre#entoperation is allo8ed for at least three fra#es follo8ing this operation.

/. If a negati'e =ustification is re:uired2 the current pointer 'alue is sent 8ith theD bits in'erted and the subse:uent negati'e =ustification opportunit" iso'er8ritten 8ith actual data. Subse:uent pointers contain the pre'ious pointer'alue decre#ented b" one. If the pre'ious pointer 'alue is ?ero2 the subse:uent

pointer is set to its #a+i#u# 'alue. -o subse:uent incre#ent or decre#entoperation is allo8ed for at least three fra#es follo8ing this operation.

(. If the align#ent of the JC 1% changes for an" reason other than rules 3 or /2the ne8 pointer 'alue shall be sent acco#panied b" the -D set to >1001>.The -D onl" appears in the first fra#e that contains the ne8 'alue. The ne8JC 1% location begins at the first occurrence of the offset indicated b" the ne8

pointer. -o subse:uent incre#ent or decre#ent operation is allo8ed for at leastthree fra#es follo8ing this operation.

#ointer interpretation

The follo8ing su##ari?es the rules for interpreting the T4 1% pointers@

1. During nor#al operation the pointer locates the start of the JC 1% 8ithin the

T4 1% fra#e.

%. &n" 'ariation fro# the current pointer 'alue is ignored unless a consistent ne8'alue is recei'ed three ti#es consecuti'el" or it is preceded b" one of rules 32 /or (. &n" consistent ne8 'alue recei'ed three ti#es consecuti'el" o'errides;i.e. takes priorit" o'er< rules 3 or /.

3. If the #a=orit" of the I bits of the pointer 8ord are in'erted2 a positi'e =ustification is indicated. Subse:uent pointer 'alues shall be incre#ented b"one.

/. If the #a=orit" of the D bits of the pointer 8ord are in'erted2 a negati'e =ustification is indicated. Subse:uent pointer 'alues shall be decre#ented b"one.

(. If the -D is interpreted as enabled2 then the coincident pointer 'alue shallreplace the current one at the offset indicated b" the ne8 pointer 'alue unlessthe recei'er is in a state that corresponds to a loss of pointer.

3/


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$ Questions:

!hat did "ou learn fro# this section$

1. Ho8 do &4 PT5 and T4 PT5 align the JC / and JC 1%$

%. The reasons for generation of the alar# and perfor#ance e'ents pertaining to the pointers.

The second ite# shall be e#phasi?ed.

Summar,

This section describes the i#ple#entation of #onitoring of SDH s"ste# signals.

The 5S H2 ,S H2 HP P H and 9P P H ha'e acco#plished the la"ered#onitoring #echanis#.

The focus is the #echanis# for the b"tes to #onitor alar#s and perfor#ances.

& ercises

!hich b"tes are used to #onitor the ,S &IS and ,S 5DI$

!hat is the #echanis# of the 5 9 alar# #onitoring$

!hat are the alar#s generated 8hen the recei'er has detected that the &4 PT5 is)00 or 10%3$

!hich b"tes i#ple#ent the la"ered error #onitoring$

3(


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SDH Principle Issue 3.0 Chapter / 9ogic Co#position of SDH *:uip#ent

Chapter # $ogic Composition of SDH %&uipment

Objectives:

To understand the co##on -* t"pes and the basic functions of the SDHtrans#ission net8ork.

To #aster the functions of the basic logic functional blocks that constitute the SDHe:uip#ent2 and their corresponding alar#s and perfor#ance e'ents #onitored.

To #aster the functions of the au+iliar" functional blocks.

To understand the functions of the co#pound functional blocks.

To #aster the corresponding alar# #aintenance signals pro'ided b" eachfunctional block2 and their corresponding alar# flo8 charts.

$.1 Common 8& of SDH networ)

The SDH trans#ission net8ork is co#posed b" connecting different t"pes of -*that are connected through optical fibre. The trans#ission function of the SDHnet8ork is perfor#ed through different -*@ add drop ser'ices2 cross connectser'ice2 net8ork error self healing2 etc. The follo8ing is a description of thefeatures and basic functions of co##on -* in the SDH net8ork.

1. TM K Terminal Multiple er

Ter#inal ,ultiple+er is used in the ter#ination station of the net8ork2 e.g. the t8oends of a chain2 8hich is a t8o port de'ice2 as sho8n in igure / 1.

TM

+STM*8

STM*M

1$5Mb s 2Mb s "$Mb s 8otes M 8

igure / 1 T, #odel

Its function is to #ultiple+ the lo8er rate signals in the tributar" port to the higherrate signal ST, - in the line port2 or to e+tract the lo8er rate tributar" signalsfro# ST, - signal. Please note that its line port inputs outputs one ST, - signal2

8hile the tributar" port can output input #ultiple paths of lo8er rate tributar"

1


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refor#2 a'oiding the accu#ulation of line noise through optical electric con'ersion2electric signal sa#pling2 =udging2 regenerating and refor#ing2 and electric opticalcon'ersion to ensure perfect trans#ission of signal 8a'e in the line. !hat isdiscussed here is the latter t"pe of regenerator. 5* is a t8o port de'ice2 ha'ingonl" t8o line ports 8 port and e port2 as sho8n in igure / 3@

STM*8 STM*8w e

&4

igure / 3 *lectric 5*

Its function is to generate the 8 side or e side recei'ed optical signal through *2sa#pling2 =udging2 regenerating and refor#ing2 * 2 and trans#it on the e or 8side again. Perhaps "ou ha'e noticed that 5* does not ha'e tributar" port as&D, has2 so &D, can be e:ui'alent to one 5* 8hen the traffic is notadded dropped at the local position ;tributar" does not add dropped signals


71/92


rate signal ;e.g. ST, 1 < 8ithin the cross connect #atri+.

4suall"2 DGC# n is used to represent the t"pe and perfor#ance of DGC ;note# n


72/92


as an e ample

STM 9 ( C D & F

F

F

4

4H H

8#

4.65"

4.65"

1$5Mb s

2Mb s"$Mb s

8otes ta)e 2Mb s

S# ST

TTF

MS#MST MS9

H#C##

##

%#9

%#9

H#T

H#T%#T %#C H#9

OH9 OH9 interface

S&MF MCF interfaceF interface

D$*D12 D1*D"

e ternal

HO9

HO

%O

w

%

7

M

S&TS S&T#

s,nchronous si!nal

igure / ( 9ogic functional blocks co#position of SDH e:uip#ent

To better understand the abo'e figure2 the na#es of the functional blocks in thefigure are listed belo8@

SPI@ S"nchronous Ph"sical Interface 5ST@ 5egenerator Section Ter#ination

,ST@ ,ultiple+ Section Ter#ination ,SP@ ,ultiple+ section protection

,S&@ ,ultiple+ Section &daptation PPI@ PDH Ph"sical Interface

9P&@ 9o8er order Path &daptation 9PT@ 9o8er order Path Ter#ination

9PC@ 9o8er order Path Connection HP&@ Higher order Path &daptation

HPT@ Higher order Path Ter#ination TT @ Trans#ission Ter#ination unction

H I@ Higher rder Interface 9 I@ 9o8er rder Interface

H &@ Higher rder &sse#bl" HPC@ Higher order Path Connection

H&@ 'erhead &ccess S*, @ S"nchronous *:uip#ent ,anage#ent unction

,C @ ,essage Co##unication unction

S*TS@ S"nchronous *:uip#ent Ti#ing Source

S*TPI@ S"nchronous *:uip#ent Ti#ing Ph"sical Interface

igure / ( is the functional block co#position figure of a T,. Its signal flo8 procedure is that the ST, - signal in the line enters the e:uip#ent fro# 5eferencePoint & of the e:uip#ent and is de#ultiple+ed to PDH signal of 1/0,b s in theorder & KB KC KD K* K K K9 K, and ST, - signal is dropped as

PDH signal of %,b s or 3/,b s ;here take the %,b s signal as an e+a#ple< in the

(


73/92


order & KB KC KD K* K K KH KI KA K . Here it is defined as therecei'ing direction of the e:uip#ent. The corresponding trans#itting direction isthe re'erse direction of these t8o paths2 it #ultiple+es the PDH signals of1/0,b s2 %,b s2 and 3/,b s to the ST, - signal fra#e in the line. Thesefunctions of the e:uip#ent are perfor#ed collaborati'el" b" all the basic functional

blocks.

S# SDH #h,sical nterface functional bloc)

SPI is the interface of e:uip#ent and optical path2 #ainl" perfor#ingoptical electric con'ersion2 electric optical con'ersion2 e+traction ti#ing of linesignal ;ST, -


74/92


e:uip#ent enters ut f ra#e state2 and 5ST functional block reports 5ecei'ingsignal ut f ra#e alar# 5 . !hen out of fra#e2 if a consecuti'e of t8ofra#es are aligned correctl"2 the 5 state ends. If 5 continues for #orethan 3#s2 the e:uip#ent enters 9oss f ra#e state2 and 5ST reports 59 alar#2sho8ing all >1> signal at Point C.

&fter 5ST correctl" aligns the fra#es for the signal input fro# Point B2 it descra#bles all the b"tes in ST, - fra#es e+cept the first line of b"tes. &fter the descra#ble2 5S H is e+tracted and processed. 5ST 'erifies B1 b"tes. If error blocksare detected2 5S BB* is generated in this ter#inal. 5ST at the sa#e ti#e e+tractsand sends *1 and 1 b"tes to H& ; 'erhead &ccess functional block< to processorder 8ire telephone connection. D1 D3 are e+tracted and sent to S*, 2 and the&, co##and infor#ation of the regenerator section in D1 D3 is processed.

%< Signal flo8 fro# C to B trans#itting direction

5ST 8rites 5S H2 co#putes B1 b"tes2 and scra#bles all the b"tes e+cept the firstline of b"tes in 5S H. The signal fra#e structure of e:uip#ent at Points &2 B2 andC is sho8n in igure / @

265 81

8 9 point ( point C ponitSTM*8 optical si!nal

STM*8 electrical si!nal

igure / Signal fra#e structure at Points &2 B2 and C

MST Multiple Section Termination functional bloc)

,ST is the source and sink of #ultiple+ section o'erhead2 processing ;ter#inating signals ;&IS


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( Tips:

,S &IS alar# #eans that the signal at Point C is all >1>. It is generated b" 5 9 S25 9 2 because 8hen 5ST recei'es 5 9 S and 5 9 2 the signal in Point C 8ill

be #ade to be all >1>. So2 the b b) of % at this ti#e is of course >111>. Inaddition2 the ,S &IS alar# in this ter#inal #a" be caused b" the fact that thesignal trans#itted b" the re#ote ter#inal is itself ,S &IS2 i.e. the trans#ittedST, - fra#e is co#posed of 'alid 5S H and signal 8hose other parts are all >1>.

If the % b"te at Point C is 1102 it #eans that this signal is the alar# signal sent back b" the re#ote ter#inal e:uip#ent@ ,S 5DI ;#ultiple+ section re#otedefect indication


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Notes:

ou ha'e heard #an" ti#es such na#es as regenerator section and #ultiple+

section2 but do "ou kno8 8hat e+actl" the" are$

5egenerator section refers to the #aintenance section bet8een the 5ST of t8oe:uip#ent ;including the t8o 5ST and the optical fibre bet8een the#mu l t ip le sec t io n ?

UU U

The regenerator section processes onl" the 5S H of ST, - fra#e2 and the#ultiple+ section processes the 5S H and ,S H of ST, - fra#e.

MS# >Multiple Section #rotection functional bloc)?

,SP is used to protect ST, - signal in #ultiple+ section in order to pre'ent errorsthat co#e 8ith it. It s8itches the signal of the error channel to the protectionchannel ;#ultiple+ section s8itching< b" #onitoring ST, - signal and e'aluating

the s"ste# state. IT4 T defines that the ti#e of protection s8itching is controlled8ithin (0 #s.

The fault condition of #ultiple+ section s8itching is 5 9 S2 5 9 2 ,S &IS2 or,S *GC ;B%


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1< Signal flo8 fro# D to * recei'ing direction

If ,SP recei'es ,S &IS sent b" ,ST or protection s8itching co##and fro#S*, to s8itch fro# pri#ar" channel to standb" channel for the infor#ation.

-or#all" the signal flo8 is transparentl" sent fro# D to *.

%< Signal flo8 fro# * to D trans#itting direction

The traffic flo8 at Point * is transparentl" sent to D.

The signal fra#e structure at Point * is the sa#e as that at Point D.

Technical details:

Co##on protection s8itching #odes include 1N12 1@12 and 1@n. Take thee:uip#ent #odel in igure / ) as an e+a#ple@

1N1 #eans that the trans#it end trans#its the sa#e infor#ation ;together< fro# theacti'e channel and the standb" channel. The recei'e end nor#all" chooses theser'ice in the acti'e channel to recei'e because the ser'ices in the acti'e channeland the standb" channel are e+actl" the sa#e ;both are #ain ser'ice


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MS9 Multiple Section 9daptation functional bloc)

The function of ,S& is to process and generate &4 PT52 and toasse#ble disasse#ble the entire ST, - fra#e2 i.e. to asse#ble disasse#ble &4to JC /.

1< Signal flo8 fro# * to recei'ing direction.

irst2 ,S& dis b"te interlea'es &4 b" di'iding &4 into n &4 / structures before processing n &4 PT5 of n &4 /. If the 'alue of &4 PT5 is in'alid pointer'alue for a consecuti'e of ) fra#es or &4 PT5 is -D for a consecuti'e of )fra#es2 the corresponding &4 / of ,S& generates &4 9 P alar#2 and the outputof the signal on the corresponding channels ;JC /< at Point is all >1>. If ,S&finds H12 H%2 and H3 b"tes are all >1> for a consecuti'e of 3 fra#es2 it isconsidered that the input at Point * is all >1> signal. ,S& at this #o#ent changesthe output on the corresponding JC / at Point to all >1>2 and generates &4 &ISalar# of the corresponding &4 /.

%< Signal flo8 fro# to * trans#itting direction

The signal at Point changes to &4 / through ,S& locating and aligning additionof &4 PT5. - &4 / is #ultiple+ed to &4 b" b"te interlea'ed #ultiple+ing#ethod. The signal fra#e structure at Point is sho8n in igure / 7.

AC$

1

1

201

igure / 7 the signal fra#e structure at Point

TTF Transmission Termination Functional bloc)

&s #entioned abo'e2 se'eral basic functional blocks #a" for# co#poundfunctional block b" fle+ible co#bination to i#ple#ent so#e co#ple+ 8ork. SPI25ST2 ,ST2 and ,S& together for# co#pound functional block TT . Its function isto carr" out optical electric signal con'ersion ;SPI< for ST, - optical line signalin the recei'ing direction2 to process 5S H ;5ST< and ,S H ;,ST


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HPC actuall" e:uals a cross connect #atri+. It functions as cross connect for thehigher order path JC / signal. *+cept the cross connect of the signals2 the trafficflo8 is transparentl" sent in HPC ;so both ends of HPC are represented b" Point1> 8ill be output in the corresponding channel at Point . HP 4-* alar# is

1%


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generated in the corresponding JC / channel of HPT.

The content of H/ b"te contains order nu#ber of the four basic fra#es in #ultifra#e. HPT trans#its it to the HP& functional block of H & co#pound functional

block ;because the order nu#ber of four basic fra#es in #ulti fra#e is onl" 'alidto %,b s2 but in'alid to 1/0,b s


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To change PDH line code to -5X code for the con'enience of the e:uip#ent to process and to e+tract at the sa#e ti#e the clock of the tributar" signal and send itto S*TS phase lock. &fter the phase lock2 the clock is sent to each functional block

b" S*TS as their 8orking clock.

!hen PPI detects no input signal2 it 8ill generate tributar" loss of signal alar# T&9 S ;%,b s< or *G9 S ;3/,b s2 1/0,b s


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HP& first locates the input JC 1% ;aligning


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A% and b( b6 of J(2 if #is#atch occurs ;8hat should be recei'ed is not consistent8ith 8hat is actuall" recei'ed1>2 and 9P 5DI alar# ;lo8er order

path re#ote defect indication< 8ill be at the sa#e ti#e sent back to the re#oteter#inal through b) of J( in corresponding path ;channel


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These are the basic functional blocks of the e:uip#ent2 but the" #a" constitutedifferent e:uip#ent through fle+ible co#binations2 e.g. the" can constitute 5* 2T,2 &D,2 and DGC and perfor# their corresponding functions.

The e:uip#ent has so#e other au+iliar" functional blocks. The"2 together 8ith the basic functional blocks2 perfor# the functions re:uired b" the e:uip#ent. Theseau+iliar" functional blocks include S*, 2 ,C 2 H&2 S*TS2 and S*TPI.

S&MF S,nchronous &'uipment Mana!ement functional bloc)

Its function is to collect the state infor#ation of other functional blocks2 and to perfor# rele'ant #anage#ent operations. This includes@ it sends co##ands toeach functional block2 collects the alar# and perfor#ance e'ents of each functional

block2 sends &, infor#ation to other -* through DCC channel2 reports

e:uip#ent alar# and perfor#ance data to the net8ork #anage#ent ter#inal2 andresponds to the co##ands gi'en b" the net8ork #anage#ent ter#inal.

The &, content of DCC ;D1 D1%< channel is deter#ined b" S*, .Corresponding S*, deter#ined b"tes are 8ritten at 5ST and ,ST through ,C 2or D1 D1% b"tes are e+tracted fro# 5ST and ,ST through ,C functional blockand then sent to S*, to process.

MCF Messa!e Communication Functional bloc)

,C functional block is actuall" a co##unication interface a#ong S*, 2 otherfunctional blocks and net8ork #anage#ent ter#inal. ,essage co##unication ofS*, ;through interface 2 < 8ith the net8ork #anage#ent is carried outthrough ,C2 and &, infor#ation is interacted 8ith the respecti'e DCCchannels in 5ST and ,ST through Interface - and Interface P2 and thus theco##unication of &, infor#ation bet8een -* is acco#plished.

Interface - in ,C sends D1 D3 b"tes ;DCC5


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Digital net8ork needs a ti#ing clock to ensure the s"nchroni?ation of the net8orkand thus the nor#al operation of the e:uip#ent. The function of the S*TSfunctional block is to pro'ide the ti#ing clock signal for the local SDH -* or

perhaps others SDH -* in the net8ork.

The sources of S*TS clock signals include@

1< Clock signal e+tracted fro# the ST, - signal of the line b" SPI functional block

%< Clock signal e+tracted fro# PDH tributar" signals b" PPI

3< *+ternal clock source e+tracted b" S*TPI ;s"nchronous e:uip#ent ti#ing ph"sical interface


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and perfor#ance e'ents #onitored b" each of these functional blocks and the principle of these e'ents is the ke" to correct anal"sis and error location in the#aintenance of the e:uip#ent. !e hope "ou 8ill ha'e good #aster" of 8hat isdiscussed here. Because the infor#ation in this part is scattered2 it is no8 puttogether here for "ou to find out its inner relations.

The follo8ing is the #a=or alar# #aintenance signals generated b" each functional block of SDH e:uip#ent and those o'erhead b"tes to 8hich these alar##aintenance signals are related.

SPI@ 5 9 S

5ST@ 5 9 ;&12 &%


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re#ote ter#inal through ,1 b"tes.

,S BB*@ #ultiple+ section background block error2 detected b" B% in recei'e

end.

,S *GC@ #ultiple+ section e+cessi'e errors2 detected b" B% in recei'e end.

&4 &IS@ ad#inistrati'e unit alar# indication signal2 H12 H%2 H3 all >1V.

&4 9 P@ ad#inistrati'e unit loss of pointer2 recei'ing a consecuti'e of )

fra#es 8ith in'alid pointers or -D .

HP 5DI@ higher order path re#ote defect indication2 local ter#inal recei'es

HP TI,2 HP S9,2 and sends back HP 5DI to re#ote ter#inal through 1 b"te.

HP 5*I@ higher order path re#ote error indication2 sends back the nu#ber of block errors detected in local ter#inal b" 'erif"ing B3 b"tes to the trans#it;re#ote< end.

HP BB*@ higher order path background block error2 displa"s the nu#ber the

block errors detected b" B3 b"tes in this ter#inal.

HP TI,@ higher order path trace identifier #is#atch2 8hat A1 should recei'e is

not consistent 8ith it actuall" recei'es2 generating this alar# in this ter#inal.

HP S9,@ higher order path signal label #is#atch2 8hat C% should recei'e is

not consistent 8ith it actuall" recei'es2 generating this alar# in this ter#inal.

HP 4-* @ higher order path une:uipped2 C%E00H e+ceeds fi'e fra#es2

generating this alar# in this ter#inal.

T4 &IS@ tributar" unit alar# indication signal J12 J%2 J3 are all >1>.

T4 9 P@ tributar" unit loss of pointer2 a consecuti'e of ) fra#es recei'es

in'alid pointers or -D .

T4 9 , ;HP 9 ,


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TTF

STM*8H#C

HO1$5Mb s 4.65"4.65" HO9

TTF

%#C %O 2Mb s"$Mb s

lower*rate tributar, si!nal

8ote M 8STM*M

w

igure / 1( T, structure of functional block

The function of T, is to cross #ultiple+ the lo8 rate tributar" signal PDH2 ST,, ;,Y-< to high rate line signal ST, -. Because HPC and 9PC functional

blocks e+ist2 this T, has lo8er order and higher order cross #ultiple+ functions.

9DM K 9dd drop Multiple er

TTF TTFSTM*8 STM*8

H#C

HO1$5Mb s4.65"4.65"

HO9

TTF

%#C %O2Mb s"$Mb s

lower*rate tributar, si!nal

8ote M 8STM*M

w e

igure / 1 &D, structure of functional block

The function of &D, is to cross #ultiple+ de #ultiple+ the lo8 rate tributar"signal ;PDH2 ST, ,< to the ST, - signals in e or 8 lines and the ST, - signalcross connect bet8een 8 or e line port.

&4 K e!enerator

S#. S#.

STM*8 STM*8

ST ST

igure / 16 5* structure of functional block

The function of 5* is to regenerate and refor# the signals2 sending the ST, -

signals on e 8 sides to the lines on 8 e sides.

%3


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-ote@ here no cross connect is necessar".

DBC K Di!ital Cross*connect

The logic structure of DGC is si#ilar to that of &D,2 the difference being that thecross connect #atri+ of the DGC is #ore po8erful than that the &D,.

The DGC is able to perfor# the cross connect bet8een #ultiple line signals ;ST, -< and #ultiple tributar" signals ;#uch #ore po8erful than the cross connectcapabilit" of &D,


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SDH Principle(Chapter1~4)

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