Cong Nghe Truyen Dan SDH

7/30/2019 Cong Nghe Truyen Dan SDH

1/118

MC LC

Trang

- Li ni u -..........................................................................4

Chng I.................................................................................6

Tng quan v k thut truyn dn ng b SDH ....................6

1.1- H THNG TRUYN DN CN NG B ..............6

1.1.1 - Nguyn tc ghp lung trong cu trc s cn

ng b................................................................6

1.1.2 - Cc tiu chun ca PDH..............................8

1.1.3 - Qu trnh ghp knh PDH.........................101.1.4 - Nhng hn ch ca PDH............................11

1.2 - GII THIU V H THNG SDH.........................15

1.2.1 - Lch s pht trin ca SDH........................15

1.2.2 - Cc tiu chun ghp knh SDH..................17

1.2.3 - Mt s khuyn ngh v SDH ca ITU-T........17

1.2.4 - Cc c im v hn ch ca phng phptruyn dn ng b SDH......................................19

1.2.5 - Nhng u im ca SDH so vi PDH...........22

1.2.6 - Nguyn tc ghp knh ca SDH.................23

1.2.7 - Chc nng cc khi...................................24

Chng II..............................................................................27

Phng php sp xp cc lung s trong SDH......................272.1 - KHI QUT.....................................................27

2.2 - QU TRNH SP XP CC LUNG TN HIU VO

CC GI..................................................................28

2.2.1- Sp xp lung 1,5 Mbit/s vo a khung VC-11

..........................................................................28


2/118

2.2.2 - Sp xp lung 2 Mbit/s vo a khung VC-12

..........................................................................34

2.2.3 - Sp xp lung 1,5 Mbit/s vo TU-12 thay th

lung 2 Mbit/s.....................................................36

2.2.4 - Sp xp lung 6 Mbit/s vo VC-2................38

2.2.5 - Sp xp lung 34 Mbit/s vo VC-3..............40

2.2.6 - Sp xp lung 45 Mbit/s vo VC-3..............42

2.2.7 - Sp xp lung s 140 Mbit/s vo VC-4........43

2.3 - QU TRNH GHP CC GI VO TRONG KHUNG

STM-1....................................................................452.3.1 - Ghp VC-4 vo STM-1................................45

2.3.2 - Ghp 3 VC-3 vo STM-1 qua AU-4...............46

2.3.3 - Ghp 3 VC-3 vo STM-1 qua AU-3..............48

2.3.4 - Ghp 63 VC-12 vo STM-1..........................49

2.3.5 - Ghp 84 VC-11 vo STM-1..........................52

2.3.6 - To khung truyn dn STM-N.....................53CHng III.............................................................................55

T chc v hot ng ca cc loi con tr trong khung tn

hiu SDH...............................................................................55

3.1 - V TR V CHC NNG CA CC LOI CON TR. 55

3.1.1 - V tr v chc nng ca con tr AU-4..........55

3.1.2 - V tr v chc nng ca con tr AU-3..........563.1.3 - V tr v chc nng ca con tr TU-3...........56

3.1.4 - V tr v chc nng ca con tr TU-2...........58

3.1.5 - V tr v chc nng ca con tr TU-12 v TU-

11.......................................................................60

3.2 - NH S A CH CC NHM BYTE V CC BYTE

.............................................................................60

2


3/118

3.2.1 - nh s a ch cc nhm byte ca khung

AUG....................................................................60

3.2.2 - nh s a ch cc nhm byte ca khung VC-

4 ........................................................................63

3.2.3 - nh s a ch cc byte ca a khung TU-2,

TU-12 v TU-11....................................................63

3.3 - CU TO V HOT NG CA CC CON TR.....64

3.3.1- Cu to ca con tr....................................64

3.3.2 - Hot ng ca cc loi con tr...................67

3.3.3 - Cc con tr trong cc khung tn hiu ni mcxch....................................................................77

3.4 - X L CON TR TI PHA THU..........................78

3.4.1 - ngha ca vic x l con tr.....................78

3.4.2 - nh s th t cc khung AU-n, TU-n.........79

3.4.3 - nh s th t cc AU-4 trong khung STM-N

..........................................................................803.4.4 - nh s th t cc TU-3 trong VC-4...........80

3.4.5 - nh s th t cc TU-2 trong VC-4...........81

3.4.6 - nh s th t cc TU-12 trong mt VC-4...81

3.4.7 - nh s th t cc TU-11 trong VC-4..........82

Chng IV.............................................................................67

Vai tr ca cc tn hiu qun l v bo dng trong h thngSDH......................................................................................67

4.1 - ON V TUYN TRONG H THNG TRUYN DN

.............................................................................67

4.1.1 - on (section)..........................................67

4.1.2 - Tuyn (Path).............................................67

4.2 - CC TN HIU QUN L V BO DNG............68

3


4/118

4.2.1 - Khi nim v SOH (Section Overhead) Mo

u on.............................................................68

4.2.2 - Tn hiu qun l v bo dng on lp

(RSOH)................................................................73

4.2.3 - Tn hiu qun l v bo dng on ghp

(MSOH)...............................................................76

4.2.4 - Tn hiu qun l v bo dng tuyn VC bc

thp....................................................................82

4.2.5 - Tn hiu qun l v bo dng tuyn VC bc

cao.....................................................................864.2.6 - Qui nh cc tn hiu bo dng v cnh bo

..........................................................................91

- Cc thut ng vit tt -.......................................................94

- ti liu tham kho -.............................................................98

- Li ni u -

S ra i ca cng ngh SDH (Synchronous Digital Hierarchy - Cng

ngh truyn dn phn cp s ng b) nh du mt thi k pht trin mi

ca mng vin thng th gii. SDH thc y cuc cch mng trong cc dch

v vin thng v dn n nh hng su rng n ngi s dng, cc nh

khai thc cng nh cc nh sn xut thit b.

Vic ngi s dng cui cng c bit l cc nh kinh doanh ngy cngph thuc nhiu hn vo cc phng tin thng tin dn n s bng n

nhu cu v cc dch v vin thng cht lng cao. Cc dch v nh hi ngh

truyn hnh, thm nhp c s d liu t xa, chuyn giao tp a mi trng (a

phng tin) i hi mt mng linh hot c kh nng p ng c yu cu

v rng di thng hu nh khng gii hn. S phc tp ca mng hin nay

xy dng da trn h thng truyn dn cn ng b PDH tc thp, iu

4


5/118

ny dn n nh iu hnh mng khng p ng ni cc yu cu ni trn.

V PDH ch yu p ng nhu cu thoi thng thng, khng ph hp vi

truyn dn v qun l cc lin kt c rng bng tn ln. SDH ra i nhm

gii quyt nhc im ny ca PDH. Kh nng trin khai cc h thng ng

b s c thc hin nhanh chng nh kh nng tng thch ca n vi cc

h thng PDH. SDH qui nh cu trc cho php cc tn hiu cn ng b kt

hp vi nhau v c ng thng vo trong mt tn hiu SDH. iu ny bo

v s u t ca cc nh iu hnh mng thit b cn ng b v cho php

h pht trin cc thit b ng b ph hp cho nhu cu ring i vi mng ca

h. Khi thit b ng b c a vo hot ng trong mng th li ch mn em li r rng. Cc nh khai thc s tit kim c ng k phn cng

trong mng, tng tin cy trong mng, dn n gim chi ph cho bo dng

v khai thc.

Kh nng qun l mng linh hot s ci thin to ln trong vic iu

khin mng truyn dn, ci thin kh nng phc hi mng gip cho vic sn

sng thng tin tt hn v vic cung cp cc dch v s nhanh hn.SDH s cung cp cho cc nh khai thc mt gii php mng cho tng

lai nh cc mng vng th (MAN), ISDN bng rng v cc mng thng tin

c nhn.

Chnh v vy vic la chn truyn dn ng b SDH lm c s cho

mng vin thng trong tng lai l hng pht trin ng n.

Vit Nam, thc hin ngh quyt ca ng ra cng nh k hochtng tc hin i ho ca ngnh bu in, cng ngh SDH c trin khai

v p dng tng bc. T nm 1994, mng SDH c khai thc, s dng

mt s tuyn vin thng lin tnh v n nay hu ht cc tnh thnh u p

dng cng ngh ny.

L mt sinh vin cao ng ca khoa in t - Vin thng, em lun

mong mun c tm hiu v nhng k thut, cng ngh ang c s dng

trong ngnh Vin thng vn dng nhng kin thc hc c vo ngh

5


6/118

nghip tng lai sau ny, cng l gp phn nh b ca mnh vo s pht trin

ca ngnh ni ring v s nghip cng nghip ho, hin i ho ca t nc

ni chung. V vy em quyt nh chn ti Cng ngh truyn dn SDH

lm n tt nghip.

Em xin chn thnh cm n thy gio - Thc s L Vn Hi, ngi

trc tip hng dn, gip em rt tn tnh trong thi gian lm n, ng

thi em cng xin cm n cc thy c gio trong khoa in t - Vin thng

trng i hc Bch Khoa H Ni gip cho em tip thu c nhng kin

thc c bn trong qu trnh hc tp em c th hon thnh n tt nghip

v cng l cho em c c nn tng trong ngh nghip tng lai.Do nng lc v thi gian c hn, bn n ca em khng th trnh

khi mt s thiu st v cn c nhng vn cha c cp su. Em rt

mong mun c tip thu kin ca cc thy c em c c kin thc

hon thin hn.

Chng I

Tng quan v k thut truyn dn ng b SDH

1.1- H THNG TRUYN DN CN NG B

1.1.1 - Nguyn tc ghp lung trong cu trc s cn ng b

Trong h thng ghp knh TDM, tn s ca h thng trong bt k mc

phn cp tc bit no cho trc cng c th x dch gi tr danh nh ti mt

lng nh no . V vy nguyn tc ca h thng ghp knh TDM c v n

6

H Ni, thng 6 nm2003

Sinh vin


7/118

gin nhng thc t khng phi nh vy. V d lung 2,048 Mbit/s ghp vi

nhau to thnh lung 8,448 Mbit/s nh sau:

Lung 2 Mbit/s c to ra t thit b ghp knh hoc tng i in t

s khc nhau nn tc bit khc nhau cht t, trc khi ghp theo bit cc

lung ny thnh mt lung c tc cao hn phi hiu chnh cho tc bit

nh nhau bng cc bit chn mang thng tin gi. Cc bit chn s c my thunhn bit v loi khi tn hiu gc khi thc hin tch knh. Mc d tc cc

lung nh nhau, nhng u thu khng nhn bit c v tr mi lung trong

lung hp thnh (lung c tc cao hn). Kiu ghp nh vy gi l cn

ng b (Plesiochronous). Trng hp thm bit gi nh trn c thc hin

tt c cc cp ghp knh ca h thng, v vy c gi l "H thng phn cp

s cn ng b PDH - Plesiochronous Digital Hierarchy"

7

Hnh 1.1 - Nguyn tc ghp knh

cn ng b.

12345J

123456

1234

Lung s 2 Mbit/s ctc bit cao hn

nh mc 1235 46

J Cc bit chn

B to xungng h

Lung s 2 Mbit/s ctc bit thp hn

nh mc

Chnbit

Chnbit

Cc bit d liuu vo

B chuynmch

Bghp

Tn hiura

5


8/118

1.1.2 - Cc tiu chun ca PDH

Hin nay trn th gii c ba tiu chun tc bit PDH, l tiu

chun Chu u, tiu chun Bc M v tiu chun Nht Bn

a-Tiu chun Chu u

Chu u da trn tc bit c s 2048 kbit/s t thit b ghp knh

PCM-30 hoc t tng i in t s ghp xen bit thnh cc tc bit cao

hn v gm c 5 mc. S hnh thnh cc mc theo tiu chun Chu u

nh hnh 1.2a.

b-Tiu chun Bc M

Bc M s dng lung s c s 1544 kbit/s t thit b ghp knh PCM-

24 hoc t tng i in t s ghp xen bit thnh cc lung s c tc

bit cao hn v gm c 4 mc. S hnh thnh cc mc theo tiu chun Bc

M nh hnh 1.2b.

8

x4

x4

x4

x4

2048kbit/s

8448kbit/s

34368

kbit/s

139264

kbit/skbit/s

564992

kbit/s

1544kbit/s

6312kbit/s

32064kbit

/s

44736

kbit/s

97728kbit

/s

400352

kbit/s

405000

kbit/s

x4

x5

x7

x3

x4

x9

Nht

BcM

Chuu

(a)

(b)

Hnh 1.2 - Cc tiu chunPDH.


9/118

c-Tiu chun Nht Bn

Hai mc u tin theo tiu chun Nht Bn hon ton ging tiu chun

Bc M v c tt c 5 mc.

ITU-T cng nhn 4 mc u tin theo tiu chun Chu u v 3 mc

u tin theo tiu chun Bc M l cc mc truyn dn PDH quc t.

9


10/118

1.1.3 - Qu trnh ghp knh PDH

Trong cu trc ghp knh cn ng b PDH (theo tiu chun Chu u)

th qu trnh ghp knh t lung 2 Mbit/s thnh lung 140 Mbit/s s phi

ghp qua tt c cc mc ghp trung gian 8 Mbit/s, 34 Mbit/s thng qua vic

s dng cc thit b ghp knh phn cp 2, 3, 4 (hnh 1.3). Khi ghp knh ta

phi thc hin vic chn

- Chn t cht khung

- Chn cc bit kim tra

10

2 Mbit/s 8 Mbit/s 34 Mbit/s140 Mit/s

13141516

DME2

DME2

DME2

DME3

64x

2Mbit/

s

12

3

4

5

6

7

8

64

63

6162

DME3

DME3

DME3

1

2

3

4

5

6

78

9

10

11

12

DME4

LTE

1

2

3

4

1

Hnh 1.3 Ghpknh PDH.


11/118

- Chn cc bit tn hiu dch v.

Qu trnh ghp knh qua cc cp:

- Cp 2: Ghp 64 lung 2 Mbit/s thnh 16 lung 8 Mbit/s dng 16 DME2



Khi tch knh th ta phi lm ngc li, c th thm nhp n lung

2 Mbit/s ta cn phi tch knh 140 Mbit/s thnh 64 lung 2 Mbit/s qua cc

bc 34 Mbit/s, 8 Mbit/s, 2 Mbit/s v cng thng qua cc thit b tch ghp

knh cp 2, 3, 4. Khi :- Tn hiu ng b c tch ra.

- Khi phc li t cht khung.

- Ly li cc bit chn vo.

1.1.4 - Nhng hn ch ca PDH

a. Tch xen phc tp, yu cu thit b cng knh lm gim cht lng

truyn dn

Hin nay nhu cu s dng dch v thoi cng nh phi thoi ngy cng

tng, ngha l ngi iu hnh mng mong mun c nhiu lung 2Mbit/s

cho thu v c th tch xen cc lung mt cch d dng, nhng k thut

PDH khng th p ng c iu . Chng hn khi 1 tuyn truyn dn qua

mt im no yu cu s dng lung 2 Mbit/s th ti phi lp t mt

khi lng ln cc thit b tch xen nh hnh 1.4

11


12/118

Vic trch ly mt lung 2 Mbit/s dng nh n gin, nhng trong

thc t khng phi nh vy. Vic s dng cc bit cn bng m cp ghp

PDH tc l vic nhn dng chnh xc v tr khung 2 Mbit/s trong mt knh140 Mbit/s l khng th c do khung tn hiu khng c cc bit nghip

v. Do nhn c mt lung cp thp, ta phi tch ring lung ny

trong lung cp cao, c lung c s 2 Mbit/s, ta phi tri qua tt c cc cp

ghp tch. iu ny s lm cho gi thnh dch v tng cao v lm gim tin

cy cng nh cht lng ca h thng.

b. Kh nng qun l v gim st mng km c bit l vi mng vin

thng tc cao

Do nhu cu thng tin trc y cha cao, cu hnh n gin, d qun l

do vy cu trc khung PDH khng to ra kh nng gim st v qun l ring.

C th l trong khung tn hiu cc b ghp 2/8, 8/34, 34/140 v 140/565 c

cc bit ng b khung (10 bit), 1 bit cnh bo ng b khung, 1 bit nghip v

v 12 bit iu khin chn (hnh 1.5a). Cn cp ghp c s 2 Mbit/s s

12

Lung 2 Mbit/s(IN/OUT)

140LTE

140

3434

8

82

140LTE

140

3434

8

82

Hnh 1.4 - Tch lung 2Mbit/s t lung140 Mbit/s.


13/118

ng b akhung v bo

hiu

ng bkhung

Bit tin Bit tin Bit tinBit tin

12 200 4 208 4 208 4

4 204

TF

= 100,4 s

1 111 010 000

Cc bit iu khin chn

Cc bit chn

Bit nghipv

CnhboT m ng b

khungT

F=125 s

TS0 TS1 TS2 ............ TS15 TS16 TS17 ...........................TS30 TS31

Khungchn

X 0 0 1 1 01 1Khung l

x 1A x x x xx

Khung0

0 0 0 0 1 AFx xKhung 1n 15

a b c d a bc d

a Cu trc khung bghp 2/8

b Cu trc khung tnhiu u ra thit bPCM-30

Hnh 1.5 - Cu trc khungtn hiu.

lng cc bit nghip v trong khung tn hiu cng rt hn ch. Mt khc,

trong khung tn hiu u ra thit b ghp knh PCM-30 ch c cc bit nh

du 'x' l cn c th s dng cho cc knh nghip v c (hnh1.5b).

c. Tc bit tiu chun ho quc t cn thp

Theo khuyn ngh ca ITU-T, tc bit cao nht c chun ho chomng vin thng quc t l 140 Mbit/s, tc bit cao nht cho mng vin

thng quc gia l 565 Mbit/s. Vi gii hn tc nh vy, trn mng vin

thng quc t khng th to ra c mt xa l thng tin v phc v cho nhiu

loi truyn thng khc nhau th hin tnh linh hot ca truyn thng s. Cng

nh vy vi mng vin thng quc gia, gii hn tc 565 Mbit/s lm hn

ch nhu cu pht trin cc dch v bng rng trong tng lai nh l knh

13


14/118

video s, yu cu tc t vi chc Mb/s n hng trm Mbit/s tu theo cht

lng.

14


15/118

d. Thit b cng knh

Thit b ghp knh bc cao v thit b u cui ng c lp vi nhau.

V d nh trong h thng thng tin quang th thit b ghp knh bc cao v

thit b u cui quang tch bit vi nhau, hn th na m ng ca hai loi

thit b ny khng nh nhau, u ra thit b ghp knh dng m HDB3 cn

u ra thit b u cui quang dng m 5B6D.

e. Trn th gii tn ti ba tiu chun truyn dn khc nhau

C 3 loi phn cp truyn dn khc v c lung c s n cc cp tc

cao, l ca Chu u, Bc M v Nht Bn. iu ny gy ra s kh

khn trong vic ho mng v ng b mng quc t.

1.2 - GII THIU V H THNG SDH

1.2.1 - Lch s pht trin ca SDH

H thng phn cp s ng b SDH (Synchronous Digital Hierarchy) l

mt h thng truyn dn mi trn th gii. SDH to ra mt cuc cch mng

mi trong cc dch v vin thng, th hin mt cng ngh tin tin, c th p

ng mt cch rng ri cc yu cu ca khch hng, ngi khai thc cng nh

cc nh sn xut.

Trong tng lai, h thng ng b SDH s ngy cng c pht trin

nh cc u im vt tri so vi PDH, c kh nng kt ni vi mng PDH

hin hnh t cho php hin i ha mng vin thng theo tng giai on

pht trin.

Lch s pht trin cc my ghp knh SDH bt u t M, ni m

nhiu nm trc y rt nhiu hng sn xut thit b truyn dn cp quang

khc nhau pht trin cc phng php khc nhau m ho cho tn hiu

ring ca h. iu ny dn n hu qu l vic qui hoch, khai thc bo

15


16/118

dng cng nh qun l mng ht sc phc tp v kh khn. loi b cc

giao tip ring v t c tnh kt ni tng h tht s gia cc hng cung

cp thit b, tiu ban T1X1 ca vin tiu chun quc gia M (ANSI -

American National Standard Institute) bt u t nm 1985 pht trin

mng tiu chun SONET (Synchronous Optical Network - Mng quang ng

b) theo xut ca cng ty BELLCORE. Cc tiu chun ca SDH bt u

hnh thnh to ra mt mng giao tip quang c th hot ng vi tt c cc

h thng truyn dn khc nhau ca cc sn phm khc nhau (theo tiu chun

Chu u hoc Bc M). Sau , cc tiu chun ny c s dng rng ri

c th x l cho mng hin ti v cho tt c cc loi tn hiu trong tng laicng nh cho c phng tin khai thc v bo dng. Mng quang ng b

da trn nguyn l ghp knh ng b, trong cp quang c s dng lm

mi trng truyn dn, v sau cc tiu chun v giao din thit b cng c

nghin cu nhm c th kt ni cc loi thit b khc nhau m khng gy tr

ngi khi p dng loi hnh mi ny vo mng hin hnh. p ng cc yu

cu cn phi lu n vic tiu chun cc tn hiu bo dng gim st,chuyn mch bo v v c vn qun l mng li ca cc loi thit b khc

nhau .

Cui nm 1988, trn c s tiu chun SONET v xt n cc tiu chun

ghp knh khc nhau chu u, M v Nht, CCITT a ra tiu chun

quc t v cng ngh truyn dn theo cu trc s ng b SDH (Synchronous

Digital Hierarchy) dng cho truyn dn cp quang v vi ba. Cc tiu chunSDH c nu trong cc khuyn ngh G707, G708, G709. Cc khuyn ngh

ca CCITT nh ngha mt s tc truyn dn c s SDH. Tc u tin

l 155,52 Mbit/s thng c gi l STM-1 (Synchronous Transport Module

level 1 - Modul truyn ti mc 1). Cc tc truyn dn cao hn l STM-4 v

STM-16 (622 Mbit/s v 2,5 Gbit/s) cng c nh ngha, cc mc cao hn

ang c nghin cu.

16


17/118

1.2.2 - Cc tiu chun ghp knh SDH

Hin nay tiu chun SDH ca ITU-T kt hp c 2 tiu chun SDH ca

chu u (ETSI) v tiu chun SONET ca M :

SONET:Synchronous Optical Network - Mng quang ng b. Synchronous

Optical Network - Mng quang ng b.

ETSI:European Telecommunication Standard Institute-Vin tiu chun vin

thng chu u. European Telecommunication

Standard Institute-Vin tiu chun vin thng chu u.

OC : Optical Carrier - truyn dn quang. Optical Carrier - truyn dn

quang.

STS :Synchronous Transport Signal - Tn hiu truyn ti ng b.

Synchronous Transport Signal - Tn hiu truyn ti ng b.STM:Synchronous Transport Module - Modul truyn ti ng b.

Synchronous Transport Module - Modul truyn ti ng b.

1.2.3 - Mt s khuyn ngh v SDH ca ITU-T

Sau y l mt s khuyn ngh v SDH m ITU-T a ra:

Cc mc tn

hiu quang

Tiu chun Tc

Mbit/sSONET ETSI

OC-1

OC-3

OC-9

OC-12OC-18

OC-24

OC-36

OC-48

STS-1

STS-3

STS-9

STS-12STS-18

STS-24

STS-36

STS-48

STM-1

STM-4

STM-16

51,84

155,52

466,56

622,08933,12

1244,16

1866,24

2488,32

17


18/118

G.702- S lng mc trong phn cp s ng b. - S lng mc

trong phn cp s ng b.

G.707- Cc tc bit ca SDH - Cc tc bit ca SDH

G.708- Giao dim nt mng SDH - Giao dim nt mng SDH

G.709- Cu trc ghp ng b - Cu trc ghp ng b

G.773- Giao thc (Protocol) ph hp vi cc giao din Q qun l

cc h thng truyn dn - Giao thc (Protocol) ph hp

vi cc giao din Q qun l cc h thng truyn dn

G.774- M hnh thng tin qun l SDH - M hnh thng tin qun

l SDHG.782- Cc kiu v cc c tnh ch yu ca thit b ghp SDH - Cc

kiu v cc c tnh ch yu ca thit b ghp SDH

G.783- Cc c tnh ca cc khi chc nng trong thit b ghp SDH -

Cc c tnh ca cc khi chc nng trong thit b ghp SDH

G.784- Qun l SDH - Qun l SDH

G.803- Cu trc mng truyn dn SDH - Cu trc mng truyn dn SDHG.825- iu khin rung pha v tri pha trong mng thng tin SDH -

iu khin rung pha v tri pha trong mng thng tin SDH

G.957 - Cc giao din quang ca cc thit b v h thng lin quan n

SDH - Cc giao din quang ca cc thit b v h thng

lin quan n SDH

G.958 - H thng truyn dn s dng cho cp si quang - H thngtruyn dn s dng cho cp si quang

Cc khuyn ngh ni trn c ITU-T xy dng s dng trn phm

vi ton th gii. Trong cc vng khc nhau c th c thay i nh ca cc

khuyn ngh ph hp vi mng ca vng . V d nh chu u, cc

khuyn ngh v SDH do ETSI ban hnh, Bc M do ANSI ban hnh.

18


19/118

1.2.4 - Cc c im v hn ch ca phng php truyn dn ng b

SDH

1. Khung 125 s

Cu trc khung c hnh thnh bng cc khi 125 s. c im ny

khng c trong phn cp s cn ng b hin dng, n cho php truy nhp t

tn hiu phn cp cao ti cc tn hiu cp thp. Ton b cc qu trnh x l c

th c thc hin c nh xen byte, do vy gy ra rung (Jitter) ca tn hiu

thu v c khc phc bng tn hiu chn dng, chn m v chn khng.

2. S hp nht cc phn cp

Cu trc ghp knh ng b c kh nng ho hp tn hiu s SDH Bc

M v chu u. Cc tn hiu s ca Bc M c th kt hp vi cc tn hiu

s ca chu u v ngc li, iu ny ch thc hin trong h thng SDH.

19


20/118

3. Cu trc phn cp

Mt trong nhng c im ni bt ca truyn dn ng b l tho hip

cc khi nim phn lp khc nhau. Da trn khi nim ny cc mo u cphn loi thnh SOH v POH trong cu trc khung, c ngha l mng thng

tin ch yu c phn thnh cc lung v on. Cc mo u cn thit cho

cc lung s khng c x l ti cc on m chng c truyn i thng

sut. Cc SOH (t mo u on) phn trn hoc di con tr s c phn

loi theo chc nng, chng c gn tng ng vi cc chc nng on lp

v on ghp knh. C ngha l cc on li c phn lp mt ln na thnhcc on ghp knh mc cao v cc on lp mc thp.

4. ng b ho bng con tr

Trong qu trnh ghp knh ng b, mng thng tin c ng b ho

nh vic hiu chnh gi tr cc con tr, iu ny c ngha l s x dch ng

b gia h thng v tn hiu thu c th x l ph hp vi con tr chn dng /

khng / m. Thng qua vic s dng b nh ng, phng php ng b ho

bng con tr to iu kin kh thi cho ng b ho bng rng. Thc hin

ng b ho theo kiu chn byte nn to ra Jitter tn s thp v bin cao.

5. Ghp knh mt bc

Trong qu trnh ghp knh ng b, cc tn hiu TUG-2 c nh xtrc tip thnh tn hiu VC-4 hoc cc tn hiu AU-3 c nh x trc tip

thnh tn hiu STM-1. Qu trnh ny gi l ghp knh mt bc. Ngoi ra khi

p dng trn mt mng thng tin, ni c tn hiu ln gi i nh vic tin hnh

mt qu trnh ghp knh, khi nim ny to iu kin d dng v kinh t cho

kt ni phn chia v kt ni cho. Ghp knh mt bc tr nn kh thi nh

khi nim Container.

20


21/118

6. Khi nim mng thng tin

Phng thc truyn dn ng b c thit lp trn c s khi nimmng thng tin. Do cc h thng thng tin quang hin nay c thit k

da trn khi nim truyn dn im ni im cho nn khng c hiu qu khi

thc hin kt ni tch nhp hoc kt ni cho thng xuyn xy ra i vi cc

tn hiu c to ra trn cc nt gia, sau khi hnh thnh mng truyn

thng. Tuy nhin cc h thng thng tin quang ngy cng c s dng nhiu

th h thng v cc tiu chun da trn mng tr nn rt cn thit v khi

nim ghp knh mt bc c p dng. Hn th na, v cc mo u th

cc SOH cn cho cc on v POH cn cho cc lung c phn loi v

mt vi on mo u trong s c gn cho vic khai thc bo dng

mng thng tin c hiu qu.

7. Mng thng tin ton cu

c im ca mng thng tin truyn dn ng b l da trn quan im

mng thng tin ton cu. Vic ng b ho c tin hnh mt s ln qua

vic s dng con tr, l yu t cho php mng truyn ng b c ng

b ho vi mng thng tin ton cu. Do vic phn cp tng thch vi cc

cp truyn dn chu u v Bc M. Nu cc mo u t bn ngoi v cu

trc ghp knh u c s dng da trn khi nim ny ca mng thng tinth mng thng tin ton cu c th thc hin c.

8. Nhng hn ch

- SDH khng tn dng ht dung lng ng truyn. Chng hn khung

STM-1 tc truyn l 155 Mbit/s ch cha c 63 lung 2 Mbit/s hoc 3

21


22/118

lung 34 Mbit/s hoc 1 lung 140 Mbit/s. Trong khi PDH 1 lung 140

Mbit/s cha c 64 lung 2 Mbit/s.

- K thut phc tp do phi ghi li s tng quan v pha gia cc tn

hiu lung v mo u.

- Vic xen byte lm tng tc Jitter hn kiu xen bit ca PDH.

1.2.5 - Nhng u im ca SDH so vi PDH

- Ghp knh n gin. Cng ngh SDH ch cn gi phi dy ti giaodin vo ra cc container, do lm gim ng k gi lp t v i dy,

cc con tr SDH phn khung trc tip khng qua cc trung gian ti bt k

mc PDH no.

- Cung cp kh nng qun l mng m t h thng trung tm. Tt c

cc chc nng cnh bo h thng, o c ch tiu v iu khin cu hnh

u c h thng qun l. iu ny cho php ng dng vn hnh v bo

dng tp trung.

- Thit b lp t n gin, bo dng d dng. Do thit b lp t c

tiu chun ho, chi ph lp t c gim ng k v vic bo dng ch

cn thay card di s ch dn ca b phn bo dng trung tm.

- H thng phn knh SDH ch ly mt tn hiu ng h t dng STM-N v pht tn hiu ng b cng ch mt ln mc .

- Mng c lp vi cc nh sn xut, cu hnh mng SDH c nh

ngha cht ch bi ITU-T, tt c cc thit b ca nh sn xut c th ni

trc tip vi nhau ti STM-N. Hot ng lun phin ca mng c thc

hin nhanh chng bi phn mm trong h thng qun l mng. Nh vy s

22


23/118

Spxp

STM-N AUG AU-

4

VC-4

TUG-3 TU-3 VC-3

C-3VC-3

TUG-2 TU-2 VC-2

TU-12 VC-12

TU-11 VC-11

C-4

C-2

C-12

C-11

AU-3

xN x1

x3x3

x7

x7

x3

x4

X l contr

Ghpngchnh

140

Mbit/s

34 Mbit/s

45 Mbit/s

6 Mbit/s

2 Mbit/s

1.5Mbit/s

Hnh 1.6 - S khi b ghp SDHtiu chun.

loi b cc thit b ni cho nhn cng ti gi phi dy. Cc dng SDH c

th nh tuyn li nh lnh ca phn mm.

- y cc chc nng cnh bo v o c ch tiu do SDH cung cp,

cc chc nng ny u c h thng qun l trung tm khi h thng ang

lm vic. Do vic s dung thit b truyn dn quang kt hp vi b

tch/xen tc linh hot SDH cho php s dng cu hnh mch vng. Cu

hnh ny c an ton cao trong trng hp hng hc thit b hay t dy,

ng thi cng tit kim c dy dn.

Nh vy vic ng dng truyn dn SDH l cn thit p ng nhu cupht trin dch v v h gi thnh mng.

1.2.6 - Nguyn tc ghp knh ca SDH

Trong h thng phn cp s cn ng b SDH th khung truyn dn cp

thp nht (cp 1) c gi l STM-1 (Synchronous Transport Module 1) c

tc chun l 155,52 Mbit/s. Qu trnh to thnh khung truyn dn STM-1

c bt u bng vic ghp cc lung tn hiu cp thp nh PDH hoc cc

lung tn hiu hnh, d liu v s c ghp t phi qua tri qua cc cp

sau y:

23


24/118

T hnh 1.6 ta thy theo tiu chun ca ITU-T, ta c th ghp vo lung

STM-1 cc lung nhnh 1,544 Mbit/s , 2,048 Mbit/s , 6,312 Mbit/s , 34,368

Mbit/s , 44,736 Mbit/s , 139,264 Mbit/s.

ghp vo lung STM-1, trc ht cc lung nhnh ni trn c sp

xp vo cc Container k hiu l C. sp xp vo cc container ny, c th

chn thm cc bit c nh v cc bit ng. Cc bit ng y c th chn m

hay chn dng tu thuc vo cc lung nhnh n nhanh hay chm. Cc ch

s ng sau C biu th tc tng ng ca cc lung nhnh. Sau cc

container ni trn c gn thm thng tin b sung qun l tuyn POH

to thnh container o VC. d dng xc nh c v tr ca VC ny trongvng ti trng mt khi cn ly chng ra t lung tng, cc con tr s ch th v

tr u ca cc VC ni trn, qu trnh ny c th hin cc n v lung

nhnh TU v cc n v qun l AU tng ng v c gi l qu trnh ng

b. to thnh lung tc cao hn, cc lung nhnh sau TU v AU c

ghp thnh mt lung chung nhm n v nhnh TUG hay cc nhm n v

qun l AUG. Qu trnh ny c gi l ghp knh.Theo s khi hnh 1.6, ta c th thy c 1 lung STM-1 cho php

ghp ti a:

4 x 7 x 3 = 84 lung 1,5 Mbit/s.

3 x 7 x 3 = 63 lung 2 Mbit/s.

7 x 3 = 21 lung 6 Mbit/s.

3 lung 34 Mbit/s.1 lung 140 Mbit/s.

1.2.7 - Chc nng cc khi

1. C-n (container) - Container mc n

K hiu Tn hiu c truyn

C-11C-12

C-3

C-4

1544 kbit/s2048 kbit/s

34368 kbit/s

44736 kbit/s

139264 kbit/s

24


25/118

Tn hiu truyn trn mng ng b trc tin phi c ng gi vo 1

container tng ng vi tc tn hiu v cu trc ca khung ng b.

Trn thc t cn c tc bo m cho s lm vic thng sut ca mng vin

thng trong thi k qu chuyn cc thit b thnh ng b mt cch trn

vn. Qu trnh ng gi vo container bao gm vic t chc, sp xp cc byte

tin v byte n trong container .

2. VC-n (Virtual container) - Container o mc n

VC-n l mt khi thng tin bao gm phn ti trng do cc C-n tng

ng cung cp v phn mo u tuyn POH. POH c s dng xc nh v

tr bt u ca VC-n, nh tuyn, qun l v gim st lung nhnh. Trong

trng hp sp xp khng ng b cc lung nhnh vo VC-n th phi tin

hnh chn bit. C 2 loi VC-n l VC-n mc thp v VC-n mc cao.

- VC-n bc thp gm c VC-11, VC-12, VC-2 cu to tng ng bi

C-11, C-12, C-2 thm cc byte POH loi byte mang thng tin iu

khin v gim st tuyn ni gia 2 VC-n ny.

- VC-n bc cao gm c VC-3, VC-4 l tp hp cc nhm khi nhnh

TUG-2 hoc 1 tp hp ca TU-3 cng vi cc byte mang thng tin

iu khin v gim st tuyn ni gia hai VC-n ny gi l POH.

3. TU-n (Tributary) - Khi nhnh mc n

TU-n l mt khi thng tin gm mt VC-n cng mc v mt con tr

khi nhnh TU-n PTR ch th khong cch t con tr khi nhnh n v tr

bt u ca container o VC-3 hoc VC-n mc thp.

4. TUG-n (Tributary group) - Nhm cc khi nhnh

25


26/118

TUG-n c hnh thnh t cc khi nhnh TU-n hoc t TUG-n mc

thp hn. TUG-n to ra s tng hp gia cc container ca mc thp v VC

mc cao hn.

5. AU-n (Administrative Unit) - Khi qun l

C 2 loi AU l AU-3 v AU-4. Cc phn t ny gm VC-n bc cao v 1

con tr khi qun l c v tr c nh trong khung tn hiu STM-1. Gi tr con

tr xc nh v tr ca VC-n trong khung (Tc l th hin quan h v pha VC-

n bc cao trong khung STM-N).

6. AUG (Administrative Unit Group) - Nhm n v qun l

C th gm 1 AU-4 hoc 3 AU-3 c ghp vi nhau t vo trong

khung STM-1.

7. STM-N (Synchronous transport module)-Modul truyn ti ng b

- STM-1: Modul truyn ti mc c s (mc 1). Phn t ny chia lm hai

phn. Phn ti trng cha thng tin cc lung nhnh cn truyn. Phn

SOH cha thng tin dnh cho qun l, ng b cc thng tin cha trong

ti trng. Phn SOH ny dnh cho c trm lp v trm ghp knh

- STM-N: Gm NxSTM-1 c cu trc ging STM-1. Do tn hiu ng

b nn mun to khung STM-N ch vic ghp cc khung STM-1 vi

nhau. (Vic ghp lung trong SDH c th ghp trc tip t lung STM-1c s thnh lung STM-N hoc t lung STM-N bc thp thnh cc

khung STM-N bc cao).

26


27/118


28/118

2.2 - QU TRNH SP XP CC LUNG TN HIU VO CC GI

2.2.1- Sp xp lung 1,5 Mbit/s vo a khung VC-11

Sp xp khng ng b

Do c im l khung VC-n mc thp nn s byte rt t so vi VC-n

mc cao, v vy VC-11 c sp xp thnh a khung c bn khung, mi

khung c 26 byte (hnh 2.1). Cc byte ny c gii thch nh sau:

- V5, J2, N2, K4 l cc byte mo u tuyn POH ca VC-11. Chcnng ca cc byte ny s c m t k hn phn sau.

- I l bit thng tin

- R l bit n c nh, bit ny khng c ngha m ch c dng

khp kch thc ca tn hiu PDH so vi tn hiu SDH.

- O l bit thng tin nghip v

- S1, S2 l cc bit chn dng iu chnh s chnh lch v tn s

gia h thng SDH v PDH.

- C1, C2 l cc bit iu khin chn. Cc bit C1 dng iu khin S1,

cc bit C2 dng iu khin S2 .

28

V5R R R R R R I R

24 BYTE

J2C1 C2 O O O O I R

24 BYTE

N2C1 C2 O O O O I R

24 BYTE

K4C1 C2 R R R S1 S2 R

24 BYTE

104Byte

I = Bit d liuO=Bit nghip vC=Bit iukhinS=Bit chnR=Bit n cnh

500s

Hnh 2.1 - Sp xp khng ng b lung 1,5Mbit/s vo VC-11.


29/118

Khi C1C1C1=000 th S1 l bit thng tin.

Khi C1C1C1=111 th S1 l bit chn.



Trong trng hp c mt li bit C th u thu da vo lut s ng ca

cc bit C xo hoc khng S1 v S2. Gi tr cc bit S1, S2 khi chn khng

c qui nh nn my thu khng m cc bit ny khi kim tra chn t m

BIP-n.Sp xp ng b theo bit

Sp xp ng b theo bit lung 1,5 Mbit/s vo VC-11 c th hin

trong hnh 2.2. Trong trng hp ny khng phi chn, hai bit u tin ca

byte th 2 trong cc khung to thnh t m ng b a khung 10101010.

29

V51 0 R R R R I R

24 BYTE

J21 0 O O O O I R

24 BYTE

N21 0 O O O O I R

24 BYTE

K41 0 R R R R I R

24 BYTE

104Byte

I = Bit d liuO=Bit nghip vR=Bit n cnh

500

sHnh 2.2 - Sp xp ng b theo bit lung 1,5Mbit/s vo VC-11.


30/118

Sp xp ng b theo byte

30


31/118

31


32/118

Hnh 2.3 l sp xp ng b theo byte. Chc nng cc byte tng t

nh ni trn. Ngoi ra cn c P0, P1 l cc bit dng cho vic bo hiu

knh chung CAS trong ch ng b byte. Cc bit S1, S2, S3 v S4 chacc bit bo hiu ca 24 knh 64 kbit/s. Pha ca cc bit bo hiu c ch th

bi P1 v P0 nh bng sau.

2 trng thi 4 trng thi 16 trng thiS1 S2 S3 S4 S1 S2 S3 S4 S1 S2 S3 S4 P1 P0A1 A2 A3 A4 A1 A2 A3 A4 A1 A2 A3 A4 0 0A5 A6 A7 A8 A5 A6 A7 A8 A5 A6 A7 A8 0 0A9 A10 A11 A12 A9 A10 A11 A12 A9 A10 A11 A12 0 0A13 A14 A15 A16 A13 A14 A15 A16 A13 A14 A15 A16 0 0

A17 A18 A19 A20 A17 A18 A19 A20 A17 A18 A19 A20 0 0A21 A22 A23 A24 A21 A22 A23 A24 A21 A22 A23 A24 0 0A1 A2 A3 A4 B1 B2 B3 B4 B1 B2 B3 B4 0 1A5 A6 A7 A8 B5 B6 B7 B8 B5 B6 B7 B8 0 1A9 A10 A11 A12 B9 B10 B11 B12 B9 B10 B11 B12 0 1A13 A14 A15 A16 B13 B14 B15 B16 B13 B14 B15 B16 0 1A17 A18 A19 A20 B17 B18 B19 B20 B17 B18 B19 B20 0 1A21 A22 A23 A24 B21 B22 B23 B24 B21 B22 B23 B24 0 1A1 A2 A3 A4 A1 A2 A3 A4 C1 C2 C3 C4 0 0A5 A6 A7 A8 A5 A6 A7 A8 C5 C6 C7 C8 1 0A9 A10 A11 A12 A9 A10 A11 A12 C9 C10 C11 C12 1 0A13 A14 A15 A16 A13 A14 A15 A16 C13 C14 C15 C16 1 0A17 A18 A19 A20 A17 A18 A19 A20 C17 C18 C19 C20 1 0

A21 A22 A23 A24 A21 A22 A23 A24 C21 C22 C23 C24 1 0A1 A2 A3 A4 B1 B2 B3 B4 D1 D2 D3 D4 1 1A5 A6 A7 A8 B5 B6 B7 B8 D5 D6 D7 D8 1 1A9 A10 A11 A12 B9 B10 B11 B12 D9 D10 D11 D12 1 1A13 A14 A15 A16 B13 B14 B15 B16 D13 D14 D15 D16 1 1A17 A18 A19 A20 B17 B18 B19 B20 D17 D18 D19 D20 1 1A21 A22 A23 A24 B21 B22 B23 B24 D21 D22 D23 D24 1 1

32

V5P1 P0 S1 S2 S3 S4 F

R64 kbit/s

Cc knh 1-24J2

P1 P0 S1 S2 S3 S4 FR

64 kbit/sCc knh 1-24

N2P1 P0 S1 S2 S3 S4 F

R64 kbit/s

Cc knh 1-24K4

P1 P0 S1 S2 S3 S4 FR

64 kbit/sCc knh 1-24

104Byte

F =Bit ng b khung

S= Cc bit bo hiu

P1 P0=Ch th pha ca bo

hiu

P1P0=00 ch th byte bo

hiu u tin ca a khung

500

s

Hnh 2.3 Sp xp ng b theo byte lung 1,5Mbit/s vo VC 11.


33/118

33


34/118

2.2.2 - Sp xp lung 2 Mbit/s vo a khung VC-12

a. Sp xp khng ng b

Mc ch ca vic sp xp ny l chuyn i lung 2 Mbit/s cn ng bti u vo C-12 thnh a khung VC-12 ng b tc l ng b ho tn hiu

PDH theo tn s ng h SDH. Cc byte POH c cng vo C-12, cc bit v

byte chn c s dng duy tr kch thc xc nh cho mt a khung VC-

12 l 140 byte. 500 s, iu ny c ngha l 1 a khung VC-12 s c truyn

ht sau 4 khung STM-1. a khung VC-12 bao gm 1023 bit thng tin I (127

byte + 7 bit), 2 bit chn (S1 cho chn m, S2 cho chn dng), 6 bit iukhin chn C1, C2, 8 bit nghip v O, 49 bit n c nh R v cc byte POH

V5, J2, N2, K4.




Khi C2C2C2=111 th S2 l bit chn.u thu cn c vo lut s ng ca 3 bit C gii ng b trong

trng hp c 1 bit trong nhm C1 hoc C2 b li. Gi tr cc bit S1, S2 khi

chn khng c qui nh v vy my thu khng m bit ny khi kim tra

chn t m BIP-n.

34


35/118

b. Sp xp ng b theo bit

V5R R R R R R R R

32 byte

R R R R R R R R

J2C1 C2 O O O O R R

32 byte

R R R R R R R RN2

C1 C2 O O O O R R

32 byte

R R R R R R R RK4

C1 C2 R R R R R S1S2 I I I I I I I

31 byte

R R R R R R R R

35

140Byte

I = Bit d liuO=Bit nghip vC=Bit iu khinchnS= Bit chnR=Bit n c nh

500s

Hnh 2.4 Sp xp khng ng b lung 2 Mbit/s vo

a khung VC-12.


36/118

Trong kiu sp xp ny khng yu cu chn, v lung 2 Mbit/s ng

b vi SDH. V vy bit S1 v S2 trong trng hp sp xp khng ng b

tng ng s l bit n v bit thng tin khi sp xp ng b theo bit. Cc bit

iu khin chn C1 v C2 tr thnh cc bit c nh 1 v 0. ITU-T khuyn ngh

loi b phng php sp xp ng b theo bit lung 2 Mbit/s v y l trng

c bit ca trng hp sp xp khng ng b v s dng cng mt b ghp

tin hnh sp xp khng ng b v ng b theo bit m khng cn b

sung bt k ng tc x l no khc.

c. Sp xp ng b theo byte

Sp xp ng b theo byte lung 2 Mbit/s vo a khung VC-12 nh

hnh 2.5.

Khi c s phn bit r rng cc knh 64 kbit/s ca lung 2 Mbit/s trong

SDH th s dng phng php sp xp ny. Byte TS0 ghp 8 bit ca khe thi

gian 0 trong khung tn hiu PCM-30. Byte TS16 c th l byte ng b a

khung hoc byte bo hiu knh kt hp (CAS) ca khung PCM-30.

Trong trng hp yu cu sp xp ng b theo byte ca 64 kbit x 31

knh th cc byte TS16 dng truyn d liu knh th 16. P0 P1 ch th pha

ca cc bit bo hiu v c cu trc tu chn.

2.2.3 - Sp xp lung 1,5 Mbit/s vo TU-12 thay th lung 2 Mbit/s

V5

R R R R R R R RTS0

TS1-TS15

TS16TS17-TS31

R R R R R R R R

J2

R R R R R R R RTS0

TS1-TS15TS16

R R R R R R R RTS17-TS31

R R R R R R R R

N2

R R R R R R R RTS0

TS1-TS15TS16

TS17-TS31R R R R R R R R

K4

R R R R R R R RTS0

TS1-TS15TS16

TS17-TS31R R R R R R R R

36

140Byte

R=Bit n cnh TS=Khe thi gian

500sHnh 2.5 Sp xp ng b theo byte lung 2 Mbit/s vo

a khung VC-12


37/118

Lung 1,5 Mbit/s ca Bc M cng c th thay th lung 2 Mbit/s

sp xp vo TU-12 v ghp vo AUG. Trc ht sp xp lung 1,5 Mbit/s

vo VC-11 nh hnh 2.2. Mi khung VC-11 c 26 byte trong khi mi

khung VC-12 li c 35 byte, v vy VC-11 phi n thm 9 byte khng mang

thng tin cho mi khung. Theo qui nh th cc byte n ny c ghp vo

ct th ba ca mi khung VC-11 mi nh hnh 2.6 v c gi l a khung

VC-11 tng ng vi a khung VC-12.

V5

J2

N2

K4

37


38/118

2.2.4 - Sp xp lung 6 Mbit/s vo VC-2

Hin nay ch s dng sp xp khng ng b (hnh 2.7a) v ng b

theo bit (hnh 2.7b), cn sp xp ng b theo byte ang nghin cu. Ngoi 4

byte VC-2 POH (V5, J2, N2, K4), trong a khung VC-2 cn c 3152 bitthng tin I, 24 bit iu khin C, 8 bit chn S, 32 bit thng tin nghip v O v

cc bit n c nh R. Trong mi khung u c 3 bit C1 iu khin bit S1

v 3 bit C2 iu khin bit S2.

V5 I I I I I I I R (24 x 8) I R R R R R R R R R R R R R R R R C1 C2 O O O O I R (24 x 8) I R R R R R R R R

I I I I I I I I C1 C2 O O O O I R (24 x 8) I R R R R R R R RR R R R R R R R C1 C2 I I I S1 S2 R (24 x 8) IJ2 I I I I I I I R (24 x 8) I R R R R R R R R

R R R R R R R R C1 C2 O O O O I R (24 x 8) I R R R R R R R RI I I I I I I I C1 C2 O O O O I R (24 x 8) I R R R R R R R R

R R R R R R R R C1 C2 I I I S1 S2 R (24 x 8) IN2 I I I I I I I R (24 x 8) I R R R R R R R R


R R R R R R R R C1 C2 I I I S1 S2 R (24 x 8) IK4 I I I I I I I R (24 x 8) I R R R R R R R R


38

: Byte

n

500

sHnh 2.6 - a khung VC-11 tng ng.


39/118

R R R R R R R R C1 C2 I I I S1 S2 R (24 x 8) I

39


40/118

a Sp xp khng ng b.

V5 I I I I I I I R (24 x 8) I R R R R R R R R

R R R R R R R R 1 0 O O O O I R (24 x 8) I R R R R R R R RI I I I I I I I 1 0 O O O O I R (24 x 8) I R R R R R R R RR R R R R R R R 1 0 I I I R I R (24 x 8) I

J2 I I I I I I I R (24 x 8) I R R R R R R R R R R R R R R R R 1 0 O O O O I R (24 x 8) I R R R R R R R R

I I I I I I I I 1 0 O O O O I R (24 x 8) I R R R R R R R RR R R R R R R R 1 0 I I I R I R (24 x 8) I

N2 I I I I I I I R (24 x 8) I R R R R R R R R R R R R R R R R 1 0 O O O O I R (24 x 8) I R R R R R R R R


K4 I I I I I I I R (24 x 8) I R R R R R R R R R R R R R R R R 1 0 O O O O I R (24 x 8) I R R R R R R R R


b Sp xp ng b.

Hnh 2.7 Sp xp lung 6 Mbit/s vo VC-2.


Khi sp xp lung s cn ng b 34 Mbit/s vo VC-3 phi s dngphng php sp xp khng ng b, ngha l s dng chn dng v chn

m nh khi sp xp lung 2 Mbit/s. Mi khung VC-3 c chia lm 3 phn

khung c cu to nh nhau, mi phn khung c 3 dng. Dng 1-3 l phn

khung T1, dng 4-6 l phn khung T2, dng 7-9 l phn khung T3 (hnh 2.8)

J1

T1B3

C2

G1

T2F2

H4

F3

T3K3

N1

40

125s

3dng

3

dng

3dng

84ct

VC-3 POH

Hnh 2.8 Sp xp lung 34 Mbit/svo VC-3.


41/118

Dng th nht v dng th hai trong mi phn khung cu to ging

nhau v trong mi dng ny c 22 byte + 12 bit n c nh R, 4 bit iu

khin chn C1 C2 v 60 byte thng tin I. Dng th ba c 23 byte + 13 bit n

c nh R, 2 bit iu khin chn C1 C2, 2 bit chn S1 S2 v 58 byte + 7 bit

thng tin I. Mi phn khung c 3 bit C1 dng iu khin bit S1 v 3 bit C2

iu khin bit S2.

C1C1C1 = 111 ch th S1 l bit chn (khng mang thng tin)

C1C1C1 = 000 ch th S1 l bit thng tin

C2C2C2 = 111 ch th S2 l bit chn (khng mang thng tin)

C2C2C2 = 000 ch th S2 l bit thng tin.

41


42/118


Hin nay ngi ta mi ch s dng kiu sp xp khng ng b nh

hnh 2.9.

Mi VC-3 chia lm 9 phn khung. Mi phn khung gm c mt byte

VC-POH, 621 bit thng tin I, 5 bit iu khin chn C, mt bit chn S, 2 bit Ov cc bit n c nh R.

CCCCC = 00000 th S l bit thng tin

CCCCC = 11111 th S l bit chn.

Gi tr bit S khi chn khng c qui nh v vy my thu khng m bit ny

khi kim tra chn.

VC-3 8R 8R RRCI

8R CCRR 8I 8R CCRR 8I

200I 200I 200I

42

85 byte

Hnh 2.9 Sp xp lung 45 Mbit/svo VC-3.


43/118

2.2.7 - Sp xp lung s 140 Mbit/s vo VC-4

J1B3C2G1F2H4F3K3N1

Sp xp lung PDH 140 Mbit/s vo VC-4 s dng phng php sp

xp khng ng b v ch c chn m. Khi mt VC-4 s c lp y

hon ton tn hiu 140 Mbit/s v byte qun l ca n (VC-4 POH).Cu trc

ca VC-4 nh trong hnh 2.10.

Mi dng c chia thnh 20 khi, mi khi c 13 byte. Cu to cc

dng u ging nhau v sp xp cc byte trong mi dng nh hnh 2.11.

43

VC-4 POH

VC-4

20 khi x 13

byte

13byte

Hnh 2.10 Cu trc ca VC-4 khi sp xp lung 140Mbit/s vo VC-4.


44/118

Mi dng c mt bit chn S, 5 bit iu khin chn C. Byte ng umt khi c th l 8 bit thng tin I (byte W), hoc 8 bit n c nh (byte Y),

hoc 1 bit iu khin chn C cng vi 5 bit n c nh v cng vi 2 bit mo

u O (byte X), hoc 6 bit thng tin I cng vi bit chn S v cng vi 1 bit

n c nh R (byte Z). 12 byte cui cng trong mi khi u l nhng byte

thng tin I. Cc bit mo u O d tr cho pht trin nghip v trong tng lai.

5 bit iu khin chn trong mi dng c chc nng iu khin bit chn Strong dng y. Khi CCCCC = 00000 th S l bit thng tin I, cn nu

CCCCC=11111 th S l bit chn (khng mang thng tin). Pha thu cn c vo

lut s ng ca cc bit C nhn bit chn hay khng chn v ra quyt nh

xo hay khng xo bit S. Tr s bit chn S khng c qui nh, v vy my

thu khng m bit ny khi kim tra chn byte B3.

POH W 96 I X 96 I Y 96 I Y 96 I Y 96 I

X 96 I Y 96 I Y 96 I Y 96 I X 96 I

Y 96 I Y 96 I Y 96 I X 96 I Y 96 I

Y 96 I Y 96 I X 96 I Y 96 I Z 96 I

44

W Y

X Z

12byte

Hnh 2.11 Cu to mi dngca VC-4.

R R R R R R R RI I I I I I I I

C R R R R R OO

I I I I I I S R


45/118

2.3 - QU TRNH GHP CC GI VO TRONG KHUNG STM-1

2.3.1 - Ghp VC-4 vo STM-1

Qu trnh ghp VC-4 vo khung tn hiu STM-1 c th hin trong

hnh 2.12 nh sau:

45

9byte

9byte

RSOHAU-4 PTR

VC-4

MSOH

VC-4AU-4 PTR

VC-4

POH

270 byte =261 + 9

125 s

9byte

9byte 261byte

261byte

125 s

125 s

STM-1

AU-4

VC-4

Hnh 2.12 - Trnh t ghp khung VC-4


46/118

Khung tn hiu ca C-4 c 260 ct x 9 dng. Nh vy khi C-4 tip nhn

t lung 140 Mbit/s trong 125 s l 2176 byte v chn thm 164 byte. VC-4

b sung thm 9 byte VC-4 POH vo ct u tin ca khung VC-4. AU-4 ghp

9 byte con tr AU-4 PTR vo v tr t ct 1 n ct 9 thuc dng 4 ca khung

STM-1. Pha ca VC-4 khng c nh trong AU-4. V tr byte u tin ca

VC-4 (J1) c ch th trong 10 bit gi tr con tr AU-4. Khi AU-4 c t

trc tip vo AUG, khi STM-1 ghp cc byte SOH vo v tr t ct 1 n ct

9 thuc cc dng 1,2,3,5,6,7,8,9 ca khung STM-1.

2.3.2 - Ghp 3 VC-3 vo STM-1 qua AU-4

Qu trnh ghp 3 VC-3 vo STM-1 qua TUG-3 nh hnh 2.13.

VC-3 gm 85 ct x 9 dng. Khi TU-3 ghp 3 byte con tr TU-3 l

H1, H2 v H3 vo u cc dng 1,2,3. Khi TUG-3 n 6 byte khng mangthng tin vo u cc dng 4,5,6,7,8,9 ca khung TU-3 c khung TUG-

3 c 86 ct x 9 dng. Tip theo ghp 3 TUG-3 thnh VC-4. V 3 TUG-3 ch

c 258 ct nn khi VC-4 ngoi vic ghp thm mt ct VC-4 POH cn phi

n thm 18 byte khng mang thng tin vo ct th 2 v ct th 3 ca khung

VC-4. Ba con tr TU-3 ghp c nh vo ct 4,5,6 thuc cc dng 1,2,3 ca

khung VC-4. Pha ca cc tn hiu VC-3 khng c nh trong VC-4. V tr cabyte J1 ca khung VC-3 trong VC-4 c ch th trong 10 bit gi tr con tr

TU-3. Cc con tr TU-3 hot ng c lp vi nhau.

3 TUG 3 c ghp vo VC-4 nh hnh 2.14. Ct u tin l 9 byte

VC-4 POH. Tip theo l 2 ct n c nh. T ct th 4 n ct 261 l ghp

xen byte 3 TUG-3. Trong cc ct mang s th t A l cc byte ti trng

46


47/118

ca TUG-3 th tht, cc ct mang s th t B l cc byte ti trng ca TUG-3

th 2 v cc ct mang s th t C l cc byte ti trng ca TUG-3 th 3.

47

Hnh 2.13 Ghp VC-3 vo

x 3

125 s

RSOHAU-4 PTR

VC-4MSOH

125 s

AU-4 PTR VC-4

125 s

H1 H1 H1H2 H2 H2

P H3 H3 H3O S S

H S S S

9dng

125 s

H1H2H3

S

9dng

125 s

H1

H2H3

TU-3 PTR

125 s

PO C-3H

9 dng

C-3125 s

STM-1

AU-4

VC-4

TUG-3

TU-3

VC-3

270 ct

9ct

261 ct

86 ct x 3 + 3 =261 ct

86 ct

86 ct

85 ct


48/118

2.3.3 - Ghp 3 VC-3 vo STM-1 qua AU-3

Qu trnh ghp 3 VC-3 vo STM-1 qua AU-3 nh hnh 2.15.

48

861861861

TUG-3(A)

TUG-3(B)

TUG-3(C)

S S A B C A B C A ....... .............

A B C A B C

VC-4POH

Hnh 2.14 - Ghp 3 TUG-3 voVC-4.

VC-3+ 2 ctn

PO S SH

PO S SH

PO S SH

A B CH1 H2H3

H1 H2H3

H1 H2H3

3 AU-3

A B C A B C A ....... ..............A B C

A B C A B C A BC

AUG

A B C

Hnh 2.15 - Gh 3 VC-3 v o STM-1


49/118

Trng hp ny dnh ghp 3 lung nhnh 45 Mbit/s thnh STM-1.

Sau khi sp xp khng ng b lung nhnh 45 Mbit/s vo VC-3 c 85 ct thmi khi VC-3 n thm 18 byte khng mang thng tin vo ct 30 v ct 59 to thnh VC-3 mi c 87 ct.

Tip khi AU-3 ghp 3 byte con tr TU-3 l H1 H2 H3 vo dng 4.Bc tip theo ghp 3 tn hiu AU-3 vo AUG, trong 9 byte AU-3 PTRc ghp vo dng 4 thuc ct 1 n ct 9 ca khung AUG, 261 ct cn li(t ct 1 n ct 270) ca khung AUG dnh ghp xen byte 3 VC-3. KhiSTM-1 ghp cc byte SOH hnh thnh khung STM-1 c 9 dng x 270 ct.

2.3.4 - Ghp 63 VC-12 vo STM-1Trnh t ghp 63 khung VC-12 vo khung STM-1 nh sau:

49

N 21 x VnPI

S S

a khung TU-12

125 s

Vn Vn Vn

9 dng

125 s

125 s

125 s

9 dng

125 s

RSOHAU-4 PTR VC-4

MSOH

AU-4 PTR VC-4

N N N 63 x Vn P P P P

O S S I I I S S SH

S S S

9dng

9dng

V1

VC-12

V2

VC-12

V3

VC-12V4

VC-12

125 s

36byte

36byte

36byte

36byte

9dng

STM-1

AU-4

VC-4

TUG-3

x 3

TUG-2

x 7

TU-12

x 3

270 ct

9ct

261 ct

261ct

12 ct x 7 + 2 ct =86 ct

4 ct x 3 = 12ct

4 ctVn

Hnh 2.16 - Gh 63 VC-12 v o


50/118

Nh ta bit, mi khung C-12 c 34 byte, khi VC-12 ghp thm mt

byte VC -12 POH to thnh khung VC-12 c 35 byte. C 4 khung VC-12

to thnh mt a khung VC-12. Khi TU-12 ghp vo u khung VC-12 th

nht, th hai, th ba mt byte con tr TU-12 v byte d tr vo u khung th

t to thnh a khung TU-12. Nh vy mi khung TU-12 c 4 ct x 9

dng (36 byte).

50

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

9

(1)

Vn

4

9

Vn

4

9

Vn

4

9

Vn Vn Vn

TUG-2

(1).........

9

12

(2) (3)

Vn Vn Vn

TUG-2

(2).........

12

Vn Vn Vn

TUG-2

(7)..........

12

(1) (2) (7)

NPIS S (1) (2) (3) (4) (5) (6) (7) TUG-3

(5) (6) (7)...........................................

86 ct

Hnh 2.17 - Trnh t h 21 khun TU-

TU-12


51/118

Khung TUG-2 c 12 ct x 9 dng, v vy ghp 3 TU-12 s c mt

khung TUG-2. Trong khung TUG-2 c 3 byte con tr TU-12 c k hiu l

Vn. Tip theo ghp 7 TUG-2 c mt TUG-3. V 7 TUG-2 ch c 84 ct nn

khi TUG-3 phi n thm 3 byte con tr khng c hiu lc NPI v 15 byte

khng mang thng tin vo ct th nht v ct th hai. T ct th ba n ct

th 86 dnh ghp 7 TUG-2. Khung TUG-3 cha 21 byte con tr TU-12 (khiu l Vn), cc ct c nh s th t 1-7 ch r cc byte trong cc ct ny

thuc TUG-2 tng ng 1-7. Bc tip theo ghp 3 TUG-3 vo khung VC-4.

Ba khung TUG-3 c 258 ct nn khi VC-4 ghp thm VC-4 POH vo ct

u tin, n 18 byte khng mang thng tin vo ct th hai v ct th ba, t

ct th t n ct th 261 l cc byte ca 3 TUG-3. Trong khung VC-4 c 9

byte NPI (Null Pointer Indication) v 63 byte con tr TU-12. Khi AU-4 ghp9 byte con tr AU-4 vo dng 4 thuc ct 1 n ct 9 ca khung STM-1.

Khung AUG hon ton ging khung AU-4. Cui cng, khi STM-1 ghp cc

byte SOH hnh thnh khung STM-1.

51


52/118

2.3.5 - Ghp 84 VC-11 vo STM-1

Trnh t ghp 84 VC-11 vo VC-3 nh hnh 2.18.

Mi VC-11 c 26 byte. Khi TU-11 ghp thm byte con tr Vn hnh

thnh khung TU-11 c 9 dng x 3 ct. 4 TU-11 ghp xen byte vo TUG-2 to

thnh khung TUG-2 c 12 ct. Khi VC-3 ghp VC-3 POH vo ct u tin

v ghp xen byte 7 TUG-2 to khung VC-3. V 7 TUG-2 ch c 84 ct nn

VC-3 phi n thm 18 byte khng mang thng tin vo ct 30 v ct 59. Sau

ta ghp tip 3 VC-3 vo STM-1 nh trnh by phn 2.3.3

52

(1)(2)(3) (4)(4)

TUG-2 #1............

(1)(2)(3) (4)(4)

TUG-2 #7..........

P #1 #2 ............ #7 #1 ...... #7 #1 ........ #7 #1........ #6 #7O S S VC- 3

TU-11

(1) (2) (3)

Hnh 2.18 - Gh 84 VC-11


53/118

2.3.6 - To khung truyn dn STM-N

Khung tn hiu STM-N c hnh thnh bng cch ghp xen byte cc

khung STM-1 hoc STM-4, STM-16...

V d nh khi ghp 4 STM-1 to thnh STM-4 nh sau

Nguyn l ghp xen byte ngha l ghp byte th nht ca STM-1 th

nht xong s ghp byte th nht ca STM-1 th hai, tip l byte th nht

ca STM-1 th ba v byte th nht ca STM-1 th t. Qu trnh nh vy cth tip din. Tng t nh vy i vi ghp 16 STM-1 thnh STM-16. Ngoi

ra ta cng c th ghp 4 khung STM-4 to thnh STM-16 nh sau:

53

b b b b . . .MUX1/4

a a a a . . .

c c c c . . .

d d d d . . .

abcdabcd ...

STM-4

STM-1 #1

STM-1 #2

STM-1 #3

STM-1 #4

Hnh 2.19- Ghp 4 STM-1 thnhSTM-4.

b b b b . . .MUX4/16

a a a a . . .

c c c c . . .d d d d . . .

aaaabbbbccccdd

dd ...STM-16

STM-4 #1

STM-4 #2

STM-4 #3

STM-4 #4

Hnh 2.20 - Ghp 4 STM-4 thnhSTM-16.


54/118

Trong trng hp ghp N khung STM-1 to ra khung STM-N th cu trc

khung STM-N Trong trng hp ghp N khung STM-1 to ra khung

STM-N th cu trc khung STM-N nh sau:

54

RSOH

N x AU-n PTRVng ti trng

MSOH125 s

9 ct x N 261 ct xN

270 ct xN

9dng

Hnh 2.21 - Cu trc khungSTM-N


55/118

CHng III

T chc v hot ng ca cc loi con tr trong khung tn hiu

SDH

3.1 - V TR V CHC NNG CA CC LOI CON TR

3.1.1 - V tr v chc nng ca con tr AU-4

Con tr AU-4 c k hiu l AU-4 PTR gm 9 byte v c ghp c

nh vo dng th 4 thuc ct 1 n ct 9 ca khung AUG.

Chc nng ca con tr AU-4 l ng chnh VC-4 trong khung AUG mt

cch linh hot v nng ng tc l cho php VC-4 x dch trong khung AUG.

V vy con tr AU-4 c kh nng thch ng s khc nhau khng nhng v pha

m c v tc khung ca VC-4 so vi khung AUG. Sau khi ng chnh, v

55

261 ct

1*= 11111111Y=1001SS11

125s

H1Y Y H2 1* 1* H3 H3 H3 VC-4

AUG

Hnh 3.1 V tr con tr AU-4 trong

khung AUG.


56/118

tr byte u tin ca VC-4 trong khung AUG c ch th bi gi tr ca con

tr AU-4.

3.1.2 - V tr v chc nng ca con tr AU-3

Khi ghp cc lung nhnh 45 Mbit/s vo AUG qua AU-3 th 3 con tr

AU-3 hot ng. Ba con tr AU-3 c k hiu l AU-3 PTR gm 9 byte l

H1H1H1H2H2H2H3H3H3 (mi AU-3 PTR c 3 byte l H1H2H3) v c

ghp c nh vo dng 4 thuc ct 1 n ct 9 ca khung AUG (hnh 3.2).

Chc nng ca AU-3 PTR l ng chnh VC-3 trong khung AUG mt cch

linh hot v nng ng, ngha l cho php VC-3 c x dch trong khung

AUG. V vy AU-3 c kh nng thch ng s khc nhau khng nhng v pha

m cn c v tc khung ca VC-3 so vi khung AUG. Sau khi ng chnh,

v tr byte u tin ca VC-3 trong khung AUG c ch th bi gi tr ca

AU-3 PTR. Cc con tr AU-3 hot ng c lp vi nhau.

3.1.3 - V tr v chc nng ca con tr TU-3

Cc con tr TU-3 c k hiu l TU-3 PTR. Mi TU-3 PTR c 3 byte

H1H2H3. TU-3 PTR th nht c ghp vo ct 4 thuc dng 1 n dng 3

ca khung VC-4. TU-3 PTR th hai c ghp vo ct 5 thuc dng 1 n

56

125s

H1H1H1H2H2H2H3 H3 H3 3 x VC-3

AUG

261 ct

Hnh 3.2 - V tr ca con tr AU-3 trong

khung AUG.


57/118

dng 3 ca khung VC-4. TU-3 PTR th ba c ghp vo ct 6 thuc dng 1

n dng 3 ca khung VC-4 (hnh 3.3).

57


58/118

Con tr TU-3 cung cp 1 phng php ng chnh VC-3 trong khung

TU-3 mt cch linh hot v nng ng. S ng chnh nng ng th hin

ch VC-3 c th x dch trong khung TU-3. Nh vy TU-3 PTR c kh nng

thch ng pha v tc khung VC-3 so vi khung TU-3. Sau khi ng chnh,

v tr byte u tin ca VC-3 trong khung TU-3 c ch th bi gi tr ca

con tr TU-3. Cc con tr TU-3 hot ng c lp vi nhau.

3.1.4 - V tr v chc nng ca con tr TU-2

Con tr TU-2 c k hiu l TU-2 PTR gm 3 byte (V1, V2, V3)

c ghp vo u cc khung th nht, th hai v th ba ca a khung TU-2

(hnh 3.4). TU-2 PTR cung cp s ng chnh linh hot v nng ng VC-2

trong a khung TU-2. Ngha l VC-2 c th x dch trong a khung TU-2.

P

O

H

S S

H1 H1 H1

H2 H2 H2H3 H3 H3

S S S

58

125s1 2 3 4 5 6

261

Hnh 3.3 - V tr con tr TU-3 trong

khung VC-4.

9dng

261ct


59/118

TU-2 PTR c kh nng thch ng pha v tc a khung VC-2 so vi a

khung TU-2. Sau khi ng chnh, v tr byte u tin ca a khung VC-2 (k

hiu V5) trong a khung TU-2 c ch th bi gi tr ca con tr TU-2 PTR.

TU-11 TU-12 TU-2V1 V1 V178 105 321

......

......

......

103 139 427V2 V2 V20 0 0

......

......

......

25 34 106V3 Chn m V3 Chn m V326 Chn dng 35 Chn

dng

107

......

......

......

51 69 213V4 V4 V452 70 214

......

......

......

77 104 320

59

Byte chn dng

Byte chnm

Byte dtr

Hnh 3.4 V tr ca con tr TU-2, TU-12 v TU-11trong a khung TU-2, TU-12 v TU-11.


60/118

3.1.5 - V tr v chc nng ca con tr TU-12 v TU-11

Con tr TU-12 c k hiu l TU-12 PTR gm 3 byte (V1, V2, V3)

c ghp vo u cc khung th nht, th hai v th ba ca a khung TU-12

(hnh 3.4). TU-12 PTR ng chnh linh hot v nng ng VC-12 trong a

khung TU-12. Ngha l VC-12 c th x dch trong a khung TU-12. TU-12

PTR c kh nng thch ng pha v tc a khung VC-12 so vi a khung

TU-12. Sau khi ng chnh, v tr byte u tin ca a khung VC-12 (k hiu

V5) trong a khung TU-12 c ch th bi gi tr ca con tr TU-12 PTR.

Con tr TU-11 c k hiu l TU-11 PTR gm 3 byte (V1, V2, V3) c

ghp vo u cc khung th nht, th hai v th ba ca a khung TU-11 (hnh

3.4). TU-11 PTR ng chnh linh hot v nng ng VC-11 trong a khung

TU-11 tc l VC-11 c th x dch trong a khung TU-11. TU-11 PTR c khnng thch ng pha v tc a khung VC-11 so vi a khung TU-11. Sau

khi ng chnh, v tr ca byte V5 trong a khung TU-11 c ch th bi gi

tr ca con tr TU-11 PTR.

3.2 -NH S A CH CC NHM BYTE V CC BYTE

Nh trnh by trong phn 3.1, gi tr cc con tr TU-11, TU-12, TU-

2, TU-3, AU-3 v AU-4 ch th v tr byte u tin ca cc tn hiu VC-11,VC-12, VC-2, VC-3 v VC-4 trong a khung TU-11, a khung TU-12, a

khung TU-2, khung TU-3 v khung AUG. Nhng mun bit v tr byte u

tin ca cc VC-n (n=12, 2, 3, 4) trong khung lin quan th phi nh s a

ch cc byte ca cc khung y.

3.2.1 - nh s a ch cc nhm byte ca khung AUG

60


61/118

Vic nh s a ch khung AUG c lin quan n hot ng ca con

tr AU-3 v AU-4 (hnh 3.5 v 3.6). Khung AUG c 9 byte con tr AU-3

hoc con tr AU-4 v vng ti trng 261 ct x 9 dng. Vng ti trng ny c

2349 byte. Nu mi byte mang mt a ch th s gi tr ca AU-3 PTR hoc

AU-4 PTR khng ch th (s gi tr ca AU-n PTR bng 210 = 1024).

Theo cch lp lun ny th hai byte mang cng a ch cng khng tho

mn, bt buc phi chia mi nhm c 3 byte. S nhm 3 byte s l 2349 : 3 =

783, c nh s th t t 000 n 782 782 782. Nhm cc byte mang a

ch 0 t lin sau byte H3 cui cng ca AU-n PTR v cc byte mang a ch

782 t cui dng th 3 ca khung AUG tip theo.

61


62/118

62

1

4

91

4

9

1 9 10 AUG 270 3 byte chn m

3 byte chn dng

H1 Y Y H2 1* 1* H3 H3 H3 0 # # 1 # #86 # #

87 # #

521# #

782# #H1 Y Y H2 1* 1* H3 H3 H3 0 # # 1 # #

86 # #

125s

250s

Hnh 3.5 - nh s a ch cc nhm byte trongkhung AUG lin quan n con tr AU-4.

1

4

91

4

9

9 10 AUG 270 3 byte chn m3 byte chn dng

H1H1H1H2H2H2H3H3H3 0 # # 1 # #86 # #

87 # #

521# #

782# #H1H1H1H2H2H2H3H3H3 0 # # 1 # #

86 # #

125s

250

sHnh 3.6 - nh s a ch cc nhm byte trong

khung AUG lin quan n cc con tr AU-3


63/118

3.2.2 - nh s a ch cc nhm byte ca khung VC-4

Vic nh s a ch cc nhm byte trong khung VC-4 c lin quann hot ng ca cc con tr TU-3 (hnh 3.7).

Vng ti trng ca khung TU-3 dng ghp 3 VC-3 gm c 2295

byte. V 3 VC-3 ghp chung vo khung VC-4 nn mi nhm mang cng mt

a ch s c 3 byte. S nhm byte bng 2295 : 3 =765 v nh s th t t

000 n 764 764 764. Nhm byte 0 t lin sau byte H3 ca TU-3 PTR v

nhm byte 764 t cui dng th hai ca khung VC-3 tip theo.

3.2.3 - nh s a ch cc byte ca a khung TU-2, TU-12 v TU-11

Khng k cc byte con tr V1, V2, V3 v byte d tr V4, a khung

TU-2 c 428 byte dnh ghp tn hiu trong a khung VC-2. Tng s byte

trong a khung t hn s gi tr ca con tr nn mi byte mang mt a ch 0

63

1 2 3 4 5 6 VC-4 261 H1 H1 H1

P H2 H2 H2 764# #O H3 H3 H3 0 # # 1 # #

84 # #H 85 # #

S S S S S

H1 H1 H1H2 H2 H2 764

# #P H3 H3 H3 0 # # 1 # #

84 # #

O 85 # #H S S S S S

125s

250s

Hnh 3.7 - nh s a ch cc nhm byte trongkhung VC-4.


64/118

n 427. Theo qui nh byte 0 t lin sau byte V2 v byte 427 t lin trc

byte V2 (hnh 3.4).

Khng k cc byte V1, V2, V3 v V4 th a khung TU-12 c 140 byte

dnh ghp tn hiu trong a khung VC-12. Cc byte trong a khung TU-12

c a ch t 0 n 139. a ch 0 t lin sau byte V2 v a ch 139 t lin

pha trc byte V2 (hnh 3.4).

S byte cn nh a ch trong a khung TU-11 l 104. a ch 0 t

lin sau byte V2 v a ch 103 t lin pha trc byte V2 (hnh 3.4).

3.3 - CU TO V HOT NG CA CC CON TR

3.3.1- Cu to ca con tr

a. Cu to ca AU-4 PTR, AU-3 PTR v TU-3 PTR

Cu to ca con tr AU-4:

Con tr AU-4 c 9 byte nh sau :H1 Y Y H2 1 H1 Y Y H2 1* 1* H3 H3 H3

Trong Y = 1001SS11, 1* = 11111111 v SS =00 l hai bit ch

th con tr AU4.

Cu to ca con tr AU-3:

Mi con tr AU-3 c 3 byte l H1 H2 H3.

Cu to ca con tr TU-3:Mi con tr TU-3 c 3 byte l H1H2H3. Cc byte H1H2H3 tham

gia vo hot ng ca cc con tr v c cu to nh hnh 3.8.

64

N N N N S S I D I D I D I D I D

H1 H2 H3

10 bit gi trcon tr Byte chnm Byte chn dng

Hnh 3.8 - Cu to cc byte H1 H2 H3 cacon tr.


65/118

- NNNN : C s liu mi (New data flag), cho php thay i gi tr con

tr khi c s thay i ca ti trng. Lc bnh thng th 4 bit N c gi

tr 0110. Nu gi tr con tr thay i do thay i ti trng th NNNN =

1001. Ni cch khc, khi NNNN = 0110 s c din gii l "khng

cho php" tc l khng cho php con tr thay i gi tr. Ngc li,

khi NNNN = 1001 th din gii l "cho php" ngha l trong trng

hp ny con tr c thay i gi tr. Cc cu trc khc ca NNNNnh 0000, 0011...u khng c hiu lc.

- SS : ch th loi con tr. i vi AU-4 PTR, AU-3 PTR v TU-3 PTR

th SS = 10.

- 5 bit I (Increment) s o gi tr khi chn dng, 5 bit D (Decrement)

s o gi tr khi chn m.

b. Cu to ca cc con tr TU-2, TU-12 v TU-11

Cc con tr ny c cu to ging nhau v u c cc byte V1, V2 v V3

nh hnh 3.9

Hai bit ch th loi con tr c qui nh nh sau:

i vi TU-2 PTR th SS = 00

65

N N N N S S I D I D I D I D I D

V1 V2 V3

10 bit gi trcon tr

Byte chnm

Byte chn dng

Hnh 3.9 - Cu to ca con tr TU-2, TU-12v TU-11.


66/118



Cc bit c s liu mi NNNN v cc bit ID thay i theo cc qui nh

nh trnh by trong phn cu to cc con tr AU-4, AU-3 v TU-3.

Gi tr ca con tr:

2 bit cui ca byte H1 (Hoc byte V1) v 8 bit ca byte H2 (hoc V2) to

thnh mt t m 10 bit ch th gi tr con tr. S gi tr c kh nng ca con

tr l 1024. Tuy nhin s gi tr thc t ca cc con tr thng thp hn 1024.Phm vi ch th gi tr cc loi con tr nh sau:

AU-4 PTR :t 0 n 782

AU-3 PTR :t 0 n 782

TU-3 PTR :t 0 n 764

TU-2 PTR :t 0 n 427

TU-12 PTR :t 0 n 139

TU-11 PTR :t 0 n 103

Gi tr con tr AU-4 ch th khong cch tnh theo nhm byte t byte

H3 ca con tr ny n byte J1 ca VC-4 trong khung AUG. Gi tr con tr

AU-3 ch th khong cch tnh theo nhm byte t byte H3 ca con tr ny n

J1 ca VC-3 trong khung AUG. Gi tr con tr TU-3 ch th khong cch tnh

theo nhm byte t byte H3 ca con tr TU-3 n J1 ca VC-3 trong khung

AUG.

Gi tr cc con tr TU-2, TU-12 v TU-11 ch th khong cch tnh theo

byte t byte V2 n byte V5 ca a khung VC-n (n=11, 12, 2) trong a khung

TU-n (n= 11, 12, 2). Khi tnh khong cch ny khng m cc byte con tr

V1, V2, V3 v byte d tr V4.

66


67/118

Sau khi chn dng gi tr con tr tng mt n v so vi lc trc khi

chn. Sau khi chn m gi tr con tr gim i mt n v so vi trc lc

chn.

3.3.2 - Hot ng ca cc loi con tr

Trong chng II trnh by qu trnh sp xp cc lung s PDH v

cc VC-n tng ng. Do s chnh lch v tc bit gia ng h trong cc

h thng PDH v ng h ca thit b SDH nn khi sp xp phi tin hnh

chn bit hiu chnh tc bit cc lung nhnh PDH. Qu trnh chn nykhng lin quan n hot ng ca cc con tr.

Hot ng chn bit trn y ch mi hiu chnh c s sai khc gia

ng h PDH v ng h SDH. Tuy nhin ng h gia cc h thng SDH

vn cha hon ton khp nhau gy ra lch tc khung gia VC-4 v AUG

hoc gia VC-3 v AUG, hoc gia VC-3 v TU-3 .v.v. ng chnh

lch pha gia tn hiu ghp v khung ghp phi s dng chn byte. Hotng chn byte din ra di s gim st ca con tr. Pha ca khung tn hiu

VC-n trong khung ghp (khung AUG hoc khung TU-n) c ch th trong 10

bit gi tr con tr. Theo qui nh th ti thiu trong 3 khung ghp lin tip gi

tr con tr khng c thay i. Nu tc khung tn hiu VC-n chm hn

tc khung ghp AUG hoc TU-n th s ng chnh c tin hnh bng

cch chn thm cc byte khng mang thng tin vo v tr byte mang a ch 0trong khung ghp AUG v TU-n (hnh 3.5, 3.6, 3.7); hoc chn thm cc byte

khng mang thng tin vo a ch 26 trong a khung ghp TU-11, a ch 35

trong a khung ghp TU-12, a ch 107 trong a khung ghp TU-2 (hnh

3.4). Trng hp ny gi l chn dng. Thng tin v chn dng c th

hin o 5 bit I ca con tr. My thu nhn c thng tin v chn dng ny

s tin hnh xo cc byte chn pha pht. Gi tr ca con tr trong

67


68/118

khung lin sau khung chn dng bng gi tr con tr trc khi chn dng

cng thm 1.

Nu tc khung tn hiu VC-n nhanh hn tc khung ghp AUG

hoc TU-n th s ng chnh c tin hnh bng cch xo cc byte H3 hoc

V3 ca con tr v ghp vo cc byte mang thng tin ca tn hiu ghp.

Trng hp ny gi l chn m. Thng tin v chn m c th hin khi o

5 bit D ca con tr. Pha thu nhn c thng tin chn m s tch cc byte

ghp vo v tr H3 hoc V3 ca con tr x l nh nhng byte thng tin

khc. Gi tr ca con tr trong khung lin sau khung chn m bng gi tr con

tr trc khi chn m tr i 1.

a. Hot ng ca AU-4 khi chn dng

Hot ng ca AU-4 PTR khi chn dng c th hin trong hnh 3.10.

Trong hnh ny l mt a khung AUG. By gi ta xt tng khung ca a

khung.

- Xt khung th nht: Gi thit trong khung ny cha c yu cu chn

dng v byte u tin ca VC-4 (byte J1) ghp vo nhm byte mang a ch

n ca khung AUG. Gi tr con tr trong khung ny bng n (n = 0..782).

- Xt khung th hai: Gi thit trong khung ny cng cha c yu cu

chn dng. Byte J1 ca VC-4 c ghp vo a ch n trong khung AUG.

Gi tr con tr trong khung ny bng n.- Xt khung th ba: Gi thit tc khung tn hiu VC-4 chm hn tc

khung ghp AUG. Trong trng hp ny khung VC-4 phi trt theo chu

k ngc tr li so vi khung ghp AUG. V vy phi tin hnh chn dng

bng cch o 5 bit I v chn 3 byte khng mang thng tin vo a ch 000.

Nh vy cc byte thng tin do VC-4 cung cp c ghp vo v tr dch sang

bn phi mt nhm byte so vi khi cha chn. Ni cch khc byte J1 ca VC-

68


69/118

4 by gi c ghp vo a ch n+1 ca khung ghp AUG. Gi tr ca AU-4

PTR vn cha thay i v bng n.

- Xt khung th t: Trong khung ny khng c yu cu chn dng.

Byte J1 ca VC-4 c ghp vo a ch n+1 ca khung ghp AUG. Gi tr

ca AU-4 PTR trong khung ny bng n+1 s c gi i.

69


70/118

b. Hot ng ca AU-4 PTR khi chn m

Hot ng ca con tr AU-4 khi chn m c minh ho trong hnh 3.11.

Xt a khung gm 4 khung AUG:

- Xt khung th nht: Trong khung ny cha c yu cu chn m. Gi

thit byte u tin ca VC-4 (byte J1) c ghp vo a ch n ca khung

ghp AUG nn gi tr ca AU-4 PTR bng n

70

125s

1

4

91

4

91

4

91

4

9

1 9 10 AUG 270 Bt u VC-4

H1 Y Y H2 1* 1* H3 H3 H3n-1 n n n n+1 n+1

Khung1

Gi tr con tr (n)

H1 Y Y H2 1* 1* H3 H3 H3n-1 n n n n+1 n+1

Khung2

Gi tr con tr (o cc bit I)

H1 Y Y H2 1* 1* H3 H3 H3 3 byte chn dng

n-1 n n n n+1 n+1

Khung3

Gi tr con tr (n+1)

H1 Y Y H2 1* 1* H3 H3 H3n-1 n n n n+1 n+1

Khung4

250

s

375s

500s

Hnh 3.10 - Hot ng ca AU-4 PTR khichn dng.


71/118

- Xt khung th hai: Trong khung ny cng cha c yu cu chn m.

Byte J1 ghp vo a ch n ca khung ghp AUG, gi tr ca AU-4 PTR bng

n.

- Xt khung th ba: Trong khung ny do tc khung tn hiu VC-4

nhanh hn tc khung ghp AUG, khung VC-4 tin theo chu k v pha

trc so vi khung ghp AUG. V vy phi tin hnh ng chnh bng cch

chn m.Trc ht con tr o 5 bit D v sau xo 3 byte H3 v ghp vo

3 byte mang thng tin ca VC-4. Nh vy cc byte thng tin ca VC-4

dch sang bn tri mt nhm byte. Byte J1 ca VC-4 ghp vo a ch n-1 ca

khung ghp AUG. Gi tr ca AU-4 PTR vn cha thay i v bng n.- Xt khung th t: Trong khung ny khng c yu cu chn m. Byte

J1 ca VC-4 c ghp vo a ch n-1 ca khung ghp AUG nn gi tr mi

ca AU-4 PTR bng n-1 v c gi i.

71

125s

1

4

91

4

91

4

91

4

9

1 9 10 AUG

270 Bt u VC-4

H1 Y Y H2 1* 1* H3 H3 H3n-1 n n n n+1 n+1

Khung1

Gi tr con tr (n)

H1 Y Y H2 1* 1* H3 H3 H3n-1 n n n n+1 n+1

Khung2

Gi tr con tr (o cc bit D)

H1 Y Y H2 1* 1* 3 byte chn mn-2 n-1 n-1 n-1 n n n n+1 n+1

Khung3

Gi tr con tr (n-1)H1 Y Y H2 1* 1* H3 H3 H3

n-2 n-1 n-1 n-1 n n n n+1 n+1

Khung4

250s

375s

500s

Hnh 3.11 - Hot ng ca AU- PTR khichn m.


72/118

Tm tt cc qui tc hot ng ca AU-4 PTR

- Khi hot ng bnh thng th gi tr ca AU-4 PTR ch r v tr bt

u ca khung VC-4 trong khung ghp AUG. Bn bit NNNN t bng 0110.

- Gi tr con tr ch c thay i trong trng hp 3, 4 v 5 sau y:

- Nu c yu cu chn dng th o cc bit I, tip chn 3 byte

khng mang thng tin vo cc byte mang a ch 0. Trong khung tip sau

khung chn dng gi tr ca AU-4 PTR tng thm 1. Nu gi tr ca AU-4

PTR trc khi chn dng bng 782 th sau khi chn dng s bng 0. Ti

thiu trong 3 khung k tip nhau gi tr ca AU-4 PTR khng c thay i.

- Nu c yu cu chn m th o 5 bit D, tip xo 3 byte H3 v

ghp vo 3 byte mang thng tin. Trong khung tip sau khung chn m gi

tr ca AU-4 PTR bng n-1. Trc khi chn m gi tr con tr bng 0 th saukhi chn m gi tr con tr bng 782. Ti thiu trong 3 khung k tip nhau gi

tr ca AU-4 PTR khng c thay i.

- Nu s ng chnh pha ca VC-4 trong AUG xy ra do cc tc ng

khc vi qui tc 3 v 4 th gi tr mi ca AU-4 PTR c to lp v phi gi

km theo c s liu mi c cu trc 1001. NDF ch xut hin trong khung u

tin m con tr to lp gi tr mi. Gi tr mi ca AU-4 PTR ch th v tr btu ca VC-4 trong khung AUG.

V d:

Gi tr ca AU-4 PTR lc khng chn n=7, lc 10 bit gi tr con tr

s l 00 0000 0111. Ti thi im c yu cu chn dng o 5 bit I: 10 1010

1101 v chn 3 byte khng mang thng tin vo sau byte H3 ca con tr. Gi

72


73/118

tr ca con tr sau khi chn dng l n+1 =8, 10 bit gi tr con tr bng 00

0000 1000.

Gi tr ca AU-4 PTR lc khng chn n=29, v c ch th trong 10

bit gi tr con tr l 00 0001 1101. Trong khung c yu cu chn m con tr

o 5 bit D: 01 0100 1000 ngay sau xo 3 byte H3 ghp vo 3 byte

d liu. Gi tr ca con tr trong khung tip sau khung chn m gim i mt

n v, ngha l bng n-1 = 28 v c ch th bi cu trc 00 0001 1100.

c. Hot ng ca TU-3 PTR khi chn dng

Hot ng ca TU-3 PTR khi chn dng c th hin trong hnh

3.12. Xt mt a khung VC-4. Trong khung VC-4 c 3 con tr TU-3 hot

ng c lp vi nhau. Gi thit ch c con tr TU-3 th hai hot ng.

- Xt khung th nht: Gi thit trong khung ny khng c yu cu chn

dng, byte J1 ca VC-3 #2 ghp vo byte gia ca nhm byte mang a ch

n. Gi tr con tr TU-3 #2 bng n.

- Xt khung th hai: Trong khung ny cng cha c yu cu chn

dng nn J1 ca VC-3 #2 vn ghp vo byte gia ca nhm byte n. Gi tr

ca con tr TU-3 #2 bng n.

73

n n n n+1 n+1n+1 H1 H1 H1 Bt u VC-3 #2

H2 H2 H2P H3 H3 H3OH S S S S S

Khung 1H1 H1 H1H2 H2 H2 Gi tr con tr = n

P H3 H3 H3OH S S S S S

Khung 2H1 H1 H1 o 5 bit I

H2 H2 H2 Byte chn dng ca VC-3#2P H3 H3 H3O

H S S S S S

Khung 3H1 H1 H1

H2 H2 H2 Gi tr con tr = n+1P H3 H3 H3OH S S S S S

125

s

250s

375s

500s

Hnh 3.12 - Hot ng ca TU-3 PTR khi


74/118

- Xt khung th ba: Do tc khung tn hiu VC-3 # 2 chm hn tc

khung ghp TU-3 nn VC-3 #2 trt li li theo chu k so vi khung ghp

TU-3. Xy ra chn dng trong khung ny. Trc htTU-3 #2 o cc bit I,

lin sau chn mt byte khng mang thng tin vo v tr byte gia ca nhmbyte mang a ch 0. Byte J1 ca VC-3 #2 by gi c ghp vo byte gia

ca nhm byte mang a ch n+1.

- Xt khung th t: Trong khung ny khng c yu cu chn dng.

Byte J1 ca VC-3 #2 c ghp vo byte gia ca nhm byte mang a ch

n+1. Gi tr ca TU-3 PTR #2 bng n+1 v c gi di.

Hot ng ca TU-3 PTR khi chn m

Hnh 3.13 l a khung VC-4 minh ha hot ng ca TU-3 PTR khi

chn m. Nh trnh by trn, 3 con tr TU-3 trong khung VC-4 hot

ng c lp vi nhau. V vy trong hnh 3.13 gi thit ch c con tr TU-3 #2

hot ng.

74

n n n n+1 n+1n+1 H1 H1 H1 Bt u VC-3 #2

H2 H2 H2P H3 H3 H3OH S S S S S

Khung 1H1 H1 H1H2 H2 H2 Gi tr con tr = n

P H3 H3 H3OH S S S S S

Khung 2H1 H1 H1 o 5 bit D

H2 H2 Byte chn mca VC-3 #2P H3 H3 H3OH S S S S S

Khung 3H1 H1 H1

H2 H2 H2 Gi tr con tr = n+1P H3 H3 H3OH S S S S S

Khun 4

125

s

250s

375s

500s

Hnh 3.13 - Hot ng ca TU-3 PTR khi


75/118

Xt ln lt tng khung ca VC-4.

- Xt khung th nht : Trong khung ny cha c yu cu chn m. Gi

thit byte J1 ca VC-3 #2 c ghp vo byte gia nhm byte mang a ch n.Gi tr ca TU-3 PTR #2 bng n.

- Xt khung th hai: Trong khung ny cha c yu cu chn m. Byte

J1 ca VC-3 #2 ghp vo a ch n. Gi tr ca TU-3 PTR #2 bng n.

- Xt khung th ba: Do tc khung tn hiu VC-3 #2 nhanh hn tc

khung ghp TU-3 nn VC-3 #2 tin theo chu k v pha trc so vi

khung ghp TU-3, v vy phi chn m. Trc tin o 5 bit D ca TU-3 PTR#2, lin sau ghp mt byte mang thng tin ca tn hiu VC-3 #2 vo v tr

byte H3 gia b xo. Gi tr ca TU-3 PTR #2 bng gi tr con tr khi

cha chn tr i 1 v bng n-1 c gi i.

- Xt khung th t: Khung ny khng c yu cu chn m. Byte J1 ca

VC-3 #2 c ghp vo byte gia ca nhm byte mang a ch n-1, v vy gi

tr ca TU-3 PTR #2 bng n-1.

Tm tt qui tc hot ng ca TU-3 PTR

- Gi tr ca TU-3 PTR lc bnh thng ch r v tr bt u ca VC-3

trong khung ghp TU-3. C s liu mi t bng 1.

- Gi tr ca TU-3 PTR ch thay i trong cc trng hp 3,4 v 5 sau

- Nu c yu cu chn dng th o cc bit I, tip chn cc bytekhng mang thng tin vo nhm byte mang a ch 0. Pha thu nhn c

75


76/118

thng tin chn dng s xo cc byte chn dng. Gi tr con tr TU-3 trong

khung lin sau khung chn dng bng gi tr ca TU-3 PTR trc khi chn

cng thm 1. Nu trc khi chn dng gi tr ca TU-3 PTR bng 764 th

sau khi chn dng s bng 0. Ti thiu trong 3 khung k tip nhau gi tr ca

TU-3 PTR khng c thay i.

- Nu c yu cu chn m th o 5 bit D, tip ghp cc byte thng

tin vo v tr H3 b xo. Pha thu nhn c thng tin chn m s tch cc

byte chn m x l nh nhng byte thng tin khc. Gi tr ca con tr TU-

3 trong khung lin sau khung chn m bng gi tr ca con tr TU-3 trc khi

chn tr i 1. Nu trc khi chn m gi tr ca TU-3 PTR bng 0 th sau khichn s bng 764. Ti thiu trong 3 khung k tip nhau gi tr con tr TU-3

khng c thay i.

- Nu s ng chnh pha ca VC-3 trong khung TU-3 xy ra do cc

nguyn nhn khc vi qui tc 3, 4 th gi tr mi ca TU-3 PTR c to lp

v gi km theo c s liu mi l 1001. C s liu mi ch xut hin trong

khung TU-3 u tin c gi tr mi ca con tr. Gi tr mi ca TU-3 PTR chth v tr bt u ca VC-3 trong khung TU-3.

Hot ng ca con tr TU-12

Hot ng ca cc con tr TU-2, TU-12 v TU-11 u ging nhau, v

vy y ch trnh by hot ng ca con tr TU-2. Hnh 3.4 v 3.9 minh ha

hot ng ca TU-12 PTR khi chn.- Hot ng bnh thng: Khi hot ng bnh thng th byte V5 ca

a khung VC-2 c ghp vo byte mang a ch n ca a khung TU-2. Gi

tr ca TU-2 PTR ch th khong cch tnh theo byte t byte V2 n byte V5

ca a khung VC-2 v bng n.

- Hot ng khi chn dng: Nu tc ca a khung VC-2 chm hn

tc a khung TU-2 th a khung VC-2 trt li theo chu k so vi akhung ghp TU-2 nn xy ra chn dng. Trc tin o cc bit I, sau

76


77/118

chn 1 byte khng mang thng tin vo v tr byte lin sau byte V3 (byte 107).

Trong a khung c chn dng th byte V5 ca a khung VC-2 c ghp

vo v tr byte mang a ch n+1 nn gi tr ca TU-2 PTR bng n+1.

- Hot ng khi chn m: Nu tc a khung VC-2 nhanh hn tc

a khung TU-2 th a khung VC-2 tin theo chu k v pha trc so vi a

khung ghp TU-2 nn xy ra chn m. Trc tin o cc bit D v sau

ghp mt byte thng tin vo v tr byte V3 va b xo. Trong a khung c

chn m th byte V5 ca a khung VC-2 c ghp vo byte mang a ch n-

1 nn gi tr ca TU-2 PTR bng n-1.

3.3.3 - Cc con tr trong cc khung tn hiu ni mc xch

Khi cn chuyn ti mt tn hiu c kch c ln hn mt C-n th phi ni

mc xch nhiu C-n. Phn ny gii thch hot ng ca cc con tr khi ni

mc xch cc C-n. Hot ng ca cc con tr khi ni mc xch cc C-n u

ging nh nhau, v vy ch cp n con tr AU-4 y (hnh 3.14).

X khung ghp AU-4 c th ni mc xch vi nhau hnh thnh mt

AU-4-XC dng chuyn ti tn hiu a dch v c dung lng ln hn mt

C-4. Con tr trong khung AU-4-XC ch th khung ny cha X khung tn hiu

VC-4. Nu dung lng mi VC-4 bng 149,760 Mbit/s th dung lng ca C-

4-4C l 599,040 Mbit/s v dung lng ca C-4-16C l 2396,160 Mbit/s. Cu

to ca VC-4-XC nh hnh 3.14

77

RSOH

AU-4 PTR

MSOH

J1B3C2G1 nF2 c C - 4 -X

C

H4 nhF3K3N1

N x 270byte N x 261

byteN x 9byte

STM-N

VC - 4 -X

C

VC - 4 - XC

POHX x 260byte

X-1

9dng

Hnh 3.14 - Cu to ca


78/118

Khung VC-4-XC gm 9 dng x X x 261 ct, trong ct u tin l

VC-4-XC POH, ct 2 n ct X+1 l cc ct n c nh (cc byte khng

mang thng tin) k hiu l S. Dng th 4 thuc ct 1 n ct 9 X ca khung

AU-4-XC dnh ghp X con tr AU-4, phn cn li ca khung AU-4-XC

c s dng ghp VC-4-XC. Trong con tr AU-4 th nht cc bit

NNNNSS vn hot ng theo cc qui tc trong mc hot ng ca con tr

AU-4 trn. 10 bit gi tr con tr ny ch th khong cch tnh theo nhm byte

t byte H3 cui cng n byte J1 ca VC-4-XC trong khung AU-4-XC. Cc

byte H1 v H2 ca X-1 con tr AU-4 cn li ch th ni mc xch v c cu

to c nh l 1001SS111111, trong SS=10.

3.4 -X L CON TR TI PHA THU

3.4.1 - ngha ca vic x l con tr

Khi my thu nhn c t nht 3 trong s 5 bit I o s xo cc byte

chn dng, cn nu nhn c t nht 3 trong s 5 bit D o th cc byte

chn m c x l nh nhng byte mang thng tin khc. Trong thng tin

SDH, khi tch mt s lung nhnh t lung STM-N th khng phi tch trnh

t t trn cao xung thp nh trong thng tin PDH. Mun tch mt lung

nhnh no th ch cn x l con tr ca lung nhnh y s bit c v tr

78


79/118

cc byte ca lung y trong khung ghp v tch chng mt cch trc tip.

Chng hn mun tch mt lung nhnh 139264 kbit/s t tn hiu 622,08 kbit/s

th x l con tr AU-4 tng ng s bit c v tr cc byte ca VC-4 thuc

lung nhnh ny trong khung STM-4 v tch cc byte ny. Hoc mun tch

mt lung nhnh 2048 kbit/s #n (n=1..63) t khung STM-1 th pha thu trc

ht x l AU-4 PTR xc nh v tr ca VC-4 trong AUG, tip theo s x l

TU-12 PTR xc nh lung nhnh ny thuc TUG-3 no v TUG-2 no.

Ni tm li mi lung nhnh u gn vi mt s a ch nht nh. Sau y

gii thiu s nh a ch cc lung nhnh trong cc khung ghp.

3.4.2 - nh s th t cc khung AU-n, TU-n

Khung STM-1 c 270 ct c nh s th t t 1 n 270. Chn ct

u tin cha SOH v AU-n PTR, 260 ct cn li cha cc byte ti trng ca

VC-4. Mi ct ti trng c gn 3 thng s l K, L, M, trong K i din

cho s th t ca TUG-3, L i din cho s th t ca TUG-2 v M l s th

t ca TU-2 hoc TU-1. Ngoi ra th hin tng dung lng cc loi lungnhnh ghp c trong khung STM-1 th th t cc lung nhnh c gn

vi s th t ca mt khe thi gian TS. Cc khe thi gian c nh s th t

t tri sang phi trong VC-4 (hnh 3.15, 3.16 v bng 3.1).

Bng 3.1 - V tr khe thi gian TS ca cc TU-n trong khung VC-4.

TU-3 TU-2 TU-12 TU-11 TS# TU-3 TU-2 TU-12 TU-11 TS# TU-3 TU-2 TU-12 TU-11 TS#

100 110 111 111 1 200 210 211 211 2 300 310 311 311 3112 112 22 212 212 23 312 312 24113 113 43 213 213 44 313 313 45

114 64 214 65 314 66120 121 121 4 220 221 221 5 320 321 321 6

122 122 25 222 222 26 322 322 27123 123 46 223 223 47 323 323 48

124 67 224 68 324 69130 131 131 7 230 231 231 8 330 331 331 9

132 132 28 232 232 29 332 332 30133 133 49 233 233 50 333 333 51

134 70 234 71 334 72140 141 141 10 240 241 241 11 340 341 341 12

79


80/118

142 142 31 242 242 32 342 342 33143 143 52 243 243 53 343 343 54

144 73 244 74 344 75150 151 151 13 250 251 251 14 350 351 351 15

152 152 34 252 252 35 352 352 36153 153 55 253 253 56 353 353 57

154 76 254 77 354 78160 161 161 16 260 261 261 17 360 361 361 18

162 162 37 262 262 38 362 362 39163 163 58 263 263 59 363 363 60

164 79 264 80 364 81170 171 171 19 270 271 271 20 370 371 371 21

172 172 40 272 272 41 372 372 42173 173 61 273 273 62 373 373 63

174 82 274 83 374 84

3.4.3 - nh s th t cc AU-4 trong khung STM-N

Trong tn hiu STM-N c N tn hiu AU-4 (hoc N tn hiu VC-4)

c nh s th t nh sau:

AU-4 (VC-4) #1: c ch th bi AU-4 PTR #1



.......

AU-4 (VC-4) #N: c ch th bi AU-4 PTR #N

3.4.4 - nh s th t cc TU-3 trong VC-4

S nh s th t cc TU-3 trong VC-4 nh hnh 3.15.

Mi VC-4 gm 3 TUG-3 c nh s th t #1, #2, #3

TUG-3 #1 chim cc ct 4, 7, 10, ....., 259 ca VC-4.

TUG-3 #2 chim cc ct 5, 8, 11,....., 260 ca VC-4.

TUG-3 #3 chim cc ct 6, 9, 12, ....., 261 ca VC-4.

Mi TUG-3 gm mt TU-3.

80


81/118


82/118


Mi TUG-3 gm 7 TUG-2 c s th t l #1 n #7 v mi TUG-2

gm 3 TU-12 c s th t t #1 n #3. V vy mi TU-12 c c trng

bi 3 thng s l #K, #L, #M, trong K l s th t ca TUG-3 (1 n 3), L

l s th t ca TUG-2 (1 n 7) v M l s th t ca TU-12 (1 n 3). V tr

cc ct trong VC-4 thuc v TU-12 (K, L, M) c xc nh theo biu thc

sau:

Xth =10+ (K-1) + 3 x (L-1) + 21 x (M-1) + 63 x (X-1) trong X=1 n 4.

V d:

TU-12 (1, 1, 1) thuc cc ct 10, 73, 136 v 199 ca VC-4;

TU-12 (3, 7, 3) thuc cc ct 72, 135, 198 v 261 ca VC-4.

3.4.7 - nh s th t cc TU-11 trong VC-4


Mi TUG-3 gm 7 TUG-2 c s th t l #1 n #7 v mi TUG-2

gm 4 TU-11 c s th t t #1 n #4. V vy mi TU-11 c c trng

bi 3 thng s l #K, #L, #M, trong K l s th t ca TUG-3 (1 n 3), L

l s th t ca TUG-2 (1 n 7) v M l s th t ca TU-11 (1 n 4). V tr

cc ct TU-11 (K, L, M) trong VC-4 c xc nh theo biu thc sau:

Xth =10+ (K-1) + 3 x (L-1) + 21 x (M-1) + 84 x (X-1) trong X=1 n 3.

V d:

TU-11 (1, 1, 1) chim cc ct 10, 94 v 178 ca VC-4;

TU-11 (3, 7, 4) chim cc ct 93, 177 v 261 ca VC-4.

82


83/118

83


84/118

S nh s

Hnh 3.15 - S nh s TU-12, TU-2, TU-3 trong VC-4.

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 256 258 260Th t ct

1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 257 259 261V

C

4

P

O

Th t khe

thi gian1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 ...... 1 2 3 1 2 3

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 ...... 1 2 3 1 2 3 K a ch

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ...... 0 0 0 0 0 0 L0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 ...... 0 0 0 0 0 0 M

2 4 6 8 10 12 14 16 18 20 66 68 70 72 256 258 260Th t ct

1 3 5 7 9 11 13 15 17 19 21 65 67 69 71 73 257 259 261V

C

4

P

Th t khe1 2 3 4 5 6 7 8 9 10 11 12 ...... 56 57 58 59 60 61 62 63 1 ...... 58 59 60 61 62 63

1 2 3 1 2 3 1 2 3 1 2 3 ...... 2 3 1 2 3 1 2 3 1 1 2 3 1 2 3 K a ch1 1 1 2 2 2 3 3 3 4 4 4 ..... 5 5 6 6 6 7 7 7 1 6 6 6 7 7 7 L

1 1 1 1 1 1 1 1 1 1 1 1 ..... 3 3 3 3 3 3 3 3 1 3 3 3 3 3 3 M

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 256 258 260Th t ct

1 3 5 7 9 11 13 15 17 19 21 23 25

Documents

Cong Nghe Truyen Dan SDH