44958156 Chuong I Tong Quan DWDM

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H thng DWDM

Chng I: Tng quan DWDM

I. TNG QUAN DWDM 1.1. Khi nim Ghp knh theo bc sng (WDM) l cng ngh ghp nhiu knh c bc sng khc nhau truyn i trn cng mt si quang. Cc b ghp v tch knh c s dng l cc thit b quang th ng. Ghp knh theo bc sng hon ton trong sut i vi d liu c truyn. V th, tc v chun d liu ca cc knh c ghp khng cn phi ging nhau. Cu trc tng qut ca mt tuyn WDM n hng, n knh nh hnh 1.1.Tx- 1 1 Tx- 2 2 1 Rx1 2 Rx2 k Rxk n Rxn

Giao tip vi pha pht thng tin cn truyn

Tx- k k Tx- n n

OA

OA

OA

Giao tip vi pha thu thng tin cn truyn

Ghp knh WDM

k

1

2

k

D EMUX

MUX

n

Ph ca knh n

Ph ca tn hiu ghp WDM

Hnh 1.1: Cu trc tng qut ca WDM v ph ca tn hiu ghp Cc lung thng tin cn truyn c a ti khi pht ca tng knh. Cc khi ny lm nhim v pht p vi bc sng khc nhau. u ra ca cc khi pht c a ti b ghp knh theo bc sng ghp thnh mt lung tng c khuych i v pht ln si quang. Trn ng truyn, c th t cc b khuych i nhm m bo v cng sut tng khong cch truyn. Ti u thu, tn hiu ny c khuych i tn hiu ln v c a ti b tch knh theo bc sng tch thnh cc knh tng t nh u pht. Cc knh bc sng ring c a ti cc khi pht tng ng chuyn tng knh thnh cc lung tn hiu ring tng ng vi pha pht.

H thng DWDM

Chng I: Tng quan DWDM

Hin ti, c hai h thng ghp knh theo bc sng c bit l h thng ghp knh theo bc sng mt cao (DWDM Dense Wavelength Division Mutiplexing) v h thng ghp knh theo bc sng th (CWDM Coarse Wavelength Division Mutiplexing). Bng 1-1: Phn chia bng tn quang Bng Bng O Bng E Bng S Bng C Bng L Bng U ngha Original bng gc Extended bng m rng Short bng ngn Conventional bng thng thng Long bng di Ultra-long bng cc di Di bc sng (nm) 1260 n 1360 1360 n 1460 1460 n 1530 1530 n 1565 1565 n 1625 1625 n 1675

DWDM l mt cng ngh ghp knh theo bc sng vi s bc sng ln trong mt bng tn hn ch. H thng ghp knh DWDM hin ti hot ng bng C hoc bng L (bng 1-1), dung lng 32 hoc 40 knh, khong knh 0,4 nm v tc ti 10G. Cc bc sng c chun ha theo khuyn ngh ITU-T G.692 (bng 1-2). Hin ti, h thng DWDM nghin cu th nghim vi dung lng knh c nng n 40G hoc s lng knh c nng n 80. Bng 1-2: Bc sng chun ha DWDM theo khuyn ngh ITU-T G.692 TT 1 2 3 4 5 6 7 8 9 10 11 12 13 14 TT Tn s trung tm (THz) cho khong knh 50 GHz 196.10 196.05 196.00 195.95 195.90 195.85 195.80 195.75 195.70 195.65 195.60 195.55 195.50 195.45 Tn s trung tm Tn s trung tm (THz) cho khong knh 100 GHz hoc hn 196.10 196.00 195.90 195.80 195.70 195.60 195.50 Tn s trung tm (THz) Bc sng trung tm (nm) 1528.77 1529.16 1529.55 1529.94 1530.33 1530.72 1531.12 1531.51 1531.90 1532.29 1532.68 1533.07 1533.47 1533.86 Bc sng trung tm

H thng DWDM

Chng I: Tng quan DWDM

TT

15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51

Tn s trung tm (THz) cho khong knh 50 GHz (THz) cho khong knh 50 GHz 195.40 195.35 195.30 195.25 195.20 195.15 195.10 195.05 195.00 194.95 194.90 194.85 194.80 194.75 194.70 194.65 194.60 194.55 194.50 194.45 194.40 194.35 194.30 194.25 194.20 194.15 194.10 194.05 194.00 193.95 193.90 193.85 193.80 193.75 193.70 193.65 193.60

Tn s trung tm (THz) cho khong knh 100 GHz hoc hn cho khong knh 100 GHz hoc hn 195.40 195.30 195.20 195.10 195.00 194.90 194.80 194.70 194.60 194.50 194.40 194.30 194.20 194.10 194.00 193.90 193.80 193.70 193.60

Bc sng trung tm (nm) (nm) 1534.25 1534.64 1535.04 1535.43 1535.82 1536.22 1536.61 1537.00 1537.40 1537.79 1538.19 1538.58 1538.98 1539.37 1539.77 1540.16 1540.56 1540.95 1541.35 1541.75 1542.14 1542.54 1542.94 1543.33 1543.73 1544.13 1544.53 1544.92 1545.32 1545.72 1546.12 1546.52 1546.92 1547.32 1547.72 1548.11 1548.51

H thng DWDM

Chng I: Tng quan DWDM

Tn s trung tm Tn s trung tm (THz) Bc sng trung tm (THz) cho khong cho khong knh 100 GHz (nm) knh 50 GHz hoc hn 52 193.55 1548.91 53 193.50 193.50 1549.32 TT Tn s trung tm Tn s trung tm (THz) Bc sng trung tm (THz) cho khong cho khong knh 100 GHz (nm) knh 50 GHz hoc hn 54 193.45 1549.72 55 193.40 193.40 1550.12 56 193.35 1550.52 57 193.30 193.30 1550.92 58 193.25 1551.32 59 193.20 193.20 1551.72 60 193.15 1552.12 61 193.10 193.10 1552.52 62 193.05 1552.93 63 193.00 193.00 1553.33 64 192.95 1553.73 65 192.90 192.90 1554.13 66 192.85 1554.54 67 192.80 192.80 1554.94 68 192.75 1555.34 69 192.70 192.70 1555.75 70 192.65 1556.15 71 192.60 192.60 1556.55 72 192.55 1556.96 73 192.50 192.50 1557.36 74 192.45 1557.77 75 192.40 192.40 1558.17 76 192.35 1558.58 77 192.30 192.30 1558.98 78 192.25 1559.39 79 192.20 192.20 1559.79 80 192.15 1560.20 81 192.10 192.10 1560.61 H thng CWDM c pht trin nhm p ng cc ng dng dung lng nh gim chi ph u t. CWDM l h thng ghp knh bc sng vi mt knh thp, yu cu x l bng tn khng cao. S knh ca CWDM nh hn hoc bng 18 vi khong knh 20nm (tng ng khong 2,5 THz), dung lng mt knh n 10G,

TT

H thng DWDM

Chng I: Tng quan DWDM

bc sng theo khuyn ngh ITU-T G.694.2. Bc sng ca CWDM c phn b nh hnh 1.2.

Hnh 1.2: Bc sng ca CWDM 1.2. ng lc pht trin S tng nhanh yu cu v dung lng, khong cch v s a dng v nh dng truyn tin lm cho cc h thng ghp knh theo thi gian (TDM) v vic tng s lng si quang khng p ng c. Trong khi, dung lng ca mt si quang rt ln th cc h thng truyn dn quang TDM, vi mt tn hiu quang trn mi si quang, ch khai thch mt phn nh trong bng tn rng ln ca si quang. Do , ny sinh nhu cu cn mt h thng c kh nng tng dung lng truyn dn trn mt si quang bng cch tn dng bng thng rng ca si, tng khong cch truyn dn v p ng ng thi nhiu nh dng thng tin. y l ng lc pht trin h thng ghp knh theo bc sng WDM. H thng WDM cho php tng dung lng truyn dn trn mt si quang, m khng tng tc xung, bng cch tn dng bng thng rng ca si quang. C th ghp cc lung s liu c tc v nh dng khc nhau. Do , h thng p ng c cc yu cu k trn. 1.3. ng dng 1.3.1. Cc kiu mng DWDM DWDM c hai kiu ng dng: kiu mng m v mng tch hp. Kiu mng DWDM m hot ng vi mi loi giao din quang u cui. H thng ny s dng cng ngh chuyn i bc sng chuyn i tn hiu quang t bc sng ca lung tn hiu cn truyn sang bc sng quy chun trong h thng. Cc tn hiu quang t cc thit b u cui khc nhau sau khi c chuyn i thnh cc bc sng khc nhau ph hp h thng theo khuyn ngh ITU-T c a ti b ghp ghp thnh tn hiu DWDM.

H thng DWDM

Chng I: Tng quan DWDM

Hnh 1.3: H thng DWDM m H thng DWDM tch hp khng s dng cng ngh chuyn i bc sng. H thng DWDM tch hp c thit k hot ng cng vi mt s mng khc nh SDH, Ethernet, ... Cc giao din quang t thit b thuc cc mng c tch hp phi c bc sng chun ha DWDM v c kt ni trc tip vo b tch ghp knh ca h thng DWDM.

Hnh 1.4: H thng DWDM tch hp Cc kiu mng ny c p dng ty thuc vo tng hon cnh c th. Trong thc t, c th kt hp c hai kiu ng dng ny trong mt h thng mng. 1.3.2. ng dng DWDM ti cc lp mng - Mng ng trc (back-bone) Cc h thng DWDM khong cch xa (long-haul) c ng dng trong mng ng trc truyn ti thng tin vi lu lng ln gia cc vng trong mt quc gia. c im ca cc h thng ny l dung lng rt ln v s dng cc cng ngh sa li FEC, khuych i Raman, nh dng xung CRZ cng vi cc trm lp tng cng v khong cch. H thng mng ng trc c xy dng di dng hnh vng hoc hnh li tng kh nng bo v lu lng. - Mng ni vng (Metropolitan) S dng cc h thng DWDM khong cch trung bnh kt ni gia cc im tp trung lu lng trong mt vng. Cc mng metro cng c xy dng dng hnh vng hoc hnh li tng kh nng bo v lu lng.

H thng DWDM

Chng I: Tng quan DWDM

1.4. u im ca DWDM H thng DWDM c cc u im sau: 1. Dung lng cc ln Bng thng truyn dn ca si quang thng thng c s dng rt ln. Nhng, t l s dng ca cc h thng n bc sng vn rt thp. Bng cch s dng cng ngh DWDM, dung lng truyn dn trn mi si quang c tng ln rt nhiu ln m khng cn tng tc bit. 2. Trong sut i vi tc bit v khun dng d liu Cc h thng DWDM c xy dng trn c s ghp v tch cc tn hiu quang theo bc sng v vic ghp tch ny c lp vi tc truyn dn v phng thc iu ch. V th, cc h thng ny trong sut i vi tc d liu v khun dng d liu. V th, c th truyn cc tn hiu vi cc c im truyn dn khc hn nhau, c th tng hp v tch cc tn hiu in khc nhau bao gm cc tn hiu s v cc tn hiu tng t, cc tn hiu PDH v cc tn hiu SDH,.v.v. 3. Bo v u t ti a trong qu trnh nng cp h thng Trong qu trnh m rng v pht trin mng, c th m rng dung lng m khng cn xy dng li h thng cp quang m ch cn thay th cc b thu pht quang. Hn na, vic tng thm dch v mi v dung lng mi c thc hin n gin bng cch tng thm bc sng. 4. Kh nng linh hot, tit kim v v tin cy cao So vi cc mng truyn thng s dng phng thc TDM in, mng DWDM c cu trc cc k n gin v cc lp mng c phn tch r rng. Lp thp nht ca mng l lp ton quang tnh t u vo b ghp ti u ra b tch knh bc sng bao gm cc b khuych i, b tn sc v cc thnh phn trn on ng truyn. Lp ny l c xy dng c nh vi tng mng v c chi ph rt thp. Lp dch v mc cao hn bao gm cc b pht p quang. Cc b pht p quang lm nhim v gom cc d liu cn truyn v pht p ti cc bc sng chun ha ca h thng. Vic thay i dung lng, thm bt dch v c thc hin bng cch thay i hoc thm bt cc b pht p. Do , mng DWDM p ng tt v kh nng linh hot v tit kim chi ph. Do c im trong sut vi tn hiu truyn nn tin cy ca mng cao hn hn so vi cc mng TDM. 5. Tng thch vi chuyn mch quang hon ton Theo d on, c th thc hin c mng chuyn mch hon ton quang trong tng lai, vic x l nh xen/r v kt ni ca tt c cc dch v vin thng c th c thc hin bng cch thay i v iu chnh cc bc sng tn hiu quang. V vy, DWDM l cng ngh c s thc hin mng hon ton quang. Hn na, cc

H thng DWDM

Chng I: Tng quan DWDM

h thng DWDM c th tng thch vi cc mng hon ton quang trong tng lai. Hon ton c th thc hin mng hon ton quang trong sut v c tin cy cao trn c s h thng DWDM hin ti.