ftth theo cong nghe gpon

7/22/2019 FTTH Theo Cong Nghe GPON

1/67

HC VIN CNG NGHBU CHNH VIN THNGCSTI THNH PH HCH MINH

KHOA VIN THNG II_____________

NTT NGHIP I HC

CHUYN NGNH: IN T- VIN THNGHCHNH QUY

NIN KHA: 2007-2012

ti:

PHN TICH THI T K MANG FTTH THEO

CNG NGH GPON

M sti: 12407160163

Sinh vin thc hin: HUNH VN T

MSSV: 407160163Lp: 07VA3Gio vin hng dn: Th.S VN VIT EM

01/2012

TP.HCM2012


2/67

HC VIN CNG NGHBU CHNH VIN THNGCSTI THNH PH HCH MINH

KHOA VIN THNG II_____________

NTT NGHIP I HC

CHUYN NGNH: IN T- VIN THNGHCHNH QUY

NIN KHA: 2007-2012

ti:

PHN TICH THI T K MANG FTTHTHEO CNGNGH GPON

M sti: 12407160163

NI DUNG- Chng I: TNG QUAN MNG TRUY NHP FTTH.- Chng II: TM HIU CNG NGH PON.- Chng III: BI TON THIT K FTTH DA TRN CNG NGH GPON.- Chng IV: PHN TICH K T QUA BA I TOAN THI T K

Sinh vin thc hin: HUNH VN TMSSV: 407160163

Lp: 07VA3Gio vin hng dn: Th.S VN VIT EM

01/2012

TP.HCM2012


3/67

MC LC

MC LC .............................................................................................................................

MCLC HNH ..................................................................................................................

MC LC BNG .................................................................................................................

LI MU ..................................................................................................................... 1

CHNG I: TNG QUAN V MNG TRUY NHP FTTH ........................................ 4

1.1. FTTH, AON, PON ...................................................................................................... 4

1.1.1 Cng ngh AON ............................................................................................ 4

1.2. So snh gia AON v PON ........................................................................................ 9

CHNG II: TM HIU CNG NGH PON ................................................................. 11

2.1. BPON chun ITU-G.983 .......................................................................................... 11

2.1.1. Kin trc cc lp .......................................................................................... 11

2.1.2. nh dng khung truyn dn ....................................................................... 13

2.1.2.1. Khung ATM ............................................................................... 14

2.1.2.2. Khung hng xung ................................................................... 15

2.1.2.3. Khung hng ln........................................................................ 16

2.1.3. Bo mt trong BPON ................................................................................... 172.1.4. Chuyn mch bo v trong BPON .............................................................. 18

2.2. EPON chun IEEE-802.3ah ...................................................................................... 19

2.2.1. Kin trc cc lp trong EPON ..................................................................... 19

2.2.1.1. Lp vt l ................................................................................... 20

2.2.1.2. Giao din mi trng Gigabit c lp ....................................... 22

2.2.1.3. Lp lin kt d liu .................................................................... 22

2.2.2. Cu trc khung truyn dn ca EPON......................................................... 232.2.3. Giao thc iu khin a im (MPMC) trong EPON ................................. 24

2.3. GPON chun ITU-G.984 .......................................................................................... 26

2.3.1. Kin trc cc lp trong GPON .................................................................... 26

2.3.1.1. GPON Physical Medium Dependent (PMD) Layer ................... 28

2.3.1.2. GPON Transmission Convergence (GTC) Layer ...................... 29

2.3.2. nh dng khung truyn dn trong GPON .................................................. 30

2.3.2.1. Cu trc khung hng xung ..................................................... 30

2.3.2.2. Cu trc khung hng ln .......................................................... 32


4/67

2.3.2.3. Phn tch mo u ca GEM ...................................................... 34

2.3.3. Phn bbng tn ng (DBA) trong GPON ............................................... 35

CHNG III: BI TON THIT K FTTH DA TRN CNG NGH GPON ........ 36

3.1. Tnh khnng phc v ca mt OLT ....................................................................... 36

3.2. Tnh ton tnh khthi v m hnh khuyn ngh vi b khuch i .......................... 39

CHNG IV: PHN TICH K T QUA BA I TOAN THI T K .................................... 45

4.1. Phn tch bai toan Tnh kha nng phuc vu cu a OLT ............................................. 45

4.2. Phn tch bai toan Tnh kha thi va m hnh khuyn nghi ..................................... 50

4.2.1 Phn tch 1:nh hng ca t l chia ......................................................... 51

4.2.2 Phn tch 2:nh hng ca khong cch t OLT n ONT...................... 54

4.2.3 Phn tch 3: S anh hng cua cng sut pha t ln m hnh trin khai ...... 55

4.2.4 Phn tch 4: Tr ng h p cn chu y khi thit k .......................................... 56

K T LU N ....................................................................................................................... 58

TVIT TT .......................................................................................................................

TI LIU THAM KHO .....................................................................................................


5/67

MC LC HNH

Hnh 1.1: Cu trc AON...................................................................................................... 5

Hnh 1.2: Cu trc AON Ethernet ....................................................................................... 5

Hnh 1.3: Cu trc mng FTTH da trn cng ngh PON .................................................. 6Hnh 1.4: Nguyn l thu/pht ONT ...................................................................................... 8

Hnh 1.5 Cc kiu kin trc ca PON ................................................................................ 8

Hnh 1.6: Vng ODN .......................................................................................................... 9

Hnh 2.1 Kin trc cc lp trong BPON ........................................................................... 12

Hnh 2.2: Cu tru c khung ATM ......................................................................................... 14

Hnh 2.3: Cu tru c khung h ng xung cu a BPON .......................................................... 15

Hnh 2.4: i nh dang cell PLOAM h ng ln ................................................................... 17

Hnh 2.5: M hnh chuyn ma ch bao vtrong PON ......................................................... 19

Hnh 2.6: Kin tru c cac lp trong EPON........................................................................... 20

Hnh 2.7: Cu tru c khung truyn dn cu a EPON .............................................................. 23

Hnh 2.8: Bn tin GATE hng xung .............................................................................. 25

Hnh 2.9: Bn tin REPORT hng ln .............................................................................. 26

Hnh 2.10: Kin tru c cac lp trong GPON ........................................................................ 27

Hnh 2.11 : Phn lp ong khung GTC ............................................................................. 29

Hnh 2.12: Cu tru c khung h ng xung .......................................................................... 30

Hnh 2.13: Cu tru c khung GTC h ng ln ...................................................................... 33

Hnh 2.14: Cu trc khung v mo u ca khung GEM ................................................. 34

Hnh 3.1: S phn b OLT ................................................................................................ 38

Hnh 3.2: M hnh kin tru c 2 tng splitter....................................................................... 40

Hnh 3.3: Lin kt v t l t OLT n ONT ........................................................................ 41

Hnh 3.4: Cc vng suy hao ca si quang ....................................................................... 42

Hnh 3.5: B khuch a i SAO11b ..................................................................................... 44

Hnh 4.1: P-OLT 7432 ....................................................................................................... 46

Hnh 4.2: M hnh 2 .......................................................................................................... 52

Hnh 4.3: M hnh kha thi ................................................................................................. 53

Hnh 4.4: M hnh 3 .......................................................................................................... 55


6/67

MC LC BNG

Bng 2.1: Cc m PTI ....................................................................................................... 34

Bng 3.1: T l chia v cc mc tc in hnh ............................................................. 37

Bng 3.2: Thng s cac loa i connecter.............................................................................. 41

Bng 3.3: Tiu chun ITU-T G.652 v suy hao s i quang ................................................ 42

Bng 3.4: Thng s splitter PLC ....................................................................................... 43

Bng 3.5: Vng bc sng khuch i ca OFA .............................................................. 44

Bng 4.1: Bng suy hao ca splitter.................................................................................. 50

Bng 4.2: Thng s khuyn nghicu a ONT va OLT ......................................................... 51


7/67

SVTH: HUNH VN T LP: 07VTA3 Trang 1

LI MU

Ti Vit Nam, nhu cu s dng dch v Vin thng ngy cng cao do mc sngc nng ln ng thi cng vic v nhu cu gii tr ngy cng i hi cht lng cc

dch v phi khng ngng c tng ln.Chng ta c th ly sgia tng nhu cu vInternet ra lm mt v d. Theo Bo

co Netcitizens Vit Nam nm 2011 ca Cimigo, xt v tc tng trng, Vit Naml quc gia c t ltng trng Internet nhanh nht trong khu vc v nm trong sccquc gia c t l tng trng cao nht trn th gii. Tnm 2000, s lng ngi sdng Internet nhn ln 120 ln. Cch y 10 nm, t l s dng Internet ca Vit

Nam nm cch xa hu ht cc nc Chu khc.

Chnh v nhng nhu cu khng ngng tng ln cng vi yu cu v cht lng

t ra cho Vin thng bi ton tng tc truyn dn.Ngy nay ngi ta quen vi mt cng ngh xut hin t10 nm trc Vit

Nam l ADSL(Asymmetric Digital Subscriber Line ng dy thu bao s bt ixng). ADSL ra i trthnh mt im nhn trong tc truyn dn ti Vit Nam. Tuynhin, hin nay vi yu cu bng thng ngy cng cao th ADSL hu nh ui sc.

Ti Vit Nam, n "a Vit Nam sm tr thnh nc mnh v cng nghthng tin v truyn thng" ca Thtng Chnh ph ti Quyt nh s1755/Q-TTgngy 22/09/2010 chra nh hng, tm nhn cho spht trin ngnh bng rng ti

Vit Nam n nm 2015 l: C bn hon thnh mng bng rng n cc x, phngtrn cnc, kt ni Internet n tt ccc trng hc, t lngi dn s dng Internett trn 50%.

V vy, Trong nm 2010, ngi ta ni nhiu ti vic bng rng di ng m c thl 3G ln ngi s khin cho ADSL phi suy thoi. Nhng theo nhiu chuyn gia, y likhng phi l iu ng lo ngi nht, m i th snh hng trc tip ti nng lc

pht trin ca ADSL trong nm 2011 v cc nm ti li l FTTx (cng ngh truyn dncp quang) v FTTH (Internet cp quang chun). Theo Bo co vin thngVit Nam,

trong nm 2009 trn th gii c 39,4 triu hgia nh s dng FTTH, con snytng ln 51,4 triu h trong nm 2010 v d kin st gn 90 triu hgia nh sdng cp quang vo nm 2012. Don, FTTH sl ngnh kinh doanh ct li ca ccnh cung cp dch v Internet.[8]

Tuy nhin, FTTH vn cn kh khn khi gi cc t hn ADSL nn vic trinkhai ti Vit Nam vn cn nhiu kh khn nht nh.

FTTH l mt trong nhng cng ngh ca FTTx. FTTx l cng ngh mng truynhp s dng ng truyn bng cp quang, cho tc upload v download cao hn v

n nh hn ADSL. FTTx c cc dng: FTTN (Fiber To The Node); FTTC (Fiber ToThe Curb); FTTB (Fiber To The Building); FTTH (Fiber To The Home), c hiu ln


8/67


lt l: Cp quang ti giao im; Cp quang ti t thit b; Cp quang ti ta nh; Cpquang ti tn nh. FTTx c th l mng truyn dn quang thng PON (PassiveOptical Network), trong tt ccc thnh phn quang chng (active) gia tng iCO (Central Office) v ngi s dng skhng cn tn ti m thay vo l cc thit

b quang thng (passive), iu hng lu lng trn mng da trn vic phn

tch nng lng ca cc bc sng quang hc ti cc im u cui trn ng truyn.Mc khc, FTTx cng c thl mng truyn dn quang chng AON (Active Optical

Network).

Trong 4 dng FTTx, th FTTH l hon chnh nht vcng ngh, tiu chun quct v ti u tin ch cho ngi dng. Trong FTTH gm c EPON (Ethernet PON),BPON (Broadband PON) v GPON (Gigabit PON). Xt trn phng din tc truyndn th EPON c tc 1Gbps cho c2 hng (IEEE 802.3 (802.3ah)), BPON c tc 155,52 Mbps cho hng ln, 155,52 hoc 622,08Mbps cho hng xung (ITU-T

G.983). GPON c tc cao nht ln ti 2,488 Gbps cho c2 hng (ITU-T G.984).


9/67


V vy em chn ti lm n tt nghip lPHN TICH THI T K MANGFTTH THEO CNG NGH GPON nhm lm r cc vn chnh sau:

Nu ro c nhng u im cu a PON ng th i lam ro cac chun cng nghcdng trong PON nh BPON , EPON va GPON v tc truyn dn , cu tru c khungtruyn va cac vn c c p trong cac chun c ITU -T va IEEE a ra.

a ra hai bai toan thit k thc t da trn cng nghGPON va phn tch kt quaca hai bi ton y nhm lm r nhng vn nht nh trong vic chn GPON lmcng nghtruyn dn, cung cp di ch vu cho khach hang.

Vi cc ni dung chnh nh trn, hon thnh mc tiu, bi bo co c phnlm cc chng vi cc mc c thnh sau:

Chng I: TNG QUAN MNG TRUY NHP FTTH Chng II:TM HIU CNG NGH PON Chng III:BI TON THIT K FTTH DA TRN CNG NGHGPON Chng IV:PHN TICH K T QUA BA I TOA N THI T K


10/67

CHNG I: TNG QUAN V MNG TRUY NHP FTTH



1.1. FTTH, AON, PONNh ni trn,mng FTTH l mng truy nhp cp quang. Trong c hai

phng n trin khai FTTH l PON v AON. Mi phng n u c u, nhc imring. Mt nhc im rt ln ca mng quang tch cc AON chnh l thit b chuynmch. Vi cng ngh hin ti, thit b chuyn mch bt buc phi chuyn tn hiuquang thnh tn hiu in phn tch thng tin ri tip tc chuyn ngc li truyni. iu ny slm gim tc truyn dn ti a c th trong h thng FTTH. Nu xtvchi ph bo dng thit bth PON li thhn hn khi cc thit b chng trongAON c thay bng cc thit b thng.

ng thi, AON c nhiu u im nh: tm ko dy xa (ln n 70km m khngcn b lp (repeater)), tnh bo mt cao (do vic can thip nghe ln (eavesdropping) trnng truyn gn nh l khng th), ddng nng cp bng thng thu bao khi cn, dxc nh li. Tuy nhin, cng nghAON cng c khuyt im l chi ph cao do: vicvn hnh cc thit btrn ng truyn u cn ngun cung cp, mi thu bao l mtsi quang ring, cn nhiu khng gian cha cp.

Trong khi , vi PON ng truyn chnh s i t thit b trung tm OLT(Optical Line Termination) qua mt thit bchia tn hiu (Splitter) v t thit bnymi ko n nhiu ngi dng (c th chia t 32 64 thu bao). Splitter khng cnngun cung cp, c tht bt ku nn nu trin khai cho nhiu thu bao th chi phgim ng k so vi AON. Do Splitter khng cn ngun nn h thng cng tit kimin hn v khng gian cha cp cng t hn so vi AON. Tuy nhin, PON cng cnhiu khuyt im nh kh nng cp bng thng khi thu bao yu cu (do kin trcim n nhiu im snh hng n nhng thu bao khc trong trng hp dnght bng thng), kh xc nh li hn do mt si quang chung cho nhiu ngi dng,tnh bo mt cng khng cao bng AON (c th bnghe ln nu khng m ha d liu).

1.1.1 Cng nghAONAON c cu trc point to point (im - im), trong kt ni gia khch hng

v CO thng qua thit bu cui ONT l mt kt ni trc tip trn mt si quang.Nhng yu cu kt ni tpha khch hng thng qua s nh tuyn ca cc router,switch, multiplexer ti CO si ra mng dch vbn ngoi. AON s dng bc sng1550nm truyn tn hiu hng xung (tCO n pha khch hng) v 1310nm truyn tn hiu cho hng ln (tpha khchhng n CO). Mt cu trc ca AON ngin c th hin trong Hnh 1.1.


11/67



Hnh 1.1: Cu trc AONMt nhc im rt ln ca mng quang ch ng chnh l thit b chuyn

mch. Vi cng ngh hin ti, thit b chuyn mch bt buc phi chuyn tn hiuquang thnh tn hiu in phn tch thng tin ri tip tc chuyn ngc li truyn

i, iu ny slm gim tc truyn dn ti a c th trong h thng FTTX. Ngoi rado y l nhng chuyn mch c tc cao nn cc thit bny c chi ph u t ln,khng ph hp vi vic trin khai i tr cho mng truy cp.

Vic cng lc xl cc yu cu truy nhp hng ln ca ngi dng ra mng dchvbn ngoi cng nh vic phn tch chuyn lung d liu tcc dch vn ngidng c thgy qu ti trong xl hoc xung t ti OLT ca CO. trnh xung ttn hiu on phn chia tnh cung cp ti ngi dng, cn phi s dng mt thit bin c tnh cht m cho qu trnh ny. Tnm 2007, mt loi mng cp quang ph

bin ny sinh l Ethernet tch cc (Active Ethernet). chnh l bc i u tincho spht trin ca chun 802.3ah nm trong h thng chun 802.3 c gi lEthernet in First Mile (EFM). Mng Ethernet tch cc ny s dng chuyn mchEthernet quang phn phi tn hiu cho ngi s dng. Nh, cpha nh cung cpv khch hng tham gia vo mt kin trc mng chuyn mch Ethernet.

Cc Ethernet Switch sgip gim xung t do x l tn hiu ti CO, n cn cpngun hot ng. Vic chuyn mch ti y da trn lp 2 v lp 3 ca cu trckhung Ethernet. Mng AON nh va ni c thc miu t trong Hnh 1.2.

Hnh 1.2: Cu trc AON Ethernet

Switch quang

Central Office

OLT

ONT

ONT

ONT

OLT

Central office

ONT

ONT

ONT1550 nm

1310 nm


12/67



1.1.2 Cng nghPONPONPassive Optical Network, hay cn c gi l mng quang thng, mt

trong nhng cng nghc s dng trong FTTH. Nh ni trn,trong PON tt ccc thnh phn quang chng (active) gia tng i CO (Central Office) v ngi s

dng skhng cn tn ti m thay vo l cc thit b quang thng (passive), iu hng lu lng trn mng da trn vic phn tch nng lng ca cc bc sngquang hc ti cc im u cui trn ng truyn. PON l cng ngh truy nhp phnchia theo thi gian (TDMA), cc user vi yu cu truy nhp ca mnh c phn bit

bng cc khe thi gian. Cu trc mt mng truy nhp FTTH da trn cng ngh PONc thc trnh by trong Hnh 1.3.

Hnh 1.3: Cu trc mng FTTH da trn cng ngh PON

IP Transport Network

ATM network

PSTN/ TDM network

Video/ audionetwork

SBC management systems

VGW EMS FTTH

EMS

VGW OLTsystem

V-OLT

Videocoupler

SFU ONT

SFU ONT

SBU ONT

MTU

MDU

Split ter 1:N

PON


13/67



Cc thnh phn trong mng FTTH trn cng ngh PON gm c:

OLT (Optical Line Termination)

t trung tm chuyn mch (COCentral Office) c nhim v giao tip vicc mng dch vv kt ni cc yu cu truy nhp ca ngi dng ra cc mngny.

C hai chc nng chnh: truyn d liu t mng dch vv phn phi cho user.ng thi sghp knh cc d liu user trc khi gi ra cc mng dch v.

Dung lng m 1 ONT c th phc vc da trn scard hng xung cami ONT. Nu mi ONT c X card, mi card c Y port, v t lSplitter l 1:Nth sthu bao (s kt ni gia ONT v OLT) c tnh:

Sthu bao = X x Y xN

V d: P-OLT 7432 ca hng Alcatel c 14 card hng xung, mi card c 4port, t lSplitter l 1:64 th sONT c th phc vln n:

14 x 4 x 64=3584 ONT

ONT (Optical Network Termination)

t cui ng dy, trc thit bngi dng ng vai tr nh ngi thngdch cho cc d liu cng nh cc cc yu cu truy nhp tpha ngi dngchuyn ln.

Gm c cc loi:- SFU ONT: l thit bt bn ngoi nh thu bao, dng cho cc hgia nh

nh. C hai giao tip chnh l giao tip POTS cho in thoi v giao tip10/100 bT Ethernet.

- MDU ONT: phc vcho khu dn c, cc ta nh, chung c vi nhiu yucu v dch v. N s cung cp nhiu giao tip hn 1 SFU ONT v h trgiao tip dch v nhiu hn.

- B-ONT: cc ONT loi B thng c cung cp cho cc doanh nghip hocmt cm cc doanh nghip loi nh.N c khnng giao tip dch v triple

play (voice, data, video).

Nu nhn trn phng din vt l, ONT c nhim v chuyn i quang-in tnhiu tnh cung cp dch v xung khch hng v ngc li. Tuy nhin, bcsng hng ln v hng xung khc nhau m tn hiu chc truyn trnm t si quang duy nht nn ti ONT, xen gia qu trnh chuyn i quang insc qu trnh tch/ghp bc sng m c thl bc sng 1310 nm v 1490nm. Qu trnh y c thc din gii trong Hnh 1.4.


14/67



Hnh 1.4: Nguyn l thu/pht ONT

VGW (Voice Gateway): giao tip gia PON ti mng PSTN/TDM.

V-ONT (the Voice ONT): nhn v khuch i/ khi phc tn hiu video t mngVideo/Audio.

EMS (The Element Management Systems): giao tip tcc mng khc n mng liSBC.

ODN (Optical Distribution Network): mng phn phi quang, l tp hp nhiusplitter c sp xp theo kiuCy, Bus, Ringty theo mc ch phc v ca nhcung cp dch v. (Hnh 1.5)

Kin trc thng c s dng hin nay l cu trc hnh cy, nh Hnh1.6.

Hnh 1.5 Cc kiu kin trc ca PON

(a) Kin trc hnh cy (s dng b 1:N) (c) Kin trc vng ring (s dng bghp 2x2)

(b) Kin trc bus (s dng bghp 1:2) (d) Kin trc hnh cy vi mt trung k tha (s dng b chia 2:N)

Bpht

Diplexer

Optical block

B nhn

1310 nm

1490 nm


15/67



Hnh 1.6: Vng ODNVi AON nh ni trn, chiu di ca on ny c th ln ti 70 Km. Tuy

nhin vi FTTH da trn cng nghPON ni chung, khong cch ny h trti a 20Km.

Trong vng ODN, haithnh phn kt ni quan trng nht d nhin l si quang vSpliter.

Splitter: c th hiu y l thnh phn quan trng trong mng quang thng gipgim thiu slng si quang s dng trong truyn dn. Mt si quang t CO s niti splitter v u ra cung cp cho nhiu kt ni. C nhiu t lchia cho splitter nh1:2; 1:4; 1:16; 1:32; 1:64. Tuy nhin trong mng PON hai t lthng c s dng l1:32 v 1:64.

1.2. So snh gia AON v PONTrong phn ny, sphn tch nhng c im gia PON v AON da vo nhng

cc tiu ch: tc h tr ti a, khong cch truyn dn, vn gia s lng siquang s dng vi s thu bao, vn vn hnh bo dng, vn bo mt, vn

cung cp bng thng t rt ra kt lun v sao PON li c la chn trin khaimnh mhn AON.

Xt v khong cch truyn dn v tc htrti aV khong cch: AON c th h trchiu di ti a 70 km v PON h trti a

20 km tOLT n ONT. Tuy nhin, nu xt trn phm vi phc v cho mt vng dn cnh mt thnh ph, th m tOLT pha nh cung cp dch vhon ton c th chn laa im ph hp vi cng ngh PON. Mt khc, mt nh cung cp dch v thngtrin khai nhiu CO nhm ph rng mt vng phc vv nhm mc ch dphng nn

vi khong cch m PON h trhon ton c th trin khai tt trn thc t.

OLT

Splitter 1:4

Splitter 1:16

Splitter 1:16

Splitter 1:16

Splitter 1:16

ONT

n 16 ONT

ti a 20 Km

1310 nm

1490 nm


16/67



V tc htrti a:hin nay AON h trti a t 100 Mbps-1 Gbps cho mithu bao hng xung, trong khi PON vi chun GPON c th h trln n 2,488Gbps cho c2 hng ln v hng xung (nu khng dng splitter, trin khai theo mhnh point to point).

Xt v slng si quang sdng vi sthu bao phc vV s lng si quang s dng, c th thy mt iu r rng rng s si quang

c s dng trong AON nhiu hn s si quang s dng trong PON nu xt v chiudi vi cng sthu bao.

Vn bo dngCc thit bnh Acess Node trong AON cn cp ngun v s lng si quang

nhiu nn AON cn khng gian cha cp ln nu nh trin khai. Trong khi viPON, mt si quang t CO sc chia s vi cc thu bao qua mt thit b thng(khng cn cp ngun) l Splitter.

Vn tng bng thng cho thu baoi vi AON vic tng bng thng cho mt thu bao nu c yu cu th n gin

hn PON rt nhiu. Bi v, vi AON, vic tng bng thng ca mt thu bao khng nhhng n bng thng ti a ca cc thu bao khc, nhng vi PON, nu bng thngca mt thu bao tng ln, ng ngha rng bng thng ti a cho cc thu bao khc sgim xung.


17/67

CHNG II: TM HIU CNG NGH PON



Nu xt vphng thc truy cp trong PON th PON gm c hai loi chnh: truycp phn chia theo thi gian (TDM/TDMA-PON) v truy cp phn chia theo bc sng(WDM/WDMA-PON). Trong bi bo co n Tt nghip ny, cng ngh truy cpPON c phn tch l TDM/TDMA PON vi cc cng ngh APON/BPON (ATMPON/Broadband PON, GPON(Gigabit PON) v EPON(Ethernet PON).

2.1. BPON chun ITU-G.983 Cn c gi l APON (ATM PON). BPON s dng phng php truy nhp phn chia theo thi gian cho cc user,

v s dng cell ATM trong truyn dn. Khong cch truyn dn tcc OLT n cc ONT l t 1020 km. BPON s dng bc sng 1310 nm cho hng ln v 1490 nm cho hng

xung. Ring bc 1550 nm c dng cho lung video hng xung.

Theo khuyn nghG 983.1 nm 1988 quy nh tc download cho BPON l622,08 Mb/s v upload l 155,52 Mb/s. G 983.1 thng 05/2005 qui nh thmtc 1244,16 Mb/s cho hng download. ng thi quy nh r s dng haisi quang cho mt kt ni, tuy nhin v bc sng s dng hng xung v

hng ln khng ging nhau nn trn thc tc thdng chung mt si quang.

C ba loi thit k cho ODN (mng phn phi quang) gia OLT v cc ONTph thuc vo suy hao ca ODN.

- Loi A: 520 dB- Loi B: 1025 dB- Loi C: 1530 dB

2.1.1. Kin trc cc lpBPON gm c hai lp chnh: lp vt l (Physical Medium Layer) v lp hi t

truyn dn (Transmission Convergence Layer). Trong lp hi t truyn dn chia lmhai lp con: lp con thch nghi (Adaptation) v lp con truyn dn PON (PONTransmission).


18/67



Hnh 2.1 Kin trc cc lp trong BPON

Lp vt l: Chnh l ODN, kt ni vt l gia OLT v cc ONT. Lm nhim v chuyn i

quang - in, iu ch, gii iu chcc bc sng 1310 nm, 1490 nm v 1550nm truyn i trn mi trng vt l.

ng b gia truyn v nhn chui tn hiu trn c sng b gia u thu vu pht.

Cc qui nh cho lp vt l:- Khong cch gia OLT v ONU ti a l 20km.- Bc sng 1260 - 1360 nm cho hng ln, 1480 - 1580 nm cho hng

xung.- Tc bit: 155,52 hoc 622,08 Mb/s cho hng xung v 155,52 Mb/s cho

hng ln.

- Dng lu lng: song hng cho tn hiu sv ch duy nht hng xungcho tn hiu analog dng truyn video.

- T l splitter: h trn 1:32, gii hn bi suy hao ca ODN. Lp hi t truyn dn (Transmission Convergence Layer - TC):

Cbn chc nng chnh l phn nh tbo, to chui xc thc kim sot li

header, tch tc tbo v to thch ng cho khung truyn dn. TC gm c hai lpcon:

Lp con thch nghi(Adaptation)l lp ph thuc mi trng truyn dn, ngvai tr chc nng trung gian gia lp vt l v lp cao hn. N s chun b mtcell ATM truyn trong ba bc. u tin a cc mu ng b ti trng

payload. Tip theo, thm vo trng SN (Sequence Number) v SNP(Sequence Number Protection) nhm cho u thu bit nhn c cell ngth thay khng. Cui cng thm vo cc byte gisao cho vng Payload 48

byte v mt cell ATM lun cnh 48 byte Payload v 5 byte Header.

Path layer

Transmissionconvergence

layer

Adaptation

PON

transmission

Physical medium layer Physical

Data Link

Network

Transport

Session

Presentation

Application

OSIBPON


19/67



Lp con truyn dn PON (PON Transmission)chu trch nhim ng b bit,ng bbyte. i vi hng truyn, thc hin ghp header v sau chuynkhung truyn dn xung lp vt l. i vi hng nhn, thc hin tch header,sau chuyn dng cell ATM ln lp cao hn xl.

Lp tuyn (Path layer)BPON da trn ATM l mt kt ni c hng, ng ngha rng phi c mt knh

o trong qu trnh truyn d liu. Lp tuyn squy nh r iu ny bng hai thng strong mt khung ATM l VPI (Vitual Path Identifier) v VCI (Vitual CurcuitIdentifier). Cc cell ATM sc chuyn mch da trn hai thng strn.

2.1.2. nh dng khung truyn dnTy theo tc truyn dn m mt khung BPON cng c cu trc khc nhau. Tuy

nhin chiu di mi khung u l 125 s. i vi tc 155,52 Mb/s s c 56 celltrong mt khung (gm c 53 cell ATM v 2 cell PLOAM - Physical Layer Operation,Administration and Maintenance). i vi tc 622,08 Mb/s (gp 4 ln) th s celltrong mt khung stng ln 4 ln l 224 cell (gm 216 cell ATM v 8 cel l PLOAM).Vi khuyn nghG 983.1 thng 05/2005 c khuyn nghthm mt tc truyn dn hng xung l 1244,16 Mb/s (8 x 155,52 Mb/s) th slng cell sl 448 cell (c 432cell ATM v 16 cell PLOAM).

Cell PLOAM ng vai tr ht sc quan trng trong hot ng truyn dn caBPON. khung hng xng, trong trng hp vic gn bng thng ng (DBA)c thit lp cell PLOAM qui nh cc Grant cho php cc ONT gi mt hay nhiucell k tip n cc TCON. cc khung hng ln, PLOAM cha cc thng tin do ccONT gi cho cc OLT v trng thi hng i, h tr cc OLT trong vic gn bngthng ng.

C hai vn gy nn skhc bit gia khung hng xung v khung hng ln:i vi khung hng xung, chnh v c n ba tc (155,52;622,08;1244,16 Mb/s)nn s lng cell ATM cng nh cell PLOAM trong mt khung thi gian cng khc

nhau nh ni trn. Nhng i vi hng ln, cn ch n y l cu trc mtcell PLOAM hng ln th khc cu trc mt cell PLOAM hng xung.


20/67



2.1.2.1. Khung ATMD liu c truyn dn trong BPON c ng vo cc khung ATM. V th cn

hiu r cell ATM trc khi ni n khung truyn dn trongBPON.

Hnh 2.2: C u tru c khung ATM

Cell ATM c cu trc nh hnh trn, gm c 48 Byte phn Payload cha d liuv 5 Byte header dng chuyn mch cc khung ATM. C hai loi cell ATM l ATMUNI (cell do thit bu cui gi ln node chuyn mch) v ATM NNI (cell gia hai

node chuyn mch), cell ATM NNI khng c trng GFC. Trong Header ca ATM cnhng thnh phn sau:

GFC (Generic Flow Control):Cung cp chc nng mang tnh cht ni b khic nhiu thit b (thng l thit b u cui) chia s chung mt giao dinATM. Trng ny thng khng c thit lp, c gi tr mc nh l 0 (nh

phn: 0000).

Virtual Path Identifier (VPI):Cng vi cc VCI s chu trch nhim xc nhch k tip khi cc cell c chuyn qua mt dycc b chuyn mch ATM

trn ng n ch cui cng ca n.

Virtual Channel Identifier (VCI):Cng vi cc VPI s chu trch nhim xcnh ch k tip khi cc cell c chuyn qua mt dy cc b chuyn mchATM trn ng n ch cui cng ca n.

Payload Type (PT):Bit u tin ca PT dng chnh cell cha d liungi dng hay thng tin iu khin (nu cell cha d liu ngi dng th nc gi trl 0 v sc gi tr 1 nu cell cha thng tin iu khin). Bit th haicho bit trng thi tc nghn (c gi trl 0 nu khng tc nghn v bng 1 nu

c tc nghn). Bit thba xc nh xem cell c phi l cell cui cng ca chuicell trong khung hay khng (nu c gi trl 1 l cell cui cng ca khung).

VPI

Payload

(48 bytes)

Header

(5 bytes)

Payload

(48 bytes)

Payload

(48 bytes)

53

by

tes

8 bits

GFC

PT CLP

HEC HEC

PT CLP

ATM cell ATM UNI cell ATM NNI cell

VPI

VPI

VCI

VCI


21/67



Cell Loss Priority (CLP):Trong qu trnh truyn i trn mng sc hin tngtc nghn xy ra, CLP cho bit liu cell no sc bv cell no s tip tcc chuyn i n ch nu c tc nghn nghim trng (CLP=0 c u tinv cell c CLP=1 s phi btrong trng hp ny).

Header Error Control (HEC):L gi tr ca checksum ca 4 byte u tintrong header, HEC c th sa c mt li trong 5 byte ca header v thc thgic cc cell thay v loi bn do li.

2.1.2.2. Khung hng xung

Hnh2.3: C utrc khung hng xung ca BPON

H

E

M

ES

SA

G

E_

20-264-10 12-18

nh dng khung truyn hng xung tc 155,52 Mb/s

53 bytes

125s; 56 cell; 53 bytes mi cell

PLOAM 1 PLOAM 2Cell

ATM 1

Cell

ATM 27

Cell

ATM 28

Cell

ATM 54.. ..

1 khe thi gian

nh dngCell PLOAM hng xung

0000

S thtca byte trong khung

2-3 11 19 28-3327 34 35 36 47 48header

7 grants 7 grants 7 grants 6 grants 10 message field

MS

G_

PO

N_

ID

C

R

C

R

C

R

C

R

ID

E

N

SY

NC

BI

PC

R


22/67



Cell PLOAM (Physical Layer Operation, Administration and Maintenance): Qunl v bo dng lp vt l. Mi cell PLOAM theo sau n l 27 cell ATM.

5 byte header: 4 byte u tin c gi tr cnh l 0000, byte HEC (header errorcorrection) tip theo dng sa li (nu c) ca header nhm xc nh chnh

xc bit u tin ca khung PLOAM.

Trng IDENT cho bit liu cell PLOAM ny c phi l cell u tin tronglung hng xung hay khng.

Hai byte ng bkhung SYNC c s dng cc OLT pht mt tn hiutham chiu 1Khz n cc ONT.

Mt cell PLOAM c tng cng 27 grant, mt b 6 hoc 7 byte grant c bov bng chui CRC (cyclic redundancy check). Mt grant s cho ONT bit khino c gi mt chui cell ATM d liu hoc cng c thyu cu ONT chyli tin trnh ranging.

MSG_PON_ID sni cho mt Node bit l cell ny c phi l dnh cho nodey khng v MSG_ID ch ra loi thng tin cha trong trng thng ip 10

byte (10 message field) theo sau.

10 message field: OLT sni cho ONT bit thi gian ranging c thay ihoc cng c thdng cho cc ci t khc ty thuc vo mc ch.

BIP (Bit-Interleaved Parity): gip cc ONT gim st t l bit li bng phngphp kim tra bit chn l.

2.1.2.3. Khung hng lnD l cell ATM hay cell PLOAM hng ln th trc cell u c 3 byte

overhead. Trong 4 bit u tin c chc nng to mt khong thi gian bo v nhmtrnh xung t trong trng hp qu trnh Ranging c s sai lch. ng thi 3 byteoverhead ny to mt khong thi gian cn thit cc OLT c bin ca tn hiu,cung cp mt khong thi gian cho qu trnh ng bbyte cho cc cell ATM.


23/67



Trong khung hng ln mt cell PLOAM c cu trc nh Hnh 2.4.

Hnh 2.4: i nh dang cell PLOAM h ng ln

Cng c 5 byte header v tip theo l 1 byte IDENT xc nh bit u tinca khung.

MSG_PON_ID v MSG_ID cng c dng cho mc ch tng t nh hng xung l xc nh ONT v ch r loi thng tin iu khin c chatrong cell PLOAM ny.

10 message byte field: trng ny cha cc thng tin OAM (Operation,Administration and Maintenance) cng nh cc bo hiu khc ca ONT gi lncho OLT. 10 byte ny c kim sot li da vo 1 byte CRC tip theo.

LCF (laser control field trng iu khin laser): 17 byte ca trng ny cnhim v cung cp cc thng tin v mc cng sut laser v t l suy hao, vicy gip cho OLT iu chnh cng sut pht laser hp l nhm m bo cngsut cho u thu (pha ONT).

RCF (receiver control field trng iu khin my thu): 16 byte ca trngny sgip cho OLT bit c mt mc ngng hp l nhm iu chnh

phn bit c hai mc tn hiu 0 v 1 trong tn hiu.

BIP (bit-interleaved parity): c cng nhim v nh trng BIP trong cellPLOAM hng xung, gim st t l li bit trong cell ny.

2.1.3. Bo mt trong BPONBPON c hai c ch bo mt, hay ni cch khc cc c chny nhm chc chn

rng lung d liu hng xung c nhn bi ONT c chnh chkhng phi btk ONT no khc.

Churning: Trong qu trnh chuyn dng d liu xung cho cc ONT, OLT sxo trn trt tcc cell v scho ONT c chnh bit cch sp xp li

bng mt kha. Kha ny khng phi do OLT cp, khi c yu cu t OLT,

4 fixedbytes

10 message bytes 17 laser control field (LCF)bytes

16 receiver control field(RCF) bytes

53 bytesheader

1 23 4 - 13 15 - 3114 32 - 47 48

H

E

M

ES

SA

G

E_

MS

G_

PO

N_

ID

ID

E

N

C

R

BI

P

S thtca byte trong khung

nh dngCell PLOAM hng ln


24/67



ONT s gi mt cell c cha kha (3 byte). Kha ny sthay i theo chu kmi giy.

M ha: lung d liu sc m ha trong qu trnh truyn nhn.Tuy nhin, c mt vn cn ni y l c mi ln mt ONT gi d liu ln th

s c tn hiu phn x quay tr li nh mt bn sao ca chnh n (phn x t ccsplitter, mi hn, connector), cc ONT khc c thpht hin v k xu c thphn tchdng d liu ny. V khng c mt qui chun c th cho vn ny, iu ny chckhuyn ngh rng trong vn thit k, lm sao cho phn suy hao do phn x tccSplitter, connector v cc mi hn phi nhhn 32dB.

2.1.4.

Chuyn mch bo v trong BPONLung d liu truyn trn mt mng cn c lin tc. iu g xy ra nu tuyn

truyn dn vt l m y l si quang bt?

Chnh iu y khng nh s cn thit cho vn chuyn mch bo v. Trongkhuyn nghG.983.1 c ba phng n cho chuyn mch bo v trong PON.

M hnh 1: Splitterc dng l loi 1:N, chc mt ng vo nhng c hai siquang t OLT kt ni n splitter nn trc khi a vo splitter, hai si phic ghp chung li. Khi mt trong hai si bt, OLT siu khin lu

lng chuyn qua si cn li. M hnh 2: Ti OLT by gic trang b hai b thu pht tn hiu, mt b

hot ng v mt b dphng. Hai si quang t hai bny kt ni n splitterloi 2:N. Khi si quang ang hot ng bt, OLT siu khin b d

phng hot ng v lu lng s c chuyn qua kt ni gia b ny vsplitter.

M hnh 3: COLT v ONT u c trang b hai bthu pht tn hiu, mt bhot ng v mt b dphng. Splitter by gil loi 1:N nhng c lp t

hai b. Khi mt trong hai si quang gia OLT v splitter hoc gia splitter vONT bt th OLT v ONT siu khin cho bthu pht dphng hot ngng thi sc cnh bo tONT cho OLT v ngc li trong trng hp ny.

Trong c ba m hnh, nu xy ra mt trong ba trng hp OLT, ONT hoc ccsplitter b hng th d nhin lu lng s b mt. ng thi, trong cba m hnh trn,khi si quang bt th chc chn rng sc mt phn no lu lng s b mt. Viclu lng b tht thot nhiu hay t ty thuc vo khnng x l chuyn mch nhanhhay chm.


25/67



Hnh 2.5: M hnh chuyn ma ch ba o v trong PON

2.2. EPON chun IEEE-802.3ahEPONEthernet passive optical networkc th hiu l PON m d liu c

ng thnh cc khung v truyn i da trn chun Ethernet. y, bi bo cophntch EPON da trn chun IEEE-802.3ah vi cc mc chnh: kin trc cc lp trongEPON, nh dng khung truyn dn, giao thc iu khin a im v vn RANGING.

2.2.1. Kin trc cc lp trong EPONCc lp trong EPON c gp thnh hai nhm, tng ng vi hai lp u tin

trong m hnh OSI 7 lp lLp vt l (Physical layer) v Lp lin kt d liu (DataLink layer).

Optical

OLT

ONT

ONTElectrical

Electrical

Electrical

1:N splitter

M hnh 1

M hnh 3

OLT

ONT

ONT

Electrical

Electrical

1:N splitter

1:N splitter

Electrical

E/O

E/O

O/E

O/E

O/E

O/E

Optical

OLTONT

ONTElectrical

Electrical

Electrical

2:N splitter

E/O

E/O

M hnh 2

Optical


26/67



iu ng ngha rng, d liu ca user sc x l vi giao thc ca nmtng trn khng c g khc so vi khung truyn dn IP v ATM. Tuy nhin hai lpPhysical layer v Data Link layer trong EPON sm nhn trch nhim ng gi dliu thnh nh dng truyn theo khung Ethernet, ng thi thng nht gia truyn nhn

chuyn d liu yu cu truy nhp ca userhng uplink v tch d liu t khungEthernet chuyn n cho userhng downlink.

Hnh 2.6: Kin tru c ca c l p trong EPON

2.2.1.1. Lp vt lTrong lp vt l gm cba lp con chnh nh sau.

Lpcon m ha vt ly - The physical coding sublayer (PCS) C th hiu lp con ny sm ha chui d liu tcc lp cao hn trc khi

truyn n hng uplink. ng thi s gii m v kim sot t s BER hp l

trc khi a d liu ln cc lp cao hn vi hng downlink. M c s dng l m khi Reed-Solomon, trong tng ny x l d liu

theo phng thc nh sau: i vi d liu tcc tng cao hn c chuynxung, n sa vo bm, sau tch ra tng khi 239 byte, thm vo 16

byte parity thnh khi d liu 255 byte trc khi chuyn ra. V n s lmiu ngc li i vi d liu c chuyn n, c ngha rng, n s bin ikhung 255 byte thnh 239 byte d liu trc khi chuyn ln cc tng cao hn.

Nu t s bit li qu trnh nhn l 10-4 hoc cao hn, n s xl t snygim xung cn 10

-12

trc khi a ln tng trn.

Vtl

Reconciliation

layer

MAC

client

Multipoint MAC Control (MPMC)

layer

MAC

instance

MAC

instance

MAC

instance

MAC

client

MAC

client

PCS

PMD

PMA

GMII

OSIPhysical

OSIDataLink


27/67



Lp con gn vi mi trng vt l - The Physical Medium Attachment (PMA)Sublayer

Vic qu nhiu mt chui bit 0 hay bit 1 lin tip c truyn i c thgyra vic mt ng b gia u thu v u pht do khng thkhi phc xung

clock chnh xc.

PMA sublayer s khc phc tnh trng trn bng cch dng m ha ng dy8b10b ca FranaszekWidmer.

Phng php m ha ng dy ny c th hiu nh sau: vi mt chui d liuc chuyn t tng trn xung, tng khi 8 bit trc khi c a qua PCSsublayer, n sc thm vo 2 bit chuyn thnh khi 10 bit. V n slmiu ngc li trc khi d liu t PCS sublayer chuyn ln.

Trong EPON yu cu, tc ng downstream v upstream cn bng l 1,0Gbps. Sau khi m ha ng dy, d liu sc tng ln 25%, tng ng tcbit lc ny l 1,25 Gbps.

Lp con ph thuc mi trng vt l- The Physical M edium Dependent (PMD)Sublayer

Lp con ny ph trch kt ni si quang ra bn ngoi, ng thi iu khinlaser v photodetector vcng sut, khuch i, lng t trong qu trnh truynnhn.

Cc thng strong EPON c PMD m nhn [1]- Tc bit: 1,25 Gb/s c hai lung hng ln v hng xung.- Bc sng: 1260 to 1360 nm chiu ln, 1480 to 1580 nm chiu xung.- Loi lu lng: tn hiu s.- T l chia: ti thiu l 1:16, c th nhiu hn khi s dng sa li FEC

(Forward Error Correction)

- S suy hao ti a cho php trong mng phn phi quang ODN (OpticalDistribution Network) l:

Lung hng ln ti bc sng 1310 nm: 5 20 dB hoc 10 24 dBtng ng vi chiu di ca ODN l 10 hoc 20 km.

Lung hng xung ti bc sng 1550 nm: 5 19.5 dB hoc 10 23.5dB tng ng vi chiu di ODN l 10 hoc 20 km.

- Di cng sut phng hng xung: -32 dBm hoc 27 tng ng vi 10hoc 20 km chiu di ODN.

- Di cng sut phng hng ln: -1 4 dBm vi 10 hoc 20 km chiu diODN.

- T l nhy/ qu ti ca my thu:


28/67



Hng xung: -24/+4 dBm v -27/+4 dBm tng ng 10 v 20 km chiudi ODN

Hng ln: -24/+2 dBm v -24/+7 dBm tng ng 10 v 20 km chiu diODN

- T l bit li cho php: 10-12- T l suy hao laser: >6dB- rng ph ca laser: Hng xung ti 1490 nm: 0,6 v 0,3 nm tng ng 10 v 20 km chiu

di ODN.

Hng ln ti 1310 nm: 3,5 v 2,5 nm tng ng 10 v 20 km chiu diODN.

2.2.1.2. Giao din mi trng Gigabit c lp (GMII) v Lp conti gii iuch (RS)

C th hiu rng, vi mi yu cu truy cp dch v ca mi user, OLT sgntng ng cho user mt cp MAC instance v MAC client.

Lp con ti gii iu ch(RS): s thc hin mt chc nng c bit ti OLTtngng vi vic nh tuyn, acc go i tin ra u ng mng li dch vtngng m user yu cu.

V trc khi d liu c a ra mang loi , GMII sm nhn nhim vghptt ccc d liu yu cu truy nhp tcc user chuyn ln truyn ra cc giaotip vt l vi tc Gigabit.

Hay ni cch khc, GMII v RS c cu hnh thc hin nhim v ca OLT.

2.2.1.3. Lp lin kt dliu MAC ( Media Access Control)MAC gm c hai phn MAC (Media Access Control) v LLC (Logical Link

Control).- MAC bao gm cc thng s thng nht gia truyn v nhn gia OLT v

ONU, bao gm c cu trc khung sc chuyn i v khe thi gian ccp pht.

- LLC l lp con c lp vi mi trng truyn. ng vai tr nh l mt giaotip gia lp lin kt d liu v tng mng, lm nhim v framing bao gmvic ng gi hng truyn v gii gi hng nhn.


29/67



iu khin MAC a im - Multipoint MAC Control (MPMC)Trong kin trc phn lp ca EPON c nhiu i tng MAC client, nhng chc

mt i tng MPMC. iu ng ngha rng vi nhiu giao thc a truy nhp tccuser sc MPMC layer xl sao cho cc yu cu truy nhp ny trn ng upstream

skhng xung t hoc chng lp ln nhau.

Mun lm c iu y th trong ln khi u u tin sc mt qu trnh tngpht hin v gn cc LLID (logical link ID) cho mt cp MAC instance (ca OLT) vMAC client (ca ONU). Do mi LLID l duy nht trong qu trnh x l ca MPMClayer.

2.2.2. Cu trc khung truyn dn ca EPON

Hnh 2.7: C u tru c khung truyn dn cu a EPON

Trong EPON, khung Ethernet c s dng truyn d liu vi cu trc khungnh Hnh 2.7.

Trng 8 bytes Preamble/SFD- SLD (start of frame delimiter) 1 byte c nhim v phn cch gia hai

trng Fixed 2 bytes.

- Fixed 2 bytes: nh ngha im bt u mt khung Ethernet.

Preamble /

SFD

Destination

address

Source

address

Length

/ typeData FCS

23 bit 24 bit

Fixed 2

bytes

Fixed 2

bytes

Mode +

LLID

LLID 8

bits

CRC 8

bits

SLD 1

bytes

LLID 7

bits

Mode 1

bits

8 bytes 6 bytes 6 bytes 2 bytes 4 bytes46 - 1500

bytes


30/67



- Mode + LLID: vi 1 bit u tin c nh ngha nhm phn bit d liung ra t mt OLT hay t mt ONU. Mode bit s bng 1 nu l ng ra tmt ONU v bng 0 nu t OLT.

- 7 bit LLID tip theo nhm phn bit cc ch sLLID, n c thphn bit27=128 a ch MAC Instance ngun v ch v 28=256 MAC client.

- CRC (cyclic redundancy check) 8bit: kim sot li cho trng LLID. Trng 6 bytes Destination address v 6 bytes Source address

- a chy chnh l a ch MAC. Mi thit bu c mt a ch MACduy nht.

- C Destination address v Source address u c chiu di l 48 bit (6bytes), trong 1 bit u tin cho bit khung Ethernet l multicast/broadcast (c gi tr bng 1) hay unicast (c gi tr bng 0)

- 47 bit tip theo c chia thnh 2 khi: 23 bit cao c gn cho nh snxut, 24 bit thp hn c gn cho thit b.

Trng Length/ type 2 bytes nhm m t loi loi khung OAM (Operation,Administration and Maintenance) v chiu di d liu trong vng Data

Trng Datac chiu di khng cnh, ti thiu l 46 bytes v ti a l 1500bytes.

Trng FCS (Frame Check Sequence trng kim tra li) 4 bytes: bo vtrng d liu bng phng php pht hin li trong khung d liu nhn c.

2.2.3. Giao thc iu khin a im (MPMC) trong EPONC nhiu loi yu cu dch vtheo hng uplink tcc user buc cc OLT phi

phn b khe thi gian v bng thng hp l, thng bo v iu khin cc ONU chng c th truyn d liu ng khe thi gian c cp.

lm vic y, giao thc iu khin a im MPMC (Multipoint MAC Control)trong EPON c thc hin di hai c ch ca hai bn tin iu khin MAC l GATEv REPORT.

Bn tin iu khin GATEhngxu ng- Khi mt OLT trong mng EPON khi ng ln u tin, n s truyn cc

bn tin GATE theo hng Downstream dng broadcast nhm pht hin racc ONU tcc bn tin phc p ngc li.

- Vi mi ONU sc duy nht gi trLLID c gn.- THnh 2.8, c ch thc hin mt bn tin GATE c hiu n gin nh

sau: OLT s gn mt cp gi tr Start time v Stop time c chiu di 64


31/67



bytes, ng thi mt gi trxung ng h ti thi im y sc ghi vobn tin ny thc hin qu trnh ng b vi cc ONU.

- C th hiu bn tin GATE l mt bn tin mang tnh cht pht hin cc linkt lun l v cp pht mt cch cng bng nhng yu cu trn lin kt lun

l y.

- Ngoi cc bn tin GATE cp pht khe thi gian cho cc LLID xc nh, OLTcng spht ra cc bn tin GATE ngu nhin nhm pht hin cc ONU mikt ni v h thng.

Bn tin iu khin REPORThngln- Khi cc ONTc xc nh qua cc lin kt lun l LLID, iu y ng

ngha rng ty cc ONTc thyu cu OLT cp pht khe thi gian datrn vic bo co thng tin trng thi ca n vhng i v thng tin ngh nhm gip ti u qu trnh ng b.

- thc hin c iu y, cc bn tin iu khin REPORT 64 bytes vi cutrc nh sau sc gi tcc ONT ti OLT.

- THnh 2.9, thng tin ca bn tin iu khin REPORT vi thng tin vhngi nhm cho OLT bit mt yu cu hin ti ca n v khe thi gian v bngthng m n cn. ng thi mt gi trxung ng h ti thi im y sc ghi vo bn tin phc v cho vic ng b.

-

S c trng hp xung t xy ra do nhiu bn tin REPORT c gi racng lc, lc ny cc ONT skhng nhn c bn tin GATE cp pht khethi gian cn thit n truyn d liu. Trong trng hp y, n s gi li

bn tin REPORT sau mt khong thi gian ngu nhin.

Hnh 2.8: Bn tin GATEhng xu ng

MA_CONTROL.request (GATE) MA_CONTROL.indication (GATE) MA_DATA.request ()

MAC Control Client

Stop

StartGenerate GATE

message

OLT

MAC Control Client

ONT

MAC

PHY

MAC Control

Clock register

Timestamp GATE

message

Stop

Start

TS

MAC

PHY

MAC Control

Laser ON/OFF

Stop

Start

TSWrite

registers

Clock register

Slot start register

Slot stop register

Upstream

DataPath


32/67



Hnh 2.9: Bn tin REPORTh ng ln

2.3. GPON chun ITU-G.984Cng nh BPON v EPON, phn tip theo sphn tch cng ngh GPON da vo

cc tiu ch: Kin trc cc lp, nh dng khung tuyn dn v i su phn tch nhim vcc trng trong khung truyn dn ca GPON.

2.3.1. Kin trc cc lp trong GPONGPON l t vit tt ca Gigabit Passive Optical Network, l mt trong s nhng

cng nghc s dng trong cng nghFTTH ni chung v PON ni ring.

V c bn, GPON c hai lp chnh: lp hi t truyn dn TransmissionConvergence (TC) Layer v lp ph thuc mi trng vt l Physical MediumDependent (PMD) Layer. TC layer v PMD layer tng ng vi hai lp Data link v

physical trong m hnh OSI.

MA_CONTROL.Indication (REPORT)

MAC

PHY

MAC Control

0

Q1

TS

Measure RoundTrip Time

Clock register

RTT register

MAC Control Client

Q0

Q1

MA_CONTROL.request (REPORT)

MAC

PHY

MAC Control

Q0

1

TS

Timestamp REPORT

message

Clock register

MAC Control Client

Q0

Q1Generate REPORT

message

OLT ONU


33/67



Hnh 2.10: Kin tru c ca c l p trong GPON

User ATM cells

Transmission Convergence (TC) Adaptationsublayer

GPON TC Framing sublayer

GPON Physical Medium Dependent (PMD) Layer

Transmission Convergence

(TC) Layer

ATM Client GEM Client

ATM Client GEM Client

User Frame (Packets)

VPI/VCI Filter

ATM TC AdaptorGEM TC Adaptor

Port ID, PTI (payload

type) filter

(TC) Adaptation sublayer

Cel

ls

GE

M

Fra

me

Alloc-ID filter Alloc-ID filter

GEM partitionATM partitionPLOAM

partition

Frame

header

GTC framing sublayer

Multiplexing/Demultiplexing based on frame location

Trans

missi

on

Conv

erge

nce

layer


34/67



2.3.1.1. GPON Physical Medium Dependent (PMD) LayerLp ny khng ging nh cc lp cao hn, tt cu l phn cng (hardware),

khng phi phn mm (software). V cc qui nh v thng s ca lp PMD trongGPON c nh ngha trong chun G.984.2:

Tc bit: 1,24416 hoc 2,48832 Gb/s hng xung v 0,15552 hoc0,62208 hoc 1,24416 hoc 2,48832 Gb/s hng ln.

Bc sng: 1260 n 1360 nm cho hng ln v 1480 n 1500 nm cho hngxung.

Loi tn hiu truyn: ch truyn tn hiu s. T l chia ca spliter: h trn 1:64 v ph thuc vo suy hao ca ODN. Da vo suy hao ca ODN, qui nh cba lp:

- Lp A: 5 n 20 dB- Lp B: 10 n 25 dB- Lp C: 15 n 30 dB

Chnh lch suy hao ln nht gia cc ONU: 15 dB Khong cch si quang ti a: 20 Km nu dng ngun pht DFB (Distributed

Feedback Laser) v 10 Km nu dng ngun pht l Laser Fabry-Perot chohng ln.

Cng sut pht trung bnh cho hng xung trn 1 si quang ti tc 1,2Gb/s:- Lp A: -4 n 1 dBm- Lp B: 1 n 6 dBm- Lp C: 5 n 9 dBm

Cng sut pht trung bnh cho hng xung trn 1 si quang ti tc 2,4Gb/s:- Lp A: 0 n 4 dBm- Lp B: 3 n 7 dBm-

Lp C: 5 n 9 dBm Cng sut pht trung bnh cho hng ln trn 1 si quang ti tc 1,2 Gb/s:

- Lp A: -3 n 2 dBm- Lp B: -2 n 3 dBm- Lp C: 2 n 7 dBm

Cng sut pht trung bnh cho hng ln trn 1 si quang ti tc 2,4 Gb/s:- Lp A: 0 n 4 dBm- Lp B: 3 n 7 dBm- Lp C: 5 n 8 dBm


35/67



T l li bit ln nht: 10-102.3.1.2. GPON Transmission Convergence (GTC) Layer

GTC Layer gm c phn lp ng khung GTC (GTC framing sublayer) v phnlp thch ng hi t truyn dn (transmission convergence (TC) adaptation sublayer).

truyn lu lng, trong GPON s dng khung GEM (GPON encapsulation-method) hoc ATM. nh hng ng ln, lu lng l c mang trong cc T-conts (Transmission containers). Bt k mt T-cont u c th mang duy nht lu lngATM hoc duy nht lu lng GEM, khng th mang c hai cng lc. kt hpmang c hai lung lu lng ATM v GEM trong cng T-cont th cn phi c h tr

bi mt vi loi ATM T-cont v T-cont khung GEM khc. chkp c hai loi lulng c mang i trong khong thi gian mt khung 125s.

Phn lp ng khung GTCLung GEM di 125s trong khung GPON.Khung d liu ca ngi dng c

chiu di ngu nhin. Giao thc ng gi GEM h trphn mnh cc khung d liungi dng ng thi chn cc mo u v gi trPTI c nh nhn dng ra ccgi phn mnh, nhm gip qu trnh ghp li ddng v khng mt mt d liu. Qutrnh ng gi GEM c thc hin qua cc trng hp sau:

Hnh 2.11 : Phn l p o ng khung GTC

Trng hp nu khung ca ngi s dng trng khp hoc ngn hn khung ca

GEM th sc t vo khung GEM m thnh 2.11a) v hnh 2.11 c).Trng hp nu khung ngi s dng di hn khung GEM th sc phn thnhcc mnh nht vo khung GEM. Hnh 2.11 b).

Chc nng:

Ghp knh v phn knh:Phn ti PLOAM v GTC c ghp knh vo khungca TC ng xung theo cc nh dng khung qui nh. nh hng ngln, mi thnh phn c tch t mt nhm ng ln ph hp n Bwmaptng ng ghp vo khung ng ln.

a)

User

GEM FrameGEM

Hader viPTI=001

GEM

Hader viPTI=001

GEM Frame GEM FrameGEM

Hader viPTI=000

User Frame

GEM FrameGEM

Hader viPTI=001

b)

c)


36/67



To mo u v gii m: Mo u khung GTC c to v c nh dngtrong khung ng xung. Cm mo u ng ln c gii m. Ngoi ra,OAM c t vo l thc thi.

Chc nng nh tuyn ni b da trn Alloc- ID: c thc hin cho d liu

n hoc t bthch ng hi t truyn dn GEM (GEM TC Adapter) i.

Phn lp thch ng hi t truyn dnPhn loi: cba loi [ITU-T G984.3]

Bthch ng hi t truyn dn ATM (ATM TC adapter) Bthch ng hi t truyn dn GEM (GEM TC adapter) Bthch ng giao din iu khin qun l ONU (OMCI adapter)2.3.2. nh dng khung truyn dn trong GPON

2.3.2.1. Cu trc khung hng xung

Hnh 2.12: C u tru c khung h ng xu ng

Khung c chiu di ti a l 125s bao gm cc khi iu khin ng xung(PCBd) ca 4 byte cho ng truyn xung v mt phn ti.

Khi iu khin ng xung (PCBd) gm: Khi PCBd c OLT gi i n ccONU bng kiu qung b.

Trng ng b vt l (Psync):Trng ny cnh 32 bit v l phn bt uca mi PCBd v n gip cho cc ONU tm ra phn bt u ca khung.

PSync

4 bytes

Ident

4 bytes

PLOAMd

13 bytes

BIP

1 bytes

PLend

4 bytes

PLend

4 bytes

US BW Map

Nx 8 bytes

Khi iu khin ng xung PCBd

PCBd

nPhn ti n PCBd

n+1Phn ti n+1 PCBd

n+2

Phn tboATM

Phn GEM, TDMv cc phn on

125us


37/67



Trng Ident c 32 bit:Mc ch ca trng ny l cho php la chn mt s khung GPON ca mt

nhm ln hn v c gi l siu khung (superframe).

Trng sa li FEC vi bit u tin chra c hay khng c li trong lin ktng xung. Bit thhai dng trong lu trv 30 bit cn li dng cho bm siukhung (superframe).

Trng thng tin vn hnh, qun l v bo dng lp vt l PLOAM ngxung (Physical layer Operation Administration and Maintenance) gm:

- 1 byte nhn dng ngi nhn ONU (ONU-ID)- 1 byte dnh cho nhn dng bn tin.(Msg ID)- 1 byte dnh cho trng kim tra d tha vng bit c ston vn

ca khung- Trng CRC dng kim tra li- 10 byte dnh cho bn tin ca trng PLOAM

Trng xen k bit chn l BIP(Bit Interleaved Parity): 1 byte cho php ONUgim st c tc bit li.

Trng chiu di phn ti ng xungPlend (payload length): di 4 bytengoi lm chc nng bo v bng cch kim tra cc d tha cc bit theo chu k(CRC) v phn ny cn c truyn li hai ln trong d liu ng xung.

Trng USBW mapl ni m OLT gi tin hiu qung b xung tt c ONUgm c cc trng:

- Cp pht ID- Trng Flag- Trng bt u v dng

Trng CRC

FEC Ind

1 bit

Reserve

1 bit

Superframe counter

30 bits

Trng ng b vt l

ONU ID

1 bytes

Msg ID

1 bytes

Bn tin10 bytes

CRC

1 bytes

Cu trc trng PLOAM


38/67



2.3.2.2. Cu trc khung hng lndi khung ng ln bng vi di khung ng xung v bng 125s. Mi

khung c th truyn dn cho mt hoc nhiu ONU hng ln OLT (hnh 2.13)

a) Cu trc khungb) Mo u hng ln lp vt lc) Khung PLOAM hng lnd) Bo co bng thng ng hng lne) Thnh phn ti khung GEM hoc phn mnhf) Header khung GEM

Cc trng trong cu trc ny:

Mo u lp vt l ng ln (PLOu) Qun l, vn hnh, bo dng lp vt l ng ln (PLOAMu) Chui nh mc cng sut ng ln (PLSu)

Phn T-cont gm: Phn ti (Payload) Bo co bng tn ng ng ln (DBRu)

Bo co bng tn ng ng ln (DBRu ) gm c hai trng con: Trng cp pht bng tn ng DBA (Dynamic Bandwidth Assignment)

chim 1, 2 hoc 4 byte

Trng CRC chim 1 bytePhn ti c cu trc GEM gm:

Mo u ca GEM Cc phn on khung phn ti

Phn mo u ca GEM c 40 bit gm cc thnh phn: Phn ch th chiu di ca ti PLI c 12 bit Nhn dng cng Port ID 12 bit Nhn dng loi ti PTI 3 bit Kim tra li mo u 13 bit

Phn ti gm c: Phn ATM cells : 53 byte trn cell Phn GEM bn cnh mang d liu cn ng bnh SONET hoc khung d

liu ca cc mnh trong gi d liu Ethernet


39/67



Hnh 2.13: C u tru c khung GTC h ng ln

T-

CON

T

T-

CON

T

PL

O

PL

O

A

PL

Su

D

BR

U

Pa

yl

oa

D

BR

U

Pa

yl

oa

PL

O

D

BR

U

Pa

yl

oa

T-

CON

T

ONU(

A)

ONU(

B)

125

s

DBA1, 2

or 4

byte

s.

CRC

1

B t

Prea

mble

a

b te

Deli

mite

r b

BIP

1

ONU

_ID 1

byte

Ind

1

byte

ONU

_ID 1

byte

Msg_

ID 1

byte

Mess

age

10

byte

CRC

1

B t

GEM

head

er

Fra

me

frag

men

GEM

head

er

Full

Nam

e

GEM

head

er

Fra

me

frag

men

PLI

12

bits

Port

_ID

12

PTI

3

bits

HEC

13

bits

a)

b)

c)

e)

f)

d)


40/67



2.3.2.3. Phn tch mo u ca GEM

Hnh 2.14: Cu trc khung v mo u ca khung GEM

Chc nng ca cc thnh phn trong mo u GEM:

PLI (12 bits): ch th chiu di ca phn ti.Kch thc 12 bit cho php phnmnh khung d liu ln n 4095 bytes. Nu khung d liu ngi dng ln hn khungny, th sc chia thnh cc phn mnhc kch thc 4095 byte hoc nhhn.

Port ID (12 bits): c s dng cung cp 4096 danh nh lu lng c gitr duy nht trong PON. Qu trnh ghp knh s da vo gi tr ca Port ID.Mi Port IDc s dng duy nht cho mt ngi dng.Mi Alloc ID hoc T-cont c th truynmt hoc nhiu Port ID cng mt lc.

PTI (3 bits): c s dng ch ra loi ni dung cha trong phn ti. Gi trny c th thay i c cho ph hp vi tng loi ni dung trong ti. Cc gi tr

ng vi tng PTI.

HEC (13 bits): cung cp vic pht hin li v c chc nng sa li cho mou.

Bng 2.1: Cc m PTI

M PTI M t

000 Phn on d liu ngi s dng, khng kt thc ca mtkhung

001 Phn on d liu ngi s dng, khng kt thc ca mt

khung

010 ng k

011 ng k

100 GEM OAM, khng kt thc ca mt khung

101 GEM OAM, khng kt thc ca mt khung

110 ng k

111 ng k

Mo uGEM 5 bytes

Phn ti GEM L bytes

PLI

12 bits

Port ID

12 bits

PTI

12 bits

HEC

13 bits

Khung GEM


41/67



2.3.3. Phn bbng tn ng (DBA) trong GPONNu theo phng php thng thng, khng p dng phn chia bng thng ng

cho cc thu bao th hin nhin bng thng c chia u cho cc thu bao. Tuy nhin,nu trin khai thc t theo hng y th bi ton vbng thng khng ti u v hiu

nng s dng v cc thu bao vi cc yu cu dch vkhc nhau cng nh yu cu bngthng cng khc nhau cho cc thi im. Theo chun G.983.4 qui nh, c hai loi

phng thc gn bng thng ng cho BPON v GPON l OLT ng vai tr chng v ONT ng vai tr chng.

OLT ng vai tr chng: OLT s tin hnh vic gim st nhu cu s dng bngthng ca ONT ti cc thi im khc nhau.Da trn s cell ATM nhn ri v khungGEM nhn ri m n nhn trong khung GTC hng ln. Vi cch thc hin nh vy,

phng thc ny cn c bit vi tn gi iu chnh bng thng ng theo hng

iu chnh cell nhn ri. Ngoi ra n cn c gi l iu chnh bng thng theohngbo co khng trng thi (NSR-Non-Status Reporting).

ONT ng vai tr chng: ONT bo co trng thi bm n OLT. Do vy nc gi l bo co trng thi bm hay bo co trng thi - SR (Status Reporting).Ch th nhu cu bng thng trong loi T-cont th c truyn trong vng overhead lpvt l c thhn l vng bo co bng thng ng DBRu. OLT s dng thng tin boco trng thi quyt nh phn bbng thng ph hp cho mi vtr ID.


42/67

CHNG III: BI TON THIT K FTTH DA TRN CNG NGH GPON


CHNG III: BI TON THIT K FTTH DA TRN CNGNGHGPON

Trong chng ny sphn tch hai bi ton thit k mng FTTH da trn cngngh GPON. Trong o bao gm ca vi c thit k dung lng m tOLT va xet n khanng tnh kha thi trin khai cho thit k d i nh.

3.1. Tnh khnng phc v ca mt OLTTrn thc t, mi OLT gm c nhiu card hng xung, mi card li gm nhiu

Port, v mi mt port s kt ni vi Splitter. Mt khc, vi mi kin trc (m y lkin trc da theo chun ITU-T) th t lsplitter cng phi c mt t l nht nh.

Trong chun G984.3 cho GPON qui nh t lny ln nht l 1:128v khongcch ln nhttOLT n ONT l 20 km.

Hn na, y chng ta cn phi phn tch xem, chng ta thit kcung cpdch vg, t tnh ton bng thng cn thit cho mi thu bao.

Nh vy, vi c cn thit y la chu ng ta phai a ra c cac loa i di ch vu cungcp ho c cac m c bng thng c th cung cp . T o , s tnh ton mi OLT c th htr ti a bao nhiu thu bao cho mi loa i di ch vu , cn bao nhiu splitter cung cploi dch vi t l chia mi splitter l bao nhiu . Trong bai toa n 1 ch p dng tnh

ton vi 1 tng splitter.Trong m hnh nay , mi OLTs cung cp y loi dch v nh c thit

k. Tuy nhin, mi OLT se cn bao nhiu card cho loa i di ch vu o tuy thuc vao s thubao cua loa i di ch vu o nhiu hay t v d nhin phi c card d phng cho nhngtrng h p pha t sinh thu bao ngoai d kin, ap ng tai cho m t card bt k nao o bi s c. Trong hnh ve d i y,bi bo cos i su phn tch v h ng thit k t hc ttr c khi tnh toan nh sau:

B c 1:Xci nh loa i di ch vu cung cp hoc m c t c cung cp.

Vi c u tin la phai xac i nh ro m hnh thit k cung cp cho loa i hnh di chv hoc loi tc nh th no , sau o se tin hanh phn tch dung lng phuc vu cuami OLT.

Tuy nhin,c th thy mt vn pht sinh xy ra y khi th phn tch theochiu h ng nh sau: gi s nh cung cp dch v mun cung cp cho mi thu bao tc 10 Mbit/s h ng xung, nh vy v i tc m t port h ng xung l 2,5Gbit/scung cp c cho 250 thu bao. Nh vycn m tt l chia splitter l 1:250. iu nay

khng phu h p theo qui i nh t l chia l n nht cho GPON la1:128.


43/67



Nh vy , vi c xac i nh bng thng cho mi thu bao khng phai la tuy tin mada trn tc h ng xung va t lsplitter ma chu ng ta i nh dung.

Tuy nhin , nh cung cp dch v vn c th a ra cc vng cung cp dch vkhc nhau da trn tc phn b cho mi thu bao ap ng v i nhu cu thc t t ng

th i im, t ng vung min, ty vo m hnh trin khai va h ng m rng di ch vu .

B c 2:Xc i nh s lng card cung cp cho mi loa i hnh di ch vu cho OLT

Theo nhmong mun ban u , mi OLT se co nhim vu cung cp u loa i hnhdch v nh thit k . V v y,bi ton ch xt n vn gn bng thng c nhcho mi thu bao cho nn chu ng ta phai phn i nh ro s lng card ph trch cho miloi dch v trn OLT l bao nhiu . Mun phn b h p l th phai hoan toan da vao

phn tch nhu cu cu a cac loa i thu bao .

Trong bai toan thit k nay , ta se ly ra m t strng h p in hnh nh sau thit k cho hthng da vao bang sau:

T c h ng xu ng T l chia T c t i a mi thu bao

2,5 Gbit/s

1:128 19,125 Mbit/s

1:96 25,5 Mbit/s

1:64 38,25Mbit/s

1:32 76,5 Mbit/s

Bng 3.1: T l chia v cc mc tc in hnh

Theo lin minh vin thng quc t ITU -T, b phn FSAN (Full Service AccessNetwork) th bng thng hng xung cung cp cho di ch vu triple-play cho m tthubao n le la 73 Mbit/s. Bao gm 3 knh HDTV (3 x 20Mbit/s=60Mbit/s), truy c pInternet tc cao (10Mbit/s), h i nghitruyn hnh (2Mbit/s),cc dch v iu khin txa (1 Mbit/s).

Dch v ADSL2+ c tc hng xungti a la

24 Mbit/s.

Nh vy, v i tc h ng xun g ti a 2,5 Gbit/s va t lchia cu a Splitter, honton c th cung cp c nhng nhu cu dch v cn thit .


44/67



B c 3:Xc i nh ca ch phn b OLT cung cp

Hnh 3.1: S phn b OLT

Trong bai toan nay , chng ta phn tch m t m hnh vi ba OLT m nhn ba vng v tr khc nhau m bo cc iu kin nh sau :

M tOLT se amnhn cung cp di ch vu cho hai vng cn li, n s khng cungcp di ch vu cho vung i a l ma no ang ng .

Khong cch t OLT vng An ranh gii vng v bin xa nht ca vng B vaC nm trong khoang khng qua 20Km va tng t cho cac OLT vung B va C .

Nh a phn tch trn , y chng ta s l i m tscard d phong cho haitrng h p chnh : m ttrong nhng card ang phuc vu bis c , khng co khanng phuc vu va danh cho trng h p co thu bao phat sinh vung di ch vu naoo ma h thng vn cha trin khai m rng ki p ap ng . V i mong munthit k rng , khi s lng thu bao tng ln , chng ta cn phi tng s lngOLT phuc vu va hoan tra la i s card d phong a mn tam trn mi OLT

p ng nhu cu hi long trong cp di ch vu cho khach hang.

A


45/67



V vy trong bi ton ny, sa ra cng thc tnh ton sthu bao m mi OLTc th phc v da trnloi dch v :

Thng su vo- S Card cung cp cho mi di ch v v s port trn mi card- Kin trc s dng(theo G984.3) cho GPON- Tc mi ng hng xung- T l chia ca splitter

Thng su ra- Sthu bao phc v ti a ca OLT da trn loa i di ch vu (ho c bng thng)

chn la.

- S Splitter cn s dng. L thuyt tnh tonQui c gi cc thng snh sau:

- S card: C- Sport trn mi card hng xung: P- Tc mi ng hng xung: T (Gb/s)- Bng thng cung cp cho mi thu bao: B (Mb/s)- T l chia ca splitter: 1: N

Da trn thng su vo v yu cu vu ra ta stnh ton nh sau:

- Sng hng xung: C x P = D ng- Sthu bao phc v ti a: C x P x N = X thu bao- S splitter: X/N = S splitter

3.2. Tnh ton tnh khthi v m hnh khuyn ngh vi b khuch iTrn thc t, cc nh cung cp dch v vn p dng khong cch truyn dn ti a

cho mng phn phi quang (tOLT n ONT) ti a l 20 Km v t lchia splitter nhchun qui nh nhng hu nh khng p dng mt tng phn chia splitter v l do lng

phn bdn c dng FTTH hin nay cha cao, nn khng thphn b tp trung c.Thay vo , thng l chia ra hai tng splitter nh hnh minh ha di y phn b:


46/67



Hnh 3.2: M h

nh kin truc 2 t ng splitter

Nh vy, gi snh chng ta chn t lphn chia splitter l 1:64, thay v chnmt tng splitter (chc mt splitter 1:64) th y ta chn phng n dng hai tngsplitter loi 1:16 v loi 1:4 phn phi. Chnh iu ny ny sinh mt vn mitrong thit k thc tl suy hao ca mng phn phi stng ln v c khnng khngtrin khai c.

Nh vy, trong bi ton ny ta s chn phng n thit k 2 tng splitter vi cc

thng sv tnh ton l thuyt nh sau: Thng su vo

- S tng splitter- Cng sut pht hng xung: Pd(dBm) t OLT- Cng sut pha t h ng ln: Pu (dBm) t ONT- Suy hao ca splitter: As (dB)- Suy hao ca connector: Ac (dB)- Suy hao ca si quang: A

o(dB/Km)

- Chiu di ODN: L=20 Km- nhy ca ONT: Sont (dBm)- nhy ca OLT: Solt(dBm)- Margin d phong cho hthng: Am (dB)

Thng su ra- Cng sut thu c ti ONT: Pont (dBm)- Cng sut thu c ta i OLT: Polt (dBm)- Kt lun vtnh kh thi: trin khai c hay khng

OLT

Splitter 1:4

Splitter 1:16

Splitter 1:16

Splitter 1:16

Splitter 1:16

ONT

n 16 ONT

ti a 20 Km

1310 nm

1490 nm


47/67



- Nu khng, a ra m hnh khuyn ngh vi b khuch i sau u pht vi li G.

L thuyt tnh ton(m hnh kt ni da trn hnh 3.3)

Hnh 3.3: Lin k t v t l t OLT n ONT

Cng sut nhn c ONT: Pont = PdAsAcAo1Am (3.1)

Cng sut nhn c OLT : Polt = PuAsAcAo2Am (3.2)

Trong :Acl tnh tng suy hao ca cc conector. ys chn 4 loi connector in hnh

thng c dng trong thit k la : ST, MPO, FDDI, MTRJ. Suy hao cu a cac loa i secli t k trong bang bn d i:

Loi Connector Suy hao

ST 0,3 dB

MPO 0,35 dB

FDDI 0.5 dB

MTRJ 0.7 dB

Bng 3.2: Thng s ca c loa i connecter

ST MPOFDDI MTRJ


48/67



Ao1 = 1 x L (vi 1l h s suy hao ca si quang hng xung)

Ao2 = 2 x L (vi 2l h s suy hao ca si quang h ng ln)

V bc sng hng xung l 1490nm va b c song h ng ln la 1310nm nnsuy hao cu a cu a s i quang h ng ln va h ng xung cung khac nhau .

Da vao ITU-T G.652 v th suy hao ca si quang di y ta c suy hao cab c song h ng xung 1490nm la1 = 0,35dB/Km;b c song h ng ln 1310nm co suy hao 2 = 0,5dB/Km.

Bng 3.3: Tiu chun ITU-T G.652 v suy hao s i quang

Hnh 3.4: Cc vng suy haoca si quang

y, suy hao tng cng ca m tsplitter c tnh theo cng thc: 10log(N), m tkhc cn c cc loi suy hao khc nh suy hao xen , suy hao vt mc, suy hao do phanhi, suy hao do phn cc (PDL). Trong o , hai loi suy hao nh hng ng k nhtca splitter l suy hao xen v suy hao phn cc .


49/67



Tuy nhin, ph hp vi thc t y ta s c hn thit k trn Splitterloi PLCca hng LinkStar. Loi ny thng c ng dng trong FTT H no i chung va PON no iring.

Bng 3.4: Thng s splitter PLC

Aml suy hao d phng cho h thng (Margin) gm co Margin cho s i quang vaMargin cho thit bi . y ta chn gi tr Am= 4dB da vao ITU-T G.709 (qui i nh cacthng s cho mang truyn tai quang).

Nu cng sut nhn c ONT hay OLT nho hn nhay cu a thit bith chu ngta khng th trin khai c ,phi cn c b khuch i t sau hng pht nhm b licng sut b thiu. y c mt vn pht sinh l s dng b khuch i loi no . C

hai loa i b khuch a i c dung nhiu nht hin nay la khuch a i quang s i (OFA-Optical Fiber Amplifier) v khuch i quang bn dn (SOA-Optical SemiconductorAmplifier).

Tuy nhin , loi khuch i quang si c nhiu loi (ty theo loi t him cpha bn trong vung khuch a i ) nhng mi loa i la i co vung b c song khuch a i quii nh.

PLC Splitter


50/67



Loi OFA Vng bc sng khuch i

EDFA

(Erbium-Doped Fiber Amplifier)

1530nm1565nm

PDFA(Praseodymium-Doped FiberAmplifie)

1280nm1340nm

TDFA

(Thulium-Doped Fiber Amplifier)

1440nm -1520nm

NDFA

(Neodymium-Doped Fiber Amplifier)

900nm, 1065nm

hoc 1400nm

Bng 3.5: Vng bc sng khuch i ca OFA

Nh vy, nu dung OFA khuch a i th phai dung loa i TDFA cho h ng xung(b c song 1490nm) v loi PDFA cho hng ln (1310nm). Tuy nhin, 2 loi ny hunh cha c dung trong cc h thng mng truyn dn quang , ch c loi EDFA cchun ho a va dung rng rai ,nhng loa i nay khng ap ng c cho bai toan thit kny.

Bi ton s dng loi SOA khuch i cho c 2 h ng ln ho c h ng xungho c cho ca 2 h ng, ty theo trng hp . V SOA c vng bc sng khuch i rtrng. C th y s dng b khuch i SOA loi SAO 11p ca hang Alphion thitk v i vung b c song c khu ch a i t 1000nm n 1600nm, v i l i nm trongkhong t 5-30dB va cng sut ngo ra bao hoa Psat = 12dBm.

Hnh 3.5: Bkhuch a i SAO11b


51/67

CHNG IV: PHN TICH KT QUA BA I TOA N THIT K


CHNG IV: PHN TCH KT QU BI TON THIT K

Trong Chng 3 a phn tch c s ly thuyt cung nh cac thng s tham chiu thit k 2 bi ton thc t . Trong chng nay , s phn tch cc kt qu cng nh nu

im han ch ma chng trnh thit k cha trin khai c lm tin cho hngnghin c u m rng.

4.1. Phn tch ba i toa n Tnh kh nng phc v ca OLT m phong cho bai toan th nht ,bi bo co s dng chng trnh Matlab lm

chng trnh h tr giao din v tnh ton .

Bi bo co s dng loi OLT ca hng Alcatel c s hiu P -OLT 7432 lm cs m phong v i cac thng s nh sau:

S card h ng xung max: 14 cardS port trn 1 card: 4 port

C 3 loi t l chia s c chn dng y : 1:32; 1:64 v 1:128 cho m phong

tng ng v i 3 m c tc ma nha cung cp di ch vu co th a ra .V i 3 t l chia y , ng vi mi t l chia s dng 4 card cung cp , nh vy sc 4 x 3 = 12 card dung cung cp di ch vu va con la i 2 card cho vn d phong nh ani Chng 3.


52/67



Hnh 4.1: P-OLT 7432

Alarm

Control

Unit

Card

2 Card

kt n imng

li

P-OLT 7432

Card

hngxu ng

Card h ng xu ng P-OLT7432


53/67



V i tl splitter1:32

Thng s u va o:S card: C = 4S port trn 1 card: P = 4T l chia: N = 32

T c h ng xu ng: V = 2,5 Gb/s

Thng s u ra :

:::S thu bao t i a = C x P x N = 4 x 4 x32 = 512 thu bao::: T c t i a cho mi thu bao la : (vx1000)/N = 78,125 Mb/s::: S spli tter 1:32cn thit= C x P = 16 spli tter

Da theo phn tch chng 3, nh cung cp dch v nu dng s card nh trnv t l chia l 1:32 th hon ton c th cung cp dch v Triple-play cho 512 thu bao.


54/67



V i tl splitter1 :64Tng t nh trn, i v i t l1:64 ta co :

Thng s u va o:

S card: C = 4S port trn 1 card : P = 4

T l chia : N = 64T c h ng xu ng: V = 2,5 Gb/s

Thng s u ra ::::S thu bao t i a = C x P x N = 4 x 4 x 64 = 1024thu bao.::: T c t i a cho mi thu bao la : (vx1000)/N = 39,0625 Mb/s.:::S spli tter 1:64cn thit= C x P = 16 spli tter.

V

i kt qua

nh trn , nh cung cp dch v c th dng 16 splitter v

i t

lchia1:64 cung cp cho 1024 thu bao v i tc ti a cho mi thu bao la39 Mb/s.


55/67



V i tl splitter1:128V i t lchia 1:128, y la t lchia l n nht c khuyn cao b i ITU -T cho

GPON, cng ng ngha rng y l mc tc thp nht m GPON c th cung cpcho m tthu bao.

Thng s u va o:

S card: C = 4S port trn 1 card : P = 4T l chia : N = 128T c h ng xu ng: V = 2,5 Gb/s

Thng s u ra :

:::S thu bao t i a = C x P x N = 4 x 4 x 128 = 2048thu bao::: T c t ia cho mi thu bao la : (vx1000)/N = 19,5313 Mb/s:::S spli tter 1:128cn thit= C x P = 16 spli tter

Da trn kt qua m phong , v i t lchia l n nht la 1:128, GPON co th cungcp tc nho nht cho mi thu bao la19,5 Mb/s.

Tm li, ty theo t l chia ca Splitter m nh cung cp dch v c th cung cpcc gi tc khc nhau . y,bi bo co dng tc 2,5Gb/s cho ca h ng xungv hng ln nn khi ni n tc ca mi thu bao la no i n t c ca 2 h ngnh nhau.

Nh vy, hon ton c th t ngc li mt vn rng: nu khach hang munm tgi dch v c tc c nh l X chng hn th nh cung cp dch v c th khng

apng c v nh bi ton ny t ra , tc cung cp cho mi thu bao phu thuchon ton v o t l chia ca splitter . Nhng thc t cung cp di ch vu vin thng hin


56/67



nay cho thy rng : nh cung cp dch v a ra cc gi tc va khach hang chon lagi tc ph hp ch khng c hng ngc li l khch hng yu cu gi tc vnh cung cp dch v thit k cung cp .

Tuy nhin , mang tm v m th bai toan thit k con phai quan tm n vn cung cp bng thng cho thu bao m t ca

ch linh hoa t , c nh vy th mi c th binFTTH no i chung va GPON no i ring lam cng nghtruyn dn chnh trong tng laic.

4.2. Phn tch ba i toa n Tnh kh thi v m hnh khuyn nghi Nh a phn tch Chng 3, y bi bo co s tha y i 3 thng s chnh cu a

m tktni t OLT n ONT : cng sut pha t, khong cch v t l chia ca splitter. Ccthng s khac nh loa i connector, loi splitter khng phn tch y v cc loi ny cth thay i d dang . V s tng splitter, vn gi nguyn la 2 tng cho thit k , v thct cac nha cung cp di ch vu thng khng dng ln hn con s ny.

Thng s cu a cac thit bisplitter, connector, suy hao cu a s i quang c no i ro Chng 3. (Hnh 3.3)

T thng s trn cu a splitter , bi bo co xy dng bng suy v i 2 tng splitternh sau:

Tng tl chia Suy hao (dB)

128 24,7

96 23.6

72 22.7

64 2148 20,5

32 17,5

24 16,8

16 14,6

12 13,8

8 11,2

4 7.9

Bng 4.1: Bng suy hao ca splitter


57/67



V nhay cu a ONT va OLT bi bo co tham kho bng IV .1/G.984.2 ITU-T.Theo bng ny th OLT v ONT c nhy -34 dBm v i chnh xac la 3dB.

Nhng trn thc t , cc nh cung cp dch v thng s dng thit b OLTv ONT c nhay -29dBm. V cng sut pht nh ni mc 2.3 ca Chng 2,ph thuc vosuy hao cua ODN.

Bng 4.2: Thng s khuyn nghicu a ONT va OLT

4.2.1 Phn tch 1:Anh hng cua tl chiaTrong trng h p nay , bi ton s th thay i t l chia trong khi gi nguyn

cng sut pha t va khoang cach nhm anh gia s anh hng cua thng s ny ln h thng nh th nao v i cac thng s nh p vao nh sau :

::: Cc thng s u va o:Cng sut pha t ta i OLT: 9 dBmCng sut pha t ta i ONT: 8 dBmKhong cch t OLT n ONT : 20 KmD nhy b thu OLT v ONT : -29 dBmLoi connector: STLoi splitter: PLC

::: Cc thng s u ra c tnh toa n nh sau :Suy hao do cac splitter (As): y ta dng hai splitter cho m t cng ra ta iOLT, trng h p u tin v i t lchia la 1:128 ta co suy hao do splitter gyra la24,7 dB.

Suy hao do connector ST gy ra: Ac = 5 x 0,3 = 1,5 dB


58/67



Suy hao cu a s i quang: - H ng xung: Ao1 = 20 x 1=0,35 x 20=7 dB- H ng ln: Ao2 = 20 x 2 = 0,5 = 10 dB

Tng suy hao cua ODN:H ng xung: AODNdown = As+Ao1+Ac+Am= 24,7+7+1,5+3 = 36,2 dB

H ng ln: AODNup = As+Ao2+Ac+Am= 24,7+7+1,5+3 = 39,2 dB

Da vao cng th c 3.1 v 3.2, ta co :Cng sut thu c ONT: Pont = PdAODNdown = 936,2 = -27,2 dBmCng sut thu c OLT: Polt = PuAODNup = 839,2 = -31,2 dBm

Nh vy, y bi ton dng cng sut pht ln nht cho hng xung v hngln, khong cch ln nht v t l chia ln nht . Kt qua cho thy , cng sut pha t h ngln d ln nht vn b thiu 2,2dBm va c khuyn nghidung M hnh 2 (dng bkhuch a i sau sau u phat ONT).

Hnh 4.2: M hnh 2


59/67



xet tnh anh hng cua t lchia ln tnh kha thi (khng dung b khuch a icho hthng )bi thit k gim t lchia xung v i ca c t lnho hn nh 1:96; 1:72;1:64

V vi t l chia 1:64 th cng sut thu cho c 2 h ng thoa man l n hn nhy, ngha l khng cn dng b khuch i .

Hnh 4.3: M hnh kha thi

V i kt qu ny, nh cung cp dch v c th cung cp 4 x 4 x 64= 1024 thu baov i tc 2 h ng la 39 Mb/s (da trn phn tch cu a muc 4.1).Nu mun cung cpnhiu hn s thu bao th phai giam khoang cach va co th dung m hn h khuyn nghi v i cac b khuch a i m i co th ap ng c . thy c iu o , bi bo co

phn tch trong trng h p th 2 nh sau.


60/67



4.2.2 Phn tch 2:Anh hng cuakhong cch t OLT n ONTBi bo co ly trng h p cu a phn tch 1 nh trn , trng h p t lchia la

1:128, cng sut pha t h ng ln d ln nht vn b thiu 2,2dBm va c khuyn nghi dng M hnh 2 (dng b khuch i sau sau u pht ONT ).Nh vy, mun dung t l chia na

y ma

khng cn du

ng b khuch a i th

pha

i gia

m khoa

ng ca

ch t

OLT va

ONTv cng sut pht cho c 2 h ng la l n nht v khng th tng ln thm . y , v ikhong cch l 15 Km th cng sut nhn c b thu OLT v ONT ln hn nhy nh hnh minh ha m t.

Nh vy v i khoang cach nay , nh cung cp dch v c th cung cp4 x 4 x 128 = 2048 thu baov i tc 2 h ng la19,5 Mb/s (nh a phn tch

mc 4.1).


61/67



4.2.3 Phn tch 3: S nh hng ca cng sutpht ln m hnh trin khaiTrong Phn tch 1, bi bo co cho thy rng , v i t lchia splitter 1:64 v

khong cch 20Km th thit k kha thi ma khng cn dung b khuch a i . Tuy nhin,o la v i cng sut phat hai u la cc a i . By gi nu trong trng h p kha thi cua

phn t

ch 1 v

i khoa

ng ca

ch OLT n ONT la

20Km va

t

lchia la

1:64 nhng gia

mcng sut pha t xung 1 m c nao o th b thu OLT v ONT u khng thuc m ctn hiu nh hn nhy nh trong hnh bn di minh ha .

T kt qua nay co th thy rng v i m t t lchia nht i nh , m tkhong cch nht

i nh th m hnh kha thi (khng cn dung b khu ch i ) v i m t ngng cng sutpht.Nh trong trng h p nay , cng sut pha t ta i O LT khng th be hn 3,5 dBm vacng sut pha t ta i ONT khng th be hn 6,5 dBm.

Hnh 4.4: M hnh 3


62/67



4.2.4 Phn tch 4:Trng h p cn chu y khithit k C mt trng h p sau y rt cn chu y trong khi thit k hthng . V i gia s

nh sau: nh cung cp dch v cn t l chia 1:128, khong cch ti a l 20Km va pha tcng sut ti a , sn sang dung b khuch a i cho ca 2 h ng nu m c cng sut thukhng u

phu

rng vu

ng cung cp di ch vu . Kt qua

c th hin trong h

nh bnd i.

Nh vy, cng sut h ng xung cn b thm hng xung l 0,2 dBm va cngsut cn bu cho hng ln l 4,2 dBm, ng ngha v i vi c cng sut pha t h ng xungti thiu la 9,2 dBm va cng sut pha t h ng ln ti thiu la 12,2 dBm. V i b khucha i loa i SAO 11p c chon dung trong thit k v i m c cng sut ng ra bao hoa la12dBm th ro rang rng khng th nao ap ng c cng sut pha t cho h ng ln .

Trong trng h p nay nha cung cp di ch vu co th thay i loa i connector v i suyhao nho hn thit k vn co th ap ng c nh hnh di minh hoa . Tuy nhin ,nu xet v lu dai , cng sut pha t a ln ti a ,b khuch a i cho cng sut ngo ra bao

ha nh vy nhng vn khng cho cng sut thu ln hn nhy nhiu th nu hthng gia tng s lao ho a, gia tng s mi han th kin tru c nay hoan toan khng th khathi.


63/67



Tm li,nh cac trng h p a phn tch nh trn , vi c tnh toan cng sut phat , tlchia hay khoang cach , loi connector c dng , loi splitter hay s i quang cho h thng u phai ht s c cn trong , trnh trng hp m hnh thit k a ra c cng sutthu ta i b thu cua OLT va ONT qua be .


64/67


K T LUN

Thng qua ni dung bn chng c a bi bo co, cng ngh mng quang truynhp FTTH v bi ton thit k mng FTTH da trn cng ngh GPON c gii

thiu mt cch r rng nht trong khnng ca ngi vit.Cng ngh FTTH da trn cng nghGPON nh c trnh bay trn, vi

mng phn phi quang thng,chim u th trong vi c trin khai mnh cc dch vbng rng vi tc c thln n 2,5 Gbps cho ca hai h ng. Tuy nhin, hin ti ccdch vnh VoIP v truyn hnh cp hu nh cha c trin khai trn cng nghnayti Vit Nam.

Nhn nhn khch quan t li ch m mng truy nhp FTTH da trn cng nghGPON c th mang li. C th khng nh rng: cng nghny s gii quyt vn kht bng thng trong tng lai v gii quyt cc yu cu ca cc doanh nghip lnhin nay. Nu trin khai cho a sngi dng th cc nh cung cp dch vni chung

phi gii quyt ng b nhiu vn gi c dch vgn gi hn vi ti tin cangi dn.

Ni dung bi bo co c gng bm st n i dung chnh cua cng. Tuy nhin,cn nhn nhn r rng ni dung vn cn nhiu vn cha lm r c . Xt v m hnhkin tru cca PON,bi bo co cha lm r c kt ni t OLT l n mang loi cung cpdch v v tnh d phng m bo cung cp d liu lin tc cho khch hng . V baiton thit k vn cha xt c cc thng s khc nh hng ln h thng nh t s tnhiu trn nhiu va t ll i bit cung nh mi lin quan gi a cac thng s nay v i tc v khong cch truyn dn . o cung chnh la h ng m cho bai bao cao .

Nh li kt, em xin gi li cm nsu sc nht n thy Vn Vit Em, trang b cho em kin thc v mng truyn ti quang cng nh trc tip phn tch nidung chnh cn thc hin cho bi bo co. Chnh nhng kin thc ny xy dng nnvn ct li ca bi bo co. Cm n bn Nguyn Thy Vn Lp 07VTA3, HcVin CN Bu Chnh Vin Thng, c s HCh Minh h trbi bo co honthnh ng thi hn.


65/67

TVIT TT

ADSL Asymmetric digital subscriber line

APD Avalanche photodiodes

APON ATM-passive optical network

ATM Asynchronous transfer mode

BPON Broadband passive optical network

CO Centre office

CRC Cyclic redundancy check

DBA Dynamic bandwidth allocation

DBRu Dynamic bandwidth report upstream

EMS Element management system

EPON Ethernet passive optical network

FCS Frame check sequence

FEC Forward error correction

FSAN Full service access network

FTTH Fiber to the home

GEM

GMII

GPON encapsulation method

Gigabit Media Independent Interface

GPON Gigabit-capable passive optical network

GTC G-PON transmission convergence

HEC Header error control

IEEE Institute of electrical and electronics engineers

IPACT Interleaved polling with adaptive cycle time

ITU-T International telecommunication union telecommunicationstandardization

LLID Logical link identifierMAC Medium access control

MIB Management information base

MPCP Multi-point control protocol

MPCPDU Multi-point control protocol data unit

NMS Network management system

OAM Operation, Administration and maintenance

ODN Optical distribution network

OLT Optical line terminal


66/67

OMCC ONT management and control channel

OMCI ONT management and control interface

ONT Optical network terminal

ONU Optical network unitOSI Open system interconnect

P2MP Point-to-multi-point

P2P Point-to-point

PCBd Physical control block downstr

ftth theo cong nghe gpon

Documents