công nghệ thông tin quang

Cng ngh truyn ti quang Nguyn Tr Nam (Modified Nguyen Van Tuan)HNG DN N TP CNG NGH TRUYN TI QUANGPHN 1: H THNG WDMCu 1(1): Phn loi h thng WDM theo khong cch cc knh bc sng s dng trong h thng.C rt nhiu cch phn loi cc h thng WDM. Tuy nhin, ph bin nht l phn loi theo khong cch cc knh bc sng s dng trong h thng. H thng WDM bng tn rng (BWDM Broad passband WDM) y l h thng WDM ra i sm nht trong lch s pht trin ca WDM. N thc hin truyn dn 2 knh bc sng, trong mi knh bc sng thuc mt ca s truyn dn (vng 850 nm, 1310 nm hoc vng 1550 nm). Nh vy, khong cch gia cc knh trong h thng ny c vi trm nm. c im ca h thng ny l chi ph h thng thp, tuy nhin dung lng v khong cch truyn dn b gii hn. CWDM: ghp knh theo bc sng mt thp y l h thng WDM ra i t u nhng nm 1990 cho php ghp nhiu hn 2 bc sng trn h thng. Khong cch gia cc bc sng kh ln (c 20 nm). ITU-T a ra chun G.694.2 quy nh v khong cch cc knh, bc sng trung tm ca h thng ny nh sau: Khong cch cc knh: 2500 GHz Bc sng trung tm: 1552.52 nm Di bc sng hot ng t 1270 nm n 1610 nm) DWDM: ghp knh theo bc sng mt cao y l h thng WDM ra i t gia nhng nm 1990 v cng chnh l cc h thng WDM hin ti ang khai thc trn th gii. H thng ny cho php ghp rt nhiu cc bc sng trn h thng. Khong cch gia cc bc sng ch c 200 GHz, 100 GHz, 50 GHz v thm ch l 25 GHz. ITU- T a ra chun G.692 quy nh v khong cch cc knh, bc sng trung tm ca h thng DWDM nh sau: Khong cch cc knh: 100 GHz Bc sng trung tm: 1552.52 nm Vng bc sng hot ng: Bng S, C, L, U.

Cu 5(2,1 ): S khi v trnh by nguyn l hot ng ca h thng thng tin quang ghp knh theo bc sng WDM n hng/ song hng.a. H thng n hng- V c s h thng WDM n hng- Nu c chc nng cc khi- Trnh by c hot ng hng pht- Trnh by c hot ng hng thuPhng thc truyn dn n hng: bc sng chiu pht trn 1 si v bc sng chiu thu trn 1 si khc

b. H thng song hngPhng thc truyn dn song hng: 2 bc sng chiu pht v chiu thu trn cng mt si

PHN 2: KHUCH I QUANG OA

Cu 1(2): Nu cc tham s c bn ca b khuch i quang.a. H s khuch i:G = Pout / PinG (dB) = 10 log (Pout / Pin) Pin va Pout la cng sut u vao va u ra ca b khuch i quang [mW]. H s khuch i c trng cho kh nng khuch i cng sut nh sng ca b khuch i. B gii hn bi cc c ch bo ha khuch i. iu ny lm gii hn cng sut quang ra cc i ca b khuch i. b. rng bng tn khuch i (B0) H s khuch i ca b khuch i quang l mt hm s ca tn s quang [G(f)]. Tc l, khi o h s khuch i G ca cc tn hiu quang cc tn s khc nhau s khc nhau. rng bng tn khuch i ca b khuch i quang Bo c xc nh bi im -3dB so vi h s khuch i nh ca b khuch i. Gi tr Bo xc nh bng thng ca cc tn hiu c th c truyn bi mt b khuch i quang. Do , n nh hng n hot ng ca cc h thng thng tin quang khi s dng chng.c. Cng sut ra bo ha Khi hot ng ch tn hiu nh, cng sut quang u ra s tng tuyn tnh vi cng sut quang u vo theo h s khuch i G: Pout = G.Pin. Tuy nhin, khi cng sut u vo Pin tng n mt mc no , h s khuch i G khng tng tuyn tnh vi tnh hiu u vo na m c th khng i thm ch bt u gim khi tip tc tng cng sut u vo. Khi , b khuch i quang t trng thi bo ha.

Cng sut u ra ti im G gim 3 dB c gi l cng sut ra bo ha Psat, out. Cng sut ra bo ha Psat, out ca mt b khuch i quang cho bit cng sut u ra ln nht m b khuch i quang c th hot ng c. Mt b khuch i quang c h s khuch i cao s c cng sut ra bo ha cao.d. Nhiu b K - H s nhiu NF Cc b khuch i quang u to ra nhiu, gy ra do pht x t pht, pha ca cc photon pht x t pht l ngu nhin. Nng lng do pht x t pht to ra cng s c khuch i khi chng truyn qua b khuch i v pha u ra. Ti u ra ca b khuch i cng sut quang thu c Pout bao gm c cng sut tn hiu c khuch i - G.Pin v cng sut nhiu pht x t pht c khuch i (ASE) - PASE.Pout = G.Pin + PASE nh hng ca nhiu i vi b khuch quang c biu din bi h s nhiu (NF).

SNRin, SNRout l t s tn hiu trn nhiu ti u vo v u ra ca b khuch i [mW]. NF ca b khuch i cng nh th cng tt.Cu 2(1): u khuyt im ca khuch i quang bn dn EDFA/ Raman.EDFARaman

u:+Ngun laser bm bn dn c tin cy cao, gn v cng sut cao.+Cu hnh n gin, h gi thnh ca h thng.+Cu trc nh gn: c th lp t nhiu EDFA trong cng 1 trm, d vn chuyn, thay th.+ Cng sut ngun nui nh: thun li cho p dng cc tuyn thng tin quang vt bin.+Ko c nhiu xuyn knh khi K cc tn hiu WDM nh b K quang bn dn.+ Hu nh ko ph thuc vo phn cc ca tn hiuu:+ Tp m nhiu thp+ Cu trc n gin, khng cn si c bit.+ D chn bng tn.+ C th t c bng thng rng nh kt hp vi laser bm.

Nhc:+Ph K ca EDFA ko bng phng+Bng tn hin nay b gii hn trong bng C v L+Nhiu c tch ly qua nhiu chng gy hn ch c ly truyn.Nhc:+Xuyn m gia cc knh tn hiu do tn x Raman kch thch SRS.+H s K thp.+ Hiu sut K thp hn so vi EDFA: K Raman cn 1 cng sut bm ln hn t cng 1 gi tr h s K.

Cu 3 (3): V s cu trc ca b khuch i EDFA theo 3 ch bm thun/ngc/2 chiu, nu chc nng cc khi v nguyn tc hot ng.a. Ch bm thun:

Bm thun vi bc sng bm 980nm. Ion erbium trong si quang EDFA lin tc c chuyn tip t vng nng lng 4I15/2 thp ln vng nng lng cao 4I11/2, sau cc ion s phn r xung vng 4I13/2 nhng khng pht x. T vng ny, khi c tn hiu nh sng kch thch th cc ion s pht x bc sng mong mun (t 1550 n 1600 nm) khi chuyn t vng nng lng 4I13/2 xung vng 4I15/2. y chnh l h thng ba mc. Thi gian sng ca ion erbium mc 4I11/2 khong 1s trong khi 4I13/2 th ti 10ms. Vi thi gian sng di, vng 4I15/2 c gi l vng n nh. Cc ion c bm ln mc cao, sau nhanh chng xung vng 4I13/2 v tn ti trong mt khong thi gian tng i di to nn s nghch o v nng .b. Ch bm ngc

Bm bc sng 1480nm Cc ion erbium ch hot ng trong hai vng nng lng 4I13/2 v 4I15/2. y l h thng 2 mc. Cc ion erbium lin tc c chuyn t vng nng lng nn 4I15/2 ln vng nng lng kch thch 4I13/2 nh nng lng bm. V thi gian tn ti mc ny di nn chng tch ly ti y to ra s nghch o nng .

c. Ch bm 2 hng

S dng c 2 ngun bm (980nm v 1480nm ngc chiu nhau).Chc nng cc khi: Si quang pha ion t him Erbium (EDF):+ nng pha tp 100 2000 ppm, l mi trng K, to ra trng thi nghch o nng . + Vng li trung tm c ng knh t 3 -6 m c pha trn ion Er3+ l ni c cng sng bm. L ni xy ra qu trnh khuch i (vng tch cc) ca EDFA. + Lp bc c chit sut thp hn bao quanh vng li, Lp v bo v bao quanh si quang to bn knh si quang tng l 250 m. + Trong gin phn b nng lng, cc ion Er3+ c th tn ti nhiu vng nng lng khc nhau c k hiu: 4I15/2 , 4I13/2 , 4I11/2, 4I9/2, 4F9/2, 4S9/2, 2H11/2. Laser bm:+ Cung cp nng lng nh sng to ra trng thi nghch o nng trong vng tch cc. Laser bm pht ra nh sng c bc sng 980nm hoc 1480nm. WDM Coupler: + Ghp tn hiu quang cn khuch i v nh sng t laser bm vo trong si quang. Loi coupler c s dng l WDM coupler cho php ghp cc tn hiu c bc sng 980/1550nm hoc 1480/1550nm. B cch ly quang:+ Ngn khng cho tn hiu quang phn x ngc v pha u pht hoc cc tn hiu quang trn ng truyn phn x ngc v EDFA. Nguyn tc hot ng:

Khi bm nh sng cho laser:+ Khi s dng ngun bm laser 980nm, cc ion Er3+ vng nn s hp th nng lng t cc photon (c nng lng Ephoton =1.27eV) v chuyn ln trng thi nng lng cao hn vng bm (1).+ Ti vng bm, cc ion Er3+ phn r khng bc x rt nhanh (khong 1s) v chuyn xung vng gi bn (2).Khi s dng ngun bm laser 1480nm, cc ion Er3+ vng nn s hp th nng lng t cc photon (c nng lng Ephoton =0.841eV) v chuyn sang trng thi nng lng cao hn nh ca vng gi bn (3).+ Cc ion Er3+ trong vng gi bn lun c khuynh hng chuyn xung vng nng lng thp (4).+ Sau khong thi gian sng (khong 10ms), nu khng c kch thch bi cc photon c nng lng thch hp cc ion Er3+ s chuyn sang trng thi nng lng thp hn vng nn v pht x ra photon (pht x t pht) (5). Khi cho tn hiu nh sng i vo EDFA, c 2 qu trnh:+ Cc photon tn hiu b hp th bi cc ion Er3+ vng nn (6). Tn hiu nh sng b suy hao+ Cc photon tn hiu kch thch cc ion Er3+ vng gi bn (7). Hin tng pht x kch thch xy ra => EDFA khuch i tn hiu nh sng ti. K tn hiu nh sng ti:+ Cc ion Er3+ vng gi bn ang trng thi kch thch nh ngun bm (7) nhn c kch thch t tn hiu nh sng ti s chuyn trng thi nng lng t mc nng lng cao vng gi bn xung mc nng lng thp vng nn v pht x ra photon mi c cng hng truyn, cng phn cc, cng pha v cng bc sng.=> Tn hiu nh sng c khuch i.Cu 4(3): Trnh by cu to v gii thch nguyn l hot ng ca b khuch i Raman/ SOA.a. B K Raman Cu to:

+ Si quang: ni xy ra qu trnh khuch i, l si quang thng truyn tn hiu nh si SMF, DSF..... Trong khuch i Raman, khng cn s dng si quang c bit nh EDFA.+ Coupler: dng ghp bc sng tn hiu vo vi bc sng bm.+ Laser bm c tn s p: dng cung cp nng lng cho cc nguyn t ca si quang chuyn ln trng thi kch thch, gip to ra s nghch o nng . Laser pht ra nh sng c bc sng thch hp ty thuc vo vng bc sng cn khuch i. y l mt u im quan trng ca khuch i Raman so vi EDFA (ch khuch i c cc bc sng bng C).+ B lc (hoc b cch ly): t hai u ca b khuch i quang ngn chn tn hiu phn x hai u b khuch i. ng thi n cng gip loi tr nhiu ASE theo hng ngc v pha u vo c th gy nh hng n tn hiu u vo.Nguyn l hot ng:

Lung nh sng bm c tn s p v nh sng tn hiu tn s s cng c a vo si quang thng qua mt coupler quang. Nng lng s c truyn t nh sng bm sang nh sng tn hiu thng quang hiu ng SRS trong si quang. C th: nh sng bm t mt laser bm c bc sng thp hn bc sng ca tn hiu cung cp nng lng cho cc nguyn t ca si quang. Khi , cc nguyn t ca si quang s hp th nng lng nh sng bm v chuyn ln mc cao hn (mc khch thch) to ra s o ln nng Khi c tn hiu nh sng ti, n s kch thch cc nguyn t ang mc nng lng cao chuyn sang trng thi nng lng thp hn v gii phng ra mt nng lng di dng photon nh sng c cng bc sng (di hn bc sng bm) v cng pha vi tn hiu n. Do , tn hiu c khuch iCc cu hnh bm K Raman Bm xui:

Bm ngc:

Bm 2 hng:

b. B K SOA Cu to

+ SOA c iu khin bi dng in, + Vng tch cc trong SOA khuch i nh sng u vo nh qu trnh pht x kch thch. + Tn hiu u ra bao gm c tn hiu truyn dn v nhiu pht x t pht c khuch i (ASE) do qu trnh khuch i gy ra. Nguyn l hot ng:+ Da trn c ch pht x kch thch ca lp tip gip PN.+ Khi c dng in iu khin, cc in t trng thi nng lng E1 c kch thch bi dng iu khin s nhy ln mc NL cao hn E2 v to nn s nghch o nng . + Khi c nh sng ti kch thch cc in t ang trng thi kch thch E2. Cc in t ny hp th nng lng nh sng tr v trng thi E1 n s gii phng ra mt nng lng Sng in t mi di dng nh sng c nng lng ln hn E2 E1. + Qu trnh kch thch cc in t trng thi E2 tip tc din ra, khi tn hiu nh sng c K.+ Cng c 1 s in t trng thi E2 khng nhn c nng lng ca nh sng ti cng tr v trng thi E1 v pht x ra cc photon. Qu trnh pht x ny gi l pht x t pht.

PHN 3: B TN SCCu 1: Trnh by cc phng php b quang b tn sc trong h thng thng tin quang.Gii php ny thng c s dng b tn sc trn cc ng truyn dn quang. Hin nay, c rt nhiu k thut c s dng nh:- S dng si quang b tn sc (DCF)- S dng cc b lc quang.- S dng cch t si quang- S dng k thut kt hp pha quang.

S dng si quang b tn sc (DCF)Phng php b tn sc bng si c tn sc m. Phng php ny da trn nguyn l sau: Tn sc ca si n mode ni chung l tng ca tn sc dn sng v tn sc vt liu. Nh vy, v mt nguyn tc vi mt cu trc thnh phn hp l c th to ra si c tn sc ln, ngc du ti bc sng cng tc nh trc. Da theo tnh cht ny, trn mi khong lp t thm mt on si c tn sc m vi di hp l th c th b c phn no tn sc.u im: Thit b b tn sc hon ton th ng. B trong khong tn sc ln.Nhc im: Suy hao ca b b tn sc ln v ph thuc vo khong tn sc phi b. Phi gim st cng sut tn hiu truyn trnh cc hin tng hiu ng. S dng b lc quangTrong k thut b tn sc bng b lc quang, thng mt b lc quang c t sau mt chng si di L km. Gi s b lc quang c hm truyn t H():

Tn hiu truyn qua b lc c biu din nh biu thc:

Bng cch khai trin pha ca H() theo chui Taylor v gi s hng bc hai s c biu thc:

Pha khng i 0 v tr thi gian 1 s khng nh hng ti dng xung v c th b qua. Pha do si sinh ra c th c b bng cch chn b lc quang sao cho c2 = - 2L. (4-23)Xung c th c phc hi hon ton ch khi H() tha mn iu kin (4-23) v cc s hng bc ba v bc cao hn trong khai trin Taylor l khng ng k.

S dng si quang cch t Bragg- Nguyn l b tn sc ca quang si cch t Bagg chu k bin i b tn sc trong cc h thng TTQ, ngi ta thng s dng si quang cch t Bragg chu k bin i tuyn tnh.Si quang cch t Bragg chu k bin i tuyn tnh l mt si quang n mode c mt on li c khc cc cch t c chu k thay i mt cch tuyn tnh dc theo chiu di ca quang si: (z) = 0 + 1(z)Trong , 0 l chu k im bt u ca on cch t, 1 l s thay i tuyn tnh dc theo chiu di ca on cch t.Ti v tr z trn on cch t Bragg, mt sng nh sng s b phn x ngc li nu bc sng ca n tha mn cng thc: B(z) = 2neff (z)(z)Trong , B(z) l bc sng Bragg ti v tr z tng ng vi chu k cch t (z).

c tnh ca quang si cch t Bragg chu k bin i l ti nhng v tr tng ng vi chu k di hn s phn x nhng nh sng c bc sng di hn.Khi cc xung tn hiu c cc bc sng di hn i vo u on si cch t c chu k di s b phn x phn u ca on cch t v nhng bc sng ngn hn s phi i mt qung ng xa hn ca on cch t sau mi phn x ngc li.

Vi s phn x ca nhng thnh phn tn hiu c cc bc sng di hn phn u ca on cch t v cc thnh phn tn hiu c nhng bc sng ngn hn s phi i mt qung ng xa hn ca on cch t sau mi phn x ngc li. Kt qu l mt khong thi gian tr d s c to ra gia thnh phn bc sng ngn so vi thnh phn bc sng di. Khong cch d c xc nh theo cng thc:

Trong cng thc trn d l khong thi gian tr, neff l chit xut hiu dng, L l di on cch t Bragg, c l vn tc nh sng trong chn khng, c l hiu s gia bc sng b phn x u on cch t (thnh phn bc sng di nht) so vi bc sng b phn x cui on cch t (thnh phn ngn nht).- S thit b b tn sc dng cch t BraggM hnh c bn ca thit b b tn sc dng cch t Bragg chu k thay i tuyn tnhCirculator l thit b ghp ni quang ch cho nh sng i ln lt cc cng 1, 2, 3 theo chiu kim ng h. Mt xung b gin rng sau khi c khuch i s i qua mt circulator ti on cch t Bragg c chu k bin i nh hnh v.

Trong m hnh c bn ca thit b b tn sc dng cch t Bragg chu k thay i tuyn tnh:Ti on cch t, thnh phn bc sng ngn ti trc do tn sc s phi i thm qung ng na trc khi c phn x ngc li ti thit b u thu. Trong khi , thnh phn bc sng di hn, n chm hn do b tn sc, s c phn x ngay khi ti cch t Bragg. Kt qu l xung tn hiu sau khi i qua thit b b c co li. Tnh ton hp l cc s liu v di on cch t Bragg, hm thay i ca chu k cc cch t L(z), ngi ta c th thu c xung nh sng c rng nh u pht.iu c ngha l:i vi k thut b tn sc bng cch t Bragg si, c th coi nh l mt b lc quang c s tn ti ca bng dng, l vng tn s m trong hu ht nh sng ti u c phn x tr li. Bng dng c bc sng trung tm bng bc sng Bragg: B= 2n , trong n l ch s mode v l chu k cch t. => Kt qu tn hiu quang ra s c b tn sc.

B tn sc kt hp pha quangTrong h thng quang c li di, s dng k thut iu chnh pha quang (OPC) b tn sc.Nguyn l ca OPC l thc hin iu chnh kt hp pha ca song nh sang di dng trng phc ti chng gia ca tuyn, sao cho nh hng ca GVD na sau ca tuyn s trung ha nh hng ca GVD na u ca tuyn.Phng php ny cn c gi l o ph gia chngPhng php s dng thng dng nht trong OPC l FWM trong mi trng phi tuyn: thng chn bc song bm trng vi bc song tn sc khng.

PHN 4: TRUYN TI QUANG IP QUANG.Cu 1: Trnh by cc giai on pht trin IP/ WDM.a. Giai on IP/ATM/SDH/WDM

y l giai on u tin trong cng ngh truyn ti IP trn quang. Trong giai on ny, cc IP datagram trc khi a vo mng truyn ti quang phi thc hin chia ct thnh cc t bo ATM c th i t ngun ti ch Ti chuyn mch ATM cui cng, cc IP datagram mi c khi phc li t cc t bo. y l giai on c y cc tng IP, ATM v SDH, do chi ph lp t, vn hnh v bo dng tn km nht. Tuy nhin, khi cng ngh cc router cn nhiu hn ch v mt tc , dung lng th vic x l truyn dn IP trn quang thng qua ATM v SDH vn c li v mt kinh t.b. Giai on IP/SDH/WDM

Giai on ny, tng ATM b loi b v cc IP datagram c chuyn trc tip xung tng SDH. Thay vo , ngi ta s dng cng ngh router vi nhng u im vt tri so vi chuyn mch ATM v mt tnh nng, dung lng v v router IP l phng tin truyn dn u vit cho cng ngh IP datagram. Ngoi ra, vic c thm k thut MPLS b sung vo tng IP s to ra hai kh nng mi: Th nht, n cho php thc hin k thut lu lng nh vo kh nng thit lp knh o VC. Th hai, MPLS tch ring mt iu khin ra khi mt nh hng nn cho php giao thc iu khin IP qun l trng thi thit b m khng yu cu xc nh r bin gii ca cc IP datagram. Nh vy, c th d dng x l i vi cc IP datagram c di thay i.c. Giai on IP/WDM

Trong giai on ny, tng SDH cng b loi b v IP datagram c chuyn trc tip xung tng quang. Gii php ny cho php truyn trc tip IP datagram trn h thng WDM, mi giao thc s c mt bc sng tng ng. Vic loi b tng ATM v tng SDH ng ngha vi vic c t phn t mng phi qun l hn v vic x l cng t hn (vic x l y thc hin theo tng lung quang). Cc bc sng khc nhau c th xen/r hoc chuyn i bc sng cc nt khc nhau nh cc thit b nh: OXC, OADM, b nh tuyn bc sng quang. S kt hp IP phin bn mi vi kh nng khi phc ca tng quang, cc thit b OAM&P v chc nng nh tuyn phn b to ra kh nng phc hi, pht hin li v gim st nhanh. Mt im mi l vi cu trc khung gn nh c th thay th cho cc chc nng m cc khung SDH thc hin trong cc kt ni Och. S tn ti ca hng lot giao thc k thut lu lng MPLS (MPLS TE) m rng kh nng hot ng cho mng quang v tng IP, c bit l cc router IP ngy nay c th giao din trc tip vi mng quang.

PHN 5: MNG TRUY NHP QUANG FTTxCu 1: Nu khi nim v nu cc u khuyt im ca FTTx. Khi nim: y l mt hnh thc truy nhp trong mng truy nhp si quang, a dch v ti khch hng. FTTx bao gm cc h thng truy nhp: Si quang ti vng dn c (FTTC). Si quang ti c quan (FTTO). Si quang ti ta nh (FTTB). Si quang ti tn nh (FTTH). u im: Dung lng ln C ly on lp di Tnh cch in tt Tnh bo mt cao tin cy cao v d bo dng Tnh linh hot ln Tnh m rng cao Nhc im: Mc d si quang rt r nhng chi ph cho lp t, bo dng, thit b u cui l rt ln. Do thit b u cui cn kh t nn khng phi lc no h thng mng FTTx cng ph hp. i vi nhng ng dng thng thng, khng i hi bng thng ln nh lt Web, Check mailth cp ng vn c tin dng. Do cng ngy ngi ta cng cn phi u t nghin cu gim cc chi ph . Cu 2(1): Cho bit cc cng ngh ca mng quang th ng PON. Mng quang th ng (PON) l mt kin trc mng im - a im, s dng cc b chia quang th ng (khng c ngun cung cp) chia cng sut quang t mt si quang ti cc si quang cung cp cho nhiu khch hng. u im ca PON l khng cn ngun cung cp nn khng b nh hng bi nhiu ngun, c tin cy cao v khng cn phi bo dng nh i vi cc phn t tch cc. Cc cng ngh PON: Cng ngh ATM PON: c ban hnh thnh tiu chun trong G983.1 ca ITU. Trn c s ny xy dng PON bng rng (B-PON) chun ITU-T G983. Mt mng APON/BPON in hnh cung cp 622Mbt/s bng thng ng xung v 155 Mbit/s ng ln. Cng ngh GPON: Chun ITU-T G984 m t s gia tng trong c bng thng v hiu sut s dng bng thng nh s dng gi ln, c di thay i. Hn na chun G984 cho php vi s la chn tc bt, c bn s dng tc 2,488 Mbit/s cho lung xung v tc 1,244 Mbit/s cho lung ln. Phng thc gi tng hp GPON (GPON Encapsulation Methed- GEM) cho php ng gi lu lng d liu ngi dng rt hiu qu, vi s phn on khung cho php m bo cht lng dch v QoS cao hn phc v cc lu lng nhy cm (dch v thi gian thc yu cu tr thp) nh truyn thoi v lung video. Cng ngh: EPON/GEPON+ Chun IEEE 802.3 Ethernet PON (EPON hay GEPON) c hon thnh nm 2004, nh mt phn ca d n Ethernet First Mile. + EPON chun IEEE 802.3 s dng khung Ethernet i xng 1,24 Gbit/s tc lung ln v lung xung.+ EPON c th ng dng cho cc mng trung tm d liu, cng nh cc mng dch v b ba thoi, d liu v video.+ Gn y, bt u t nm 2006, tip tc thc hin chun EPON tc cc cao 10Gigabit/s (chun XEPON hay 10- GEPON). WDM PON: ???

Cu 3: Cu hnh tham chiu v nu cc khi chc nng c bn ca mng truy nhp quang FTTx.

Cc khi chc nng c bn ca mng truy nhp FTTx Khi chc nng OLT+ Khi u cui ng quang OLT cung cp giao din quang pha mng vi ODN, ng thi cng cung cp t nht mt giao din pha mng dch v.OLT c th chia thnh dch v chuyn mch v dch v khng chuyn mch. OLT cng qun l bo hiu v thng tin gim st iu khin n t ONU, t cung cp chc nng bo dng cho ONU. OLT c th lp t tng i ni ht hoc mt v tr xa. Khi chc nng ONU/ONT: + Khi mng quang ONU/ONT t gia ODN v thu bao. Pha mng ca ONU c giao din quang, cn pha thu bao l giao din in. Do , ONU c chc nng bin i quang/in. ng thi c th thc hin chc nng x l v qun l bo dng cc loi tn hiu in. ONU c th t pha khch hng (FTTH/B) hoc ngoi tri (FTTC). Khi chc nng ODN:+ Khi mng phn phi quang ODN t gia ONU vi OLT. Chc nng ca n l phn phi cng sut tn hiu quang. ODN ch yu l linh kin quang khng ngun v si quang to thnh mng phn phi quang th ng. Nu ODN c thay th bng b ghp knh quang th tr thnh mng phn phi quang hnh sao tch cc.

PHN 6: QUN L V IU KHIN QUANGCu 1: Trnh by phng php bo v trong mng vng (ring) quang UPSR/2S mng vng 2 si n hng chuyn mch bo v tuyn (2F USHR/P) nh hnh 3.21. 2F USHR/P l mt c cu mng vng trng thi bnh thng, nhng khi t cp ti mt im no shot ng theo kiu mng ng thng. Ngha l trong trng thi t cp th si hot ng v si bo v u i chung trong mt cp. Hnh 3.21a l hot ng ca mng vng hai si n hng vi githit l nt A v nt C ang lin lc vi nhau. trng thi bnh thng, tn hiu truyn ng thi trn csi hot ng (W) v si bo v(P). Tn hiu pht v tn hiu thu ca mt nt ADM truyn trn hai si khc nhau v cng hng vi nhau, trong hnh l cng hng kim ng h. Ti pha thu c chuyn mch bo vv chuyn mch tip xc vi si hot ng W. Hnh 3.21b m ttrng thi cp b t trn on BC. Khi cp t, ti u vo nt C mt tn hiu, tc l c cnh bo LOS. Ngay sau , chuyn mch ti C hot ng v chuyn sang tip xc vi si P bn tri. Chuyn mch trang bcho tt ccc tn hiu lp tuyn nn gi l chuyn mch bo v tuyn.

2F USHR hot ng chuyn mch trong cc trng hp sau y: (1) Pht hin LOS hoc AIS ng kch hot ci t AIS tuyn trong tt ccc tuyn ca lung xung. (2) Pht hin AIS tuyn trn mt hoc hai lung nhnh skhi ng chuyn mch bo v ca cc lung khc. Ch rng trong c ch iu khin ny, chuyn mch bo v c th tr v hoc khng tr v. Hnh 3.22 l th d minh ho hot ng ca 2F USHR/P khi cp b t. cho n gin, gi thit dung lng ca mng vng bng 622,08 Mbit/s v c bn ADM xen r tn hiu VC-4. Mi ADM lin lc vi tt cc ADM khc qua knh STM-1. Chstrong hnh 3.22 ch r kt ni gia cc ADM. Th d2-1 c ngha l ADM #2 lin lc vi ADM#1. Githit nh vy nhm lm n gin vic m thot ng ca mng vng, khng gy nh hng g n s chuyn mch bo v.

trng thi bnh thng, tn hiu STM-4 truyn trn cc vng theo hng kim ng h v c hng ngc chiu kim ng h. Khi 2 si gia nt 1 v nt 4 b t, my thu ti nt 1 pht hin LOS v a ra cnh bo . V cch iu khin gn vo chai hng nn trong tho lun sau y ca vng ngc hng kim ng hcng p dng cho vng cng hng kim h. Sau khi nt 1 xc nhn LOS hoc pht hin AIS ng, n xen AIS tuyn vo tt ccc VC-4. Ti giao din STM-1 ca nt 1 trng thi ca tn hiu nhnh c kim tra. Vic pht hin AIS tuyn thuc mt trong 2 tn hiu nhnh STM-1 kch hot chuyn mch bo vlung nhnh v cho php b chn la chn tn hiu nhnh tin cy hn. V nt 1 gn im t cp nn tt ccc giao din STM-1 ca nt 1 thc hin chuyn mch bo v. u ra nt 1 trn vng ngc chiu kim ng h c AIS tuyn trong tt ccc VC-4 ca n, trcc VC-4 c bsung ti nt ny. Ti nt 2, bghp tc bit cao khng pht hin c bt k cnh bo no, v khung SDH khng bao gibgin on. Sau khi rknh, cc giao din STM-1 2a v 2b ca nt 2 pht hin AIS tuyn v thc hin chuyn mch bo v. Giao din 2c tng ng vi kt ni gia nt 1 v nt 2 khng b nh hng ca t cp nn khng yu cu chuyn mch bo v. i vi cc knh ni chuyn tip qua nt 2, chc knh 4-3 (kt ni gia nt 4 v nt 3) mang AIS tuyn. Cc knh 1-3 v 1-4 bt ngun tnt 1 nn u truyn ti sliu tin cy. p dng thut ton nhtrn cho nt 3 thy rng chc knh 4-3 yu cu chuyn mch bo v. Hn na, ba knh ni chuyn tip (2-1, 1-4, 2-4) u mang tn hiu tin cy. i vi nt 4, khng c mt giao din STM-1 no yu cu chuyn mch bo v. Cc ADM trn vng cng chiu kim ng hhot ng hon ton ging nhcc ADM trn vng ngc chiu kim ng h. V 2F USHR/P l mt dng ca chuyn mch knh v kch hot chuyn mch khi c AIS tuyn nn khng yu cu giao thc APS (c ngha khng cn hot ng ca K1 v K2). Kt qul cu trc 2F USHR/P c lp hon ton vi qu trnh pht trin v tiu chun ho giao thc APS.Cu 2: Cc phng php iu khin trong mng quangC 3 phng php iu khin trong cc mng IP trn quang: Phng php iu khin tnh: p dng cho giai on u t chc truyn ti IP/ WDM v vic iu khin gia IP v WDM c thc hin theo mt phng thc cp pht c nh. Phng php iu khin ng: p dng cho giai on th hai, cc mng WDM c chuyn i t cu trc vng ring hay im-im sang cu trc mesh vi cc h thng DWDM. Trong giai on ny, iu khin WDM thng qua vic cp pht cc bc sng c thc hin bng d liu iu khin nhm m bo tn dng mng mt cch hiu qu. Phng php iu khin tch hp: Gii php iu khin tch hp s dng trong m hnh gii php mng ngang hng. Trong , mt phng iu khin u dng c mng WDM v IP, ng thi kt ni quang c dn hng bi nh tuyn IP.PHN 7: MT S CNG NGH, K THUT V XU HNG NGHIN CU TRONG MNG TRUYN TI QUANGCu 1(3): Nu khi nim v ASK, FSK, PSK, v dng sng tn hiu ti cc u vo v u ra b iu bin trong thng tin quang Coherent, vi tn hiu u vo b iu bin l tn hiu s ng vi dy bit 110100101, sng mang quang n sc Cu 2: Trnh by k thut chuyn mch burst quang v chuyn mch gi quang. - c im ca chuyn mch burst/gi quang - Hnh v m t hot ng ca nt chuyn mch burst/gi quang. -Nu c nguyn tc hot ng.

a. Chuyn mch Burst quangTrong chuyn mch burst quang, mo u iu khin burst c truyn dc tuyn iu khin v pht trc burst mt khong thi gian. Nh vy, mo u iu khin s n cc nt chuyn mch trung gian trc, cho php mi nt chuyn mch thc hin cc tnh ton chuyn mch v tin hnh ci t kt ni cho chuyn mch ng thi im trc khi burst d liu n. Theo cch ny, burst d liu quang c th c gn vo ng i ca n qua mng t u vo n u ra. Tr gia mo u iu khin v burst tng khi s lng cc chng v tr x ly ti cc nt chuyn mch trung gian tng. Hnh 3.8 m t hot ng ca nt WDM chuyn mch burst quang.Chuyn mch burst quang dnh sn mt ng gi yu cu thit lp v sau gi burst m khng cn i xc nhn thit lp. S d nh vy l v thi gian truyn burst l tng i nh.

Hnh 3.8- Chuyn mch burst quang

b. Chuyn mch gi quangTrong chuyn mch gi quang, mo u iu khin gi cng c th c x l nh nhn v c gi cng vi gi d liu dc theo cng tuyn. Xt n thi gian cn thit tnh ton quyt nh chuyn mch, gi d liu thng c nh tuyn qua ng dy tr quang lc n chuyn mch trung gian. Gi tr tr c chn sao cho khi gi d liu c pht hin t ng dy tr th ci t kt ni cho quang c thc hin. Gi tr tr ny l cc b v khng i ti mi nt chuyn mch trung gian v c lp vi cc tuyn ring bit m cc gi chim c. Hnh 3.9 m t hot ng ca h thng WDM chuyn mch gi quang nh vy.Cc gi trong mng quang c chiu di c nh hoc thay i. Gi c chiu di c nh ging nh t bo ATM v mt th d ca gi c di thay i l gi IP. Gi c chiu di thay i tim thng tin iu khin vo mng nn c hiu qu hn. Tuy nhin, kch c gi chiu di thay i khng th qu ln hoc ti thiu phi nh hn dung lng ca ng dy tr quang. V vy, gi kch c ln cn c phn on truyn. Chn chiu di gi da trn ng dng v cc c tnh lu lng.

Hnh 3.9 - Chuyn mch gi quang C hai h chuyn tip trong chuyn mch gi quang: datagram v mch o. Trong chuyn tip datagram, m u gi truyn trong bng hoc ngoi bng c kim tra ti mi nt trung gian v khng c thi gian lch v ti trng v m u c chuyn ti cng nhau. Cch ny c s dng trong IP. Trong chuyn tip mch o, cc mch o c thit lp trc khi cc gi c gi i trn cc mch o. Mch ny l o vi ngha l khng dnh sn rng bng tn bt k. Mch o c cng i vo trong bng chuyn mch. Cng vo phi hp s th t nhn dng mch o i vo vi mt cng ra. Cc mch o thit lp c s dng trong khi chuyn tip.

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X l gi iu khin(Thit lp/ dnh sn bng thng)

2

C cu chuyn mch

O/E/O

2

1

Cc gi iu khin

1

Bc sng iu khin

Cc t pht d liu

Thi gianlch

2

1

2

1