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HC VIN CNG NGHBU CHNH VIN THNG

CSTI THNH PH H CH MINH

KHOA VIN THNG II

_____________

N

TT NGHIP I HCCHUYN NGNH: IN T- VIN THNG

H: HON CHNH KIN THC I HC CHNH QUY

ti:

THIT K FTTH DA TRN CNG NGHMNG QUANG THNG

M s ti: 09407360001

Sinh vin thc hin: HNG NG NGC N

MSSV: 407360001

Lp: 07VTH1

Gio vin hng dn: Thc s VN VIT EM

TPHCM2009

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HC VIN CNG NGHBU CHNH VIN THNG CNG HA X HI CHNGHA VIT NAM

C STHNH PH H CH MINH c lpTDoHnnh Phc

-------- o0o -------- -------- o0o --------

Thnh ph HCh Minh, ngy thng nm 2009

PHIU NHN XT N TT NGHIP HI HC

( Dnh cho ngi hng dn )

1. Tn ti tt nghip: ...................................................................................................................................................................................................................................

.............................................................................................. M ti: ..................

2. H tn sinh vin thc hin: .................................................... Lp: ..........................Ngy sinh: ............................................................................. MSSV: ......................

3. Tng qut v s liu cc kt qu thc hin:S trang: ............................................................ Schng (phn): ........................

S bng s liu: ................................................. S hnh v: ...................................

S ti liu tham kho: ........................................ Phn mm s dng: ......................

Hin vt (sn phm phn mm, phn cng): ..............................................................

4. Nhng u im chnh ca n tt nghip:4.1. Ni dung thc hin: .............................................................................................................................................................................................................................

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

4.2. Kt qu sn phm: ................................................................................................................................................................................................................................

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

4.3. Khnng p dng: ................................................................................................................................................................................................................................

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

4.4. Hnh thc trnh by: ..............................................................................................................................................................................................................................

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

5. Nhng thiu st chnh ca n tt nghip:

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

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

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

6. ngh: c bo v Bsung thm bo v Khng c bo v7. nh ga chung: im s : ................ /10 ; im ch: ..............................................

Xc nhn ca B mn/Khoa Gio vin hng dn

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HC VIN CNG NGHBU CHNH VIN THNG CNG HA X HI CHNGHA VIT NAM

C STHNH PH H CH MINH c LpTDoHnh Phc

------ -- o0o -------- ------ -- o0o --------

Thnh ph HCh Minh, ngy .. thng .. nm 2009

PHIU NHN XT N TT NGHIP HI HC

( Dnh cho ngi c duyt )

1. Tn ti tt nghip: .......................................................................................................................................................................................................................................................

.............................................................................................. M ti: ............................

2. H tn sinh vin thc hin: .................................................... Lp: ....................................Ngy sinh: ............................................................................. MSSV: ................................

3. Tng qut v s liu cc kt qu thc hin:S trang:.................................................................. Schng: .......................................

S bng s liu: ....................................................... S hnh v: .......................................

S ti liu tham kho: .............................................. Phn mm s dng: ..........................

Hin vt (sn phm phn mn, phn cng): .........................................................................

4. Nhng u im chnh ca n tt nghip:4.1. Ni dung thc hin: ......................................................................................................

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

4.2. Kt qu sn phm: ........................................................................................................

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

4.3. Khnng p dng: ........................................................................................................

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

4.4. Hnh thc trnh by:......................................................................................................

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

5. Nhng thiu st chnh ca n tt nghip:............................................................................................................................................

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

6.

ngh: c bo v Bsung thm bo v Khng c bo v7. 3 cu hi sinh vin phi tr li trc Hi ng:a).........................................................................................................................................

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

b) ........................................................................................................................................

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

c).....................................................................................................................................................................................................................................................................................

8. nh gi chung: im s: ................. /10 ; im ch: ......................................................( Ghi ch: Trong trng hp thay i im chm gio vin phi k tn xc nhn ).

Xc nhn ca B mn/Khoa Gio vin c duyt

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Vi lng bit n su sc em xin gi n:

Ba mv gia nh ngi h trkhng nhng v vt cht mcn l tinh thn v l ngun ng vin rt ln ca em trong sutqu trnh hc tp.

Cc qu thy c ca trng Hc vin Cng nghBu chnh vinthng csti Tp.HCM ni chung v cc thy c khoa in t-Vin thng ni ring nhng ngi ging dy truyn t

nhng kin thc bch cho em trong sut 2 nm hc qua.

Thy Vn Vit Em_ngi hng dn, ch bo tn tnhhng dn em trong sut thi gian thc hin v hon thnhlun n tt nghip ny.

Cc bn ng lp in t - Vin thng nin kha 20072009 h tr, ng vin nhau trong qu trnh hc tp cng nh

trong thi gian lm lun vn tt nghip ny.

Mt ln na em chn thnh cm n!

Tp.HCh Minh, ngy 01 thng 10 nm 2009

Sinh vin thc hin

HNG NG NGC N

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LI MU

Cc k thut trong thng tin quang c th cung cp gii php ng dng cho hin ti v

tng lai. Thng qua s pht trin ca si quang th kin trc mng vin thng cng ngy

cng pht trin mnh m, cung cp tc rt cao truyn d liu c dung lng ln. Mt s

thun li ca h thng thng tin quang l: dung lng bng thng cao, truyn dn di, ng

tin cy.

Nhng nm gn y, vic gia tng dung lng mng truyn dn cng vi vic pht trin

cc ng dng v dch v mi n khch hng to ra hin tng gi l tht c chai trong

mng truy nhp. Khng nghi ngg na mng quang l mt gii php cn thit v quan trng

trong vn truyn dn. Trong , mng quang thng PON (Passive Optical Network) l

mt gii php trin vng y ha hn trong mng truy nhp lm gim bt hin tng tht

c chai. Mng PON l mng im n a im m khng c cc thnh phn tch cc trong

tuyn truyn dn t ngun n ch, cbn th n bao gm si quang v cc thit b thng.

iu ny lm tit kim chi ph bo dng, phn phi thit b, cp ngun v tn dng c

kin trc mng quang.

Hin nay c 2 mng PON c chun ha ty theo k thut lp 2 c s dng l ITU-T

and IEEE. Chun PON u tin da vo ATM nh l APON v BPON v da vo giao thc

ng gi GFP c bit nh l GPON. Th 2 l chun IEEE 802.3ah ni ln nh l mt ng

cvin y ha hn cho mng truy nhp bng rng th h k tip, l EPON.

Lun n tt nghip ny c trnh by gm 4 chng vi ni dung nh sau:

Chng 1: Tm hiu cng ngh mng quang th ng PON (Passive OpticalNetwork). Chng ny gii thiu v mng PON, cc thnh phn c bn trong mng

PON v phn loi cc loi PON.

Chng 2: Tm hiu FTTH (Fiber to the home). Chng ny tm hiu c th ccloi PON chun theo ITU-T: APON/BPON, GPON v EPON, sau gii thiu mun

mrng mng PON chun ny bng cch s dng b khuch i quang nh th no?

Chng 3: M hnh thit k v bi ton thit k FTTH. Chng ny nu ra mhnh thit k, bi ton thit k FTTH da trn cng ngh mng quang thng PON

theo chun ITU-T v hng mrng ca mng PON.

Chng 4: Chng trnh thit k. Gii thiu chng trnh thit k. p dng Visualbasic. Net gii quyt chng trnh.

Do thi gian nghin cu khng nhiu v qu trnh thit k chc chn khng trnh khi

mt s thiu st nht nh. Mong c s gp ph bnh qu bu ca qu thy c sau ny

em tip tc nghin cu su hn.

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Tp.HCM, ngy 01 thng 10 nm 2009

Sinh vin thc hin

HNG NG NGC N

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i

MC LCMC LC .............................................................................................................................. iDANH MC CC HNH V ............................................................................................... iv

DANH MC CC BNG .................................................................................................... viCHNG 1

TM HIU CNG NGH MNG QUANG THNG PON ......................................... 11.1. Gii thiu mng quang thng PON ............................................................................. 11.1.1. Cng ngh PON ........................................................................................................... 11.1.2. c im chnh ca h thng PON ............................................................................... 11.2. Thnh phn cbn ca mng quang thng PON ........................................................ 21.2.2. OLT ............................................................................................................................. 41.2.2.1. Phn li OLT ............................................................................................................. 4

1.2.2.2. Phn dch v OLT ..................................................................................................... 51.2.2.3. Phn chung OLT ....................................................................................................... 51.2.3. ONU ............................................................................................................................ 51.2.3.1. Phn li ONU ............................................................................................................ 51.2.3.2. Phn dch v ONU .................................................................................................... 61.2.3.3. Phn chung ONU ...................................................................................................... 61.2.4. ODN ............................................................................................................................ 61.2.4.1. Si quang v cp quang ............................................................................................. 61.2.4.2. Splitter ...................................................................................................................... 71.3. Ti sao PON li pht trin ............................................................................................... 81.4. Phn loi PON................................................................................................................. 9Chng 2TM HIU FIBER TO THE HOME .................................................................................... 112.1. APON/BPON ................................................................................................................ 112.1.1. M t h thng APON/BPON..................................................................................... 122.1.2. Kin trc phn lp APON/BPON ............................................................................... 132.1.3. Khung truyn dn APON/BPON ................................................................................ 132.1.4. Bc sng trong APON.............................................................................................. 162.1.5. Kin trc chuyn mch bo v.................................................................................... 17

2.2. GPON ........................................................................................................................... 182.2.1. M t h thng GPON ................................................................................................ 182.2.2. Lp truyn dn hi t GPON (GTC) ........................................................................... 192.2.3. Khung truyn dn GPON ........................................................................................... 202.2.3.1. Cu trc khung down ............................................................................................... 202.2.3.2. Cu trc khung up ................................................................................................... 242.2.3.3. nh x lu lng vo ti GTC ................................................................................. 282.2.4. Sp xp giao thc GPON ............................................................................................ 302.2.5. Phn bbng tn ng DBA trong GPON .................................................................. 32

2.2.6. Bo mt ...................................................................................................................... 332.2.7. Sa li FEC ................................................................................................................ 332.3. EPON............................................................................................................................ 34

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ii

2.3.1. Kin trc tng Ethernet v EPON ............................................................................... 342.3.2. Lp ph thuc mi trng vt l PMD ca EPON ....................................................... 362.3.3. Hot ng burst mode v Loop Timing trong EPON .................................................. 362.3.4. Khung Ethernet .......................................................................................................... 372.3.5. Giao thc iu khin a im ..................................................................................... 37

2.3.5.1. Ranging trong EPON ............................................................................................... 382.3.5.2. Hot ng Gate v Report ....................................................................................... 382.3.5.4. Khi d liu giao thc iu khin a im ............................................................... 402.3.5.5. Tng khm ph ONU ......................................................................................... 412.3.5.6. M phng P2P trong EPON ..................................................................................... 422.3.6. So snh EPON v GPON ............................................................................................ 452.4. SuperPON ..................................................................................................................... 462.5. Phn bbng tn ........................................................................................................... 472.5.1. Phng php phn bbng tn cnh ...................................................................... 472.5.2. M t hot ng phn phi bng tn ng cbn ...................................................... 48

2.5.3. IPACT ........................................................................................................................ 492.5.4. Phn phi bng thng ti thiu c m bo ............................................................ 522.5.5.3. Phn bbng thng ng......................................................................................... 402.5.5.7. M ha v bo v .................................................................................................... 452.6. Chc nng hot ng, qun l v bo dng trong mng quang thng PON ............. 532.6.1. Qun l mng cbn................................................................................................... 542.6.2. Cc chc nng qun l ................................................................................................ 552.6.2.1. Qun l thc thi ........................................................................................................ 552.6.2.2. Qun l cu hnh ...................................................................................................... 55

2.6.2.3. Qun l k ton ........................................................................................................ 552.6.2.4. Qun l li ............................................................................................................... 552.6.2.5. Qun l bo mt ....................................................................................................... 562.6.3. Hot ng, qun l v bo dng trong FTTH ............................................................ 572.7. ng dng ...................................................................................................................... 582.7.1. Trn th gii ............................................................................................................... 582.7.2. Ti Vit Nam.............................................................................................................. 59Chng 3

M HNH THIT K V BI TON THIT K FFTH DA TRN CNG NGHMNG QUANG THNG PON ............................................................................ 61

3.1. tng m hnh thit k............................................................................................... 613.2. Bi ton thit k ............................................................................................................ 623.2.1. Bi ton 1

Thit k FTTH da trn m hnh chun ITU-T ca mng PON ........................................ 623.2.2. Bi ton 2

Tnh cng sut thu c OLT v ONU v so snh vi nhy ca thit bsau a rakt lun c thit kc FTTH da trn m hnh chun ITU-T ca mng PON khng?62

3.2.3. Bi ton 3S dng b khuch i quang tng cng sut pht ca OLT trong m hnh thit k

FTTH da trn mng PON ........................................................................................... 643.2.4. Bi ton 4

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iii

S dng b khuch i quang b suy hao do t l b chia splitter gy nn trong m hnhthit k FTTH da trn mng PON ............................................................................... 65

3.3. Gi s mt s thit b OLT v ONU .............................................................................. 67Chng 4

CHNG TRNH THIT K ......................................................................................... 694.1. Gii thiu chng trnh ................................................................................................. 694.2. Hng dn thc hin chng trnh ................................................................................ 69PH LC ............................................................................................................................ 79TI LIU THAM KHO .................................................................................................... 81TVIT TT ..................................................................................................................... 82

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iv

DANH MC CC HNH V

Hnh 1. 1 : M hnh h thng mng PON [1]. ......................................................................... 2Hnh 1. 2 : Giao din kt ni OLT n mng li v giao din kt ni ONU n khch hng

[9]. ......................................................................................................................................... 3Hnh 1. 3 : Cc khi chc nng OLT [6]. ............................................................................... 4Hnh 1. 4 : Cc khi chc nng ONU [6]................................................................................ 5Hnh 1. 5 : c tuyn suy hao ca si quang [1]. .................................................................... 7Hnh 1. 6 : Cc loi splitter..................................................................................................... 8Hnh 1. 7 : Vic trin khai si quang trong mng truy nhp [10] ............................................. 9Hnh 2. 1 : M hnh h thng BPON [1], [10] ...................................................................... 11Hnh 2. 2 :Kin trc phn lp APON/BPON ........................................................................ 13Hnh 2. 3 : Cu trc khung download v up load ca APON ................................................ 16Hnh 2. 4 : K hoch phn b bc sng ca ITU-T G.983.3 ............................................... 17Hnh 2. 5 : Kin trc chuyn mch bo vc a ra trong ITU-T G.983.1 ....................... 18Hnh 2. 6 : Khi nim iu khin a truy nhp GPON [5] ..................................................... 20Hnh 2 .7 : Khung down GTC [5] ......................................................................................... 20Hnh 2. 8 : M t chi tit khung down GTC.......................................................................... 21Hnh 2. 9 : Cch trng thi ng b ONU [5] .................................................................... 22Hnh 2. 10 : Khung up GTC [5] ............................................................................................ 24 Hnh 2 .11 : M t chi tit khung up GTC [1] ....................................................................... 25Hnh 2. 12 : Cc cell ATM hng up ln [5] ..................................................................... 27Hnh 2. 13 : Cc khung GEM hng up ln [5] ................................................................. 27Hnh 2. 14 : Bo co DBA hng up ln [5] ...................................................................... 27Hnh 2. 15 : Cu trc header v khung GEM [5]................................................................... 28Hnh 2. 16 : Cch trng thi m t GEM [5] ...................................................................... 29Hnh 2. 17 : nh xv phn on d liu ca user thnh ti GEM [5] .................................. 30Hnh 2. 18 : Ghp d liu khn cp s dng th tc phn khung GEM [5] ........................... 30Hnh 2. 19 : Th tc sp xp GPON giai on 1 : Th tc ng k s serial cho ONU mi [1]............................................................................................................................................ 31Hnh 2. 20 : Th tc sp xp GPON giai on 2 : Th tc o tr [1] ................................ 32Hnh 2. 21 : V d khung down cho tc 2.488 Gbps [5] ................................................... 33Hnh 2. 22 : V d khung up ln [5] ...................................................................................... 34Hnh 2. 23 : Kin trc lp P2P Ethernet v lp P2MP EPON [1] .......................................... 35Hnh 2. 24 : Khun dng khung Ethernet chun. .................................................................. 37Hnh 2. 25 : Th tc sp xp EPON [1]. ............................................................................... 38Hnh 2. 26 : Hot ng Gate ca EPON [1] .......................................................................... 39Hnh 2. 27 : Hot ng Report ca EPON ............................................................................ 40Hnh 2. 28 : Khun dng ca khi d liu giao thc iu khin a im MPCPDU .............. 41Hnh 2. 29 : Th tc d tm tng trong EPON ................................................................. 41Hnh 2. 30 : Cc ONU khng thy lu lng trc tip vi nhau m phi thng qua OLT ..... 42Hnh 2. 31 : M phng P2P trong EPON .............................................................................. 43

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v

Hnh 2. 32 : Nhn khung MAC trong EPON ........................................................................ 44Hnh 2. 33 : M phng hot ng OLT qung b lu lng v ONU truyn P2P trong EPON............................................................................................................................................ 45Hnh 2. 34 : MAC P2P v qung b trong EPON ................................................................. 45Hnh 2. 35 : Minh ha v tr ca b khuch i t sau b OLT ............................................ 47Hnh 2. 36 : Minh ha v tr ca b khuch i t gn splitter b suy hao cho splitter ..... 47

Hnh 2. 37 : Phn b khe thi gian cnh [3] ..................................................................... 48Hnh 2. 38 : M hnh phn bbng tn ng cbn [1] ....................................................... 48Hnh 2. 39 : Cc bc thut ton polling [3] ......................................................................... 52Hnh 2. 40 : Cc bc ca giao thc phn bbng thng ti thiu........................................ 53Hnh 2. 41 : Cc thnh phn h thng qun l mng in hnh v mi quan h ca chng [13]............................................................................................................................................ 54Hnh 2. 42 : Cc tin trnh qun l li [13] ............................................................................ 56Hnh 2. 44 : Bng cp nht xp hng s dng FTTH chu ............................................. 58Hnh 2. 43 : OLT khi to loop-back iu khin t xa [13] .................................................. 58Hnh 3. 1 : M hnh thit k mng PON ............................................................................... 61Hnh 3. 2 : Minh ha khong cch truyn cn tng v v tr ca b khuch i trong trong biton mun tng cng sut pht ............................................................................................. 64Hnh 3. 4 : Minh ha v tr ca b khuch i trong trong bi ton b suy hao cho splitter .... 66Hnh 3. 5 : Lu gii thut ca bi ton s 2, 3 v 4 ............ Error! Bookmark not defined.Hnh 4. 1: Giao din chnh ca chng trnh ........................................................................ 71Hnh 4. 2 : Giao din ca chng trnh thit k h thng da vo s thu bao nhp ty ..... 71Hnh 4. 3 : Giao din xut hin bng thng bo khi khng nhp vo s thu bao .................. 72Hnh 4. 4 : Giao din kt qu chng trnh thit k h thng da vo s thu bao nhp ty 72Hnh 4. 5 : Giao din chng trnh thit k FTTH da trn cng ngh quang thng ......... 73Hnh 4. 6 : Giao din csd liu ca chng trnh thit k mng PON chun theo ITU-T. 73Hnh 4. 7 : Giao kt qu chng trnh thit k mng PON theo chun ITU-T ....................... 75Hnh 4. 8 : Giao din thit k mng PON c s dng b khuch i quang tng cng sutpht ...................................................................................................................................... 75Hnh 4. 9 : Giao din kt qu tnh ton khi s dng b khuch i tng cng sut pht. .. 76Hnh 4. 10 : Giao din thit k mng PON c s dng b khuch i quang b suy hao chosplitter. ................................................................................................................................. 77Hnh 4. 11 : Giao din kt qu ca chng trnh thit k PON s dng b khuch i quang

b suy hao cho splitter.......................................................................................................... 78

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vi

DANH MC CC BNG

Bng 1. 1 : Lit k suy hao ca cc bchia splitter tng ng. ............................................... 8Bng 1. 2 : M t s khc nhau ca APON/BPON, GPON v EPON. .................................. 10

Bng 2. 1 : Tc down v up ca APON/BPON. ............................................................... 12

Bng 3. 1 : Lit k cc thng s gi s thit b OLT trong PON. .......................................... 67Bng 3. 2 : Lit k cc thng s gi s thit b ONU trong mng PON. ................................ 68

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 1

THIT K FTTH DA TRN CNG NGH

MNG QUANG TH NG

Chng 1: TM HIU CNG NGH MNG QUANG THNG PON

Chng ny gii thiu v mng quang thng PON, cc thnh phn c bn ca mngquang thng PON v phn loi cc loi PON.

1.1. Gii thiu mngquang th ng PON1.1.1. Cng ngh PON

PON l t vit tt ca Passive Optical Network tm dch l mng quang thng.

Cng ngh mng quang thng PON cn c hiu l mng cng ngh quang truy nhpgip tng cng kt ni gia cc nt mng truy nhp ca nh cung cp dch vv ngi s

dng. Cng nghPON c bit ti u tin l TPON (Telephony PON) c trin khai

vo nhng nm 90, tip nm 1998, mng BPON (Broadband PON) c chun ha da

trn nn ATM. Hai nm 2003 v 2004 nh du sra i ca hai dng cng ngh Ethernet

PON (EPON) v Gigabit PON (GPON), c th ni hai cng ngh ny mra c hi mi cho

cc nh cung cp dch v gii quyt hng lot vn truy nhp bng thng rng ti ngi s

dng u cui. Thnh vin mi nht trong gia nh PON l WDM PON (Wavelength

Division Multiplexer PON).Trong cng ngh PON, tt c thnh phn active gia tng i CO (Central Office) v

ngi s dng s khng cn tn ti m thay vo l cc thit b quang thng, iu

hng cc traffic trn mng da trn vic phn chia nng lng ti cc im u cui trn

ng truyn chnh v vy m ngi ta gi l cng ngh mng quang thng (PON).

V tr ca h thng PON trong mng truyn dn: Mng quang thng PON l mt dng

ca mng truy nhp quang. Mng truy nhp h trcc kt ni n khch hng. N c t

gn u cui khch hng v trin khai vi slng ln. Mng truy nhp tn ti nhiu dng

khc nhau do nhiu l do khc nhau v PON l mt trong nhng dng . So vi mng truynhp cp ng truyn thng, si quang hu nh khng gii hn bng thng (hng THz). Vic

trin khai si quang n tn nh thu bao s l mc ch pht trin trong tng lai.

1.1.2. c im chnh ca h thng PON c trng ca h thng PON l thit b thng phn phi si quang n tng nh

thu bao s dng b chia splitter c th ln ti 1:128.

PON h trgiao thc ATM, Ethernet. PON h trcc dch v voice, data v video tc cao. Khnng cung cp bng thng cao.

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 2

Trong h thng PON bng thng c chia s cho nhiu khch hng iu ny s lmgim chi ph cho khch hng s dng.

Khnng tn dng cng ngh WDM, ghp knh phn chia theo di tn v cung cpbng thng ng gim thiu s lng cp quang cn thit kt ni gia OLT v

splitter.

PON thc hin truyn dn 2 chiu trn 2 si quang hay 2 chiu trn cng 1 si quang. PON c th h trtopo hnh cy, sao, bus v ring.

1.2. Thnh phn c bn ca mng quang th ng PON1.2.1. M hnh h thng

Mt h thng mng PON biu din trn hnh 1.1 bao gm cc thit b kt cui ng

quang (OLTsOptical line terminators) t ti trm trung tm (CO- Central Office) v b cc

thit b kt cui knh quang (ONUsOptical network units) c t pha ngi s dng.

Gia chng l h thng phn phi mng quang (ODN Optical distribution network) bao

gm cp quang, cc thit b ghp/tch thng.

OLT c kt ni n mng li/metro thng qua giao tip (hnh 1.2):

ODN

Mngli/

metro

Si quang

OLTCentralOffice

Splitter

Splitter

Splitter

Splitter

Si quangONU

ONU

ONU

ONU

ONU

ONU

ONU

ONU

ONU

Hnh 1. 1 : M hnh h thng mng PON [1].

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 3

V5: giao tip ny ni n mng PSTN/ISDN. E1: giao tip vi mng DDN. FE/GE v ATM: giao tip vi mng IP/ATM.

Hnh 1. 2 : Giao din kt ni OLT n mng li v giao din kt ni ONU n khch hng [9].

Giao din kt ni n cc thit b ca khch hng gm c cc loi sau (hnh 1.2):

POTS (Plain Old Telephone Service): l h thng in thoi tng t ch gi mttn hiu tng t trn mi cp dy, mi tn hiu ring bit ny c coi l mt

knh. S dng POTS v modem gi tn hiu tng t cung cp mt knh

64kbit/s. Modem v ng dy in thoi truyn thng kh ph hp cho mc chs dng Internet gi th in t. Tuy nhin, nu chng ta cn gi v nhn mt

khi lng d liu ln th s mt kh nhiu thi gian.

Dch v POTS c nhng c im sau y:

o Cc ng dy hin thi ch s dng hai cp dy xon.o Tn hiu trn cp ni chng cui l tn hiu tng t.o Cn modem chuyn tn hiu s thnh tn hiu tng t.

xDSL: cung cp kt ni xDSL bng thng cao kh nng ti a ln 50Mbps, viyu cu khong cch cp ng khong 500m v ti a n 1000m.

FE (Fast Ethernet): cung cp cc dch v tc ln ti 100Mbps cho khch hng. 2B+D: cung cp 2 knh B c tc mi knh l 64 kbps c dng cho thoi, fax,

truyn d liu v truy cp Internet; 1 knh D c tc 16 kbps c dng

truyn tn hiu iu khin.

V.24/V.35: ni vo cc thit b.

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Chng 1: Tm hiu cng ngh mng quang th ng PON

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1.2.2. OLTOLT cung cp giao din quang v pha mng phi quang ODN v cung cp t nht mt

giao din quang trn mng pha mng truy nhp quang. OLT c thc t bn trong

tng i hay ti mt trm t xa.

S khi chc nng ca OLT c m thnh 1.3.

Mt OLT c thc chia lm 3 phn: phn li, phn dch v v phn chung.

1.2.2.1. Phn li OLTPhn li OLT bao gm:

Chc nng kt ni cho c s ha cung cp cc kt ni gia phn mng li/metrovi phn mng phi quang ODN.

Chc nng ghp knh truyn dn cung cp vic truyn v ghp cc knh trn mngphi quang ODN. V dnh d liu i t mng li/metro n mng phi quang ODN

th n c nhim v l truyn cn d liu i t mng phi quang ODN n mng

li/metro th n phi c ghp knh trc khi truyn n mng li/metro.

Chc nng giao din ODN cung cp mi trng truyn dn quang kt ni OLT vimt hoc nhiu ONU bng vic s dng thit b thng. N iu khin qu trnh

chuyn i quang/in v in/quang. c th thc hin c ch chuyn mch bo v

v lm d dng cho vic x l thit b thng splitter th OLT s c cc chc nng

giao din ODN ging nh phn mng phi quang ODN.

V5, E1,ATM,FE/GE

Mngli/metro

ODNChc nngport dch v

Chc nngOAM

Chc nng cpngun

Chc nngghp knhtruyn dn

Chcnng

kt nichoc

s ha

Phn li OLTPhn dch v OLT

Phn chung OLT

Chc nnggiao din ODN

Chc nnggiao din ODN

Hnh 1. 3 : Cc khi chc nng OLT [6].

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 5

1.2.2.2. Phn dch v OLTPhn dch v OLT th c chc nng port dch v. Cc port dch v s truyn t nht tc

ISDN v s c th cu hnh mt s dch v hay c th h trng thi hai hay nhiu dch v

khc nhau v dnh dch v truyn hnh phn gii cao (HDTV- high definition TV), game

online, truyn d liu... Bt k khi TU (tributary unit) cng u cung cp hai hay nhiu port

c tc 2 Mbps ph thuc vo cch cu hnh trn mi port. Khi TU c nhiu port c th

cu hnh mi port mt dch v khc nhau.

1.2.2.3. Phn chung OLTPhn chung OLT bao gm chc nng cp ngun v chc nng hot ng, qun l v bo

dng (OAM-Operation, Administration and Maintenance). Chc nng cp ngun chuyn i

ngun ngoi thnh ngun mong mun. Chc nng OAM cung cp cc phng tin iu

khin hot ng, qun l v bo dng cho tt c khi OLT. Trong iu khin ni b, mt

giao din c thc cung cp cho mc ch chy th v giao din Q3 cho mng truy nhp

n h thng ang hot ng thng qua chc nng sp xp.

1.2.3. ONUONU t ti pha khch hng, ONU cung cp cc phng tin cn thit phn phi cc

dch vkhc nhau c iu khin bi OLT. M hnh cc khi chc nng ca ONU c m

thnh 1.4.

Mt ONU c th chia lm 3 phn: phn li, phn dch v v phn chung.

1.2.3.1. Phn li ONUPhn li ONU gm:

POTS,V24/V35,

xDSL,2B+D

KhchhngODN

Chc nngport user

Chc nngOAM

Chc nng cpngun

Chc nng giaodin ODN

Chc nngghp knhtruyn dn

Chcnngghpkhch

hng vdch v

Phn li ONU

Phn chung ONU

Phn dch v ONU

Hnh 1. 1 : Cc khi chc nng ONU [6].

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Chc nng ghp khch hng v dch v c nhim v nu v pha khch hng th dliu sc ghp trc khi truyn n ODN cn nu v pha ODN th cc dch v s

tch ra ph hp cho tng user yu cu dch v.

Chc nng ghp knh truyn dn cung cp cc chc nng phn phi tn hiu giaODN v khch hng.

Chc nng giao din ODN cung cp cc chc nng chuyn i quang/in hayin/quang.

1.2.3.2. Phn dch v ONUPhn dch v ONU cung cp cc chc nng port ca user.

Chc nng port ca user cung cp cho cc giao din dch v ca khch hng v b thch

nghi ca chng l 64 kbps hay n64 kbps. Chc nng ny c thc cp bi mt khch

hng hay mt nhm khch hng. N cng cung cp cc chc nng chuyn i tn hiu ty

thuc giao din vt l (v dnh rung chung, bo hiu, chuyn i A/D v D/A).

1.2.3.3. Phn chung ONUPhn chung ONU bao gm chc nng cp ngun v chc nng hot ng, qun l v bo

dng OAM. Chc nng cp ngun cung cp ngun cho ONU (v d nh chuyn i AC

thnh DC hay ngc li). Ngun c thc cp ti ch hay t xa. Nhiu ONU c th chia s

ngun. ONU c th hot ng bng ngun d phng.

Chc nng OAM cung cp cc phng tin iu khin cc chc nng hot ng, qun

l v bo dng cho tt c khi ca ONU.1.2.4. ODN

Mng phi quang ODN cung cp mi trng truyn dn quang cho cc kt ni vt l t

ONU n OLT.

ODN bao gm cc thnh phn sau:

Si quang v cp quang. Cc connector. Cc thit b thng nh splitter. Mi ni.

1.2.4.1.Si quang v cp quang

Si quang l mt thnh phn quan trng trong mng n to s kt ni gia cc thit b.Hai thng sc bn ca si quang l suy hao v tn sc tuy nhin si quang ng dng trongmng PON th ch cn quan tm n suy hao khng quan tm n tn sc bi khong cchtruyn ti a ch l 20 km v tn sc th nh hng khng ng k. Do ngi ta s dng

si quang y l si quang c suy hao nh ch yu l s dng si quang theo chun G.652(theo khuyn ngh G.982).

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 7

Hnh 1. 2 : c tuyn suy hao ca si quang [1].

Nhn vo c tuyn suy hao ca si quang hnh 1.5 ta thy bc sng 1310 nm th suy

hao si quang khong 0.4 dB/km v bc sng 1490 nm th suy hao si quang khong0.3 dB/km.

Cc loi cp quang s dng trong mng PON:

Cp gc (cp phn b t OLT n splitter): thng l loose-tube loi cp ny thc khuyn nghng dng hu ht mng PON.

Cp phi (cp phn b tsplitter n dy drop): c th s dng cp loose-tube hocribbon.

Dy drop (ko n nh thu bao).1.2.4.2. Splitter

Thnh phn c nhc ch yu trong mng PON l splitter. Splitter l thit b thng,

cng dng ca n l chia cng sut quang t mt si ra nhiu si khc nhau.

T OLT n ONU c th s dng nhiu dng splitter c t b chia l 1:2; 1:4; 1:8;

1:16;1:32; 1:64; 1:128. Hnh 1.6 s dng mt splitter c t l chia ln nh 1:32 hay 1:64 hay

c th s dng splitter nhiu lp vi lp th nht s dng splitter 1:2 v lp th 2 s dng 2

splitter 1:4.

Hu ht h thng PON c b chia splitter l 1:16 v 1:32. T l chia trc tip nh hng

qu suy hao ca h thng v suy hao truyn dn. T l ca splitter cng cao cng c ngha l

cng sut truyn n mi ONU s gim xung do suy hao ca b chia splitter 1:N tnh theo

cng thc 10logN (dB) nn nu t l bchia m tng ln gp i th suy hao stng ln 3

dB.

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 8

Da vo cc bchia nh l 1:2; 1:4; 1:8; 1:16;1:32; 1:64; 1:128 ta c suy hao tng ng

lit k bng 1.1.

Bng 1. 1 : Lit k suy hao ca cc bchia splitter tng ng.

S port Suy hao splitter (dB)

2 3

4 6

8 9

16 12

32 15

64 18

1.3. Ti sao PON li pht trinTrong FTTH nu da vo mng quang chng th si quang sc ko t trm trung

tm n nh thu bao. y l kiu kin trc n gin s dng k thut P2P nhng chi ph ko mt si quang t trm trung tm n nh khch hng l v cng c . Ta gi s c N

thu bao vi khong cch truyn L tnh t trm trung tm CO th ta cn c 2N b thu pht vNL chiu di si quang (y gi s rng si quang truyn 2 hng) (hnh 1.7a). gim

Splitter

Splitter

Splitter

Splitter

OLT

ONU

ONU

ONU

ONU

ONU OLT

ONU

ONU

ONU

ONU

ONU

ONU

ONU

ONU(a) (b)

Hnh 1. 3 : Cc loi splitter

(a) Sdng Splitter c t l b chia 1:32 hay 1:64(b) Sdng Splitter c t l b chia 1:2 v hai splitter c t l b chia 1:4.

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 9

vic trin khai si quang, ta c th s dng trm chuyn mch t xa; iu ny lm gim vics dng chiu di si quang nhng li tng s b thu pht ln thnh 2N+2 bi c thm mtlin kt thm vo mng (hnh 1.7b). Thm vo , trm chuyn mch t xa ny th cn ngunin hot ng. Mt trong nhng chi ph cao nht ca mng l cung cp v duy tr ngunin hot ng trong mng. Do , vic thay th trm chuyn mch t xa ny thnh splitter th

s tit kim rt nhiu chi ph bi splitter hot ng m khng cn cp ngun. Mng PON tiu b thu pht quang, trm trung tm v trin khai si quang. B thu pht trong mng PONch cn N+1v si quang trin khai c di L (hnh 1.7c). Bi nhng li ch ca n va titkim chi ph va d trin khai nn mng PON pht trin rt nhanh chng trong mng truynhp.

Hnh 1. 7 : Vic trin khai si quang trong mng truy nhp [10]

1.4. Phn loi PONXt vk thut th mng PON c th chia lm 2 loi: th nht l da vo k thut ghp

knh phn chia theo thi gian s dng hng down v k thut truy cp ghp knh theo thigian hng up th ta c cc loi nh sau APON/BPON (ATM PON/Broadband PON,GPON(Gigabit PON) v EPON(Ethernet PON); th hai da vo k thut ghp knh theo bcsng th ta c WDM PON. Trong n tt nghip ny ch yu nghin cu v ATM/BPON,GPON v EPON.

Bng 1.2 m t s khc nhau ca BPON, GPON v EPON ta c ci nhn khi qut v 3loi mng PON ny sc trnh by c thchng k tip.

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Chng 1: Tm hiu cng ngh mng quang th ng PON

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 10

Bng 1. 2 : M t skhc nhau ca APON/BPON, GPON v EPON.

Thng s APON/BPON GPON EPON

Tc bit Down: 155, 622, 1244

Mbps

Up: 155, 622 Mbps

Down: 155, 622, 1244,

2488 Mbps

Up: 155, 622, 1244

Mbps

Down v up: 1250

Mbps

Khong cch Ti a: 20 km Ti a: 60 km Ti a: 20 km

Qu suy hao 10-25 / 10-28 / 15-30

dB

5-20 / 10-25 / 13-28 / 15-

30 dB5-21 / 10-26 dB

B chia Ti a: 1:64 Ti a: 1:128 Ti a ln hn 1:16

Bc sng

Down:1480-1500nm

Up: 1260-1360 nm

Cung cp tn hiu video

1550 nm

Down:1480-1500nm

Up: 1260-1360 nm

Cung cp tn hiu video

1550 nm

Down:1480-1500nm

Up: 1260-1360 nm

Cung cp tn hiu video

1550 nm

Giao thc Cell ATM Khung GEM Khung Ethernet

Dch v Ethernet, TDM, POTS Ethernet, TDM, POTS Ethernet

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Chng 2: Tm hiu Fiber to the home

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Chng 2: TM HIU FIBER TO THE HOMEChng ny s m t c th cc loi APON/BPON, GPON, EPON nh s dng k thut

g, cu trc khung ca tng loi, gm c cc th tc g n hot ng ra sao theo chun ITU-Tv cch mrng mng PON bng cch s dng b khuch i ra sao trong superPON.

2.1. APON/BPONAPON/BPON c chun ha bi ITU-T. APON (ATM-PON) v BPON (Broadband

PON)l tn khc nhau ca kin trc TDM-PON da trn ITU-T G.983. Tn BPON phc v

cho mc ch tip th, cn tn APON th ni r khung ATM c dng truyn trong chun

ITU-T G.983. ATM c 53 cell trong 5 cell header v 48 cell t i. Bi v kch ccnh,

ATM c th m bo cht lng dch v v d nh phn bbng thng, m bo

trATM c thit k h trc thoi v d liu v th m n ph hp cho ng dng FTTH.

2.1.1. M t h thng APON/BPONHnh 2.1 ch ra kin trc ca BPON (Broadband PON). Trong kin trc ny, OLT kt ni

n ONU qua splitter 1:N. Khong cch truyn dn ti a l 10-20 km. Lu lng up ln t

ONU c truyn bc sng 1310 nm v down tOLT l bc sng 1490 nm v bc

sng 1550 nm c dng down video. D liu down xung s truyn tt c cc gi d liu

n tt c ONU v n s nhn gi m ng a ch ca n cn hng up ln th cc gi t

cc ONU s truyn ln lt cc gi n OLT thng qua siu khin ca OLT. OLT s qui

nh khe thi gian m ONU no c truyn ti thi im c thtrnh c sng

.

1310 nm

1490 nm

1550 nm

OLT dnh cho video

CO

Splitter

122N

122N

122N

1 1

2

N

TDMA

TDM

122N

1 1 2 N

ONU 2

ONU N

ONU 1B kt hp bc sng

OLT dnh chothoi/d liu

20 km

Hnh 2. 1 : M hnh h thng BPON [1], [10]

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Chng 2: Tm hiu Fiber to the home

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 12

Trong thit b, OLT thng c to thnh line card v c ghp vo trong b khung v

kt ni n mng li/metro. Cn ONU th c mt hay nhiu port dnh cho kt ni thoi

(T1/E1) v data (10/100BASE-T Ethernet) n khch hng.

G.983.1 l khuyn ngh cho APON/BPON ra i nm 1998 vi tc 155.52Mbps v

622.08Mbps. Phin bn mi hn ra i nm 2005 thm vo tc truyn dn 1244.16 Mbps.

Nh cung cp dch v APON/BPON c th la chn thc thi tc truyn dn down v up

i xng hay bt i xng. Bng 2.1 ch ra s kt hp tc down v up ca APON/BPON.

Bng 2. 1 : Tc down v up ca APON/BPON.

Tc down (Mbps) Tc up (Mbps)

155.52 155.52

622.08 155.52

622.08 622.08

1244.16 155.52

1244.16 622.08

C G.983.1 v G.984.1 ghi r gii php 2 si quang vi si quang down v up chuyn

dng. Bc sng 1310nm c dng c2 hng trong gii php 2 si. Tuy nhin, trn thc

t khng h thng no trin khai gii php 2 si quang. Th nht l do hng down ta s

dng bc sng 1490 nm v up s dng bc sng 1310 nm, hai bc sng ny khc nhau ta

c th s dng trn cng mt si quang m khng gy nhiu trn ng truyn; th hai ta c

th tit kim c chi ph v n gin hn trong vic lp t.

Tt c chun ITU-T PON c 3 loi thit k lp truyn dn quang gia OLT v ONU vi

suy hao mng phn phi quang ODN khc nhau. 3 loi c chnh trong ITU-T G.982 l:

Loi A: 520 dB Loi B: 1025 dB Loi C: 1530 dBThit k loi C th yu cu qu cng sut rt nghim ngt v si quang. V cc l do thc

t v chi ph, loi B+ vi suy hao 28 dB c gii thiu hu ht cc nh cung cp dch v.

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Chng 2: Tm hiu Fiber to the home

SVTH:Hng ng Ngc n Lp:07VTH1 Trang 13

2.1.2. Kin trc phn lp APON/BPONM hnh phn lp mng ATM c trnh by trn hnh 2.2 gm c lpng v lp mi

trng truyn dn, lp mi trng truyn dn phn chia thnh lp mi trng vt l v lp

hi ttruyn dn TC.

Trong mng ATM-PON lp ng tng ng vi lp ng o ca lp ATM. Lp vt lthc hin giao tip quang ca mng (hay chnh l mng phn phi quang ODN). Lp ny thc

hin cc chc nng: chuyn i in-quang, nhn/truyn cc tn hiu n/i lpvt l ti

mt trong ba bc sng 1310, 1490, 1550nm, kt ni vi si quang ca ODN.

Lp hi t truyn dn TC tng ng vi lp 2 trong m hnh OSI. Lp TC c phn chia

thnh lp con truyn dn PON v lp con thch ng. Lp con thch ng c chun ha da

trn chun ATM trn c s cp ng truyn thng [ITU I.732]. Chc nng ca lp ny l

chuyn i khung 125s thnh cell ATM. Lp con truyn dn PON th thc hin cc chc

nng nh sp xp, cp pht khe thi gian, cp pht bng tn, bo mt, ng chnh khung,ng bburst, ng b bit/byte.

Trong h thng APON/BPON, cc kt ni gia ONU v OLT c thit lp nh l mtmch o ATM. Mi mch o c chnh bi s nhn dng ng o (VPI- Virtual Path

Identifier) v nhn dng knh o (VCI- Virtual Channel Identifier) m n c ghi vo trong

cell bao gm lung d liu ca n. VPI v VCI l s liu cung cp cc cp khc nhau ca tn

hiu ATM c ghp hay chuyn mch. Nhiu mch o VC c th tn ti ng o ring.

Mt kt ni ATM c chnh bi cp VPI/VCI.

2.1.3. Khung truyn dn APON/BPONITU-T G.983.1 nh r kin trc tham chiu, c im ca b thu pht, cu trc khung

truyn ti v cc chc nng sp xp trong APON/BPON. Tn hiu APON/BPON c truyntrong khe thi gian. Mi khe thi gian cha mt cell ATM hay mt cell hot ng, qun l v

Lp ng

Lp mi trng

truyn dn

Lp con thch ng

Lp con truyn dnPON

Lp vt l

Lp hi t truyn dn TC

Hnh 2. 2 :Kin trc phn lp APON/BPON

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SVTH:Hng ng Ngc n Lp:07VTH1 Trang 14

bo dng lp vt l (PLOAM - Physical Layer Operation, Administration and Maintenance).

Cell PLOAM c dng truyn thng tin qun l ca lp vt l nh l cc bn tin giao thc

dng cho vic sp xp, trn key vi d liu v cp nht.

Cc khe thi gian download l cc cell ATM v PLOAM c di mi cell l 53 byte.

Mt cell PLOAM c chn vo c mi 28 khe thi gian (hay 27 cell ATM). tc

155.52Mbps, APON/BPON quy nh khung down c 54 cell ATM l truyn d liu nh vy

tc down thc s l:

54/56 155.52 Mbps = 149.97 Mbps

V 2 cell PLOAM dnh cho ng b, iu khin li, bo mt, bo dng v phn phi bng

thng.

Khung up ln c 53 khe nh vy khung up ln thc stc d 155.52 Mbps l:

53/56 155.52 Mbps = 147.19 Mbps

V mi khe up ln c chia thnh nhiu khe con, mi khe con cha 3 byte overhead t

trc cell ATM v PLOAM. Bn cnh mi khe up ln c thc chia thnh nhiu khe

nh. Hnh 2.3 (a,c) m t khung down v up ca APON/BPON ti 155.52 Mbps. Cu trc

khung ti 622.08 Mbps v 1244.16 Mbps th tng t ngoi tr s khe thi gian trn khung

tng ln ln lt 4 v 8 ln.

Cu trc PLOAM down m thnh 2.3 (b) n gm cc phn sau:

5 byte header c thc m tbn di:

Header cellPLOAM

Byte 1 Byte 2 Byte 3 Byte 4 Byte 5

0000 0000 0000 0000 0000 0000 0000 1101 HEC = 01110110

Vng IDENT c nm vtr u tin trong PLOAM down. K tip l 2 byte ng b. PLOAM c 27 grant, c mi 6-7 grant th c kim tra CRC. MSG_PON_ID nh a ch cho mi ONU. Trong th tc sp xp ONU c gn s

nhn dng PON_ID. S nhn dng ny c gi tr t0 n 63.

MSG_ID m t loi bn tin. MESSAGE_FIELD cha bn tin cnh bo, x l cc bn tin nhn c ONU lin

quan n th tc sp xp.

BIP8 (bit-interleaved parity) c 8 bit cho php ONU kim tra tc li bit BER.Mibit ca BIP8 s XOR vi tt c bit cng v tr trong mt byte. ONU s so snh vi

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BIP8 nhn c vi BIP8 c tnh trn lung nhn c, mi bit khng ging sc tnh ton.

Vic truyn cell ATM, cell PLOAM hng up ln c iu khin bi OLT thng qua

cell PLOAM truyn hng down. G.983 yu cu ti thiu c mi 100 ms c mt cell

PLOAM trn mt ONU. 3 byte u hng up ln cha thi gian ngh, li mu v ranh

gii bt u cell.

APON/BPON chnh thi gian ngh ti thiu l 4 bit. N cung cp thi gian nghgia 2 cell hay khe con lin ktrnh ng .

Li mu ly pha ca cell n hay khe con ng b bit v khi phc bin . Ranh gii l phn chnh bt u cell ATM hay khe con, m c thc dng

thc hin ng b byte.

Ni dung ca vng ny c lp trnh v c nh r trong OLT trong bn tin c t

u ca khung hng up ln.

MESSAGE_

ID

MSG_

PON_

ID

BIP

56 khe thi gian download

ATM1

PLOAM1

ATM27

PLOAM2

ATM28

ATM54

SYNC

khe thi gian (53 byte)Header(5 byte)

HEC

7 grant 10 message field7 grant 7 grant 6 grant

1 2-3 4-10 11 12-18 19 20-26 27 28-33 34 35 36 47 48

IDENT

CRC

CRC

CRC

CRC

CRC

(a)

(b)

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SVTH:Hng ng Ngc n Lp:07VTH1 Trang 16

Khun dng cell PLOAM up ln c m thnh 2.3 (d) bao gm cc phn sau:

Ging nh khung down n cng c 5 byte header v 1 byte IDENT bt u khung up. MSG_PON_ID v MSG_ID phc v cho vic nhn dng ONU. Byte CRC truyn cnh bo cc thng tin hot ng, qun l v bo dng t ONU. 17 byte iu khin ngun laser: s dng cho ONU bo co cc mc cng sut v t

l extinction cho mi ngun laser ca ONU chng c th duy tr gi tr thch hp.

16 byte iu khin bthu c dng b thu ca OLT hiu chnh mc ngngcho vic pht hin mc 0 v mc 1.

BIP cng c chc nng tng tnh khung down.2.1.4.Bc sng trong APON/BPON

Trng hp h thng truyn 2 si quang, h thng APON/BPON dnh vng ca sbc

sng 1260-1360 nm cho chng down v up. Trng hp truyn mt si, vng bc sng1480-1500 nm c dng hng down, vng bc sng 1260-1360 nm dng hng up v

Thi gianngh

Mt khe con

Chia thnh cc khe con

53 khe thi gian upload

PLOAM ATM hayPLOAM

ATM hayPLOAM

Khe thk

ATM hayPLOAM

ONU x ONU y ONU z

3 byteoverhead

153 byte

khe thi gian(53 byte)

3 byteoverhead

MSG_

ID

MSG_

PON_

ID

khe thi gian (53 byte)

Header(5 byte)

HEC

10 message field

1

IDENT

BIP

(d)

2 3 4-13 14 15-31 32-47 48

CRC

17 byte iu khin ngunlaser

16 byte iu khin b thu

(c)

Hnh 2. 3 : Cu trc khung download v up load ca APON

(a) Khun dng khung down tc 155 Mbps ; (b) Khun dng bn tin PLOAM down ; (c)Khun dng ca bn tin up ln ; (d) Khun dng bn tin PLOAM up ln [4]

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SVTH:Hng ng Ngc n Lp:07VTH1 Trang 17

vng mrng. Vng mrng gm 2 phn: phn 1 bc sng 1539-1565 nm cung cp cc

dch vk thut s v phn 2 bc sng 1550-1560 nm dng cho vic phn phi video. Hai

bng 1360-1480 nm, t 1565 nm tri c dnh cho nghin cu tng lai. Hnh 2.4 m t

k hoch phn bbc sng ca ITU-T G983.3.

2.1.5. Kin trc chuyn mch bo v Hu ht mng APON/BPON, GPON v EPON u theo cu trc hnh cy cung cp cc

kt ni im n a im. Splitter c trin khai chia tn hiu quang nhn c n tt c

si quang c phn b. Hnh 2.5 ch ra 4 loi kin trc bo v vi cc cp bo v khc

nhau. Vc bn th chng lm ging ht ng link si quang gc v cc thit b chnh.

Hnh 2.5 (a) c 2 si quang gc gia OLT v splitter, trong c mt si d phng, cu

hnh ny ch c si quang gc c bo v. Hai si quang ny c s phi hp vi nhau do

m khi si quang chnh bt th n chuyn sang si d phng. Trong sut qu trnh chuynmch th suy hao tn hiu thm ch l suy hao cc cell truyn l tt yu, do tt c kt ni

gia cc node dch v v thit bu cui sc gi li trong lc chuyn mch si quang.

OLT khng c thit b dphng do nu OLT b li th mng sngng hot ng. Tt c

ONU v si quang dphng u trnn v dng khi OLT b li. Trong loi bo vny ngi

ta s dng splitter 1:N.

Hnh 2.5 (b) c 2 b thu pht quang ti OLT v 2 si quang gc gia OLT v ONU. Cu

hnh ny yu cu mch d phng nng trong OLT v khng c d phng trong ONU. OLT li

hay si quang gia OLT v splitter bt th n chuyn mch sang b d phng thng qua b

iu khin t OLT. Suy hao tn hiu v suy hao cc cell l tt yu trong qu trnh chuyn

mch. Trong loi bo vny ngi ta s dng splitter 2:N.

Hnh 2.5 (c) khng ch c 2 b thu pht OLT m cn c 2 b thu pht ONU v 2 b

splitter. y l mt kin trc bo vy ca FTTH. Mch dphng nng c t ti

OLT v ONU. Trong cu hnh ny, li bt k im no cng c thc khi phc bng vic

chuyn mch n thit b dphng. Do chi ph cho cu hnh ny l rt cao v n khng

kinh t khi mch d phng chc dng khi mng chnh c li.

Bng mrng

S dng dchv s ha

S dngcho tng lai

S dngcho tng lai

APONdownstream

APONupstream

Bc sng (nm)1500 1539 1550 1560 1565148013601260

Bng mrngS dng phn

phi video

Hnh 2. 4 : K hoch phn bbc sng ca ITU-T G.983.3

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SVTH:Hng ng Ngc n Lp:07VTH1 Trang 18

2.2. GPONGPON vit tt ca t Gigabit Passive Optical Network. GPON l s pht trin ca

APON/BPON n hot ng tc ln ti hng Gbps v c chun ha thnh ITU-TG.984. GPON khng ph thuc vo ATM, GPON s dng lp con truyn dn hi t (GTC-GPON Transmission Convergence), khung GTC c thng gi cc cell ATM. Khng gingnh APON/BPON, khung GTC c thng gi trc tip cc gi d liu thng qua phng

php ng gi GPON (GEM- GPON Encapsulation Method). Phn ti khung GTC cha c

ATM v GEM.

2.2.1. M t h thng GPONKin trc GPON th tng t APON/BPON c m tphn 2.1.1. Tuy nhin, i

vi h thng GPON th tc tng ln n hng Gigabit v ng thi b chia splitter y

ln ti 1:128 trong khi b chia splitter ca APON/BPON ch c 1:32 v khong cch ti a

gia OLT v ONU ln ti 60 km ch khng phi l 20 km nh trong APON/BPON.

Bng 2.2 lit k tc bit ca GPON trong G.984.3.

2:N

2:N

2:N1:N

Si quang

Splitter

Si quang

Splitter

Si quang

Splitter

OLT

ONU#N

OLT

ONU#1

ONU#N

ONU#1

ONU#N

OLT

ONU#1

a (b)

c

Hnh 2. 5 : Kin trc chuyn mch bo vc a ra trong ITU-T G.983.1

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SVTH:Hng ng Ngc n Lp:07VTH1 Trang 19

Bng 2. 2 : Lit k tc d bit ca GPON trong G.984.3

Tc down (Mbps) Tc up (Mbps)

1244.16 155.52

1244.16 622.08

1244.16 1244.16

2448.32 155.52

2448.32 622.08

2448.32 1244.16

2448.32 2448.32

Khi tc bit tng ln n hng gigabit th cn c b pht cng sut cao v do dn n

l cng cn c bthu c nhy cao hn. iu ny c thc khc phc bng cch s dng

c ch cn bng cng sut. Cch cn bng cng sut h trcho vic iu chnh cc mc

cng sut ca ONU lm gim vng chnh lch cng sut nhn c OLT. Mt ONU gn

OLT th suy hao thp, s khi to cng sut nhhn