Phân tích và thiết kế FTTH trên GPON

B CNG THNGTRNG I HC CNG NGHIP THC PHM TP.HCMKHOA CNG NGH THNG TIN

BO CO THC TP TT NGHIP

TI: PHN TCH MNG FTTH THEO CNG NGH GPON

Sinh vin thc hin: HUNH PHC HON MSSV:2001120073Lp:03DHTH1

TP.HCM 2016

Ni dung

1 Gii thiu phm vi v l do la chn chuyn ............................................................ 5 2 Gii thiu mng truy nhp quang ti thu bao (FTTH) v GPON ................................ 6 2.1 Khi nim v u im FTTH ................................................................................. 6 2.2 Kin trc v thnh phn ca mng PON ................................................................ 6 2.3 Cc chun mng PON ............................................................................................ 7 2.4 GPON ..................................................................................................................... 8 3 nh ngha v vit tt ..................................................................................................... 8 3.1 nh ngha .............................................................................................................. 8 3.2 Cc ch vit tt..................................................................................................... 11 4 Kin trc mng truy nhp quang .................................................................................. 14 4.1 Kin trc mng ..................................................................................................... 14 4.1.1 FTTB .......................................................................................................... 15

4.1.1.1 FTTB cho MDU ...................................................................................... 15

4.1.1.2 FTTB cho doanh nghip.......................................................................... 15 4.1.2 FTTC v FTTCab ....................................................................................... 16 4.1.3 FTTH .......................................................................................................... 16 4.2 Cu hnh mng tham chiu .................................................................................. 16 4.2.1 Giao din nt dch v SNI .......................................................................... 17 4.2.2 Giao din mng ngi dng UNI ............................................................... 18 4.2.3 Cc dch v ................................................................................................. 18 4.2.4 Thit b u cui ng dy OLT .............................................................. 19 4.2.5 Thit b u cui mng ONU/ONT ............................................................ 20 5 Cc c tnh c bn ca GPON .................................................................................... 20 5.1 Tc bit ............................................................................................................. 20 5.2 Khong cch logic ................................................................................................ 20 5.3 Khong cch vt l ............................................................................................... 21 5.4 Khong cch si quang chnh lch ...................................................................... 21 5.5 T l chia ............................................................................................................... 21 6 Cu trc phn lp ca mng quang GPON .................................................................. 21 6.1 Lp ph thuc phng tin vt l PMD .............................................................. 21 6.1.1 Tc tn hiu danh nh ........................................................................... 21 6.1.2 Phng tin vt l v phng thc truyn ................................................. 22 6.1.3 Tc bit.................................................................................................... 22

6.1.3.1 Tc ng xung ............................................................................... 22

6.1.3.2 Tc ng ln .................................................................................... 22 6.1.4 M ha ng dy ...................................................................................... 226.1.5 Bc sng hot ng 23

6.1.5.1 ng xung 23

6.1.5.2 ng ln 236.1.6 Ngun pht ti giao din Old v giao din Oru 23

6.1.6.1 Cc loi ngun pht 23

6.1.6.2 c tnh ph 23

6.1.6.3 Cng sut pht trung bnh 23

6.1.6.4 T l chnh lch logic 24

6.1.6.5 H s phn x ln nht ca thit b o ti bc sng my pht 246.1.7 ng truyn quang gia giao din Old/Oru v giao din Ord/Olu 25

6.1.7.1 Di suy hao 25

6.1.7.2 Suy hao phn x quang nh nht ca mng cp ti im tham chiu R/S

bao gm cc connector 25

6.1.7.3 H s phn x ring l gia im tham chiu S v R 256.1.8 B thu ti giao din Ord v Olu 25

6.1.8.1 nhy thu nh nht 25

6.1.8.2 Mc qu ti nh nht 26

6.1.8.3 Mt mt ng truyn quang ln nht 26

6.1.8.4 Khong cch logic ln nht 26

6.1.8.5 Khong cch logic chnh lch ln nht 26

6.1.8.6 H s phn x ln nht ca b thu thit b o ti bc sng my thu 26

6.1.8.7 Chnh lch mt mt ng truyn quang 26

6.1.8.8 Hiu nng Jitter 26

6.1.8.9 Kh nng chng cc bit lin tip ging nhau (CID immunity) 27

6.1.8.10 Kh nng chu cng sut phn x 27

6.1.8.11 Cht lng truyn dn v hiu nng li 27

6.2 Lp hi t truyn dn GTC 27

6.2.1 Tng quan 27

6.2.2 Ngn xp giao thc trong mt phng iu khin/qun l (C/M planes) 29

6.2.3 Ngn xp giao thc trong mt phng ngi dng 30

6.2.4 Cc chc nng chnh h thng GTC 32

6.2.4.1 iu khin truy nhp phng tin (Media access control flow) 32

6.2.4.2 ng k ONU 33

6.2.5 Cc chc nng ca cc phn lp trong h thng GTC 33

6.2.5.1 Phn lp ng khung GTC (GTC framing sub-layer) 33

6.2.5.2 Phn lp thch ng GTC v giao din vi cc thc th lp trn 33

6.2.6 Dng lu lng v cht lng dch v QoS 34

6.2.6.1 Mi lin h gia GTC v qun l d liu ngi dng 34

6.2.6.2 Khi nim cp pht ti nguyn ................................................................ 34

6.2.6.3 m bo cht lng dch v QoS ........................................................... 35 6.2.7 Cp pht bng tn ng DBA .................................................................... 36

6.2.7.1 Yu cu cp pht bng tn ng ............................................................. 36

6.2.7.2 Cc loi T-CONT v tham s hot ng ................................................. 37

6.2.7.3 Hot ng DBA ....................................................................................... 37

6.2.7.4 Kha cnh qun l .................................................................................... 38 6.2.8 Cu trc khung GTC .................................................................................. 38

6.2.8.1 Cu trc khung ng xung .................................................................. 39

6.2.8.2 Cu trc khung ng ln ....................................................................... 40 7 Bo v i vi phn mng quang th ng PON ......................................................... 41 7.1 Cc dng chuyn mch bo v ............................................................................. 41 7.2 c im v cu hnh mng GPON kp .............................................................. 42 7.2.1 Cc kiu cu hnh chuyn mch ................................................................. 42 7.2.2 Cc c im .............................................................................................. 45 7.3 Cc yu cu i vi chuyn mch bo v ............................................................ 45 7.4 Cc trng thng tin yu cu trong khung OAM ................................................ 45 7.5 Bo mt ................................................................................................................ 45 8 Ph lc A - Cc thng s giao din quang ng xung tc 1244 Mbit/s ............. 46 9 Ph lc B - Cc thng s giao din quang ng xung tc 2488 Mbit/s ............. 47 10 Ph lc C Cc thng s giao din quang cho ng ln tc 155 Mbit/s ................ 48 11 Ph lc D Cc thng s giao din quang cho ng ln tc 622 Mbit/s ............. 49 12 Ph lc E- Cc thng s giao din quang cho ng ln tc 1244 Mbit/s ............. 51

13 Ph lc F Cc thng s giao din quang cho ng ln tc 1244 Mbit/s s dng

c ch nh mc cng sut pht cho ONU ........................................................................ 53 14 Ph lc G Mt n s mt cho tn hiu ng xung ............................................ 54 15 Ph lc H Mt n s mt cho tn hiu ng ln ................................................. 55 16 Ph lc I Jitter i vi ONU ..................................................................................... 56Chuyn mng truy nhp quang n thu bao GPON

1 Gii thiu phm vi v l do la chn chuyn

Mng truy nhp quang th ng (PON) bao gm cc ng quang i t nh cung cp dch v c dng chung cho mt s khch hng. S c mt ng quang i n mt nhm khch hng gn nhau v mt a l. Ti y ng quang dng chung ny s c chia tch thnh cc ng quang ring bit i n tng khch hng.

Vi mng PON, tn hiu c truyn bng tia laser v c gi ti ch khng cn cc cu kin in t tch cc trong mng ngoi v. Nh cung cp mng do c th tit kim c chi ph ng k bng vic dng chung cc si quang trong mng ni ht, dng chung thit b trong tng i.

Thng 6/2007 va qua ITU phi hp vi Telcordia t chc th nghim cc thit b mng quang th ng tc gigabit GPON c xy dng da trn khuyn ngh ITU-T G.984. Cng ngh mng quang th ng PON c s dng trong mi trng mch vng ni ht kt ni cho cc khu dn c v khu vn phng vo mng ton quang mt cch hiu qu. Cuc th nghim trnh din kh nng phi hp hot ng ca thit b GPON, y chnh l tnh nng ni tri gip gim chi ph thit b. Cc nh sn xut thit b Alphion, Cambridge Industries Group, Hitachi, Huawei, iamba Networks, LS Cable, PMC-Sierra, Tellabs, Terawave Communications, TXP Corporation, XAVi Technologies, ZTE Corporation cng thc hin trnh din kh nng phi hp hot ng dch v 3 trong 1 triple-play.

B khuyn ngh G.984 ca ITU a ra tiu chun cho mng PON tc gigabit (GPON) l phin bn mi nht i vi cng ngh mng PON. Mng GPON c dung lng mc gigabit cho php cung cp cc ng dng video, truy nhp internet tc cao, multimedia, v cc dch v bng thng rng. Cng vi dung lng mng gia tng, tiu chun mi ny a ra kh nng x l IP v Ethernet hiu qu hn.

Chuyn ny gii thiu v mng truy nhp quang c kh nng h tr bng tn theo yu cu cho cc dch v dnh cho gia nh v doanh nghip vi tc ng xung 1.2 Gbit/s v 2.4 Gbit/s v tc ng ln 155 Mbit/s, 622 Mbit/s, 1.2 Gbit/s v 2.4 Gbit/s da trn tiu chun ITU G.984. Chuyn gii thiu c mng GPON (Gigabit-capable Passive Optical Network) i xng v khng i xng bao gm cc c tnh c bn cn thit da trn yu cu dch v ca nh iu hnh mng.

Mc ch tiu chun G.984.1 l ci thin h thng PON theo tiu chun G.983.1 thng qua cc yu cu v cung cp dch v, cc chnh sch bo mt, tc bit danh nh... m bo tnh lin tc so vi cc h thng trc, tiu chun G.984.1 s duy tr mt s yu cu trong tiu chun G.983.1.

Chuyn a ra cc c tnh c bn v h thng GPON thc hin lp vt l v lp hi t truyn dn. Cc c tnh ny bao gm mt s v d v dch v, giao din mng ngi dng UNI (User Network Interfaces) v giao din nt dch v SNI (Service Node Interfaces) v t a ra cu hnh trin khai chnh.

Trang 5/56Chuyn mng truy nhp quang n thu bao GPON

2 Gii thiu mng truy nhp quang ti thu bao (FTTH) v GPON

2.1Khi nim v u im FTTH

Trc y cc h thng mng truy nhp c s dng ch yu l cp ng, ng dng cho cc dch v c lu lng thp. Vic s dng cp ng c nhng li ishc nh chi ph thp, kh nng lp t v trin khai n gin. Tuy nhin, cp ng c nhiu hn ch nh bng thng nh, kh nng chng nhiu km, suy hao ln, phm vi truyn nh.

Cng ngh truyn dn bng cp quang khc phc hon ton cc nhc im ny. Truyn dn bng cp quang khng b nhiu do tn hiu c truyn bng nh sng, suy hao nh, phm v truyn dn gp hng chc ln so vi cp ng v c bit l bng thng ca cp quang c th ln ti hng trm GHz p ng c hon ton nhu cu truyn dn.

Nhng nm gn y do s pht trin ca cng ngh lm cho vic sn xut cp quang d dng v gi thnh ca cp quang cng nh cc thit b u ni cp h, do vy cp quang c s dng rng ri. Thc t ti Vit nam cng nh trn th gii l cc mng li hu ht l mng quang nhng mng truy nhp vn ch yu s dng cp ng. Mng cp quang truy nhp vn cn nh l v mi ch c trin khai ch yu cc nc c nn cng ngh thng tin pht trin nh M, Hn Quc, Nht Bn....

Tuy nhin vi s bng n v nhu cu bng thng hin nay, vic trin khai mt h thng mng truy nhp quang n tng h gia nh l mt xu th tt yu. chnh l mng FTTH Fiber to the home.

2.2Kin trc v thnh phn ca mng PON

Mng FTTH bao gm cc ng quang i t nh cung cp dch v c dng chung cho mt s khch hng. S c mt ng quang i n mt nhm khch hng gn nhau v mt a l. Ti y ng quang dng chung ny s c chia tch thnh cc ng quang ring bit i n tng khch hng.

Mng truy nhp quang th ng PON l kiu mng im-a im. Mi khch hng c kt ni ti mng quang thng qua mt b chia quang th ng, v vy khng c cc thit b in ch ng trong mng phn chia v bng thng c chia s t nhnh n ngi dng. Tn hiu ng xung c pht qung b ti cc thu bao, tn hiu ny c m ha trnh vic xem trm. Tn hiu ng ln c kt hp bng vic s dng giao thc a truy nhp phn chia theo thi gian. OLT s iu khin cc ONU s dng cc khe thi gian cho vic truyn d liu ng ln.

Trong mng PON, OLT l thnh phn chc nng chnh ca h thng t tng i. ONU l thit b t pha ngi dng.ONU kt ni ti OLT bng cc si quang v khng c cc thnh phn ch ng gia. B chia tn hiu (splitter) l thnh phn rt quan trng cua h thng, theo tiu chun ITU G.983.1 mt b chia s dng ti a cho 32 khch hng.


Hnh 1 Kin trc mng PON

2.3Cc chun mng PON

C ba loi tiu chun chnh cho mng PON nh sau:

ITU-T G.983

o APON (ATM Passive Optical Network): l chun mng PON u tin, da trn cng ngh ATM.

BPON (Broadband PON): l chun da trn APON. N h tr thm cng ngh WDM, bng thng ginh cho ng ln c cp pht ng.. N cng cung cp mt giao din qun l chun OMCI gia OLT v ONU cho php nhiu nh cung cp dch v cng hot ng.

ITU-T G.984

GPON (Gigabit PON) l s nng cp ca chun BPON. y l chun mi nht, h tr tc cao hn, bo mt c tng cng v s a dng, linh hot trong vic la chn giao thc lp 2: ATM, GEM hoc

Ethernet.

IEEE 803.3ah

EPON (Ethernet PON hay GEPON gigabit Ethernet PON): l mt chun ca IEEE/EFM cho vic s dng giao thc Ethernet truyn d liu

So snh cc tiu chun c ch ra trong bng sau:


Cng ngh

BPON (APON)GE-PON

GPON

(EPON)

c tnh

Tc- ng155/622 Mbps1.0/1.0 Gbps

1.25/2.5 Gbps

ln/ng xung

Giao thc c bnATMEthernet

GEM

phc tpCaoThp

Cao

Chi ph

CaoThp

Cha r

T chc tiu chunITU-TIEEE

ITU-T

Tiu chun hon thinRi, 1995Ri, 2004

Ri

Trin khai quy m ln100,000 thu bao1,000,000thuMith

bao

nghim

Khuvctrin khaiBc MChu

Mith

chnh

nghim

Bng 1 So snh cc tiu chun PON

2.4GPON

H thng GPON thng thng gm mt thit b kt cui ng dy OLT (Optical Line Termination) v thit b kt cui mng ONU (Optical Network Unit) hay ONT (Optical Network Termination) c ni vi nhau qua mng phn phi quang ODN (Optical Distribution Network). Quan h gia OLT v ONU l quan h mt-nhiu, mt OLT s kt ni vi nhiu ONU.

B khuyn ngh G.984 ca ITU a ra tiu chun cho mng PON tc gigabit (GPON) l phin bn mi nht i vi cng ngh mng PON. Mng GPON c dung lng mc gigabit cho php cung cp cc ng dng video, truy nhp internet tc cao, multimedia, v cc dch v bng thng rng. Cng vi dung lng mng gia tng, tiu chun mi ny a ra kh nng x l IP v Ethernet hiu qu hn.

Mc ch tiu chun G.984.1 l ci thin h thng PON theo tiu chun G.983.1 thng qua cc yu cu v cung cp dch v, cc chnh sch bo mt, tc bit danh nh... m bo tnh lin tc so vi cc h thng trc, tiu chun G.984.1 s duy tr mt s yu cu trong tiu chun G.983.1.

3 nh ngha v vit tt

3.1nh ngha

Sau y l cc nh ngha c s dng thng xuyn trong ti liu.


Chc nng tng thch AF (Adaptation Function): AF l thit b i km thc hin chuyn giao din thu bao ONU/ONT thnh giao din UNI theo yu cu ca nh cung cp dch v mng hoc chuyn giao din UNI thnh giao din thu bao ONU/ONT. Cc chc nng ca AF ph thuc vo giao din thu bao ONU/ONT v giao din UNI. AF cng c s dng chuyn giao din mng OLT thnh giao din SNI theo yu cu ca nh cung cp mng dch v hoc chuyn i giao din SNI thnh giao din mng OLT.

Khong cch logic: l khong cch ln nht c th t c trong mng truyn dn nu khng tnh n qu cng sut ng truyn quang cho php.

Khong cch si quang chnh lch: Mt OLT s c kt ni ti nhiu ONU/ONT. Khong cch si quang chnh lch l s chnh lch gia khong cch xa nht v khong cch gn nht t ONU n OLT.

Tr truyn dn trung bnh: l trung bnh gi tr tr ng ln v ng xung gia cc im tham chiu, tr ny c xc nh bng cch o tr tng ng truyn 1 vng ng ln v ng xung v chia 2.

Mng truy nhp quang OAN (Optical Access Network): Mng OAN bao gm cc ng link truy nhp dng chung cc giao din mng v c h tr bi h thng truyn dn truy nhp quang.

Mng phn b quang ODN (Optical Distribution Network): thc hin truyn dn quang t OLT ti ngi dng v ngc li, s dng cc cu kin quang th ng.

Thit b kt cui ng dy OLT (Optical Line Termination): cung cp giao din pha mng

Thit b kt cui mng ONT (Optical Network Termination): l thit b ONU cung cp chc nng cng giao din cho ngi dng trong mng FTTH.

Thit b mng quang ONU (Optical Network Unit): cung cp giao din pha ngi dng (trc tip hoc t xa) ca mng OAN v c kt ni ti mng

ODN.

Khong cch vt l ln nht: l khong cch ln nht c th t c trong mt mng truyn dn FTTx in hnh.

Mt phng iu khin/qun l (C/M-plane): x l thng tin iu khin v qun l cho h thng GPON. D liu trn giao din OMCI c chuyn qua mt phng ny.

Cp pht bng tn ng (DBA): l qu trnh ONU (v cc T-CONT lin kt vi chng) yu cu bng tn ng v phng thc kim sot gi tin ri ti OLT hay bo co trng thi b m t cc ONU gi ti OLT, OLT cp pht li bng tn ng ln cho cc ONU ty theo bo co .

Chc nng vn hnh qun l v bo dng (embedded OAM): cung cp cc chc nng OAM cm ng theo thi gian bao gm cp pht quyn, chuyn mch bo mt v cc chc nng lin quan n DBA.


Th tc ng khung chung (GFP): l phng thc to khung v ng gi c p dng cho loi d liu bt k, c ITU-T chun ha.

Ch ng gi GPON (GEM): l phng thc ng gi d liu trong mng GPON. Mc d d liu no cng c th c ng gi nhng c mt s loi d liu ph thuc vo tnh trng dch v. GEM cung cp phng thc giao tip hng kt ni nh ATM. Khi nim v nh dng khung tng t nh th tc ng khung chung.

Mng quang th ng Gigabit (G-PON): GPON l h thng truyn dn quang bng rng t -1-ti- nhiu-im. GPON c th truyn ti mi loi d liu bng cch s dng chc nng phng thc truyn dn ATM hoc GEM.

Phn lp ng khung GTC (GTC framing sub-layer): l mt phn ca phn lp hi t truyn dn GPON TC. Phn lp ny c nhim v nhn ra khung v m t cc phn d liu trong khung.

Cp pht bng tn ng khng bo co trng thi (NSR-DBA): thc hin cp pht bng tn m khng cn bo co t ONU. Tuy nhin n thc hin cp pht bng tn ng bng cch gim st lu lng do chnh OLT thc hin.

Chc nng vn hnh, qun l v bo dng lp vt l (PLOAM): N cung cp chc nng qun l mng PON nh nh mc, kch hot ONU, thit lp knh qun l OMCC v truyn ti cnh bo.

Cng (port): Cng l n v c ghp knh trn mt T-CONT trong GEM. Mt hoc nhiu cng c th c xc nh trn mt T-CONT. D liu c truyn gia OLT v ONU qua cc cng. Cng tng tng vi knh o/ng o trong ATM. Mi cng c nhn dng bi nhn dng cng Port-ID c xc nh trong

GEM.

Cp pht bng tn ng bo co trng thi (SR-DBA): Thc hin cp pht bng tn theo bo co t pha ONU.

Phn lp tng thch hi t truyn dn (TC adaptation sub-layer): l mt phn ca phn lp hi t truyn dn GPON. Phn lp ny c nhim v lc d liu c truyn theo VPI/VCI hoc theo Port-ID. Ngoi ra i vi giao din OMCI, phn lp ny tip thu s khc nhau gia ATM v GEM da trn OMCI cung cp giao din chung cho thc th OMCI

Container truyn dn (T-CONTs): c s dng qun l cp pht bng tn ng ln trong phn mng PON ca lp hi t truyn dn. T-CONT thng c s dng ti u vic s dng bng tn ng ln trong mng PON.

T-CONTs mang cc knh ATM hoc/v cng GEM v bo co trng thi b m ti cc OLT lin kt vi chng.

T-CONTs nhn cc quyn truy nhp (grant) ng, c nhn dng bi Alloc-ID t OLT.

Mt T-CONT c th mang lu lng ATM hoc GEM vi cc mc dch v khc nhau..


Mt T-CONT c th cung cp cho mt hoc nhiu hng i vt l v tng hp chng va mt b m logic duy nht.

Mi bo co trng thi DBA-T-CONT tng kt trng thi ca b m logic ca T-CONT

Mt T-CONT l mt thc th truyn ti trong lp hi t truyn dn thc hin truyn ti trong sut thng tin ca cc lp cao hn t u vo n u ra.

Thng tin i qua mt T-CONT s khng b thay i tr khi c s gim cht lng trong qu trnh truyn.

Mt quyn truy nhp c cp ch lin kt vi duy nht mt T-CONT. Cc T-CONT din ra v mt vt l trong phn cng v phn mm ca ONU..

Lp hi t truyn dn (TC): Lp hi t truyn dn c v tr gia lp phc thuc vt l v cc client ca GPON. Lp ny bao gm phn lpwps ng khung GTC v phn lp thch ng hi t truyn dn.

Mt phng ngi dng (U-plane): x l d liu ngi dng trong h thng GPON. U-plane cung cp giao tip gia cc client ATM v client GEM

3.2Cc ch vit tt

AALATM Adaptation LayerLp tng thch ATMABRAvailable Bit RateTc bit kh dngAFAdaptation FunctionChc nng tng thchAlloc-IDAllocation IdentifierNhn dng cp phtANAccess NodeNt truy nhpANIAccess Node InterfaceGiao din nt truy nhpAPDAvalanche PhotodiodeDiode quang kiu thcAPONATMoverPassiveOpticalATM qua mng quang th ng

Network

APSAutomatic Protection SwitchingChuyn mch bo v t ngATMAsynchronous Transfer ModeCh truyn khng ng bBERBit Error RatioT l li bitBIPBit Interleaved ParityBit chn l xen kBRIBasic Rate InterfaceGiao din tc c bnBWmapBandwidth Mapnh x bng tnC/MControl/Management planesMt qun l/iu khinplanes

CBRConstant Bit RateTc bit c nhCIDConsecutive Identical DigitS ging nhau lin tip

Trang 11/56

Chuyn mng truy nhp quang n thu bao GPON

CPLChange Power Level

Mc cng sut thay i

CRCCyclic Redundancy Check

Kim tra li vng d

DACTDeactivate (ONU-ID)

B kch hot

DBADynamic Bandwidth AssignmentCp pht bng tn ng

DBRDeterministic Bit Rate

Tc bit xc nh

DBRuDynamicBandwidthReportBo co bng tn ng ng

upstream

ln

DFDeactivate Failure

Li b kch hot

DFBDistributed FeedBack laser

Laser feedback phn b

E/OElectrical/Optical

in/quang

FECForward Error Correction

Sa li

FTTBFibre to the Building

Mng quang n ta nh

FTTCab/CFibre to the Cabinet/Curb

Mng quang n t cp

FTTHFibre to the Home

Mng quangnhgia

nh/thu bao

GEMG-PON Encapsulation Mode

Ch ng gi GPON

GFPGeneric Framing Procedure

Th tc ng khung chung

GFRGuaranteed Frame Rate

Tc khung m bo

GPMG-PONPhysicalMediaLp ph thuc vt l GPON

(Dependent)

GPONGigabit-capable Passive OpticalMng quang th ng gigabit

Network

GTCGPON Transmission ConvergenceLp hi t truyn dn GPON

HECHeader Error Control

Kim tra li tiu

LCDLoss of Cell Delineation

M t mt gi

LCDALoss of Channel Delineation forM t mt knh cho ATM

ATM

LCDGLoss of Channel Delineation forM t mt knh cho GEM

GEM

LCFLaser Control Field

Trng iu khin laser

LIMLine Interface Module

Module giao din ng dy

LTLine Terminal

u cui ng dy

MDUMulti-dwelling Unit

n v gi tin nhiu a ch

MLMMulti-Longitudinal Mode

Ch a chiu dc

MPNMode Partition Noise

Nhiu chia mode

NRZNon Return to Zero

M ng dy NRZ

NSR-DBANon Status Reporting DBA

Cp pht bngtnkhngbo


co trng thiNTNetwork Termination

Kt cui mngO/EOptical/Electrical

Quang/inOAMOperation,Administration andVn hnh, qun l v bo dng

Maintenance

OANOptical Access Network

Mng truy nhp quangODFOptical Distribution FrameGi phn phi quangODNOptical Distribution NetworkMng phn phi quangOLTOptical Line Termination

Thit b kt cui ng dyOMCCONU ManagementandControlKnh iu khin v qun l

Channel

ONUOMCIONU ManagementandControlGiao din iu khin v qun l

Interface

ONUONTOptical Network TerminationThit b kt cui mng quangONUOptical Network Unit

Thit b kt cui mng quangONU-IDONU Identifier

Nhn dng thit b kt cui

mng quangOpSOperations System

H iu hnhORLOptical Return Loss

Suy hao phn x quangPCBdPhysicalControlBlockKhi iu khin vt l ng

downstream

xungPCRPeak Cell Rate

Tc gi nhPDUProtocol Data Unit

n v bn tin giao thcPEEPhysical Equipment Error

Li thit b vt lPINPhotodiodewithoutinternalDiode quang khng thc ni

avalanche

PlendPayload Length downstreamChiu di ti tin ng xungPLIPayload Length Indicator

Ch th chiu di ti tinPLOAMPhysical Layer OAM

OAM lp vt lPLOAMdPLOAM downstream

OAM lp vt l ng xungPLOuPhysical Layer Overhead upstreamTiu lp vt l ng lnPLSuPowerLevelling

SequenceChui mc cng sut ng ln

upstream

PONPassive Optical Network

Mng quang th ngPort-IDPort Identifier

Nhn dng cngPOTSPlain Old Telephone ServiceDch v in thoi truyn thngPRBSPseudo Random Bit SequenceChui bi gi ngu nhin


PRIPrimary Rate Interface

Giao din tc chnhPSTNPublicSwitchedTelephoneMng din thoi chuyn mch

Network

cng cngRMSRoot Mean Square

Cn qun phngSDHSynchronous Digital HierarchyMng s ng bSLMSingle-Longitudinal ModeCh n chiu dcSNSerial Number

S seriSNIService Node Interface

Giao din nt dch vSOASemiconductor Optical AmplifierB khuch i quang bn dnSR-DBAStatus Reporting DBA

Cp pht bng tn ng bo co

trng thiTCTransmission ConvergenceHi t truyn dnT-CONTTransmission Container

Container truyn dnU planeUser plane

Mt phng ngi dngUNIUser Network Interface

Giao din mng-ngi dngVCVirtual Channel

Knh oVCIVirtual Channel IdentifierNhn dng knh oVPVirtual Path

ng oVPIVirtual Path Identifier

Nhn dng ng oWDMWavelength Division MultiplexingGhp knh phn chia theo bc

sng

4 Kin trc mng truy nhp quang

4.1Kin trc mng

Hnh 2 Kin trc mng cho thy kin trc mng GPON vi quy m t mng quang n h gia nh FTTH (Fiber to the Home) n mng quang n ton nh FTTB (Fiber to the Building) n mng quang n t cp FTTCab (Fiber to the Cabinet). Mng truy nhp quang OAN c s dng chung cho mi kin trc mng trong hnh 1 to iu kin xy dng mt mng truy nhp quang trn ton cu. Phn quang ca mng c th bao gm cc phn t th ng hoc b ng v kin trc mng ny c th l im-im hoc im-a im.


Hnh 2 Kin trc mng

Trong hnh:

UNI l giao din gia mng vi ngi dng

SNI l giao din gia OLT vi mng li

S khc nhau chnh gia cc dch v FTTB, FTTCab v FTTH l dch v cung cp khc nhau, v vy trong ti liu ny cc dch v ny s c xem xt tng ng nhau.

4.1.1 FTTB

Dch v mng quang n ta nh bao gm hai trng hp: dnh cho khu vc chung c MDU (multi-dwelling units) v dnh cho khu vc doanh nghip. Mi trng hp ny li bao gm cc tiu ch dch v nh sau:

FTTB cho MDU

Bao gm cc dng dch v nh sau:

Dch v bng rng khng i xng (dch v broadcast s, video theo yu cu, download file ...)

Dch v bng rng i xng (broadcast ni dung, email, trao i file, o to t xa, khm bnh t xa, chi game trc tuyn...)

Dch v in thoi truyn thng v ISDN: mng truy nhp phi h tr mt cch linh hot cung cp cc dch v in thoi bng hp.

4.1.1.2FTTB cho doanh nghip


Dch v bng rng i xng (broadcast ni dung, phn mm nhm, email , trao i file...)



- ng thu knh ring: mng truy nhp phi h tr mt cch linh hot cung cp dch v thu knh ring vi cc mc tc khc nhau.

4.1.2 FTTC v FTTCab





Cc dch v mng trc xDSL.

FTTH





4.2Cu hnh mng tham chiu

M hnh mng GPON FTTx c ch ra trong hnh 3.

Hnh 3 M hnh tham chiu cho mng GPON

Trong hnh:

WDMModule ghp knh quang theo bc sng

NEThit b mng s dng bc sng khc so vi OLT v ONU

Trang 16/56

Chuyn mng truy nhp quang n thu bao GPON

AFChc nng tng thch (c th bao gm trong thit b ONU)SNIGiao din nt dch vUNIGiao din mng ngi dngSim trn si quang ngay sau OLT hoc im kt ni quang ONURim trn si quang ngay trc ONU hoc im kt ni quang OLTA/BNu chc nng AF bao gm trong ONU th im ny khng cn thit.

Nu WDM khng c s dng cc im ny khng cn thit

Giao din quang ti im tham chiu R/S gia ONU v ODN i vi ng ln gil Oru, i vi ng xung gi l Ord. Giao din quang ti im tham chiu S/R gia OLT v ODN i vi ng ln gi l Olu, i vi ng xung gi l Old. Cc giao din c th hin trong hnh sau.

Hnh 4 Cu hnh vt l chung ca mng phn b quang ODN

4.2.1 Giao din nt dch v SNI

Giao din nt dch v SNI l giao din gia mng truy nhp v mt nt dch v. Nu pha mng truy nhp-giao din nt dch v v nt dch v-giao din nt dch v khng cng mt a im th kt ni t xa gia mng truy nhp v nt dch v c th c s dng bi ng truyn ti trong sut. Trong thit b OLT s bao gm giao din

Cc v d v giao din nt dch v c ch ra trong bng 2.


SNIGiao din vt lDch v

1000BASE- X (IEEE802.3)-EthernetITU-T Rec. G.965V5.2POTS, ISDN (BRI), ISDN

(PRI)ITU-T Rec. G.703PDHDS3, ATM, E1, E3ITU-T Rec. G.957STM-1,4,16E1. ATMANSI T1.107PDHT1, DS3ANSI T1.105.06,OC3, OC12T1, DS3, ATMANSI T1.117

Lu : Mt s dch v i km trong GPON nhng khng c giao din nt dch v ring

Ct dch v cho thy cc dch v m giao din vt l c th h tr c

Bng 2V d giao din nt dch v SNI v cc dch v

4.2.2 Giao din mng ngi dng UNI

Thit b ONU/ONT bao gm giao din UNI v thit b OLT bao gm giao din SNI nh ch ra trong hnh 2. Giao din UNI ty thuc vo dch v do nh khai thc mng cung cp. V d v giao din UNI c ch ra trong bng sau.

UNIGiao din vt lDch v

10BASE-T (IEEE802.3)-Ethernet

100BASE-TX (IEEE802.3)-Ethernet

1000BASE- T (IEEE802.3)-Ethernet

ITU-T Rec. I.430-ISDN (BRI)

ITU-T Rec. I.431-ISDN (PRI), T1, ATM

ITU-T Rec. G.703PDHDS3, ATM, E1, E3

ITU-T Rec. I.432.5Giao din kim loi 25 Mbit/sATM

ITU-T Rec. G.957STM-1,4ATM

ANSI T1.102, ANSI T1.107PDHT1, DS3

Bng 3 V d giao din ngi dng-mng UNI v cc dch v

4.2.3 Cc dch v

GPON c xy dng cung cp tt c cc dch v hin c v c cc dch v mi cho cc thu bao gia nh v doanh nghip s dng do kh nng truyn bng rng ca mng. Cc dch v c th do cc nh khai thc mng cung cp s ty thuc vo cc iu kin quy ch ring ca tng th trng i vi nh khai thc mng.


4.2.4 Thit b u cui ng dy OLT

Thit b u cui ng dy OLT (optical line terminal) c kt ni ti mng chuyn mch qua cc giao din chun. V pha mng phn phi, OLT bao gm cc giao din truy nhp quang theo tiu chun GPON v tc bit, qu ng truyn, jitter,... OLT gm ba phn chnh sau y:

Chc nng giao din cng dch v (service port Interface Function);

Chc nng u ni cho (cross-connect function);

Giao din mng phn phi quang (ODN interface)

Cc khi chc nng chnh ca OLT c m t trong Hnh 5 S khi chc nng

OLT.

Hnh 5 S khi chc nng OLT

a. Khi li PON (PON core shell)

Khi ny gm hai phn, chc nng giao din ODN c m t trong mc sau v chc nng ni t truyn dn (PON TC - Transmission Convergence) bao gm khung tn hiu, iu khin truy nhp phng tin, OAM, DBA v qun l ONU. Chc nng PON TC bao gm khung tn hiu, iu khin truy nhp phng tin, OAM, DBA v qun l ONU. Mi PON TC la chn mt phng thc truyn dn nh ATM, GEM hoc c hai.

b. Khi u ni cho (cross-connect shell)

Khi u ni cho cung cp ng truyn gia khi PON v khi dch v. Cng ngh kt ni ph thuc vo cc dch v, kin trc bn trong OLT v cc yu t khc. OLT cung cp chc nng u ni cho ty thuc vo phng thc truyn dn la chn (GEM, ATM hay c hai).

c. Khi dch v (service shell)

Khi thnh thc hin chuyn i gia cc giao din dch v v giao din khung TC ca phn mng PON.


4.2.5 Thit b u cui mng ONU/ONT

Hu ht cc khi chc nng ca ONU tng t nh cc khi chc nng ca OLT. Do ONU hot ng vi mt giao din PON (hoc ti a 2 giao din khi hot ng ch bo v), chc nng u ni cho (cross-connect function) c th c b qua. Tuy nhin, thay cho chc nng ny th c thm chc nng ghp v tch knh dch v (MUX v DMUX) x l lu lng. Cu hnh tiu biu ca ONU c th hin trong Hnh 6 S cc khi chc nng ONU. M?i PON TC s la chn mt ch truyn dn ATM, GEM hoc c hai.

Hnh 6 S cc khi chc nng ONU

5 Cc c tnh c bn ca GPON

5.1Tc bit

V c bn, GPON hng ti tc truyn dn ln hn hoc bng 1.2 Gbit/s. Tuy nhin, trong trng hp dch v xDSL khng i xng cho FTTH hoc FTTH th khng cn thit n tc cao nh vy. GPOn nh ngha 7 dng tc bit nh sau:

ng ln 155 Mbit/s, ng xung 1.2 Gbit/s;

ng ln 622 Mbit/s up, ng xung 1.2 Gbit/s;

ng ln 1.2 Gbit/s up, ng xung 1.2 Gbit/s;



ng ln 1.2 Gbit/s up, ng xung 2.4 Gbit/s;

ng ln 2.4 Gbit/s up, ng xung 2.4 Gbit/s.

Khong cch logic

Khong cch logic l khong cch ln nht gia ONU/ONT v OLT ngoi tr khong vt l. Trong mng GPON, khong cch logic ln nht l 60 km.


5.3Khong cch vt l

Khong cch vt l l khong cch vt l ln nht gia ONU/ONT v OLT. Trong mng GPON, c hai ty chn cho khong cch vt l v 10 km v 20 km. i vi vn tc truyn ln nht l 1.25 Gbit/s th khong cch vt l l 10 km.

5.4Khong cch si quang chnh lch

Trong mng GPON khong cch si quang chnh lch l 20 km. Thng s ny c nh hng n kch thc vng ph mng v cn tng thch vi tiu chun ITU-T Rec. G.983.1.

5.5T l chia

i vi nh khai thc mng th t l chia cng ln cng tt. Tuy nhin t l chia ln th i hi cng sut quang pht cao hn h tr khong cch vt l ln hn. T l chia 1:64 l t l l tng cho lp vt l vi cng ngh hin nay. Tuy nhin trong cc bc pht trin tip theo th t l 1:128 c th c s dng.

6 Cu trc phn lp ca mng quang GPON

Cu trc phn lp ca mng GPON c cho trong bng sau:

Phn lp tng tch

Lp hi thi t truyn dn

(TC adaption sub-

truyn dn

layer).

(TC-

Phn lp ng

Transmission

khung GTC

convergence)

(GTC framing sub-

layer)

Lp ph thuc phng tin vt l

(Physical Media Dependence)

Bng 4 Cu trc phn lp mng GPON

Chc nng c th ca mi lp v phn lp c phn tch trong cc mc tip theo.

6.1Lp ph thuc phng tin vt l PMD

Cc thng s ca lp PMD c ch ra sau y v c tham chiu ti cc gi tr trong ph lc t A n F.

6.1.1 Tc tn hiu danh nh

Tc ng truyn l cc tc bi s ca 8 kHz. H thng c chun ha s c cc tc danh nh nh sau (ng xung/ng ln):

1244.16 Mbit/s/155.52 Mbit/s,

1244.16 Mbit/s/622.08 Mbit/s,

1244.16 Mbit/s/1244.16 Mbit/s,


2488.32 Mbit/s/155.52 Mbit/s,

2488.32 Mbit/s/622.08 Mbit/s,

2488.32 Mbit/s/1244.16 Mbit/s,

2488.32 Mbit/s/2488.32 Mbit/s.

Cc thng s trn l cc gi tr trong trng hp xu nht, gi thit hot ng trong nhiu loi iu kin mi trng (nhit , m) v chu nh hng ca yu t thi gian. Cc thng s ny tng ng vi vi cc thng s trong mng quang t c t l li bit BER 1 1010 trong trng hp iu kin suy hao v tn sc ng truyn ln nht.

6.1.2 Phng tin vt l v phng thc truyn

Tn hiu c truyn c hng ln v hng xung bng phng tin truyn dn. Vic truyn dn song hng c thc hin bng cch ghp knh theo bc sng WDM truyn trn mt si quang hoc truyn n hng trn hai si quang.

Tc bit

Tc ng xung

Tc bit tn hiu t OLT ti ONU l 1244.16 hoc 2488.32 Mbit/s. Khi OLT v

u xa ang hot ng tc danh nh ca n th tc ny c theo di bi mt ng h lp 1 vi chnh xc 1 10- 11. Khi u xa hot ng ch t do, tc ca tn hiu ng xung c theo di bi ng h lp 3 vi chnh xc 4.6 10-6. Khi OLT hot ng ch t do, tc ca tn hiu ng xung c theo di bi ng h lp 3 vi chnh xc 3.2 10-5.

Tc ng ln

Tc bit tn hiu t ONU ti OLT l 155.52, 622.08, 1244.16 hoc 2488.32 Mbit/s.

Khi ang trng thi hot ng v c cp quyn, ONU s pht tn hiu vi chnh xc bng chnh xc ca tn hiu thu c ng xung. ONU s khng pht tn hiu khi khng ang trng thi hot ng hoc khng c cp quyn.

6.1.4 M ha ng dy

M ha ng ln v ng xung s dng m NRZ.

Phng thc ngu nhin ha khng c nh ngha trong lp ph thuc vt l. Quy nh s dng mc logic quang l:

pht mc cao cho bit 1

pht mc thp cho bit 0


Bc sng hot ng

ng xung

Di bc sng hot ng cho ng xung trong h thng s dng mt si quang l

1480-1500 nm.

Di bc sng hot ng cho ng xung trong h thng s dng hai si quang l

1260-1360 nm.

ng ln

Di bc sng hot ng cho ng ln l 1260-1360 nm.

6.1.6 Ngun pht ti giao din Old v giao din Oru

Cc thng s cho ngun pht c cho sau y v c tham chiu trong cc ph lc t A n F.

Cc loi ngun pht

Ty thuc vo c tnh suy hao/tn sc cc loi ngun pht c th s dng l laser ch a chiu MLM (Multi-Longitudinal Mode) v laser ch n chiu SLM (Single-Longitudinal Mode). Ty thuc vo tng ng dng s la chn ngun pht thch hp. Ngun pht SLM c th c s dng thay cho ngun MLM m khng lm gim hiu nng ca h thng.

c tnh ph

i vi laser MLM, rng ph c tnh bng cn qun phng (RMS) ln nht ca rng ph trong cc iu kin hot ng chun. rng ph RMS l trung bnh ca cc lch qun phng chun ca phn b ph. Khi o rng ph RMS cn tnh n cc trng hp khng thp hn 20 dB so vi mc nh.

i vi laser SLM, rng ph ln nht c tnh bng rng nht ca nh bc sng trung tm, o t 20 dB thp hn bin ln nht ca bc sng trung tm trong iu kin hot ng chun. Ngoi ra, kim sot nhiu phn chia ch trong h thng SLM, cn xc nh gi tr nh nht ca t l nn bin gii phn chia gia hai ch .

Cng sut pht trung bnh

Cng sut pht trung bnh ti giao din Old v Oru l cng sut trung bnh ca chui s gi ngu nhin c pht vo si quang. Cng sut pht trung bnh c cho di dng mt di cho php ti u ha chi ph v bao gm tt c cc mc cng sut cho php hot ng trong cc iu kin chun, kt ni my pht suy gim, chu suy hao php o v yu t lo ha. Lu , khi o cng sut pht ti giao din quang Oru cn tnh n bn cht pht theo cm ca lu lng ng ln do ONU pht.

6.1.6.3.1 Cng sut pht quang khng c u vo ti my pht


i vi hng ln, ONU s khng pht cng sut vo si quang ti tt c cc khe thi gian m ONU c cp pht nhng ONU c th pht mc cng sut quang nh hn hoc bng cng sut pht khi khng c u vo my pht. ONU s p ng yu cu trong thi gian ca khe thi gian bo v c phn cho n.

T l chnh lch logic

Mc logic quang c quy nh nh sau:

Mc cao cho logic 1

Mc thp cho logic 0

T l chnh lch logic EX c nh ngha nh sau:

EX = 10 log10 (A/B)

Trong A l mc cng sut quang trung bnh ti im gia ca logic 1 v B l mc cng sut quang trung bnh ti im gia ca logic 0.

T l chnh lch logic cho hng ln c p dng cho bit u tin ca cm mo u (preamble) ti bit cui cng ca cm tn hiu.

H s phn x ln nht ca thit b o ti bc sng my pht

S phn x t thit b ONU/OLT t mng cp quang c xc nh bng h s phn x ln nht cho php ca thit b o ti giao din Old/Oru. Thng s ny s tun theo Bng 5 Cc thng s lp ph thuc vt l cho mng quang ODN.

Thng sn vGi tr

Loi cp quangITU-T Rec. G.652

Di suy hao (ITU-T Rec. G.982)dBMc A: 5-20

Mc B: 10-25

Mc C: 15-30

Suy hao chnh lch ng truyndB15quang

Mt mt ng truyn quang ln nhtdB1

Khong cch logic chnh lch ln nhtkm20Khong cch si quang ln nht giakm20im tham chiu S/R v R/S

T l chia nh nhtB gii hn bi suy hao ng truyn v

gii hn a ch ONU. PON s dng cc

b chia th ng (chia 16 hoc 32

ng).

Truyn song hngS dng 1 si quang WDM hoc hai si

quang

Bng 5 Cc thng s lp ph thuc vt l cho mng quang ODN


ng truyn quang gia giao din Old/Oru v giao din Ord/Olu

Di suy hao

C ba mc ca di suy hao c s dng cho mng quang thu ng :

5-20 dB: loi A;

10-25 dB: loi B;

15-30 dB: loi C.

Cc thng s mc suy hao c tnh ton vi cc gi tr thu c trong trng hp xu nht bao gm suy hao do u ni, cc b suy hao quang (nu s dng) hoc do cc thit b quang th ng khc ... bao gm tt c cc trng hp sau:

Thay i cu hnh mng cp trong tng lai (thm cc u ni, tng thm chiu di cp..)

Thay i v hiu nng ca cp quang do cc yu t mi trng

Suy gim ca cc kt ni, suy hao quang (nu s dng) hoc cc thit b quang th ng khc gia im tham chiu S v R

Suy hao phn x quang nh nht ca mng cp ti im tham chiu R/S bao gm cc connector

Suy hao phn x quang ton phn ORL (Optical Return Loss) nh nht ti im tham chiu R/S trong mng ODN phi ln hn 32 dB.

H s phn x ton phn ti im tham chiu S/R cho mt m hnh ODN b chi phi bi cc connector trong gi phn phi quang ODF (Optical Distribution Frame). H s phn x ln nht ca mt thnh phn ring l trong mng l -35dB. H s phn x t 2 connector ODF c th l -32 dB. Tuy nhin ty theo m hnh mng m h s phn x ton phn c th xu hn -32dB.

H s phn x ring l gia im tham chiu S v R

Cc h s phn x ring l trong mng ODN phi tt hn 35 dB.

B thu ti giao din Ord v Olu

nhy thu nh nht

nhy thu nh nht c xc nh bng gi tr nh nht c th chp nhn c ca cng sut thu trung bnh ti im tham chiu R t c t l li bit BER l 10-10. nhy thu cn c tnh n mt mt cng sut do s dng my pht trong iu kin hot ng tiu chun vi t l chnh lch logic, thi gian ln v xung ca xung, suy hao phn x quang ti im tham chiu S, suy gim connector thu vi cc gi tr trong trng hp xu nht. nhy thu khng bao gm mt mt cng sut do tn sc, jitter hoc phn x t ng dn quang, cc yu t ny c tnh ring khi cp pht mt mt ng truyn quang ln nht. Cc yu t lo ha s c tnh ring do cc yu t ny thng l vn gia nh cung cp mng v nh sn xut thit b.


Mc qu ti nh nht

Mc qu ti my thu l gi tr ln nht c th chp nhn c ca cng sut trung bnh thu c ti im tham chiu R t t l li bit BER 10-10. My thu s c mnh nht nh chng li mc cng sut quang tng khi khi ng hoc do xung t c th xy ra khi ang t mc, trong cc trng hp ny th t l li bit 10-10 s khng c m bo.

Mt mt ng truyn quang ln nht

B thu c th chu c mt mt ng truyn quang khng vt qu 1dB khi tnh n suy hao ton phn do phn x, can nhiu gia cc tn hiu, tp m. Trong hng ln cc loi laser c ch ra trong cc ph lc c h s mt mt ng truyn quang nh hn 1 dB qua mng ODN. Nh ch ra trong lu 4 ph lc D v lu 5 ph lc F, vic tng mt mt ng truyn quang ti ng ln do tn sc ti tc 622 Mbit/s (hoc ln hn) c th chp nhn c, trong trng hp mt mt ng truyn quang vt qu 1 dB th s c b bng cch tng cng sut pht nh nht hoc tng nhy thu nh nht.

Khong cch logic ln nht

Khong cch logic ln nht l chiu di ln nht c th t c trong h thng truyn dn khi khng tnh n qu ng truyn quang. Khong cch logic ln nht c o bng km v khng b gii hn bi cc thng s ca lp PMD, nhng b gii hn bi lp hi t truyn dn.

Khong cch logic chnh lch ln nht

Khong cch logic chnh lch ln nht l s chnh lch ln nht v logic gia tt c cc ONU trong cng mng. Khong cch ny c o bng km v khng b gii hn bi cc thng s ca lp PMD, nhng b gii hn bi lp hi t truyn dn.

H s phn x ln nht ca b thu thit b o ti bc sng my thu

S phn x t thit b (ONU/OLT) v pha mng cp c th hin bng h s phn x cho php ln nht ca thit b o ti giao din Ord v Olu.

Chnh lch mt mt ng truyn quang

Chnh lch mt mt ng truyn quang l s khc nhau ng truyn quang gia mt mt ng truyn quang thp nht v mt mt ng truyn quang nh nht trong mt mng ODN. Chnh lch mt mt ng truyn quang ln nht thng l

dB.

Hiu nng Jitter

Cc yu cu v jitter trong mng GPON bao gm cc thng s sau y:

6.1.8.8.1 Truyn Jitter


Cc thng s truyn jitter ch c p dng cho ONU

Hm truyn jitter c nh ngha nh sau:

jitter cua tin hieu duong len UI

tocdobitdu ongxuong

truyen jitter = 20 log10

jitter cua tin hieu duong xuong UI

tocdobitdu onglen

Hm truyn jitter ca ONU c th hin trong ph lc I-1, khi jitter tn hiu sin u vo ln ti mc mt n trong ph lc I-2 c p dng vi cc tham s trong hnh cho mi tc bit.

6.1.8.8.2 To Jitter

Cc thng s to jitter ch c p dng cho ONU.

ONU s khng to ra jitter t nh ti nh ln hn 0.2 Ui ti tc bit 155.52 hoc

622.08 Mbit/s v khng ln hn 0.33 UI ti tc bit 1244.16 Mbit/s, khng c jitter

i vi u vo ng xung v vi bng tn o theo bng trong ph lc t C n E.

Kh nng chng cc bit lin tip ging nhau (CID immunity)

OLT v ONU c kh nng chng cc bit lin tip ging nhau nh c ch ra trong bng t ph lc A n ph lc H.

6.1.8.10 Kh nng chu cng sut phn x

Kh nng chu cng sut phn x l t l cho php ca cng sut trung bnh u vo quang ca giao din Ord v Olu trn cng sut trung bnh quang phn x khi cc nh sng phn x l nh sng nhiu ti giao din Ord v Olu.

Kh nng chu cng sut phn x c nh ngha ti nhy thu nh nht.

6.1.8.11 Cht lng truyn dn v hiu nng li

thit k cu trc khung, phi m bo tiu ca gi tin sao cho t l li bit truyn dn trong khong 10-6 trnh li hoc down h thng. Cc c tnh li ca lp ph thuc vt l trong mi trng mng ni ht c th c xem xt nn p dng c ch sa li i vi cc byte ca tiu .

Cht lng truyn dn trung bnh cn c t l li bit thp hn 10-9 trong ton mngPON.

Lp hi t truyn dn GTC

Tng quan

Ngn xp giao thc cho lp hi t truyn dn GPON (GTC) c minh ha trong Hnh 7 Ngn xp giao thc h thng GTC. Lp GTC bao gm hai phn lp: phn lp ng khung GTC (GTC framing sub-layer) v phn lp tng tch hi t truyn dn (TC adaption sub-layer). Nhn t quan im khc th GTC bao gm mt mt qun l v iu khin C/M thc hin qun l dng lu lng ngi dng, bo mt v cc c tnh OAM v mt mt phng ngi s dng (U-plane) thc hin truyn lu lng ngi dng.

Trang 27/56

OMCI adapterChuyn mng truy nhp quang n thu bao GPON

Trong hnh 7, phn ATM, GEM, OAM v PLOAM trong phn lp ng khung GTC c phn bit theo v tr trong mt khung tn hiu GTC. Ch c phn OAM mang thng tin vn hnh, qun l v bo dng c kt cui ti phn lp ng khung GTC ly cc thng tin iu khin cho phn lp ny v thng tin trong phn OAM c gn trc tip vo tiu ca khung GTC. Thng tin vn hnh, qun l v bo dng lp vt l PLOAM (Physical layer Operation Administration and Maintenance) c x l ti khi PLOAM trong phn lp ny. Cc gi tin dch v SDU (Service Data Unit) trong phn ATM v GEM c chuyn thnh/t gi tin giao thc PDU (Protocol Data Unit) ca phn ATM v GEM ti mi phn lp thch ng hi t tng ng. Ngoi ra cc PDU cn bao gm d liu knh OMCI, c xem xt phn lp hi t ny v c trao i vi thc th giao din iu khin v qun l ONU (OMCI-ONU Management and Control Interface). Cc thc th OAM, PLOAM v OMCI thuc mt qun l v iu khin (C/M plane). Cc SDU ngoi tr phn OMCI v ATM, GEM thuc mt ngi s dng (U plane).

Lp ng khung GTC l trong sut i vi tt c mi d liu c pht v lp ng khung GTC trong OLT l lp ngang cp trc tip vi cc lp ng khung GTC trong

ONU.

Khi iu khin cp pht bng tn ng (DBA control) l khi chc nng chung, c trch nhim cp pht bng tn ng cho ton b cc ONU.

ATM clientOMCIGEM client

PLOAMG-PON Transmission Convergence (GTC) layer

TC adaptation sub-layer

ATM TC adapterGEM TC adapter

DBA control

GTC framing sub-layer

G-PON Physical Media Dependent (GPM) layer

Hnh 7 Ngn xp giao thc h thng GTC

Trong lp hi t GTC, OLT v ONU khng cn thit phi c c 2 ch h tr giao thc ATM hay GEM. Vic nhn dng ch no ang c yu cu ngay khi ci t h thng. ONU thng bo ch lm vic ATM hay GEM thng qua bn tin Serial_Number. Nu OLT c th giao tip vi mt trong s cc ch m ONU a ra th n s tin hnh thit lp knh giao din iu khin v qun l ONU (OMCI) v


thit b ONU s xut hin trong mng. Nu OLT khng h tr ch hot ng m ONU a ra th ONU s c xp vo hng i nhng s c thng bo khng tng thch vi h thng ang hot ng.

6.2.2 Ngn xp giao thc trong mt phng iu khin/qun l (C/M planes)

Mt phng iu khin v qun l trong phn lp GTC bao gm 3 phn:

OAM v PLOAM: qun l cc chc nng ph thuc phng tin vt l PMD v cc lp GTC.

OMCI: cung cp h thng qun l ng b cc lp cao hn (lp dch v)

Knh OAM c thc hin bi cc thng tin trong tiu ca khung GTC. Knh ny c ng truyn vi tr nh truyn cc thng tin iu khin khn cp v mi mu tin u c nh x vo mt trng ring bit trong tiu ca khung GTC. Cc chc nng s dng knh ny bao gm: chc nng cp pht bng thng, chc nng chuyn mch chnh, chc nng bo hiu cp pht bng tn ng. Cc thng tin chi tit v knh ny s c cp n trong mc v chi tit khung GTC.

Knh PLOAM bao gm cc thng tin c dnh ring ch trong khung GTC. Knh ny c dng cho tt c cc thng tin qun l GTC v PMD khc khng c gi qua knh OAM.

Knh OMCI c dng qun l cc lp dch v nm trn lp GTC. GTC cung cp 2 la chn v giao din truyn ti cho lu lng qun l ny l ATM v GEM. Chc nng GTC cung cp phng tin cu hnh cc knh ty chn ny sao cho p ng c kh nng ca thit b bao gm nhn dng lung giao thc truyn ti (VPI/VCI hoc Port-ID).

Cc khi chc nng ca mt C/M c ch ra trong hnh 8.


PLOAMOMCI

TC adaptation sub-layer

OMCI adapter

VPI/VCI

Port-ID

filter

filter

ATM TC adapter

GEM TC adapter

GTC framing sub-layer BW granting

Alloc-ID

Alloc-ID

Embedded

Key switching

DBA

filter

filter

OAM

PLOAM

ATM partition

GEM partition

Frame

partition

header

Multiplexing based on frame location

Hnh 8 Cc khi chc nng trong mt iu khin v qun l

6.2.3 Ngn xp giao thc trong mt phng ngi dng

Lung lu lng trong mt phng ngi dng c xc nh bng loi lu lng (ATM hoc GEM) v tn lung o (VPI) hay nhn dng cng (Port-ID). Hnh 8 tng kt cc nhn dng theo lu lng v theo VPI/Port-ID. Loi lu lng c th hin phn ng xung hoc s nhn dng ng ln (allocation ID hay Alloc-ID) mang d liu. Port-ID gm 12 bit c dng xc nh lung trong trng hp lu lng l GEM. VPI c s dng i vi trng hp lu lng l ATM.

T-CONT l khi truyn dn (transmission container) bao gm nhiu lung lu lng, c xc nh bi nhn dng Alloc-ID. T-CONT c chc nng cp pht bng tn v iu khin QoS bng cch cp pht bng tn vi s khe thi gian khc nhau. Lu lng ATM v GEM khng th c cng nhn dng Alloc-ID.


Hnh 9 Ngn xp giao thc cho mt phng ngi dng

Tng kt cc hot ng trong mi lung lu lng nh sau:

Lu lng ATM trong lp GTC

ng xung, cc t bo ATM c truyn trong phn ATM (ATM partition) ti tt c cc ONU. Phn lp ng gi ONU thu cc t vo v b tng thch hi t truyn dn ATM (ATM TC adapter) lc cc t bo da trn nhn dng ng o VPI. Ch c cc t bo vi VPI thch hp mi c a ti chc nng ATM client.

ng ln, lu lng ATM c truyn trong mt hoc nhiu T-CONTs. Mi T-CONT c lin kt vi mt lu lng ATM hoc GEM duy nht. OLT nhn cc thng tin gn vi T-CONT c nhn dng l Alloc-ID, v cc t bo c chuyn tip ti b thch ng hi t truyn dn ATM (ATM TC adapter) v sau n ATM client.

Lu lng GEM trong lp GTC

ng xung, cc khung GEM c truyn trong phn GEM (GEM partition) v ti tt c cc ONU. Phn lp ng gi ONU lc cc khung v b tng thch hi t truyn dn GEM (GEM TC adapter) lc cc t bo da trn port-ID. Ch c cc


khung c Port-ID thch hp mi c cho chuyn ti chc nng GEM client.

ng ln, lu lng GEM c truyn trn mt hoc nhiu T-CONT. Mi T-CONT c lin kt vi mt lu lng ATM hoc GEM duy nht. OLT nhn cc thng tin gn vi T-CONT, v cc t bo c chuyn tip ti b thch ng hi t truyn dn GEM (GEM TC adapter) v sau n GEM client.

6.2.4 Cc chc nng chnh h thng GTC

Sau y l hai chc nng chnh ca lp hi t truyn dn mng GPON (GTC)

iu khin truy nhp phng tin (Media access control flow)

Lp GTC thc hin iu khin truy nhp cho lu lng ng ln. V c bn cc khung d liu ng s ch ra v tr lu lng ng ln s c php truyn trong cc khung ng ln c ng b vi cc khung ng xung.

Hnh 10 iu khin phng tin trong h thng GTC (one T-CONT per ONU case)

Khi nim iu khin truy nhp phng tin trong h thng GTC c minh ha trong hnh 10. OLT gn cc con tr (pointer) vo khi iu khin vt l ng xung PCBd, con tr ny cho bit thi gian ONU bt u v kt thc vic truyn d liu. Vi cch ny, ch mt ONU c th truy nhp phng tin ti thi im bt k, v khng c xung t trong qu trnh truyn. Cc con tr trong cc byte thng tin cho php OLT iu khin phng tin hiu qu ti bng tn c nh 64 kbit/s. Tuy nhin mt s OLT c th chn cch thit lp cc gi tr cho con tr ti cc tc ln hn v thc hin iu kheienr bng tn bng c ch ng.

Vic iu khin truy nhp phng tin c thc hin trong mi T-CONT tuy nhin trong hnh 9 khng minh ha trng hp ONU ch c 1 T-CONT.


ng k ONU

Vic ng k ONU c thc hin trong th tc discovery t ng. C hai phng thc ng k ONU. Trong phng thc A, s serial ca ONU c ng k ti OLT qua h thng qun l (NMS hoc EMS). Trong phng thc B, s serial ca ONU khng c ng k ti OLT qua h thng qun l.

Cc chc nng ca cc phn lp trong h thng GTC

Phn lp ng khung GTC (GTC framing sub-layer)

Phn lp ng khung GTC thc hin ba chc nng sau y:

1. Ghp knh v phn knh

Cc thnh phn PLOAM, ATM v GEM c ghp knh vo khung TC ng xung ty theo thng tin v ranh gii trong tiu ca khung. Mi thnh phn c trch ra t mt ng ln ty theo ch th trong tiu .

2. To tiu v gii m

Tiu khung TC c to v nh dng trong khung ng xung. Tiu trong khung ng ln c gii m.

3. Chc nng nh tuyn ni b da trn Alloc-ID

nh tuyn da trn Alloc-ID c thc hin i vi d liu n/t b thch ng hi t truyn dn ATM v GEM

Phn lp thch ng GTC v giao din vi cc thc th lp trn

Phn lp thch ng bao gm 3 b thch ng phn lp hi t: b thch ng hi t truyn dn ATM (ATM TC adapter), b thch ng hi t truyn dn GEM (GEM TC adapter) v b thch ng giao din iu khin qun l ONU (OMCI adapter). Cc b thch ng hi t ATM v GEM xem xt cc PDU ca phn ATM v GEM trong phn lp ng khung GTC v nh x cc PDU vo tng phn.

Cc b thch ng cung cp giao din sau y cho cc thc th lp trn:

Giao din ATM

Phn lp ng khung GTC v b thch ng hi t truyn dn ATM lin kt vi n cung cp cc giao din TAM chun theo tiu chun ITU-T Rec. I.432.1 cho cc dch v ATM. Cc thc th lp ATM thng c th c s dng nh l cc

ATM client.

Giao din GEM

B thch ng hi t truyn dn GEM c th c cu hnh tng thch cc khung vo nhiu loi giao din truyn khung khc nhau.

Cc b thch ng cn nhn dng cc knh OMCI theo tn knh o/tn ng o (VPI/VCI) i vi ATM v theo Port-ID i vi GEM. B thch ng OMCI c th trao i d liu knh OMCI cho cc b thch ng ATM TC v GEM TC. B thch ng OMCI nhn d liu t cc b thch ng TC ny v truyn n ti thc th OMCI v chuyn d liu t thc th OMCI ti cc b thch ng TC ny.


6.2.6 Dng lu lng v cht lng dch v QoS

Mc ny a ra mi quan h gia lp GTC v lu lng ngi dng, v cc c im v cht lng dch v QoS do GTC qun l trong mng PON.

6.2.6.1Mi lin h gia GTC v qun l d liu ngi dng

1. Dch v ATM

H thng GTC thc hin qun l lu lng i vi cc T-CONT v mi T-CONT c nhn dng bi 1 Alloc-ID. Mt T-CONT c th bao gm 1 hoc nhiu ng o v mi ng o VP c th bao gm mt hoc nhiu knh o VC. OLT gim st lu lng trn mi T_CONT v thc hin iu chnh vic cp pht bng tn sao cho ti nguyn mng PON c phn b hp l. H thng GTC khng theo di v duy tr cc mi lin h QoS gia cc VP v VC m cc ATM client ti mi u cui ca mng PON s thc hin chc nng ny.

2. Dch v GEM

H thng GTC thc hin qun l lu lng i vi cc T-CONT v mi T-CONT c nhn dng bi 1 Alloc-ID. Mt T-CONT c th bao gm 1 hoc nhiu GEM Port-ID. OLT gim st lu lng trn mi T_CONT v thc hin iu chnh vic cp pht bng tn sao cho ti nguyn mng PON c phn b hp l. H thng GTC khng theo di v duy tr cc mi lin h QoS gia cc Port-ID m cc GEM client ti mi u cui ca mng PON s thc hin chc nng ny.

Khi nim cp pht ti nguyn

Ti nguyn c th c cp pht cho cc lin kt logic theo phng thc tnh hoc ng. Trong trng hp cp pht ti nguyn ng, OLT s kho st tnh trng tc nghn bng cch kim tra cc bo co cp pht ti nguyn ng (DBA) t ONU v/hoc t chnh lung lu lng ti. Do OLT c th cp pht y ti nguyn cho cc ONU. Cc chc nng chnh ca b cp pht ti nguyn ng DBA trong GPON c cho trong bng 6.

G-PON DBA

n v iu khinT-CONT

Nhn dng T-CONTAlloc-ID

n v bo co- T bo ATM i vi phn ATM

- Cc khung c di c nh (mc nh

l 48 bytes) i vi phn GEM

C ch bo coTrng OAM (bo co bng tn ng

ng ln DBRu) trong ch 0 v bo

co trng thi loi T-CONT l phng thc

mc nh.

Bo co DBRu trong ch 1 v 2 v bo

co DBA cua ONU l phng thc ty

chn.

Th tc trao iG-PON OMCI


Lu :

ch 0: gi 2 byte DBRu ch 1: gi 3 byte DBRu ch 2: gi 5 byte DBRu

Chi tit v cc ch c tham chiu n ti liu ITU-T G.984.3 mc8.4.2

Bng 6 Cc chc nng chnh ca G-PON DBA

Trong trng hp cp pht bng tn tnh, OLT s cp pht bng tn theo bng tn cung cp, chi tit phng thc ny tham chiu n ti liu ITU-T G.983.1

m bo cht lng dch v QoS

Chc nng cp pht ti nguyn ng DBA cung cp nhiu loi QoS khc nhau. Lp hi t GPON a ra 5 loi T-CONT vi cc c tnh tng t nh T-CONT trong tiu chun ITU-T G.983.4 nh sau:

T-CONT loi 1: c bng tn c nh, bng tn c dnh ring v c cp pht theo chu k vi tc c nh v tr truyn dn c iu khin. Cc tham s m t v lu lng cho T-CONT loi 1 l bng tn c nh: t trc. T-CONT loi 1 c th p ng vi mi loi QoS. Cc OLT khng h tr DBA c th s dng T-CONT loi 1 m bo QoS. Cc OLT c h tr DBA s dng T-CONT loi 1 ny h tr lu lng thi gian thc. Cc OLT h tr DBA lun cung cp bng tn c nh cho cc kt ni trn T-CONT loi 1 m khng cn kim tra c thng tin cn truyn hay khng.

T-CONT loi 2: c bng tn cung cp c m bo. Bng tn c m bo ngha l bng tn trung bnh c cp pht c nh trong cc khong thi gian xc nh. Bng tn ny khc vi bng tn c nh trong T-CONT loi 1 c iu khin cho mt di tr nh. T-CONT loi 1 m bo tr truyn v s thay i tr v tc truyn cn T-CONT loi 2 ch m bo tc truyn. Ch cc OLT h tr DBA mi h tr T-CONT loi 2. Cc tham s m t v lu lng cho T-CONT loi 2 l: bng tn m bo: t trc. ng dng cho T-CONT loi 2: c th h tr tt c cc mc QoS tr mc 1 (dch v phi thi gian thc).

T-CONT loi 3: c bng tn m bo v bng tn khng m bo. T-CONT loi 3 s c cp pht bng tn tng ng vi bng tn c m bo ch khi n c cc gi tin cn truyn tc tng ng hoc ln hn bng tn c m bo. Bng tn khng m bo s c cp pht T-CONT loi 3 vi bng tn m bo ang yu cu thm bng tn tng ng vi bng tn c m bo ca cc T-CONT ring l trong mng PON, chng hn theo phng thc vng trn Round Robin. Tng bng tn m bo v bng tn khng m bo cp pht cho T-CONT loi 3 khng vt qu bng tn ti a (gi tr t trc). Thng s m t lu lng cho T-CONT loi 3 l: bng tn m bo: t trc, bng tn khng m bo: cp pht ng, bng tn ti a: t trc. ng dng cho T-CONT loi 3: c th h tr tt c cc mc QoS tr mc 1 (dch v phi thi gian thc).


T-CONT loi 4: c n lc cho bng tn tt nht (best-effort) nhng bng tn khng c m bo cung cp. T-CONT loi 4 ch s dng bng tn khng c cp pht c nh, bng tn m bo hay bng tn khng m bo cho cc loi T-CONT khc trong mng PON. Bng tn best-effort c cp pht u nhau cho cc T-CONT loi 4, v d theo phng thc vng trn Round robin, cho ti khi cp pht n bng tn ti a. Thng s m t lu lng cho T-CONT loi 4 l: Bng tn best-effort: cp pht ng, bng tn ti a: t trc.

T-CONT loi 5: c th p ng tt c cc loi QoS c cp trong mng PON. T-CONT loi 4 cn c th c bin i thnh cc loi T-CONT khc. Thng s m t v lu lng cho T-CONT loi 5 l: bng tn c nh: t trc, bng tn m bo: t trc, bng tn khng m bo: cp pht ng, bng tn n lc tt nht: cp pht ng, bng tn ti a: t trc. T-CONT loi 5 c th h tr mi ng dng thi gian thc hay ng dng m bo ti nguyn. C ch truyn cc gi tin trong T-CONT v cc chnh sch cung cp m bo QoS lp ATM ph thuc vo vic trin khai thit b ONU/ONT.

Trong trng hp truyn dn l ATM vic cp pht ti nguyn c thc hin s dng VCC hoc VPC. VCC v VPC c nh dng bi cc thng s m t lu lng v c truyn trong cc T-CONT ty theo yu cu QoS. C ch nh x gia m bo QoS v loi T-CONT do nh iu hnh qun l.

Trong trng hp truyn dn l GEM th cc t bo ATM c thay th bng cc khi tin c chiu di c nh. Cc kt ni GEM c xc nh bng cng c th c nh dng lu lng bi cc thng s m t lu lng v c th c truyn trong mt loi T-CONT.

6.2.7 Cp pht bng tn ng DBA

Trong c ch cp pht bng tn ng, khi cc gi tin GEM c di thay i th s c chun ha thnh cc khi c di c nh.

This clause describes DBA specifications for G-PON. G-PON DBA for ATM is the same as ITU-T Rec. G.983.4 except for management issues, such as negotiation procedure. G-PON DBA for GEM also adopts the same architecture as ITU-T Rec. G.983.4 as the default method. In short, even when variable length packets are supported in GEM, these packets are normalized by the fixed length data block in DBA operations. In short, the number of blocks is mapped into the number of cells in ITU-T Rec. G.983.4.

Yu cu cp pht bng tn ng

Cc chc nng DBA c thc hin i vi mi loi T-CONT. Cc chc nng ny c phn loi thnh cc phn sau:

Pht hin trng thi tc nghn do OLT v/hoc ONU thc hin

Bo co trng thi tc nghn ti OLT

Cp nht bng tn cp pht bi OLT theo cc tham s c cung cp


OLT thc hin cp quyn theo bng tn c cp nht v theo loi T-CONT

Qun l i vi hot ng DBA

DBA cung cp cc tnh nng bo m QoS di dng cc loi T-CONT nh nu phn trn.

Cc loi T-CONT v tham s hot ng

Trong GPON DBA c 5 loi T-CONT nh nu chi tit trn. Mi loi T-CONT c m t bng cc tham s hot ng ring. Tuy nhin n v ca tham s hot ng c ch ra nh sau:

i vi ATM: s lng t bo.

i vi GEM: s lng khi c chiu di c nh.

i vi GEM, khi c chiu di c nh do OMCI tha thun c chiu di mc nh l 48 byte.

Hot ng DBA

Hot ng DBA bao gm 2 ch : DBA bo co trng thi (SR-DBA) v DBA khng bo co trng thi (NSR-DBA) trong mi T-CONT. Chc nng bo co DBA l tu chn i vi ONU. Cc OLT bt buc phi h tr c ch bo co v khng bo co, do vy tt c cc ONU c cung cp cc mc i vi chc nng DBA. Cc ch ny c th hin bng tnh hung dch v v kh nng ca ONU c cho trong bng sau y.

SR ONUNSR ONU

DBA OLTSR-DBA hoc/v NSR-DBANSR-DBA

Bng 7 Tng kt cc ch hot ng DBA

Hot ng ca mi ch c tng kt nh sau:

SR-DBA

bo co trng thi tc nghn ca T-CONT, khi mt T-CONT gi d liu ng ln t ONU ti OLT, s lng t bo hay khi tin trong b m T-CONT c thit lp trong trng DBA ca bo co bng tn ng ln DBRu. Nu OLT khng mun cho php truyn d liu cho T-CONT, OLT c th cp thi gian cho ring bo co DBRu . Tuy nhin, c th c trng hp OLT nhn c bo co nhng khng p dng bo co i vi vic cp nht bng tn. Mt khc, nu mt T-CONT khng th bo co s t bo hay gi tin c lu tr trong b m, n s gi ti OLT mt m s khng c gi tr trong trng DBA. Hnh 10 tng kt cc hot ng DBA. Trong ch ny, vic truyn trng tin DBA trong DBRu l bt buc nu OLT yu cu v nu thiu trng DBA, khun dng ca d liu ng ln khng c nhn ra.

NSR-DBA

OLT nhn dng trng thi tc nghn ca tng T-CONT bng cch gim st dng lu


lng n. Trong ch ny, trng DBA trong DBRu khng c gi i do OLT s khng yu cu. Trong tnh hung ngoi l khi OLT yu cu DBRu th ONU phi gi bn tin ny mc d ni dung thng tin s b OLT b qua.

Hnh 11 Tng kt hot ng SR-DBA

Kha cnh qun l

hot ng c ch DBA c mt s thng s cn c cung cp v tha thun bi cc chc nng qun l. OLT v ONU s dng cc chc nng qun l tha thun v ch hot ng DBA, v p li thch hp vi cc yu cu ca hai bn. Tt c cc thng s DBA s c cung cp v tha thun bi giao din iu khin qun l ONU ca GPON (GPON OMCI).

6.2.8 Cu trc khung GTC

Hnh 12 ch ra cu trc khung hi t truyn dn lp GTC cho ng ln v ng xung.

Hnh 12 Cu trc khung hi t truyn dn lp GTC


Khung ng xung bao gm khi iu khin vt l ng xung (PCBd), phn ATM (ATM partition) v phn GEM (GEM partition). Khung ng ln bao gm nhiu cc cm truyn dn. Mi cm ng ln s bao gm ti thiu l tiu lp vt l PLOu, ngoi ti tin cm ng ln cn c th bao gm phn Oam lp vt l PLOAMu, chui mc cng sut ng ln PLSu v phn bo co bng tn ng ng ln. Khung ng xung cung cp tham chiu thi gian chung cho ton mng PON v cung cp bo hiu iu khin chung cho ng ln.

Khi nim iu khin truy nhp phng tin c minh ha trong Hnh 13 Khi nim iu khin truy nhp phng tin hi t truyn dn lp GTC. Vic sp xp cc trng trong hnh c n gin ha cho vic minh ha.

Hnh 13 Khi nim iu khin truy nhp phng tin hi t truyn dn lp GTC

OLT gi con tr (pointer) trong khi iu khin vt l ng xung PCBd ch ra thi im m mi ONU c th bt u v kt thc vic truyn d liu ng ln. Bng cch ny, ti mi thi im ch c mt ONU duy nht c th truy nhp phng tin v khng c va chm trong qu trnh hot ng bnh thng. Cc con tr c cho di dng n v l byte, cho php OLT iu khin phng tin theo cc mc bng tn c nh 64 kbit/s. Tuy nhin, mt s OLT c th la chn thit lp cc con tr v kch thc khe thi gian theo mc ln nht v iu khin bng tn tt hn thng qua lp lch ng. Hnh 13 ch ra trng hp con tr (pointer) c pht theo th t tng nhng y khng phi l yu cu bt buc ca giao thc.

Cu trc khung ng xung

V d cu trc khung ng xung c cho trong Hnh 14 Cu trc khung ng xung hi t truyn dn lp GTC. Khung c chiu di 125 ms cho c tc d liu 1.24416 Gbit/s v 2.48832 Gbit/s do khung di 19440 byte trong h thng tc


1.24416 Gbit/s v di 38880 byte trong h thng tc . Chiu di ca PCB ng xung l nh nhau cho c hai tc v ph thuc vo s lng cu trc cp pht i vi mi khung.

Hnh 14 Cu trc khung ng xung hi t truyn dn lp GTC

Cu trc khung ng ln

V d cu trc khung ng ln c cho trong Hnh 15 Cu trc khung ng ln

GTC.

Hnh 15 Cu trc khung ng ln GTC

di khung bng di ca khung ng xung i vi cc loi tc . Mi khung bao gm cc truyn dn cho mt hoc nhiu ONU. BWmap (nh x bng tn) thc hin sp xp cc truyn dn ny. Trong qu trnh cp pht bng tn theo s iu khin ca OLT, ONU c th pht t 1 ti 4 loi tiu PON v d liu ngi dng. Cc loi tiu ny nh sau:

Tiu lp vt l ng ln (PLOu);

Qun l vn hnh v bo dng lp vt l ng ln (PLOAMu);

Chui nh mc cng sut ng ln (PLSu);

Bo co bng tn ng ng ln (DBRu).

Hnh 16 Tiu khung ng ln GTC ch ra chi tit ni dung ca cc tiu ny.


Hnh 16 Tiu khung ng ln GTC

OLT s dng trng flag trong Bwmap ch ra thng tin PLOAMu, PLSu hay DBRu s c truyn trong mi ln cp pht bng tn hay khng. Lch truyn cc thng tin ny trong OLT cn phi tnh n nhu cu v bng tn v tr ca cc knh ph thuc khi thit lp tn s truyn dn.

Mi khi mt ONU n lt s dng phng tin mng PON t mt ONU khc, n phi gi mt bn copy mi ca thng tin tiu lp vt l ng ln PLOu. Trong trng hp mt ONU c nhn 2 nhn dng cp pht (Alloc ID) lin tip (thi gian kt thc ca 1 nhn dng nh hn 1 so vi thi gian bt u ca nhn dng tip theo), th ONU s b qua vic gi thng tin PLOu cho nhn dng cp pht th 2. ONU c th b qua vic gi ny nhiu ln bng vi s nhn dng cp pht m OLT cp cho n. Yu cu cp pht quyn truy nhp lin tc gip OLT trnh vic b qua cc khong trng gia cc ln truyn ca cng mt ONU. Cc cp pht truy nhp phi lin tc hoc theo lch trnh nu chng xut pht t hai ONU khc nhau.

Sau tiu truyn dn l d liu ti tin ca ngi dng c gi cho n khi vic cp pht c ch nh bi con tr kt thc (StopTime pointer).

7 Bo v i vi phn mng quang th ng PON

i vi ngi qun tr mng truy nhp, kin trc bo v ca mng GPON cn thit trong vic tng cng tin cy cho mng truy nhp. Tuy nhin, vic trin khai mng bo v cn c xem xt nh mt c ch ty chn v vic ny ph thuc vo iu kin kinh t ca tng nh khai thc mng. Mc ny a ra mt s cu hnh mng bo v kp c th s dng cho h thng GPON.

7.1Cc dng chuyn mch bo v

C hai loi chuyn mch bo v tng t vi chuyn mch bo v trong h thng

SDH:

Chuyn mch t ng

Chuyn mch bt buc

Chuyn mch t ng c kch thch khi pht hin ra cc li nh mt tn hiu, mt

khung, gim tn hiu (t l li bit BER thp hn mc ngng quy nh) ...


Chuyn mch bt buc c kch hot trong qu trnh qun tr mng nh nh tuyn li tuyn quang, thay th si quang...

C hai loi chuyn mch ny u c th thc hin trong mng GPON nu c yu cu tuy y l cc chc nng ty chn. C ch chuyn mch thng c thc hin bi chc nng OAM, do trng thng tin OAM cn c t ch trong khung

OAM.

Hnh 17 M hnh h thng bo v kp m t m hnh h thng bo v kp cho mng truy nhp. Cc phn lin quan n vic bo v trong mng GPON c th l mt phn bo v gia giao din ODN trong OLT v giao din ODN trong ONU qua mng ODN, khng bao gm giao din SNI trong OLT

Figure 3 shows the duplex system model for the access network. The relevant part of the protection in the GPON system should be a part of the protection between the ODN interface in the OLT and the ODN interface in the ONU via the ODN, excluding the SNI redundancy in the OLT.

Hnh 17 M hnh h thng bo v kp

7.2c im v cu hnh mng GPON kp

Mt s kiu h thng GPON kp c cho trong cc hnh t 18 n 2`. Giao thc iu khin cho mi cu hnh s c a ra c lp cho tng loi. V d, h thng kp trong hnh 18 khng yu cu giao thc chuyn mch i vi OLT/ONU v chuyn mch y ch p dng cho si quang. Cn trong hnh 19, cu hnh ny khng yu cu giao thc chuyn mch v chuyn mch ch c thc hin trong

OLT.

7.2.1 Cc kiu cu hnh chuyn mch

Loi A: c th hin trong hnh 18, l cu hnh chuyn mch kp i vi si quang. Trong trng hp ny ONU v OLT l cu hnh n.

Loi B: c th hin trong hnh 19, l cu hnh kp i vi OLT v si quang gia OLT v b chia quang, b chia quang c hai cng u ra/u vo pha OLT. Cu hnh ny gim chi ph nhn i s lng ONU tuy ch c pha OLT l c th khi phc c.

Loi C: c th hin trong hnh 20, l cu hnh kp c pha OLT v ONU. Trong cu hnh ny, vic khc phc s c ti mt im bt k u c th thc hin bng cch


chuyn mch sang h thng standby. V vy, cu hnh kp y c chi ph cao nhng an ton cao.

Loi D: c th hin trong hnh 21. Nu ONU c ci t trong ta nh ca khch hng , c th i dy kp trong ta nh. Ngoi ra, nu mi ONU do mt ngi dng s hu ring, tin cy ca h thng s ph thuc vo tng ngi dng v s lng gii hn cc ONU c th c trong cu hnh kp. Cu hnh ny cho php nhn i mt phn v pha ONU. Hnh 21 cho thy mt v d trong c ONU kp v ONU n. Nguyn tc hot ng nh sau:

S dng hai b chia quang N:2 kt ni b kt cui ng dy LT(0) trong ONU#1 ti b chia N(0) v LT(1) trong ONU#1 ti b chia N(1).

Kt ni LT trong ONU#N ti mt trong cc b chia

S dng hai b chia quang N:2 kt ni LT(0) trong ONU#1 ti b chia

S dng hai b chia quang 2:1 kt ni LT(0) trong OLT ti b chia (0) v LT(1) trong OLT ti b chia (1)

S dng hai b chia quang N:2 v hai b chia quang 2:1 trong mt cng ca b chia (1) c kt ni ti b chia N(0) v mt cng ca b chia (0) kt ni ti b chia N(1)

S dng phng thc ch ch trong c OLT v ONU trnh va chm tn hiu quang t LT(0) v LT(1) trong OLT hoc LT(0) v LT(1) trong ONU#1.

Hnh 18 H thng GPON kp: h thng quang kp


Hnh 19 H thng GPON kp: OLT kp

Hnh 20 H thng GPON kp: h thng kp ton b

Hnh 21 H thng GPON kp: cu hnh kp mt phn


7.2.2 Cc c im

Loi A: Trong trng hp ny, mt tn hiu v mt khung l khng th trnh c trong qu trnh chuyn mch quang. Tuy nhin, tt c mi kt ni gia nt dch v v thit b u cui s c gi li sau khi chuyn mch quang.

Loi B: cu hnh ny yu cu ch ch lnh i vi mch d phng pha OLT. Trong trng hp ny, mt tn hiu hoc mt khung nhn chung l khng th trnh c trong qu trnh chuyn mch. Tuy nhin, tt c mi kt ni gia nt dch v v thit b u cui s c gi li sau khi chuyn mch quang.

Loi C: trong trng hp ny, ch ch nng i vi c mch thu d phng c th thc hin c pha ONU v OLT. Ngoi ra chuyn mch khng va chm (khng c mt khung) cng c th thc hin trong cu hnh ny.

Loi D: loi ny c c im ging loi B.

Cc yu cu i vi chuyn mch bo v

Chc nng chuyn mch bo v nn l chc nng ty chn

C chuyn mch t ng v chuyn mch bt buc c th trong h thng GPON nu cu thit mc d y l cc chc nng ty chn

Mi cu hnh nu trn u c th trin khai mc d y l cc chc nng ty chn

C ch chuyn mch thng c thc hin bi chc nng OAM, v vy, trng thng tin OAM phi c d tr trong khung OAM.

Mi kt ni gia nt dch v v thit b u cui phi c gi sau khi chuyn mch.

Ty theo yu cu cui cng vic trin khai nt dch v POTS yu cu qu trnh mt khung phi nh hn 120 ms. Nu thi gian mt khung di hn khong thi gian ny, nt dch v s ct kt ni v yu cu thit lp li cuc gi sau khi chuyn mch bo v. Do GPON h tr pht trin cc dch v hin ti nh POTS v ISDN, cn phi xem xt thi gian ngt kt ni ny.

7.4Cc trng thng tin yu cu trong khung OAM

Do c tnh tng t nh chuyn mch bo v trong h thng SDH, chuyn mch bo v trong h thng GPON yu cu t hn 10 m s dng trong c ng ln v ng xung nhn dng trng thng tin trong khung OAM. Do vy cn phi xem xt vic nh x trng thng tin trong khung OAM cho chuyn mch bo v.

Bo mt

Do c tnh pht multicast (pht ti nhiu a ch) ca mng PON, GPON cng cn cc c ch bo mt m bo yu cu sau:

Ngn chn ngi dng khc gi m d liu ng xung

Ngn chn ngi dng khc gi mo ONU/ONT hay ngi dng khc

Cho php trin khai vi chi ph hiu qu


8 Ph lc A - Cc thng s giao din quang ng xung tc 1244 Mbit/s

Thng sn vH thng dngH thng dng

1 si quang

2 si quang

B pht OLT Transmitter

(giao din quang Old)

Tc bit danh nhMbit/s

1244.16

1244.16

Bc sng hot ngnm

1480-1500

1260-1360

M ha ng dyNRZ ngu nhinNRZ ngu nhin

S mt n mt pht

Ph lc G

Ph lc G

H s phn x quang nh nht ca ODNdB

Ln hn 32

Ln hn 32

ti giao din Olu v Old (Lu 1 v 2)

Cc loi ODN

A

B

CA

B

C

Cng sut pht trung bnh nh nhtdBm-4

+1

+5-4

+1

+5

Cng sut pht trung bnh ln nhtdBm+1

+6

+9+1

+6

+9

T l chnh lchdB

Ln hn 10

Ln hn 10

Mc chu nh hng ti cng sut mydB

Ln hn -15

Ln hn -15pht ph

Vi Laser SLM rng ln nhtnm

1

1

-20 dB (Lu 3)

Vi Laser SLM T l nn nh nhtdB

30

30

B thu ONU (Giao din quang Ord)

H s phn x ca thit b o ti bcdB

Nh hn -20Nh hn -20sng my thu

T l li bit BER

Nh hn 1010Nh hn 10-10Cc loi ODN

A

B

CA

B

C

nhy nh nhtdBm-25

-2

-26-25

-25

-25

5

Qu ti nh nhtdBm-4

-4

-4-4

-4

-4

(Lu 4)

Kh nng chng cc bit lin tip gingbit

Ln hn 72

Ln hn 72

nhau

Kh nng chng jitter

Ph lc I

Ph lc I

Kh nng chu cng sut phn xdB

Nh hn 10

Nh hn 10

Lu 1 Gi tr H s phn x quang nh nht ca ODN ti giao din Oru v Ord v Olu v Old phi ln hn 20 dB trong cc trng hp c nu trong ph lc tiu chun Appendix I/G.983.1.

Lu 2 Cc gi tr h s phn x b pht ONU cho trng hp H s phn x quang nh nht ca ODN ti giao din Oru v Ord v Olu v Old l 20 dB c m t trong ph lc tiu chun Appendix II/G.983.1.

Lu 3 Gi tr rng ln nht -20 dB v t l nn nh nht c tham chiu ti tiu chun ITU-T Rec. G.957.

Lu 4 Mc qu ti 6 dBm c yu cu trong ODN loi C, gi tr qu ti -4dBm c la chn y dng chung cho b thu ONU trong tt c cc loi ODN.


9 Ph lc B - Cc thng s giao din quang ng xung tc 2488 Mbit/s

Thng snH thng dngH thng dng

v

1 si quang

2 si quang

B pht OLT Transmitter

(giao din quang Old)


2488.32

2488.32

Bc sng hot ngnm

1480-1500

1260-1360


S mt n mt pht

Ph lc G

Ph lc G


Ln hn 32

Ln hn 32


Cc loi ODN

A

B

CA

B

C

Cng sut pht trung bnh nh nhtdBm0

+5

+30

+5

+3

(Lu 4)

(Lu 4)


+9

+7+4

+9

+7

(Lu 4)

(Lu 4)

T l chnh lchdB

Ln hn 10

Ln hn 10

Mc chu nh hng ti cng sut mydB

Ln hn -15

Ln hn -15

pht ph

Vi Laser SLM rng ln nhtnm

1

1

-20 dB (Lu 3)

Vi Laser SLM T l nn nh nhtdB

30

30

B thu ONU (giao din quang Ord)

H s phn x ca thit b o ti bcdB

Nh hn -20

Nh hn -20

sng my thu

T l li bit BER

Nh hn 1010

Nh hn 1010

Cc loi ODN

A

BCA

B

C

nhy nh nhtdBm-21

-21-28-21

-21

-28

(Lu 4)

(Lu 4)

Qu ti nh nhtdBm-1

-1-8-1

-1

-8

(Lu 4)

(Lu 4)

Kh nng chng cc bit lin tip gingbit

Ln hn 72

Ln hn 72

nhau

Kh nng chng jitter

Ph lc I

Ph lc I


Nh hn 10

Nh hn 10



v1 si quang2 si quang


Lu 2 Cc gi tr h s phn x b pht ONU cho trng hp H s phn x quang nh nht ca ODN ti giao din Oru v Ord v Olu v Old l 20 dB c m t trong ph lc tiu chun AppendixII/G.983.1.


Lu 4 Cc gi tr trong bng c gi thit s dng laser DFB cng sut cao cho b pht OLT v b thu da trn APD cho ONU. Khi s dng laser DFB v cng ngh khuch i quang bn dn SOA hoc i t laser cng sut cao hn cho b pht OLT, cho php b thu da trn PIN cho ONU, cc gi tr ny c th l:

Cng sut pht trung bnh ln nht cho b pht OLT: +12 dBm Cng sut pht trung bnh nh nht cho b pht OLT: +8 dBm nhy thu nh nht cho ONU: -23 dBm

Qu ti nh nht cho b thu ONU: -3 dBm

10 Ph lc C Cc thng s giao din quang cho ng ln tc 155 Mbit/s


v

1 si quang

2 si quang

B pht ONU (giao din quang Oru)


155.52

155.52

Bc sng hot ngnm

1260-1360

1260-1360


S mt n mt pht

Ph lc H

Ph lc H

H s phn x ln nht ca thit b o ti bcdB

Nh hn -6

Nh hn -6

sng my pht

H s phn x quang nh nht ca ODN tidB

Ln hn 32

Ln hn 32

giao din Olu v Old (Lu 1 v 2)

Cc loi ODN

A

B

CA

BC


-4

-2-6

-4-2

Cng sut pht trung bnh ln nhtdBm-0

+2

+4-1

+1+3

Cng sut quang pht khi khng c tn hiu udBmNh hn nhy nhNh hn nhy

vo my pht

nht -10

nh nht-10

Cho php pht ln nhtbits

2

2

B cng sut pht ln nhtbits

2

2

T l chnh lchdB

Ln hn 10

Ln hn 10

Mc chu nh hng ti cng sut my phtdB

Ln hn -15

Ln hn -15

ph

Vi Laser SLM rng ln nht -20 dBnm

5.8

5.8



v

1 si quang

2 si quang

Vi laser SLM rng ln nht -20 dBnm

1

1

(Lu 3)

Vi laser SLM T l nn nh nhtdB

30

30

Truyn jitter

Ph lc I

Ph lc I

To Jitter trong di tn 0.5 kHz to 1.3 MHzUI p-p

0.2

0.2

B thu OLT (Giao din quang Olu)

H s phn x ca thit b o ti bc sngdB

Nh hn -20Nh hn -20

my thu

T l li bit BERNh hn 10-10Nh hn 10-10

Cc loi ODN

A

B

CA

B

C

nhy nh nhtdBm-27

-30

-33-27

-30

-33

Qu ti nh nhtdBm-5

-8

-11-6

-9

-12

Kh nng chng cc bit lin tip ging nhaubit

Ln hn 72

Ln hn 72


Nh hn10

Nh hn 10




11 Ph lc D Cc thng s giao din quang cho ng ln tc 622 Mbit/s


1 si quang2 si quang


Tc bit danh nhMbit/s622.08622.08Bc sng hot ng (lu 5)nmMLM loi 1 hocMLM loi 1 hoc

SLM: 1260~1360SLM: 1260~1360

MLM loi 2:MLM loi 2:

1280~13501280~1350

MLM loi 3:MLM loi 3:

1288~13381288~1338


S mt n mt phtPh lc HPh lc H

H s phn x ln nht ca thit b o tidBNh hn -6Nh hn -6bc sng my pht

H s phn x quang nh nht ca ODN tidBLn hn 32Ln hn 32giao din Olu v Old (Lu 1 v 2)



1 si quang

2 si quang

Cc loi ODN

A

B

CA

B

C


1

-1-6

1

-1

Cng sut pht trung bnh ln nhtdBm1

+4

+41

+4

+4

Cng sut quang pht khi khng c tn hiudBmNh hn nhy nhNh hn nhy nh

u vo my pht

nht -10

nht -10

Cho php pht ln nhtbits

8

8

B cng sut pht ln nhtbits

8

8

T l chnh lchdB

Ln hn 10

Ln hn 10

Mc chu nh hng ti cng sut my phtdBLn hn -15

Ln hn -15

ph

Vi Laser MLM rng ln nht -20 dBnmMLM loi 1:1.4MLM loi 1:1.4

(lu 4)

MLM loi 2:2.1MLM loi 2:2.1

MLM loi 3:2.7MLM loi 3:2.7

Vi laser SLM rng ln nht -20 dBnm

1

1


30

30

Truyn Jitter

Ph lc I

Ph lc I

To Jitter trong di tn 0.5 kHz to 1.3 MHzUI p-p

0.2

0.2

B thu OLT (giao din quang Olu)

H s phn x ca thit b o ti bc sngdBNh hn -20Nh hn -20

my thu

T l li bit BERNh hn 10-10Nh hn 10-10

Cc loi ODN

A

B

CA

B

C

nhy nh nhtdBm-27

-27

-32-27

-27

-32

Qu ti nh nhtdBm-6

-6

-11-6

-6

-11

Kh nng chng cc bit lin tip ging nhaubit

Ln hn 72

Ln hn 72


Nh hn 10

Nh hn 10




Lu 4 Cc loi b pht p ng yu cu rng ph hp hn c cho php di bc sng trung tm rng hn. Cc loi laser trn c h s mt mt ng truyn nh quang hn 1 dB qua mng ODN. C th s dng cc loi laser c thng s quang khc nhng phi tha mn cc iu kin sau y:

1) Ton b di bc sng khng vt qu 1260~1360 nm

2) Cc mt mt trong ng truyn quang tng qu 1 dB s c n b bng cch tng cng sut pht nh nht hoc tng nhy thu nh nht.


12 Ph lc E- Cc thng s giao din quang cho ng ln tc 1244 Mbit/s

Thng snH thng dng

H thng dng

v

1 si quang

2 si quang



1244.16

1244.16

Bc sng hot ngnm

1260-1360

1260-1360

M ha ng dyNRZ ngu nhin

NRZ ngu nhin

S mt n mt pht

Ph lc H

Ph lc H

H s phn x ln nht ca thit b o tidB

Nh hn -6

Nh hn -6

bc sng my pht


Ln hn 32

Ln hn 32


Cc loi ODN

A

B

CA

B

C


2

+23

2

+2

(Lu 4)

(Lu 4)


+3

+7+2

+3

+7

(Lu 4)

(Lu 4)

Cng sut quang pht khi khng c tndBmNh hn nhy nh nhtNh hn nhy nh nht

hiu u vo my pht

-10

-10

Cho php pht ln nht (lu 3)bits

16

16

B cng sut pht ln nht (lu 3)bits

16

16

T l chnh lchdB

Ln hn 10

Ln hn 10

Mc chu nh hng ti cng sut mydBLn hn -15

Ln hn -15

pht ph

Vi Laser MLM rng ln nhtnm

(Lu 4)

(Lu 4)

-20 dB

Vi laser SLM rng ln nhtnm

1

1

-20 dB


30

30

Truyn Jitter

Ph lc I

Ph lc I

To Jitter trong di tn 4.0 kHz tiUI p-p

0.33

0.33

10.0 MHz


H s phn x ca thit b o ti bcdBNh hn -20

Nh hn -20

sng my thu

T l li bit BERNh hn 1010

Nh hn 1010

Cc loi ODN

A

B

CA

B

C

nhy nh nhtdBm-24

28

-29-24

28

-29

(Lu 5)

(Lu 5)


Thng snH thng dng

H thng dng

v

1 si quang

2 si quang

Qu ti nh nhtdBm-3

7

-8-3

7

-8

(Lu 5)

(Lu 5)

Kh nng chng cc bit lin tip gingBit

Ln hn 72

Ln hn 72

nhau


Nh hn 10

Nh hn 10


Lu 2 Cc gi tr h s phn x b pht ONU cho trng hp H s phn x quang nh nht ca ODN ti giao din Oru v Ord v Olu v Old l 20 dB c m t trong ph lc tiu chun Appendix II/G.983.1.


Lu 4 Cc loi laser MLM khng h tr khong cch si quang trong Bng 5 Cc thng s lp ph thuc vt l cho mng quang ODN c th c s dng nu khong cch si cp quang trong mng ODN gia im tham chiu R/S v S/R gii hn trong 10 km. Cc loi laser trong ph lc D c th c trin khai h tr khong cch si quang ny vi tc 1244.16 Mbit/s. Cc loi laser ny c p dng cho cc iu kin nh trong lu 4 ca Ph lc D Cc thng s giao din quang cho ng ln tc 622 Mbit/s.

Lu 5 Cc gi tr trong bng c gi thit s dng b thu da trn PIN cho OLT i vi loi A. Ty thuc vo s lng ONU kt ni ti OLT, c th s dng b thu da trn APD cho OLT cho php s dng laser kinh t hn cng vi cc ONU c cng sut pht nh hn. Trong trng hp ny, cc gi tr cho ODN loi A l:

Cng sut pht trung bnh nh nht cho b pht ONU: - 7 dBm Cng sut pht trung bnh ln nht cho b pht ONU: -2 dBm nhy thu nh nht cho OLT: -28 dBm

Qu ti nh nht cho b thu OLT: -7 dBm


13 Ph lc F Cc thng s giao din quang cho ng ln tc 1244 Mbit/s s dng c ch nh mc cng sut pht cho ONU

Thng snH thng dng

H thng dng

v1 si quang

2 si quang


Cc loi ODN

AB

CAB

C


+222

+2

(Lu 2)

(Lu 2)

Cng sut pht trung bnh ln nhtdBm+3+3

+7+3+3

+7

(Lu 2)

(Lu 2)


Cc loi ODN

ABCABC

nhy nh nhtdBm232829232829

(Lu 2)

(Lu 2)

Qu ti nh nhtdBm8131481314

(Lu 2)

(Lu 2)

Lu 1 Bng ny ch ra cc thng s Ph lc E- Cc thng s giao din quang cho ng ln tc 1244 Mbit/s c s thay i do s dng c ch nh mc cng sut pht cho ONU, ngha l cng sut pht ca b pht OUN v nhy v qu ti b thu OLT. Cc thng s v lu khc s p dng gi tr nh trong ph lc E.

Lu 2 Cc gi tr trong bng c p dng vi gi thit s dng b thu da trn PIN cho OLT i vi mng ODN loi A. Ty thuc vo s lng ONU kt ni ti OLT c th trin khai b thu da trn APD cho OLT, cho php s dng cc laser kinh t hn vi cng sut pht thp hn ti ONU. Trong trng hp ny, cc gi tr cho ODN loi A s l:

Cng sut pht trung bnh nh nht cho b pht ONU: - 7 dBm Cng sut pht trung bnh ln nht cho b pht ONU: -2 dBm nhy thu nh nht cho OLT: -28 dBm

Qu ti nh nht cho b thu OLT: -10 dBm

Tc ng ca c ch nh mc cng sut khng nhiu, do gii hn v cng sut nh nht pht m bo s mt (eye-diagram).


14 Ph lc G Mt n s mt cho tn hiu ng xung

1244.16 Mbit/s2488.32 Mbit/s

x1/x40.22/078--

x2/x30.40/0.60--

x3-x2--0.2

y1/y20.20/0.800.25/0.75

B pht

B suy

B chuyn i

B toquang

hao*

quang in **

dng sng

B suy hao s c s dng khi cn thit

Tn s cut-off (tn s suy hao 3 dB) ca b lc bng 0.73 ln tc bit danh nh u ra


15 Ph lc H Mt n s mt cho tn hiu ng ln

155.52 Mbit/s622.08 Mbit/s1244.16 Mbit/s

x1/x40.10/0.900.20/0.800.22/078

x2/x30.35/0.650.40/0.600.40/0.60

y1/y40.13/0.870.15/0.850.17/0.83

y2/y30.20/0.800.20/0.800.20/0.80

B pht

B suy hao

B chuyn i

B toquang

quang in

dng sng

B suy hao s c s dng khi cn thit

Tn s cut-off (tn s suy hao 3 dB) ca b lc bng 0.73 ln tc bit danh nh u ra


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