Cong Nghe Truy Nhap NGN

8/13/2019 Cong Nghe Truy Nhap NGN

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2/112

CC CNG NGHTRUY NHP TRONG MNG THHSAU

Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPTii

Trong qu trnh bin son, mc d gio vin rt cgng, tuy nhin khng thtrnh khi nhng thiu st. Rt mong nhn c kin ng gp ca cc bn c nhng ln xut bn sau cht lng ca ti liu c tt hn.

TRUNG TM O TO BU CHNH VIN THNG 2


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MC LC

Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPT iii

MC LCLI NI U..............................................................................................................i MC LC..................................................................................................................iii DANH SCH HNH ...................................................................................................vDANH SCH BNG......................... ........................ .......................... ..................... viiCHNG 1 - PHT TRIN CA MNG VIN THNG & PHNG THCTRUY NHP ..............................................................................................................1

1.1 MNG TRUY NHP & MNG VIN THNG......................... .................21.1.1 Mng NGN v cc cng nghtruy nhp.................................................2 1.1.2 Nhng giai on pht trin ca mng truy nhp.....................................3

1.2 CNG NGHTRUY NHP HU TUYN................... ......................... .....51.3 CNG NGHTRUY NHP V TUYN....................... ......................... ....61.4 NHNG CNG NGHTRUY NHP HU TUYN CNH TRANH .......6

1.4.1 Cng ngh PLC......................................................................................61.4.2 Cng ngh CM.......................................................................................8

1.5 SO SNH & NH GI CC CNG NGHTRUY NHP......................8CHNG 2- HCNG NGH xDSL ....................................................................11

2.1 CNG NGHTRONG H xDSL ..............................................................122.2 KIN TRC HTHNG....................... ......................... ......................... ..152.3 ADSL, ADSL2, ADSL2+............................................................................17

2.3.1 ADSL....................................................................................................17 2.3.2 ADSL2..................................................................................................21 2.3.3 ADSL2+...............................................................................................23

2.4 HDSL, HDSL2,SHDSL, HDSL4.................................................................262.4.1 HDSL ...................................................................................................262.4.2 HDSL2.................................................................................................27 2.4.3 SHDSL .................................................................................................272.4.4 HDSL4.................................................................................................28 2.5 VDSL v VDSL2 .......................................... ......................... ..................... 282.5.1 VDSL....................................................................................................28 2.5.2 VDSL2..................................................................................................29

2.6 Tnh hnh trin khai ti Vitnam..................................................................30CHNG 3- CNG NGHTRUY NHP QUANG...............................................31

3.1 CC MNG QUANG THNG PON................. ..................................323.2 APON .........................................................................................................35

3.2.1 Kin trc phn lp APON.....................................................................353.2.2 Lp vt l.............................................................................................36 3.2.3 Lp hi ttruyn dn TC .....................................................................36

3.3 EPON..........................................................................................................37 3.3.1 Kin trc EPON...................................................................................373.3.2 M hnh ngn xp EPON......................................................................383.3.3 Giao thc EPON..................................................................................383.3.4 Bo mt trong EPON ...........................................................................393.3.5 Nhng bc pht trin tip theo...........................................................39

3.4 METRO ETHERNET ...................... ......................... ..................................403.4.1 Li ch khi dng dch vEthernet.........................................................403.4.2 M hnh dch vEthernet.....................................................................40


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5/112

DANH SCH HNH

Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPT v

DANH SCH HNH

Hnh 1.1 Mng thhsau v cc cng nghtruy nhp................................................3

Hnh 1.2 Srai ca cc dng thit btruy nhp......................................................4

Hnh 1.3 Thit bDLC thh 3....................................................................................5Hnh 1.4 Thit btruy nhp IP cho mng thhsau.....................................................6

Hnh 2.1 Lch spht trin ca cc cng nghtrong hxDSL...................................12

Hnh 2.2 Kin trc chung ca hthng sdng hcng nghxDSL .........................16

Hnh 2.3 Cu trc hthng ADSL..............................................................................17

Hnh 2.4 Phn chia bng tn ADSL khi sdng kthut FDM..................................18

Hnh 2.5 S khi thu v pht ADSL.......................................................................20

Hnh 2.6 Tcsliu ng xung ca ADSL2+ so vi ADSL2.............................24

Hnh 2.7 Ghp hai ng ADSL2+............................................................................25Hnh 2.8 M hnh hthng sdng VDSL.................................................................28

Hnh 2.9 Tnh hnh trin khai xDSL ti Vit nam ca VNPT ......................................30

Hnh 3.1 S logic hthng mng PON..................................................................33

Hnh 3.2 Cu hnh chung ca mt mng PON ...........................................................34

Hnh 3.3 Cu trc phn lp mng APON...................................................................36

Hnh 3.4 Ngn xp EPON..........................................................................................39

Hnh 3.5 Mng MAN thnghip ti thnh phHCh Minh.....................................42

Hnh 3.6 Mng MAN ti Ninh Bnh............................................................................44

Hnh 4.1 Cc cng nghtruy nhp v tuyn...............................................................48

Hnh 4.2 Xu hng hi tca cng nghtruy nhp v tuyn.....................................49

Hnh 4.3 Mc lch sca truy nhp v tuyn.............................................................49

Hnh 4.4 Spht trin ln 4G tcc cng nghWAN................................................50

Hnh 4.5 Hthng IMT 2000.....................................................................................52

Hnh 4.6 Cc cng nghtruy nhp v tuyn cnh tranh.............................................56

Hnh 5.1in thoi di ng Iridium...........................................................................59Hnh 5.2 Nguyn l hotng ca DirectPC .............................................................60

Hnh 5.3 Vng phsng ca vtinh IPSTAR.............................................................61

Hnh 5.4 Cu hnh trm thu bao...............................................................................63

Hnh 6.1 Cu hnh mng WLANc lp....................................................................68

Hnh 6.2 Cu hnh mng WLAN c s. ......................................................................68

Hnh 6.3 Cu hnh WLAN dng blp.......................................................................69


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Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPTvi

Hnh 6.4 Kin trc WLANy .............................................................................. 69

Hnh 6.5 Cc chun trong h802.11......................................................................... 72

Hnh 6.6 im truy nhp AP ..................................................................................... 73

Hnh 6.7 Cu ni v tuyn......................................................................................... 74

Hnh 7.1 Cu hnhim-a im (PMP) ................................................................... 80

Hnh 7.2 Cu hnh mt li MESH............................................................................ 81Hnh 7.3 Cc phn lp giao thc Wimax cho hai lp cui cng................................ 81

Hnh 7.4 Qu trnh truyn dn.................................................................................. 84

Hnh 7.5nnh khe thi gian trong OFDM............................................................ 88

Hnh 7.6 Kin trc hthng AS.MAX ca hngAirSpan............................................ 93


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DANH SCH BNG

Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPT vii

DANH SCH BNG

Bng 1.1 nh gi chung vcc cng nghtruy nhp.................................................9

Bng 1.2 So snh vgi thnh cc cng ngh...........................................................10

Bng 2.1 Cc cng nghtrong h xDSL ...................................................................14Bng 2.2 Tc khong cch cc loi VDSL.............................................................29

Bng 3.1 So snh cc gii php mng PON...............................................................34

Bng 6.1 Tmtt cc tiu chun WLAN trn thgii.................................................70

Bng 7.1 Cc tham sca SOFDMA.........................................................................86

Bng 7.2 Thng hiu ca cc nh cung cp thit bWimax.....................................89


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Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPT2

1.1MNG TRUY NHP & MNG VIN THNG1.1.1 Mng NGN v cc cng nghtruy nhp

Mng NGNMng vin thng thhsau c nhiu cch gi khc nhau nh Mng a dch v,

Mng hi t, Mng phn phi hay mng nhiu lp. Cho ti nay cc tchc v cc nhcung cp thit bvin thng trn thgii rt quan tm n NGN nhng vn cha cmt nh ngha r rng. Do vy ta chc thtm nh ngha NGN nh sau:

NGN l mng c htng thng tin duy nht da trn cng nghchuyn mch gi,trin khai cc dch vmt cch a dng v nhanh chng, l shi tgia thoi v dliu, gia cnh v di ng

c im NGNNGN c 4 c im chnh:

- Nn tng l hthng m.- NGN l do mng dch vthc y nhng cc dch vtrn NGN phi c lp

vi mng li.

- NGN l mng chuyn mch gi da trn nhng giao thc thng nht.- L mng c dung lng ngy cng tng, c tnh thch ng ngy cng tng v

c dung lng p ng nhu cu.

Trong NGN giao thc IP thc t trthnh giao thc ng dng vn nng cp dng lm c scho mng a dch v. Hin ti mc d vn cn gp nhiu kh khnso vi mng chuyn mch knh vkhnng htrlu lng thoi v cung cp cht

lng dch vm bo cho sliu, nhng vi tc thay i nhanh chng nhiu cngnghmi ang c p dng ssm khc phc iu ny trong tng lai gn.

Cc cng nghtruy nhp v mng NGNNh trong hnh 1.1 kt ni ngi dng vo mng NGN ngi ta c thsdng

mt cng nghhoc c thkt hp mt vi cng nghkhc nhau to ra hng lotnhng phng thc kt ni khc nhau. Nhng cng nghkt ni hin nay ang csdng phbin bao gm :

- V tuyn (GSM, 3G, 4G, WLAN, WMAN)- Hu tuyn xDSL, PON, CM, PLC


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CHNG 1 - PHT TRIN CA MNG VIN THNG & PHNG THC TRUY NHP

Chng trnh bi dng kin thc IP v NGN cho ks TVT ca VNPT 3

Hnh 1.1Mng thhsau v cc cng nghtruy nhp

Tuy nhin, t c cu trc nh mong mun trn hnh 1.1 th mng truy nhp

ni ring v mng vin thng ni chung phi tri qua nhng giai on qu vinhiu trng thi khc nhau tng ng vi nhng xut pht im (mng truyn sliu,thoi truyn thng PSTN, mng di ng, mng di ng ni ht) v gii php sdngkhc nhau. Chng ta c th tng kt li (nhn thng pht trin tmng PSTN)

nhng thhca mng truy nhp nh trong hnh 1.2.

1.1.2 Nhng giai on pht trin ca mng truy nhpHnh 1.2 cho chng ta thy mc pht trin ca cc dng thit b truy nhp trong

mng vin thng vi xut pht im l mng PSTN.

Dng thit bhtrdch vbng rng u tin v c tch hp pha thu bao lDLC thh3 hay NDLC ra i vo nhng nm cui thk20. Thit bny c nhiu

im tng ng vi ATM DSLAM do cng s dng mt cng ngh v kin trctng tnhau. Cc NDLC thu ni v phi hp hot ng vi nhau to thnh mtmng ATM din rng thng nht, chuyn mch gi vi bng thng tng i ln cho

php cung cp cc dch vdliu mt cch tng i mm do (hnh 1.3). c tnh

ca dng thit b ny nh sau:

- Cung cp gii php truy nhp bng rng tm thi qua mng li ATM.- Sdng cng nghxDSL truy nhp dliu tc cao.- Chun V5.x giao din vi mng PSTN.- Kt ni ATM vi mng ng trc hay qua mng IP.- Htrcc dch vthoi/fax, ISDN v dliu bng rng.


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Hnh 1.2Sra i ca cc dng thit btruy nhp

Tuy nhin dng thit bny c mt snhc im sau:

- Bng thng v dung lng hn ch.- Nt cchai trong vng ring truy nhp nu phn ln cc thu bao u sdng

dch vxDSL v nt cchai trong mng li ATM.

- Kh mrng dung lng.- Kin trc phc tp, qua nhiu lp (Ip qua ATM qua SDH/DSL).- Gi thnh v chi ph tng i cao.

Tip sau DLC thh3 l dng thit btruy nhp IP. y l dng thit btruy nhptin tin nht hi tnhiu cng nghnn tng trong mng thhsau NGN (hnh 1.4).

Dng thit bny chy trn nn tng mng IP/MPLS v sdng in truy nhp IP-ANvi mt sc im sau:

- Bng thng/ Dung lng hu nh khng hn ch (Trn thc t hu nhkhng tc nghn vi bng thng trong khong 1-10Gbps).

- Truy nhp bng rng IP.- Ddng mrng v tch hp vi mng NGN (Trn nn mng chuyn mch

mm).

- Cung cp tt ccc dch vqua mt mng IP duy nht mc d hthng nyvn h trcc u cui tng t truyn thng. Thit bny phi hp hotng vi mng IP qua cng phng tin MG.

Nm 1890 Cp ng

1-2G DLCNm 1970

V5 DLCGia th p k 90

NGDLCCui thp k 90

Truy nh p IP


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- Gi thnh tnh cho tng thu bao v chi ph vn hnh mng thp.- Kin trc n gin (IP over SDH)

Hnh 1.3Thit bDLC thh3

Trong giai on qu hin nay, vic u t vo mng truy nhp mang li hiuquvmt kinh tv kthut th ngoi gii php sdng cp ng n khu vc thu

bao cn c thsdng cc thit btruy nhp tch hp, quang ha mng truy nhp vtn dng ti a nhng cng ngh truy nhp v tuyn, hn na ph hp vi xu thtt yu l tin ti hi tmng NGN khi m c sh tng mng hin ti cha sn

sng h trcc thit b truy nhp IP tin tin nht th cn phi c dng thit btruynhp p ng tt ccc yu cu sau:

- Htrcc giao din PSTN truyn thng, cc u cui tng t.- C khnng cung cp cc dch vbng rng v cc dch vmi khc.- Htrgiao din V5.x v c thkt ni ti cc tng i ni ht ang sdng

(c thng vai tr nh l thit bDLC).

- Ddng nng cp, tch hp khi chuyn sang mng NGN.- m bo thi gian trin khai v chi ph pht thin thu bao khng qu cao.

1.2CNG NGHTRUY NHP HU TUYNHin nay trn thtrng nhng nh khai thc vi c shtng khc nhau a ra

nhng dch vtruy nhp da trn cng nghkhc nhau nh:

- Cng nghmodem bng tn thoi, xDSL, ISDN da trn cp ng xon- Cng nghmodem cp CM trn mng cp truyn hnh cp CATV- Cng ngh PLC trn mng cp in lc- Cng nghtruy nhp quang trn mng CATV, PLC, PSTN

Cp quang

DLCDLC

Trung k

IP

EX

PSTN

ATM

EX

Cp ng

B-RAS


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Tuy nhin, xt vtnh kinh tcng nh sn nh vgii php kthut hcngnghxDSL vn l gii php hp l trong nhng nm ti.

1.3CNG NGHTRUY NHP V TUYNVi sxut hin ca Wimax, cng nghtruy nhp v tuyn cho thy shi t

mt cch r rng gia cnh v di ng, mng truy nhp v tuyn stin ti cung

cp dch vkt ni c tc cao hn, phc vnhng dch va dng hn v sc stha hip gia tnh di ng v tc .

Hnh 1.4Thit btruy nhp IP cho mng thhsau

1.4NHNG CNG NGHTRUY NHP HU TUYN CNH TRANH1.4.1 Cng nghPLC

Vic sdng mng li phn phi in cho mc ch truyn thng c bit

n tnhng nm u ca thk20. Bng cch sdng phng thc iu chkhobt tt cc hthng PLC u tin c sdng cho vic truyn thng ni bnhmthc hin nhim viu khin v o c txa, tuy nhin cc h thng ny tc truyn tin rt thp. Ngy nay vi spht trin nhanh chng ca cng ngh, c bit l

cng nghsn xut vi mch tch hp cho tng ng dng c bit ASIC cho phpPLC c nhng bc pht trin nhy vt v ha hn trthnh mt trong nhng cng

nghtruy nhp bng rng, tc cao.Trong mt vi nm gn y cng nghPLC ang pht trin mnh mdo nhng

nguyn nhn sau:

- Nhu cu truy nhp Internet bng thng rng ang bng n. Trong khi cccng ngh truy nhp bng thng rng khc v cc l do khc nhau cha p

ng c.

IP hay MPLS

IP hay MPL S switch-router

Chuynmch mm

PSTN

Gateway

Gateway truy nhp

xDSL

My T IP

POTS/PSTN


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- Mng li in h thsn c khp ni, di tn trn ng dy in chac s dng ht.

- i vi cc nh khai thc vin thng mi vic xy dng mng truy nhp cung cp dch vtrc tip ti khch hng i hi chi ph ln v tn nhiuthi gian, cng sc.

Do nhng c im hp dn nu trn, PLC nhn c squan tm ht sc cbit ca cc nc Chu u, Bc M, Nht v gn y l mt snc Chu khc. Chu u, trong nhng nm gn y c kh nhiu cuc thnghim mng truy nhp

v mng gia nh sdng cng nghPLC. Trong nm 1999, ETSI cng t ra mtdn mang tn EP PLT pht trin cc tiu chun v cc c tk thut cho h

thng PLC. Thng 3 nm 2000, ti ThuS, din n PLC c thit lp nhm mctiu lin kt cc thnh vin quan tm n cng nghPLC bao gm 51 thnh vin ti 17

quc gia v 3 lc a. Ti Bc M, lin minh cng nghip Bc M thit lp mt tchc c tn l HomePlug nhm thc hin mc tiu cung cp mt din n to ra cc

c tmcho pht trin h thng PLC cho cc sn phm v mng truy nhp tc cao, mng gia nh sdng cng nghPLC. Hai lnh vc ng dng hin nay ca PLC

l truy nhp ni ht v kt ni mng trong nh. Cc dch vca PLC c thc cungcp m bo lun sn sng ti mi in v khng cn thi cng cp bao gm:

- Truy nhp Internet bng thng rng (ti 45Mbs hoc hn ), cc kt ni nylun online.

- Dch vthoi v fax.- Kt ni LAN trong nh cho cc my PC v my in cng nh cc thit b

truyn thng khc

- Cc dch vbng hp khc (house automation, health care...).Cn cvo dung lng cung cp v cu hnh sdng m ta c thphn loi cng

nghPLC nh sau y.

Nu xt bng tn sdng, ti Nht, bng tn khng cn ng k cho PLC t10-450 Khz trong khi ti Chu u l t10 -148.5 Khz, cc hthng PLC vn hnh ditn ny sc xem nh l cc hthng PLC bng hp. Gn y nhiu quc gia trong

c Nht bt u cn nhc n vic mrng di tn hot ng cho PLC ln ti 30Mhz. Ti Chu u, ETSI xc nh khoch phn bbng tn t1,6 Mhz n 10

Mhz cho truy nhp ni ht, di tn t10 Mhz n 30 Mhz c u tin dnh cho ngdng mng gia nh, nhng h thng nh vy c thc coi l cc h thng bng

rng.

Nu xt theo cu h nh xdng chng ta c thc nhng cu hnh ca mng truynhp PLC nh:

- Cu hnh sdng mng hthFiber-LV- Cu hnh sdng mng trung thv hthMV&LV


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- Cu hnh sdng trung thv v tuyn MV & Wireless- Cu hnh sdng cp quang FTTH

Do bn cht s khai ca ng cp in khng phi l truyn dn tn hiu thngtin cho nn khng c mt sm bo hiu nng no khi thc hin truyn thng trncp in nhn tquan im truyn dn tn hiu. PLC sgp phi hai trngi rt ln

sau:- Chng nhiu (do cc ngun in hoc ngoi in) v suy hao trn ng dy.- Cc c tnh c bit ca knh truyn dn sdng cp in, nh l cc c

tnh trkhng thay i theo thi gian ca ng dy in, rt nhiu nhn t

gy ra cc dng tp m tn hiu.

Ti Vit nam EVN thnghip thnh cng PLC ti trsTrn Nguyn Hn, tuy

nhin cng vi nhng trngi nh cp trn, khnng trin khai trn din rngvn cn ng.

1.4.2 Cng nghCM

L cng nghcho php truy xut thng tin tc cao n cc server txa nh ccserver Internet hay cc server video theo yu cu qua mng truyn hnh cp vi tc

thay i ph thuc vo h thng modem cp, kin trc mng cp ng trc v lulng trn modem.

Tc theo chiu xung c thln n 27Mbps, tuy nhin y l dung lng tngcng ca mi ngi chia ra do cu trc mng dng nhnh, thng th dung lng camt thu bao cht1-3Mbps. chiu ln c tht c 10Mbps nhng thng l 1-

2,5 Mbps

u im ca modem cp l tn dng c mng truyn hnh cp sn c nn gimchi ph, cc linh kin tn scao cn thit cho hot ng ca modem cp trnn rt

rv c bn i tr. Nhng cng do lm vic tn scao v c n 90% cp itrong nh m cc cp ny thng c lp t vi v, cu thnn dgy nhiu cho

tivi v cc thit bkhc, gii php y l cn phi i li dy nh. Hn na do vicsdng chung cc knh ng ln nn dgy tc nghn.

1.5SO SNH & NH GI CC CNG NGHTRUY NHPChng ta c thso snh cc cng nghtruy nhp trn nhiu gc cnh khc nhau :

Bng 1.1 Cho chng ta so snh chung nht gia nhng cng ngh

Bng 1.2 : nh gi vcc cng ngh truy nhp trn kha cnh kinh tkhi trin

khai


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Bng 1.1nh gi chung vcc cng nghtruy nhp

Bng thngCng

Ngh Tc ln

Tc xung

u im Nhc im

Dial-up(V90)

33.6 Kbps 56.6 Kbps Phm vi cung cp rngGi thnh r

Tc rt chm

xDSL(ADSL)

1.5Mbps 8Mbps Tc cao

tin cy cao

Nhiu chun khcnhau

Modem

Cp

Ti a 10Mbps

Ti a 30Mbps

Tc cao.

Gi thnh r.

Chun thng dng.

Cu trc v bng tnphi chia s

ISDN 128Kbps 128Kbps Sdng rng ri.

Tng thch vi DSL

Tc chm

Chi ph cao

Kh qun l gim st

Vtinh 33.6 Kbps 400 Kbps Kh nng ng dngrng ri

Tc lung ln thp.

Chi ph thit bcao.

tin cy cha cao.

nh hng do tc dng

ca thi tit

Vtuyn di

ng

Thay i Thay i C kh nng di ng,trin khai dch vnhanh

Nhiu chun cngngh, kh khn khi

trin khai trn dinrng

V

tuyn cnh

Thay i Thay i Tc cao.

Nhiu cp ng dng.

Chi ph thit bcao.

Phm vi ng dng hnch.

Phthuc vo cly vanten

Cp

quang

Ln Ln Tc cao, cht lngkt ni cao

Gi thnh t

PLC 18 Mbps 45 Mbps C mt khp ni trnng dy in lc

Cha c chun chung


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19/112


CHNG 2

HCNG NGHxDSL

Hcng nghxDSL ang c sdng rng ri bi nhng u im vkinh tv

kthut ca chng. Chng ny trnh by chi tit vkin trc ca hthng sdng hcng nghxDSL, cc cng nghtrong hv khnng ng dng ca chng, ni dungca chng 2 gm:

q Cng nghtrong hxDSLq Kin trc hthngq ADSL, ADSL2, ADSL2+q HDSL, HDSL2, SHDSL, HDSL4q VDSL & VDSL2q Tnh hnh trin khai ti Vit Nam


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2.1 CNG NGHTRONG HxDSL

Hnh 2.1Lch spht trin ca cc cng nghtrong hxDSL

Nh cp chng 1, xDSL l hcng nghng dy thu bao s gmnhiu cng nghc tc , khong cch truyn dn khc nhau v c ng dng vo

cc dch vkhc nhau, vi x thay cho cc k t: A, H, V, I, S, Lch spht trinca cc cng nghtrong hc thhin trong hnh 2.1 .

1986

1992

1995

Modem bng tn thoi DDS, T1 v E1

ISDN T1.601

HDSL

BDSP hiu nng cao

ADSL T1.413

1998ADSL T1.413 phin bn 2

ATMGim mo uThch ng tc

SDSL

1999ADSL lite G992.2 ADSL dmt G992.1

2000T1 pointer-G992.2

T1 pointer-G992.1

ADSL2:G992.4

In-line filter: T1.421

VDSL: T1.424

ADSL G992.3

SHDSL: G991.2HDSL4

TC-PAMBng tn xc nh

TIU CHUN QUN L BNG TN

CHUN QUC T

Bt i xnga tc

HDSL2 T1.41BUAWG

Khng c

bchia

G.hs


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CHNG 2 - HCNG NGHxDSL


C thphn loi xDSL theo c tnh truyn dn gia hai chiu ln v xung nhsau (bng 2.1 tng kt c im ca mt scng nghtrong h):

- Truyn dn hai chiu i xng gm: HDSL/HDSL2, SHDSL c chunho v nhng phin bn khc nh: SDSL, IDSL

- Truyn dn hai chiu khng i xng gm ADSL/ADSL. Lite (G.Lite),ADSL2, ADSL2+ c chun ho v mt s tn gi khc cha cchun ho nh: RADSL, UADSL, CDSL.

- Cng ngh VDSL, VDSL2 cung cp c dch v truyn dn i xng vkhng i xng.

HDSL/HDSL 2: Cng ngh ng dy thu bao s truyn tc d liu caoHDSL sdng 2 i dy ng trong mi i dy sdng hon ton sng cng cung cp dch vT1 (1,544 Mbps), 2 hoc 3 i dy cung cp dch vE1 (2,048Mbps)

SDSL: Cng nghDSL mt i dy truyn i xng tc 784 Kbps trn mt i

dy, ghp knh thoi v s liu trn cng mt ng dy, sdng m 2B1Q. Cngnghny cha c cc tiu chun thng nht nn khng c phbin cho cc dch vtc cao. SDSL chc ng dng trong vic truy cp trang Web, ti nhng tp dliu v thoi ng thi vi tc 128 Kbps vi khong cch nhhn 6,7 Km v tcti a l 1024 Kbps trong khong 3,5 Km.

SHDSL: L cng ngh kt hp ca HDSL 2 v SDSL vi tc thay i t

192Kbps n 2,134 Mbps, khong cch tng ng vi tc ti a l 2km. Trongthc t, n c th cu hnh dng 2 i dy cung cp tc t 384Kbps n

4,264Mbps.

ADSL,ADSL2 v ADSL2+: Cng nghDSL khng i xng, ADSL cung cp tctruyn dn khng i xng ln ti 8 Mb/s lung xung v 16- 640 Kb/s lung lnvi khong cch truyn dn 5km v gim i khi tc ln cao. Mt dng ADSL khcgi l ADSL Lite hay ADSL khng sdng b lc xut hin tu nm 1998

chyu cho ng dng truy cp Internet tc cao. ADSL2 thm nhng ci tin viu chv m ha lm tng hiu qusdng bng thng. ADSL2+ mrng bng tncho chiu xung ti 2.2 Mhz.

ReachDSL l cng ngh DSL i xng p ng nhu cu ca thu bao cc

khong cch xa. bsung cho cng nghADSL tiu chun (DMT hay G.lite), ccsn phm ReachDSL cung cp tc dliu t128 Kbps n 1 Mbps v c thit k

lm vic vi iu kin ng dy v i dy trong nh ddi hn. Mt trong cc lich ca ReachDSL l khng cn phi lp t cc btch dch v thoi, iu ny cho

php khch hng hon ton c thtlp t cc blc. Khc vi cc hthng ADSLc di vng thu bao gii hn trong khong 6 Km k t tng i, cc h thng

ReachDSL mrng dch vn hn 6,5Km v hin nay c cc ng dy vt qu10 Km.


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ADSL2

-RE

8 Mbps xung

1 Mbps ln

5km (tc cng cao th

khong cchcng ngn )

Reach

Extende

Truy xut Internet, Videotheo yu cu, tng tc a

phng tin, truy xut LANtxa.

VDSL

26 Mb/s i xng

13 - 52 Mb/s lungxung

1,5-2,3 Mb/s lung

ln

300 m - 1,5km

(tutc )

1 iNh ADSL nhng thm

HDTV

VDSL2100Mbps ln/xung

G.993.2

300 m - 1,5

km (tu tc)

1 iNh ADSL nhng thm

HDTV

Vi mt hcc kthut DSL khc nhau, vic p dng chng sao cho ph hp vc hiu qucao l mt vn cn xem xt. Mi loi kthut c nhng tnh nng, cth v im mnh, im yu ring. Trong hxDSL th cc cng ngh bt i xng

nh ADSL, ADSL2, ADSL2+ l nhng cng nghc sdng nhiu nht, phbinnht trn thgii.

Nhn xt nh gi vc im ca xDSL:

- Xy dng tnh mm do mc cn thit htrcho cc ng dng. Tnhmm do thhin y l: Khnng htrnhiu loi hnh dch v, kh

nng mrng pht trin tmt vi thu bao ti hng ngn thu bao, khnng qun l tin cy mng im - im trong vic htrnhng ng.

- Cho php mng ca nh cung cp dch vNPS v ngi sdng dch vtndng mt sc tnh ca cu trc c sh tng hin nay nh nhng giaothc lp 2, 3 ging nh Frame Relay, ATM v IP v tin cy nhng dch

vmng. xDSL c th trin khai nhng dch vc da trn cc gi tinhoc tbo ging nh Frame Relay, IP hoc ATM hay trn nhng dch v

knh ng bbit.

- xDSL p ng c yu cu i hi thi gian thc, tc cao- Khnng xDSL ngy cng phong ph vi rt nhiu cc phin bn mi nh

ADSL2, HDSL2

- Qua nhng kt qunghin cu, cc nh cung cp dch vtha nhn rng hcng nghxDSL khng phi l thhtng lai ca mng truy nhp m chl gii php hin ti ca truy nhp mng.

2.2K IN TRC HTHNG


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Hthng xDSL bao gm nhng thit bpha nh cung cp dch v, nhng thit bkhch hng, nhng thit bny c ni vi nhau thng qua mch vng ng dy

thu bao. Hnh 2.2 thhin kin trc chung ca mt hthng sdng xDSL, hnh 2.3thhin chi tit nhng thit btrong mt hthng ADSL thng dng, cc cng ngh

khc trong c thc sdng vi cu hnh tng t(skhc bit chyu l c thsdng blc hoc khng tng ng vi vic c sdng dch vthoi truyn thng

hay khng).

PSTNPSTN

PSTNPSTN

Hnh 2.2Kin trc chung ca hthng sdng hcng nghxDSL

Thit bnh cung cp dch vkt niGm c cc bchia c lp t ni cc mch vng thu bao kt cui trn gi

phi dy chnh MDF, u ra c hai i dy. i thnht kt ni ti mng chuynmch thoi cung cp dch vthoi truyn thng. i dy thhai kt ni ti khi ktcui ADSL trung tm ATU-C. truyn dn hiu qu, cc khi ATU-C c kt hpvi chc nng ghp knh to nn bghp knh truy nhp DSL l DSLAM trong tng

i trung tm v c kt ni ti mng cc nh cung cp dch vthng qua mng bngrng ATM hoc IP.

Pha khch hngBao gm cc bchia c lp t ni cc mch vng thu bao kt cui, u ra kt

ni ti khi kt cui ADSL u xa ATU-R ti u cui khch hng sdng ADSL vmt u ti u cui khch hng sdng thoi.

Mch vng thu baoL mt i dy ng xon i ni thu bao v tng i trung tm. Tuy nhin, h

thng ADSL c th trin khai c trn thc t, th ta phi xem xt c s tngthch phca cc dch vADSL trn mch vng thu bao v n nh hng su sc ti

cht lng dch vADSL.


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- Tc bit pht (vpha mng) ln ti 1 Mbit/s.- Dch vin thoi truyn thng POTS.

Hthng truyn dn c thit khot ng trn cp ng xon i, nhiu cdy hn hp. Cng nghADSL c xy dng da trn iu kin khng c cun giacm v c mt vi trng hp hn ch ca nhnh rc chp nhn. Nhng p

dng cng nghtin tin nng cao tc truyn dn, c thcung cp cho thu baodch vbng rng mt chiu nh dch vtruyn hnh scht lng cao HDTV, dchvtrao i sliu tc trung bnh v dch vin thoi thng thng.

Kthut iu chHin c 3 kthut iu ch c sdng l QAM, CAP v DMT, trong k

thut iu cha tn ri rc DMT c sdng rng ri.

iu chDMT l kthut iu cha sng mang. DMT chia phtn sthnh ccbng tn nh. Mi bng tn nhc thc iu chc thmang mt slng bt

nht nh ty thuc vo cht lng knh truyn ti bng tn .

C thtrong ADSL, trong gii ph t26 KHz n 1,1 MHz c chia thnh ccknh khong 4 KHz, gi l cc knh con, cc bt c iu chtrong mi knh con

bng kthut QAM, hnh 2.4.

Hnh 2.4Phn chia bng tn ADSL khi sdng kthut FDM

Kthut truyn dn song cngTrong ADSL sdng mt i dy cho vic truyn song cng nn phi chia bng

tn hot ng thnh bng tn ttng i ti thu bao v bng tn tthu bao ti tng

Tn s[kHz]

Tnhiu

4 25 138 1 104

Lung xungLung ln

256 Knh

Khong knh4.3125 kHz


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i (n gin l kthut ghp knh theo tn s FDM) hoc phi sdng kthut tritting vng EC.

Trong cng nghADSL c FDM v k thut trit ting vng EC c thc s

dng kt hp ng thi iu ny l do skhng i xng ca bng tn ADSL, cc ditn c thgi chng ln nhau nhng khng trng kht vo nhau. y l c th ring

ca ADSL so vi cc cng nghDSL khc. Kthut ghp knh theo tn s.

Kthut ny cho php di tn pht tch khi di tn thu trnh txuyn m v cdi tn bo vgia chng.

Phng php ny c u im sau:

- Trit tiu c NEXT v hai di tn scch nhau bng bng tn bo v.- Khng cn sng bgia pht v thu.- c pht trin tlu nn t c schn mui cng ngh.- Tuy nhin vn cn tn ti mt snhc im:- Khng sdng hiu qubng thng v lung ln v xung 2 di tn khc

bit nhau v cn c di tn bo v.

- Tc lung xung di tn cao nn bgim nhanh chng khi cly truyndn tng do suy hao min tn scao nhanh.

- Vn xy ra hin tng NEXT mc d trng hp l tng cc b cp ucng loi nhng vn c cc h thng DSL khc nhau hot ng trong cng

b cp .

Kthut trit ting vng ECKthut ny sdng mt knh duy nht cho cpht v thu nn phtn hiu ca

chng trm ln nhau v tn ti ting vng ca tn hiu pht ln trong tn hiu thu nncn mt bkhting vng ti pha thu.

Ting vng gm thp hai loi: ting vng u gn v u xa. Mc ch ca b

trit ting vng l trit ting vng u gn cn tn hiu u xa nh hng khng ngknn c thbqua.

Nh vy, k thut ny cho php hai modem sdng ton bbng thng c sntrn chai hng.

u im:

- Tn dng hiu qubng thng v phhai hng trm ln nhau.- Ci thin ng ktc truyn nht l khi cly di v tn hiu hng xung

c sdng bng tn thp l vng m suy hao nhhn.

Nhc im:


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- Khng loi bc NEXT do c nhiu h thng khc nhau lm vic trongcng b cp m b trit ting vng khng th loi b c xuyn m t

chng.

- Vic chto nhng blc sthch ng rt phc tp nht l khi lm vic vitn scao. V vy, cc modem ADSL hin nay vn sdng kiu FDM khi

yu cu tc cao cha gay gt lm. Nguyn l thu pht

tm hiu r hn v nhng k thut m ha v iu ch c s dng trongADSL ta c thtm hiu s nguyn ca bthu pht ADSL (nm trong ATU-C vATU-R) hnh 2.5, vi chc nng ca tng khi c m tchi tit sau y.

Hnh 2.5 S khi thu v pht ADSL

Khi to khung: Nhn cc knh dliu, EOC, AOC v cc bt chthri to khungv siu khung theo tc thothun sau qu trnh khi to. Sliu trn ng truyndn ADSL c btr thnh cu trc siu khung.

CRC: To 8 bt kim tra li v t trong khung thnht ca mi siu khung. Trongmt lung, CRC skim tra tt ccc bt chuyn qua trcc byte FEC, CRC ca siu

khung trc v khung ng b. CRC gip pht hin c bao nhiu siu khung saukhi thu xut hin mt li khng thsa c bng FEC.

Khi trn: Thc hin trn lung nhanh v lung chm mt cch c lp nhm mcch trnh cc cc bt ging nhau xut hin lin tip. Ti u thu qu trnh din ra

ngc li vi cng qui lut.

Khi FEC: Thm bt d vo phn d liu nhm sa mt sbt b li sau bgiiiu chpha thu (y sdng m Reed Solomon).

DataData

EOCEOC

AOCAOC

BitBit chch

thth

DataData

EOCEOC

AOCAOC

BitBit chch

thth

BBtt ookhungkhung

CRCCRC

CRCCRC

CRCCRC

CRCCRC

TrTrnn

TrTrnn

TrTrnn

TrTrnn

MM hahaRSRS

MM hahaRSRS

MM hahaRSRS

MM hahaRSRS

anan xenxenanan xenxenSSpp xpxp

vvmm haha

chchmmiimm

IIDDFF

TT

IIDDFF

TT

ThThmmTinTin

tt

vvngng

ThThmmTinTin

tt

vvngng

D/AD/AD/AD/A

BBgigiiikhungkhung

CRCCRC

CRCCRC

GiGiiitrtrnn

GiGiiitrtrnn

GiGiiimm

GiGiiimm

GiGiiianan xenxen GiGiii

mmgigiiisspp

xpxp

FFDDQQ

DDFF

TT

TTchchtintintt

vvngng

TDQTDQ

ADC+ADC+fillterfillter

BBgigiiikhungkhung

CRCCRC

CRCCRC

GiGiiitrtrnn

GiGiiitrtrnn

GiGiiimm

GiGiiimm

GiGiiianan xenxen GiGiii

mmgigiiisspp

xpxp

FFDDQQ

DDFF

TT

TTchchtintintt

vvngng

TDQTDQ

ADC+ADC+fillterfillter


29/112


30/112



ADSL a ra mt ch tuchn cho php truyn s liu ADSL trn bng tnthoi do tng thm 256Kbps cho tc dliu ng ln.

Htrng dng thoi trn bng tn ADSL

C ba phng thc c bn truyn lu lng thoi trn ng dy cp ng sdng bng tn DSL l: Thoi qua chtruyn dn cn ng b(VoATM), thoi

qua giao thc internet (VoIP) v thoi phn knh trn DSL (CVoDSL).CVoDSL l mt ci tin ca cng nghng dy thu bao s. Phng thc ny

truyn lu lng thoi TDM mt cch trong sut qua bng tn DSL. CVoDSL l duy

nht gia cc gii php thoi qua DSL trong n truyn thoi trong lp vt l, chophp truyn cc knh thoi trn bng tn DSL trong khi vn duy tr cPOTS v truy

nhp Internet tc cao. y l mt phng thc n gin, linh hot, hiu quvmtchi ph cho php thit bthhsau c chc nng thoi.

Htrchc nng ghp ngc ATM (IMA) trong ATM TPS-TC:

Tc s liu ti khch hng c thtng ng kbng cch ghp nhiu ng

in thoi cng nhau. thc hin vic ghp, chun ADSL2 h trchc nng ghpngc ATM (IMA) c trin khai cho cu trc ATM truyn thng. Thng qua IMA,ADSL2 c thghp hai hoc nhiu i dy ng trong mt tuyn ADSL. Kt qu lt c tc ng xung linh hot hn c th l : 20 Mbps trn 2 i ghp, 30Mbps trn 3 i ghp, 40 Mbps trn 4 i ghp.

Cc tnh nng lin quann PMS-TCVic phn khung linh hot hn, htrti 4 khung mang, 4 ng

Sliu c truyn khc nhau c thc tp hp vo cc cu trc khc nhau khi

chng truyn qua chc nng PMS-TC pht. Nhm cu trc ny c gi l cu trckhung.

Gim tiu khung

Hthng ADSL2 gim tiu khung bng cch sdng khung vi cc tiu cakhung c thlp trnh c. Do , khng nh trong chun ADSL thhthnht s

bit tiu trn khung l cnh v chim 32Kbps ca ti sliu thc t, trong chun.

ADSL2 s bit tiu chun trong khung c th lp trnh c chim t 4 n 32Kbp.Trong cc hthng ADSL thhthnht, trn cc ng dy in thoi c tc sliu thp (v d128Kbps) th 32Kbps (hoc 25% tc s liu tng) c cung cp

pht cnh cho thng tin tiu . Trong cc hthng ADSL2, tc sliu tiu c thgim xung cn 4Kbps, do cung cp thm 28Kbps cho ti sliu.

Cc tnh nng lin quann PMDChun on

Bthu pht ADSL2 c tng cng khnng chun on. Khnng chun oncung cp cc cng cgii quyt nhng vng mc trong v sau khi to, gim

st trong khi cung cp dch vv nng cao nng lc. Do cc bthu pht ADSL2


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cung cp khnng thc hin o tp m ng dy, suy gim mch vng v tstnhiu trn tp m ti hai u ng dy. Kt quca nhng php o ny c tp hp

li bng cch sdng ch kim tra chun on c bit ngay c khi cht lngng dy l qu ti c thhon thnh kt ni ADSL2.

Ngoi ra, ADSL2 cn cung cp c khnng gim st hiu nng thi gian thc,

khnng ny cung cp thng tin vcht lng ng dy v iu kin tp m ti haiu ng dy.

Thchng tc

Cc ng dy in thoi c bn vi nhau trong b cp nhiu i cha 25 hocnhiu hn cc i dy xon. Kt qul tn hiu in tmt i gy ra ttrng trn

cc i gn ktrong b cp. Hin tng ny c gi l xuyn m v c thcn trc tnh tc sliu ADSL. Kt qul nhng thay i ca cc mc xuyn m c th

lm t kt ni trong ADSL. Xuyn m chl mt nguyn nhn gy t kt ni trn hthng ADSL. Cc nguyn nhn khc c thl do nhiu sng v tuyn AM, nhng thay

i vnhit v nc trong b cp.ADSL2 gii quyt vn ny bng cch thch ng lin tc tc sliu theo thi

gian thc. Ci tin ny, c gi l thch ng tc lin tc (SRA), cho php hthng

ADSL2 thay i tc ca kt ni trong khi cung cp dch vm khng lm ngt dchvhoc gy li bit. ADSL2 pht hin ra nhng thay i trong iu kin knh (v d,mt trm v tuyn AM ni ht ngng pht vo bui ti) v thch ng tc sliu viiu kin mi trong sut vi ngi sdng.

Khi to nhanh

Khi to bthu pht ADSL c yu cu cho kt ni gia ATU-C v ATU-R thit lp mt tuyn thng tin gia chng. ADSL thhthnht chh trch

khi to thng thng. Tuy nhin ADSL2 h tr c hai ch : ch khi tothng thng v chkhi to nhanh. Thtc khi to thng thng mt khong t

10 ti 15 giy trong khi thtc khi to nhanh chmt khong t2 ti 3 giy. Cc iu ny l do th tc khi to nhanh da vo vic lu trv sdng li cc

tham struyn dn tkhi to thng thng trc nh gim ng kthi gianiu khin.

Ci thin vmt cng sut

Cc bthu pht ADSL thhthnht hot ng chcng sut ln nht sutngy m ngay ckhi khng c sdng. p ng vn ny, chun ADSL2

a ra chqun l cng sut gip gim cng sut tiu thtrong khi vn duy trchc nng lun lun kt ni ca ADSL cho ngi sdng.

2.3.3 ADSL2+

Gii thiu chung


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Cng nghADSL2+ l thnh vin mi nht trong hcc chun ADSL. ADSL2+c chun ho trong ITU G.992.5 vo thng 5 nm 2003. C th coi ADSL2+ l

ADSL thhthba hoc l phin bn delta ca ADSL thhthhai ADSL2.

Cng ging nh ADSL2, ADSL2+ sdng i dy ng xon truyn ng thithoi v sliu tc cao gia kt cui mng (ATU-C) v kt cui khch hng (ATU-

R). Tuy nhin, trong khi ADSL2 sdng bng tn t0-1,1Mhz th ADSL2+ sdngbng tn t 0-2,2Mhz. Cng ging nh ADSL2, ADSL2+ dnh bng tn c s

truyn thoi, bng tn thp truyn s liu ng ln v bng tn cao truyn sliu ng xung.

Vi bng tn ng xung ca ADSL2+ gp i so vi bng tn ng xung ca

ADSL2, nn ADSL2+ tng ng ktc sliu trn ng dy in thoi c khongcch nhhn 3 km. Cthl ADSL2+ c tht c tc sliu ng xung ti

25Mbps, trn ng dy c khong cch 1 km tc sliu ng xung c thtc 24Mbps v c tht c 20Mbps vi khong cch l 1.5 km, hnh 2.6.

Hnh 2.6Tc sliu ng xung ca ADSL2+ so vi ADSL2

ADSL2+ l ADSL2 vi bng tn mrng n c chun ho da trn chun ca

ADSL2. Do , ADSL2+ mang y cc c tnh ca ADSL2. Tuy nhin, ADSL2+ cn c thm mt stnh nng mi nhm p ng tc sliu cao hn trnmch vng c khong cch ngn hn l mrng bng tn, ghp t tc caohn v mt stnh nng khc ca ADSL2+.

Mrng bng tnTrong khi hai thnh vin trong h cc chun ADSL2 l G.992.3(G.dmt.bis) v

G.992.4(G.lite.bis) sdng bng tn ng xung ti 1,1Mhz v 552Mhz tng ng

di mch vng ( Kilofeet)

Tc

d

liu(Mbps)


33/112



th ADSL2+ s dng bng tn ng xung ti 2.208Mhz tng ng vi 512 sngmang con. Nh vy bng tn ca ADSL2+ tng gp i so vi bng tn ng xung

ca ADSL2 cn bng tn ng ln ca ADSL2+ khng thay i so vi ADSL2. Chitit vci thin tc ca ADSL2+ so vi ADSL2 c thhin trn hnh 2.6.

Ghp t tc cao hnK thut ghp nhiu ng dy in thoi nhm mc ch t tc s liu cao

hn v ci thin khong cch l kthut mi c a ra trong cng nghADSL2.

Cng ging nh ADSL2, vic ghp ADSL2+ cng thc hin ghp nhiu ngADSL2+. Chi tit vso snh tc khi ghp c thhin trn hnh 2.7.

Hnh 2.7Ghp hai ng ADSL2+

Vic ghp nhiu i dy in thoi trong ADSL2+ c mt sc im nh sau:- Vic ghp htrkhnng tng gii phng v khi phc cc i dy m

khng vn scan thip ca con ngi. Mt khc, vic ghp c thc thchin tng bng phn mm.

- Vic ghp htrcc tc sliu khc nhau (vi tl4/1) gia cc i dy.iu ny rt c ngha trong trng hp cc ng dy ng c dung lngthp hn cc ng dy khc th khng cn thit phi gim tc sliu trncc ng dy c dung lng cao hn.

- C thghp ti 32 i dy.- Cc cng trn cart thu bao ADSL2+ c ghp mt cch ngu nhin. Ngha

l vic ghp c thc hin bng cch kt hp bt kcng no v vic ghprt mm do.

- Chun ghp ATM c sdng trn bt klp vt l no. Ngoi ADSL2+,n c thc sdng cho cc dch vDSL khc.

Mt stnh nng khc ca ADSL2+

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

ADSL2+ ghpADSL2+ADSL

di mch vng (Kilofeet)

Tcd

liu(Mbps) 50

45403530

252015105


34/112



Ngoi cc tnh nng mi c trnh by trn, ADSL2+ cn c thm mt stnhnng mi nh sau:

- ADSL2+ c kh nng h tr ti 3 t m trn mt k hiu, trong khi ADSL2 chc thh tr ti a 2 tm/trn k hiu. Gi trny c quynh khc nhau trong chun ITU G.992.3 v G.992.5. Cthl G.992.3 quy

nh skhung ghp sliu trn k tv stm FEC trn k hiu cc i l2. Trong khi , G.992.5 quy nh skhung ghp sliu trn k hiu v st

m trn k hiu cc i l 3.

- Di siu khin ca ngi vn hnh thng qua CO-MIB, vic iu khinphng xung vi PSD pht cc i ti im tham chiu U-C trn sng

mang ph cho php vic cu hnh theo yu cu ca tng vng (v d, BcM, Chu u hoc Nht Bn) v cu hnh theo cc mi trng trin khai (v

d, trm trung tm (CO) hoc trm u xa (RT)).

- Vic nh dng phng xung trong thi gian showtime (dng PSD phttrong bng thng l khng phng) ci thin linh hot ca PSD pht ngxung.

2.4HDSL, HDSL2,SHDSL, HDSL4

2.4.1 HDSL

HDSL nguyn bnKhi nim ban u vng dy thu bao stc cao HDSL xut hin vo nm

1986 phng th nghim AT&T Bell v Bellcore. Cc thit kthit bthu pht HDSLthc cht l thit kISDN c bn mc cao hn. Hthng HDSL mu xut hin nm

1989. Thit bHDSL u tin c Bell Canada a vo hot ng vo nm 1992 docng ty Tellabs Operation Inc sn xut. Thng 10 nm 1998, ITU thng qua khuyn

nghG.991.1 cho HDSL thhthnht, tiu chun ny da trn tiu chun ETSI TM-03036. ITU bt u nghin cu xy dng khuyn nghHDSL thhth2 (HDSL2) l

G.991.2, a ra nm 2000.

HDSL c a dng hn T1 truyn thng l bi v HDSL cung cp cc c tnhchun on (bao gm o SNR) v HDSL gy xuyn m t hn cc hthng truyn dn

khc do tn hiu truyn c hn chtrong bng tn hp hn T1 truyn thng.

Khnng vng dng HDSLHDSL truyn ti hai hng 1,544Mbit/s hoc 2,048 Mbit/s trn ng dy in

thoi di n 3,7 km vi dy 0,5 mm (24 AWG) i dy xon khng c blp trunggian v c th tng chiu di ln gp i vi 1 b lp trung gian. HDSL l phngthc truyn dn tin cy cho tt ccc vng phc vvi tlli bt l 10-9n 10-10. Hthng HDSL DS1 (1,544 Mb/s) sdng hai i dy, mi i dy truyn 768 kbit/s ti

hiu dng (784 kbit/s) trn mi hng. H thng HDSL E1 (2048 kbit/s) c th lachn sdng hai hoc 3 i dy, mi i dy sdng hon ton song cng. HDSL


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SHDSL l cng ngh kt hp ca HDSL 2 v SDSL vi tc thay i t192kbps n 2,134 Mbps, khong cch tng ng vi tc ti a l 2km. Trong thc

t, n c thcu hnh dng 2 i dy cung cp tc t384kbps n 4,264Mbps.

2.4.4 HDSL4

Sdng 4 i dy truyn tc nh trong HDSL2 do vy n c thgim

bng tn sdng, ko di cly truyn dn, gim slng trm lp, do vy n c tht c cli l 3,4km thay v 2,7km nh HDSL2, ng thi n cng lm gim tcng nhin n cc hthng khc.

2.5VDSL v VDSL2

2.5.1 VDSL

L mt cng nghtrong hxDSL VDSL cung cp cc ng thu bao svi tcrt cao. Cng nh cc cng nghkhc trong hxDSL nh ADSL, HDSL, SDSLcng nghVDSL c sdng cung cp cc dch vbng rng nh cc knh tivi,

truy nhp dliu vi tc rt cao, hi nghqua video, video tng tc, truyn thpdliu v tn hiu video trn cng mt ng dy cho cc thu bao dn c v kinh

doanh trong lc cha lp t c mng cp quang n tn nh thu bao. Hnh 2.8 mtcc m hnh hthng sdng cng nghVDSL.

Cng nghVDSL sdng phng thc truyn dn ging nh ADSL nhng cng

nghVDSL c khnng cung cp s liu vi tc rt cao gn gp 10 ln tc truyn dn ca ADSL. Tc truyn dn ca VDSL lung xung t ti 52 Mb/strong chiu di khong 300m, v lung xung t tc thp 1,5 Mb/s vi chiu dicp 3,6km. Tc lung ln trong chkhng i xng l 1,6- 2,3 Mbps, tc

lung trong chi xng l 26 Mbps.Trong VDSL chai knh s liu u hot ng tn scao hn tn ssdng

cho thoi v ISDL nn cho php cung cp cc dch vVDSL bn cnh cc dch vang tn ti.

Khi cn tng tc lung xung hoc chi xng th hthng VDSL sdng

trit ting vng.

Hnh 2.8 M hnh hthng sdng VDSL

STMChuyn mch gi

ATMATM

STMChuyn mch gi

Ton bATM

Dchv ONU

VDSLH

U

BTE

Cp quang Mng vng

Cp ngVDSL


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Ngoi vic c khnng cung cp tc cao hn nhiu so vi tc truyn dnca ADSL, VDSL cn yu cu khong ng nhhn ADSL nn kthut truyn dn

ca VDSL khng phc tp bng kthut truyn dn ADSL. Mc d c nhiu u imnh vy nhng k thut ny vn cha c sdng rng ri l v cha la chn

c c chiu ch, bng tn, phng php ghp knh thch hp. Hn na, mt schipset ca modem sdng cng ngh VDSL vn cn t nn cng nghny cha

c sdng nhiu trong thc t. Tuy nhin y l mt cng nghha hn trong mtvi nm tip theo y.

Trong ngha l bc m tin ti mng truy nhp quang (APON, BPON,GPON), VDSL c sdng trong cc mch vng ni ht truyn tn hiu tkhimng quang ONU ti cc thu bao. Bng 2.2 m ttc v khong cch tONU ti

thu bao.

Bng 2.2Tc khong cch cc loi VDSL

Tcthu (Mbit/s) Tc pht (Mbit/s) Khong cch (met)

52 6,4 1000- 300

26 3,2 2500- 800

26 26 1000- 300

13 13 1800- 600

13 26 3750- 1200

2.5.2 VDSL2

L cng nghmi nht trong hxDSL n c thcung cp tc ln ti 250Mbps,n c thit kcung cp kt ni cho cc dnh vvoice, video, data, HDTV vgame tng tc.

VDSL2 c miu t trong chun G993.2, n l sm rng ca chun G993.1

dnh cho VDSL, n cung cp cc tc bt bt i xng, i xng (song cng) ln ti250Mbps vi bng tn sdng ln ti 30MHz.

VDSL2 sgim tc rt nhanh t250Mbps ti ngun n 100Mbps ti khongcch 500m, 50Mbps ti khong cch c1km, sau vi cly t1,6km th tc ca

n nh l ADSL2+.

VDSL2 cng cho php h tr tc lung xung t1 n 4Mbps trong khongcch t4 n 5km, do vy n khng ging nh VDSL n c thc sdng cho cnhng cli trung bnh.


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2.6Tnh hnh trin khai ti Vitnam

Hnh 2.9Tnh hnh trin khai xDSL ti Vit nam ca VNPT

xDSL c ng dng n ltrong cc lnh vc Vit nam ngay tnhng ngyu ra i, n nm 2002 VNPT bt u thnghim trin khai trn din rng vihai hthng sdng IP-DSLAM v ATM-DSLAM. Chi tit vtng bc trin khai

c thhin trn hnh v2.9.

B H Ni

B Hi Phng

B Tp. HCM

Bnh Dngng Nai

Hi Dng

Qung Ninh

NghAn

Hu

Lm ng

Nng

Khnh Ha

B Ra - Vng Tu

Kin GiangAn Giang

Cn Th

k Lk

Pha 1

Pha 2

Pha 3

Pha 1+

Pha 1+

xDSL 64/64

Hng Yn

Tng sthu bao n

thng 2nm 2006 l

96392

B H Ni

B Hi Phng

B Tp. HCM

Bnh Dngng Nai

Hi Dng

Qung Ninh

NghAn

Hu

Lm ng

Nng

Khnh Ha

B Ra - Vng Tu

Kin GiangAn Giang

Cn Th

k Lk

Pha 1

Pha 2

Pha 3

Pha 1+

Pha 1+

xDSL 64/64

Hng Yn

Tng sthu bao n

thng 2nm 2006 l

96392


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CHNG 3

CNG NGHTRUY NHP QUANG

Vi gi thnh ngy cng gim, cng ngh truy nhp quang thng v ang

c s dng rng ri. Chng ny gii thiu tng quan cc cng ngh truy nhpquang thng v tp trung vo trnh by vo cng nghEPON v kin trc v tchc ca mng truy nhp sdng quang thng, ni dung chnh chng 3 gm:

q Cc mng quang thng PON

q APON

q EPON

q Metrro Ethernet


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3.1CC MNG QUANG THNG PONTa c th phn mng truy nhp quang thnh h thng tch cc v thng ph

thuc vo cc c tnh ca thit bgia trm trung tm v nh ca thu bao.

Hu ht cc mng vin thng ngy nay u da trn cc thit btch cc, ti tngi ca nh cung cp dch vln thit bu cui ca khch hng cng nh cc trm

lp, cc thit bchuyn tip v mt scc thit bkhc trn ng truyn. Tch cc cngha l cc thit bny cn phi cung cp ngun cho mt sthnh phn, thng l b

xl, cc chp nhvv.

Vi mng quang thng PON tt ccc thnh phn tch cc gia nt dch v vngi sdng skhng cn m thay vo l cc thit bquang thng, iu

hng cc lu lng trn mng da trn vic phn tch nng lng ca hoc cc bcsng quang hc ti cc im u cui trn ng truyn. Vic thay thcc thit btch

cc stit kim chi ph cho cc nh cung cp dch vv hkhng cn cn n nnglng v cc thit bchng trn ng truyn na. Cc bghp/tch thng ch

lm cc cng vic n thun nh cho i qua hoc chn nh sng li V th, khngcn nng lng hay cc ng tc xl tn hiu no v t, gn nh ko di v hn

thi gian trung bnh gia hai ln li MTBF, gim chi ph bo tr tng thcho cc nhcung cp dch v. Mt hthng mng PON thng thng bao gm cc thit bkt cuiknh quang OLT t ti CO v bcc n vmng quang ONU c t ti nh ngisdng. Gia chng l h thng mng phn phi quang ODN bao gm cp quang,

cc thit bghp/tch thng, hnh 3.1.

Cng nghtruy nhp quang c thc nhn nhn theo mc cp quang ha mngtruy nhp vi khi nim vkin trc mng FTTx theo kiu cu hnh sao, bao gm h

cc kin trc sau:

- Cp quang ti tn Office FTTO.

- Cp quang ti tn khu dn c FTTC.

- Cp quang ti tn khu cng sFTTB.

- Cp quang ti tn hgia nh FTTH.

Ngoi ra, nh trn hnh 3.2, cn cvo vic phn tch thng tin ca ngi dng tac thphn chia cc mng PON nh sau:

Mng WDMA PON, do gi cca gii php ny t cho nn cha l mt gii

php cho mng truy nhp ti mc cng nghhin nay. C mt vi gii php ci tinnh l WRPON (gii php ny sdng mt AWG thay v mt bhp tch quang datrn bc sng), mc d vy gi ccng khng phi l r.

Mng TDMA PON sdng gn cc khe thi gian cho cc thu bao khc nhau v

sdng hai bc sng cho lung ln v lung xung. TDMA PON c bit n banu l APON v sau c thay thbi tn l BPON nm 2001.


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- G984.3 : M tnhng c tnh vkhung hi t truyn dn ca GPON; bntin, phng php xc nh khong, hot ng, gim st, nhng chc nng

bo dng, v bo mt.

Vi mt hng pht trin khc, khi m Ethernet pht trin rng khp, mng quangthng da trn Ethernet EPON hnh thnh nm 2001, ng gi dliu trong khung

Ethernet theo chun IEEE 802.3, sdng m ng 8b/10b hot ng vi tc 1Gs dng MAC ca 802.3. Sau nay nhng phin bn tip theo cho php EPON hot

ng nhng tc cao hn na.

Hnh 3.2Cu hnh chung ca mt mng PON

Trong cc gii php mng PON, gii php EPON c htrv pht trin nhanhnht. Nhiu nh cung cp dch v chn gii php ny lm mng truy nhp vtruyn ti lu lng mng Metro (MEN) cung cp a dch v. Tuy nhin c chduy tr v phc hi mng ca gii php EPON cn chm nn chc thp dng cho

mng c quy m va v nh. Bng 1.1 m tnhng so snh c bn ca cc cng nghPON hin nay:

Bng 3.1So snh cc gii php mng PON

APON BPON EPON GPON WDM PON

Tiu chunFSAN ITU-T

G.983

FSAN ITU-T

G.983

EFM IEEE

802.3ah

FSAN ITU-T

G.984Cha

Khung ATM

ATM,Ethernet,

Phn bVodeo

Ethernet

GPON

Kiu nggi

Khng phthuc

(a) Cu trc hnh cy (sdng bchia 1xN)

(b) Cu trc bus (sdng bchia 1x2) (c) Cu trc vng (sdng bchia 2x2)


43/112

CHNG 3 - CNG NGHTRUY NHP QUANG


Tc xung

622-1244 M 1,244 G 1-10 G 2,488 G1-10 G

n knh

Tc ln 155-622 M 622 M 1-10 G 2,488 G1/10 G

n knh

S thubao/nhnh 16 32 16 64 100s

Bng tn/

Thu bao20 M 20 M 60 M 40 M 1-10 G

Dch vVideo

RF RF RF/IP RF/IP RF/IP

Gi thnh Thp Thp Thp nht Trung bnh Cao

3.2APONAPON l skt hp gia phng thc truyn ti khng ng bATM vi mng

truy nhp quang thng PON.

Mng APON sdng cng nghATM l giao thc truyn tin. Cng nghATMcung cp smm do theo khi nim trong sut dch vv phn bbng tn, ngoira cn c nhng tnh nng rt hu ch cho hot ng khai thc v bo dng cc kt

ni tu cui n u cui nh gim c chi ph hot ng ca mng. Cc uim ca ATM c kt hp vi mi trng truyn dn l si quang vi ti nguyn

bng tn dng nh l v hn to ra mt mng truy nhp bng rng c bit ti

nh l BPON.3.2.1 Kin trc phn lp APON

M hnh phn lp mng ATM c trnh by trn hnh 3.3 gm c lp mi trngtruyn dn v lp ng, lp mi trng truyn dn phn chia thnh lp mi trng

vt l v lp hi ttruyn dn .

Trong mng ATM-PON lp ng tng ng vi lp ng o ca lp ATM Lpdi cng l lp phng tin vt l thc hin giao tip vi phn quang ca mng (hay

chnh l mng phn phi quang ODN). Lp ny thc hin cc chc nng: chuyn iin-quang, nhn/truyn cc tn hiu n/i phng tin vt l ti mt trong ba bc

sng quang (1310, 1490, 1550nm), kt ni vi si quang ca ODN. Cu trc ca lptun theo tp cc tham squang in c chun ha.

Lp ng Chuyn i tbo ATM v cc khung dliu ngi dng

Lp Lp Lp con Thch ng Lp thch ng ca B-ISDN


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hi

t

truyn

dnLp con truyn dn

PON

-Xp xp

-Cp pht khe tbo

-Cp pht bng tn

-Bo mt v an ton

-ng chnh khung

-ng bcm(Burst)

-ng bbit/byte

Mi

trng

truyn

dn

Lp vt l -Tng thch E/O

-Ghp bc sng

-Kt ni si quang

Hnh 3.3Cu trc phn lp mng APON

Gia lp phng tin vt l v lp ng (giao in m qua tbo ATM c

phn phi ti lp khch hng) l lp hi ttruyn dn TC (tng ng vi lp 2 trongm hnh OSI). Lp TC c phn chia thnh lp con truyn dn PON v lp con thchng nm trn, tng ng vi lp con hi t truyn dn ca m hnh B-ISDN. Lp

con thch ng c chun ha da trn chun ATM trn c scp ng truyn thng

[ITU I.732]. Chc nng ca lp ny l chuyn i gia khung 125s mc ngi dng

(n vdliu giao thc PDU) v tbo ATM.

3.2.2 Lp vt l

Lp ny khng ging nh cc lp trn l cc thnh phn phn cng chkhng

phi l phn mm. Phn cng ny c nh ngha bi cc chun [G.983.1 & G.983.3]v tun theo cc tham ssau:

- Tc bit: 155.52 hoc 622.08Mb/s ng xung v 155.52Mb/s ngln

- Bc sng: 1260 n 1360nm ng ln, 1480 n 1580nm ng xung

- Dng lu lng: schai hng, htrtng tng xung

- T l chia cng sut quang: ln n 32, con sny b gii hn bi suy hao

ODN

3.2.3 Lp hi ttruyn dn TC

Lp con truyn dn PON ca lp hi ttruyn dn

Lp con truyn dn TS hon ton lm vic vi t bo. Theo hng v, lp ny

nhn cc tbo ttn hiu in do lp phng tin vt l a n, ng bti mc bitv byte, gii hn tbo v khung c xc nh, mo u c tch v xl, chuyn

cc lung t bo ln lp cao hn tip theo. Theo hng i, qu trnh x l din rangc li. Trong lp ny, giao thc sp xp c sdng m bo rng cc tbo


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n tcc ONU khc nhau khng chng lp ln nhau. Ngoi ra n cn thc hin haichc nng quan trng khc l gn bng tn ng (DBA) v mt m ha.

Lp con thchng ca lp hi ttruyn dn

y l lp m c schuyn i din ra gia tbo ATM v PDU (c thl:

SONET/SDH, xDSL, cc PDU da trn khung 125s [ITU I.732] ca cc cng ty in

thoi). Lp ny khng cung cp giao din vi cc lu lng trn c s gi nhEthernet hay IP. cung cp nhng giao din ny ta phi c 1 phn mm chuyn i

thm vo, phn ny khng trong phm vi chun.

3.3EPON

3.3.1 Kin trc EPON

Kin trc IEEE 802 cho rng tt cmi trm truyn thng trong tng phn ca mtmng LAN u c kt ni ti mt thit b dng chung. Trong mt thit b dng

chung, tt ccc trm u c coi nh thuc vmt phm vi truy nhp n, y

phn ln cc trm c thpht tn hiu mt thi gian v tt ccc trm khc c thnhn tn hiu trong ton bkhong thi gian .

Nhng vng a truy nhp c thc ni lin vi nhau bng mt thit bc gil bridge. Nhng bridge la chn chuyn tip nhng gi tin to ra mt cu trc ca

mng LAN bao gm ton bcc vng truy nhp. Vic la chn chuyn tip sngnchn vic truyn dn mt gi tin trong nhng vng m khng cha bt cmt trmch ca gi tin ny. Cu ni ca nhiu LAN uc sdng mrng cung cp khnng qun l c lp ca nhng vng truy nhp, tng strm hoc phm vi vt l

ca mt mng xa hn gii hn ca nhng phn LAN ring bit v ci thin s

lng u vo.Trong mt trng hp xa, mt vng truy nhp c thbao gm mt trm. Tiu

biu l nhiu vng trm n c kt ni bng lin kt im - im (P2P) ti mtbridge, cu hnh ca mt LAN chuyn mch.

Da vo khi nim vng truy nhp, nhng bridge khng bao gichuyn tip mtkhung tr li cng li vo ca n. Trong trng hp vng truy nhp bao gm nhiu

trm, n c cho rng ton bcc trm kt ni ti cng ging nhau trn bridge cthlin lc vi mt trm khc khng thng qua bridge. Trong trung hp LAN chuynmch, khng thc sddng tip nhn trong vng truy nhp ca ni gi, v khng

c khung no c chuyn tip trli.C mt vn cn quan tm trong phng thc hot ng bridge ny l: Ngi

dng kt ni ti nhng ONU khc trong cng mt PON khng ththuc cng LANv khng c khnng lin lc vi mt ngi dng khc lp 2 (lp lin kt dliu).

Nguyn nhn l phng tin PON khng cho php cc ONU lin lc theo mt hngkhc, bi tnh nh hng ca nhng btch/ghp thng. OLT chc mt cng n

kt ni ti tt ccc ONU, v mt bridge c t vo trong OLT skhng bao gi


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Hnh 3.4Ngn xp EPON.

3.3.4 Bo mt trong EPON

Cc kthut PON rt hn chtrong vic chng nghe ln v chng n cp cc dchv, nhng xut vc cu bo mt trong tiu chun 802.3ah khng c c nhng

htrcn thit, thay vo l cc tiu chun vc cu bo mt trong 802.1ae. Do cc

tiu chun ny khng hon thnh vo ng lc cc tiu chun vEPON ra i nn huht cc mng EPON c trin khai trn thgii hin nay u sdng mt c chbomt duy nht. Trong vi trng hp, cc nh cung cp dch vvin thng ln a ra

c chbo mt ring ca mnh, c chny khng nhng p ng c cc yu cu kthut cn thit m cn c thc coi l mi trng gim st ni ht. V d, hthngmt m ha thng tin AES khng c khoch bo mt khi c ng dng ti TrungQuc v cc nh cung cp EPON phi sdng phng php xo trn do cng ty

vin thng Trung Quc cung cp bo mt cho ng xung.

C cu mt m ha ca EPON c da trn thut ton mt m ha tin tin AES

do vin kthut v tiu chun ca Hoa Kxut bn [FIPS197]. AES cho php sdngcc tkha 128 bit, 192 bit hay 256 bit. Cu trc khung Ethernet bao gm cphn mu v IPG khng bthay i ph hp vi cc tiu chun ca IEEE v trnh nhng

b sung sau ny ca tiu chun IEEE 802.3. m bo tnh c nhn cao, phngphp ny mt m ha ton b mt khung Ethernet, bao gm c phn tiu ca

Ethernet v trng FCS. Cc bn tin OAM v MPCP cng c mt m ha.

3.3.5 Nhng bc pht trin tip theo

Lin kt dliuVt l

Mng

M hnh tham chiu OSI

Mi trng PON

MDI

PMD

PMA

PCS

GMII

Ha hp

MAC

iu khin MAC a im

OAM (ty chn)

LLC hoc MAC khc

LANLp CSMA/CD

Nhng lp cao hn

MAC : iu khin truy nhp mi trng

CSMA/CD: a truy nhp cm nhn sng mang/pht hin xung t.

GMII: Giao din c lp mi trng Gigabit

PCS: Lp con m ha vt lPMD: Phthuc mi trng vt l


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Nhng tim nng ca EPON l g? Cu hi ny c trli bi nhm lm vicIEEE 802.3 vo thng 3 nm 2006 khi hthnh cng trong vic nghin cu t c

cu hnh EPON 10 Gb/s.

EPON 10 Gb/s l mt bc tin mi trong vic tng dung lng, n h trhiuqucho vic truyn tn hiu truyn hnh cht lng cao v nhu cu htrmng ng

trc v tuyn thhktip. Nghin cu ca IEEE 802.3 vEPON 10 Gb/s tp trungvo nh ngha mt lp vt l im a im mi, duy tr lp MAC, iu khin MAC

v tt ccc lp bn trn khng bthay i theo phm vi rng nht c th. iu ny cngha l cc sng mang vn c kin trc nh c v c tng thch vi h thngqun l mng NMS, cc hot ng ca lp PON, qun l v hthng OAM...

Nhm nghin cu EPON 10 Gb/s t ra nhng mc tiu cho ctruyn dn trnng dy i xng v bt i xng. Hthng i xng shot ng tc 10 Gb/s

clung ln v lung xung. Hthng bt i xng sdng lung xung 10 Gb/sv lung ln 1 Gb/s, a s ging nh cc tiu chun sn c ca IEEE 802.3ah cho

lung ln.im nhn mnh ca cu trc i xng l hot ng truyn dn theo chcm

tc 10 Gb/s. M ha ng dy 64b/66b c dng trong lp vt l Ethernet 10Gb/s l cn thit FEC.

EPON 10 Gb/s c nh gi l c tnh hiu qukinh tcao, n cung cp bngthng ln hn mng CATV sdng DOSIS 3.0. y chnh l nguyn nhn ch yulm cho EPON 10 Gb/s l mt cng nghc khnng thay thcho cc mng CATV

thhtip theo. N cng cho php thay i mt cch t bin bng thng dliu snc cho cc thu bao m khng cn vic ngi qun l ng dy thay i cch phn

phi video sn c.

3.4METRO ETHERNET

3.4.1 Li ch khi dng dch vEthernet

Nhiu nh cung cp dch v cung cp dch vMetro Ethernet. Mt snh cung

cp mrng dch vEthernet vut xa phm vi mng ni th(MAN) v vun nphm vi mng din rng (WAN). Hng ngn thu bao c s dng dch v

Ethernet v slng thu bao ang tng ln mt cch nhanh chng. Nhng thu baony bthu ht bi nhng li ch ca dch vEthernet em li, bao gm:

- Tnh dsdng- Hiu quvchi ph

- Linh hot.

3.4.2 M hnh dch vEthernet

Tt ccc dch vEthernet sc mt vi thuc tnh chung, nhng dch vkhcnhau skhc nhau vmt scc thuc tnh. Dch vEthernet c cung cp bi mng

MEN ca nh cung cp. Thit bkhch hng CE gn vo mng MEN qua giao tip


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ngi s dng-mng UNI s dng chun giao din Ethernet chun vi tc 10Mbit/s, 100Mbit/s, 1Gbit/s hoc 10Gbit/s.

C thc nhiu UNIs kt ni n MEN tmt vtr. Nhng dch vc xc nh

theo quan im ca thu bao. Nhng dch vny dng cc cng nghtruyn dn haycc giao thc MEN khc nhau nh SONET, DWDM, MPLS, GFP, Tuy nhin,

di gc thu bao, kt ni mng vpha thu bao ca giao din UNI l Ethernet. Kt ni Ethernet o

Mt thuc tnh c bn ca dch vEthernet l kt ni Ethernet o EVC. EVC cnh ngha bi MEF l mt skt hp ca hai hay nhiu UNIs trong UNI l mtgiao din Ethernet, l im ranh gii gia thit bkhch hng v mng MEN ca nh

cung cp dch v.

Ni mt cch n gin, EVC thc hin 2 chc nng:

- Kt ni hai hay nhiu vtr thu bao (chnh xc l UNIs), cho php truyn cc

frame Ethernet gia chng.

- Ngn chn d liu truyn gia nhng v tr thu bao (UNI) khngcng EVC tng t. Kh nng ny cho php EVC cung cp tnh ring

t v s bo mt tng tknh o cnh PVC trong Frame Relay hayATM.

MEF nh ngha 2 kiu ca EVCs.

- im - im

- a im - a im

EVC c th c dng xy dng mng ring o lp 2

Khun khnh ngha dch vEthernet.

Hin ti MEF v ang xc nh (v cha thnh chun) hai kiu dch vEthernet:

- Kiu dch vE-Line l dch vim-im

- Kiu dch vE-LAN l dch va im - a im

Kiu dch vEthernet Line

Kiu dch vE-Line l dch v cung cp kt ni Ethernet o im-im gia 2UNIs. Dng n gin nht, dch vE-Line c thcung cp bng thng i xng cho

dliu gi nhn trn hai hng khng c cc m bo tc gia hai UNI 10 Mbps.Dng phc tp hn, dch vE-line c thcung cp tc thng tin cam kt CIR v

thuc tnh vtr, jitter,

Ghp dch v cho php kt hp nhiu EVC trn mt cng vt l UNI duy nht.

Mt dch vE-Line c thcung cp im n im EVCs gia UNIs tng tnhvic sdng Frame Relay PVCs ni lin cc site vi nhau.

Mt dch vE-Line cng cung cp vic kt ni im ti im gia UNIs tng tvi mt dch vthu knh ring TDM.


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Tm li, mt E-Line Service c thc dng xy dng nhng dch v tngtnh Frame Relay hay thu knh ring. Tuy nhin, bng thng Ethernet v vic kt

ni th tt hn nhiu.

Kiu dch vEthernet LAN

Kiu dch vE-LAN cung cp kt ni a im, tc l n c thkt ni 2 hoc hn

nhiu UNIs. Dliu ca thu bao c gi tmt UNI c thc nhn ti mt hocnhiu dliu ca UNIs khc.

Mi site (UNI) c kt ni vi mt a im EVC. Khi nhng site mi (UNIs)

c thm vo, chng sc lin kt vi a im EVC nu trn do vy nn n ginha vic cung cp v kch hot dch v. Tpha thu bao, dch v E LAN lm cho

MEN trng ging mt mng LAN o.

Tm li, MEF nh ngha hai kiu dch vchnh E-Line v E-LAN, tuy nhin cchng, tchc tham gia MEF c cch sdng tn cho hai lai dch vny khc nhau.

V dnh Cisco a ra cc dch vchuyn tip Ethernet (ERS) v dch vhu tuyn

Ethernet (EWS) cho loi E-Line; dch va im chuyn tip Ethernet (ERMS) vdch va im Ethernet (EMS) cho loi E-LAN

3.4.3 Tnh hnh trin khai

Hnh 3.5Mng MAN thnghip ti thnh phHCh Minh

Hin nay VNPT c chu trng v trin khai thnghip mng MAN sdngMetro Ethernet ti nhng tnh thnh ln trong cnc. Trn hnh di y m tcu


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hnh thnghim ti thnh phHCh Minh v Ninh Bnh c trng cho thnh phlnv tnh thng thng.


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Hnh 3.6Mng MAN ti Ninh Bnh


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CHNG 3- CNG NGHTRUY NHP QUANG


3.4.4 Nhng cng nghc sdng

Nh chng ta c ththy trn m hnh trin khai nhng cng nghc thc sdng dng l :

- Truyn ti Ethernet qua SDH, EOS

- RPR

- EPON vi cng nghcthl GE- MPLS v GMPLS

Truyn ti Metro Ethernet qua SONET/SDH

Khi nim truyn d liu qua mng SONET/SDH l c cu truyn ti lu lngcung cp mt schc nng v cc giao din nhm mc ch tng hiu quca vic

truyn dliu qua mng SONET/SDH.

C cu ca truyn dliu qua mng SONET/SDH bao gm 3 giao thc chnh: Th

tc ng khung tng qut GFR, lin kt chui o VCAT v c cu iu chnh dung

lng ng truyn LCAS. C3 giao thc ny c ITU-T chun ho ln lt bicc tiu chun G7041/Y.1303, G.704, G.7042/Y.1305. Giao thc GFR cung cp th

tc ng gi khung d liu cho cc dng lu lng khc nhau (Ethernet, IP/PPP,RPR..) vo cc phng tin truyn dn TDM nh l SONET/SDH hoc cc mng

truyn ti quang. Giao thc VCAT cung cp cc thtc ci t bng thng cho knhkt ni mm do hn so vi nhng th tc p dng trong h thng truyn dn TDM

trc . Giao thc LCAS cung cp th tc bo hiu u cui ti u cui thchin chc nng iu chnh ng dung lng bng thng cho cc kt ni khi sdng

VCAT trong kt ni SONET/SDH.

RPR

Thng 12 nm 2000, IEEE thnh lp mt nhm nghin cu vcng nghmng

vng gi phc hi (IEEE 802.17) nhm a ra cc tiu chun cho giao thc RPR.Cng nghRPR c sdng truyn ti cc gi s liu trn mng vng tc

hng Gigabit/s.

Gii php ny sdng cc Router kt ni cp quang vi cng nghmi RPR h

trIP hoc thm ch MPLS p ng tt ccc dch vkhc nhau. RPR l cng nghcho cho mng ththhmi ang c cc hng vin thng ln tp trung pht

trin (50 nh sn xut thit bv chip - Cisco, Nortel, Siemens, Redstone, ). Cngnghny kt hp tnh u vit ca phng thc bo vng nh cng nghSDH

cho php khnng hi phc tuyn cc nhanh mc 50 ms. Cng vi khnng nha chkt ni theo a ch(dng a chMAC) v phn loi lu lng cho cht lngdch vnh cng nghEthernet lp 1.

RPR tha khai c trng quan trng ca mng SONET/SDH.


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- C thkt ni theo cu hnh RING.

- C thkhi phc ng truyn nhanh khi ng cp quang bt


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CHNG 4

CC MNG TRUY NHP

KHNG DY BNG RNG

Bn cnh cng nghtruy nhp quang thng vi gi thnh h, bng thng ln vcht lng kt ni cao, cc cng nghkt ni v tuyn vi u im vkhnng di

ng cng vi nhng ci tin rt nhanh vtc , n nh vi mc gi thnh c thchp nhn c v ang khng nh l mt xu hng pht trin tt yu. Chngny trnh by khi lc vcc cng nghkt ni v tuyn c sdng trong mng

truy nhp v xu hng pht trin ca n. Ni dung c trnh by trong chng ny vcc chng tip theo nhn mng n nhng ng dng trong mng MAN v LAN, bao

gm nhng ni dung chnh nh sau:q Gii thiu chung

q Pht trin ca truy nhp v tuyn hi tn 4G

q So snh nh gi cc cng ngh


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4.1GII THIU CHUNGChng ta c thnhn nhn truy nhp v tuyn theo quan im ca IEEE theo hnh

4.1 di y:

Bluetooth

802.15

802.11b

802.11g

802.11a

HiperLAN2

2.5G/3G

GSM/GPRS

CDMA/1x/3x

4G

Tc s liu thp

Khong cch ngn

Notebook/PC n th.b/

My in/Bn phm/.tho i

Tc s liu cao hn

K/c trung bnh di hn

Truy nhp n km

cui c ng, c nh

Tc s liu thphn

Khong cch di hn

Cc my cm tay &

th.bPDA n Internet


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CHNG 4 - CC MNG TRUY NHP KHNG DY BNG RNG


1G (~95) 4G (05~)3G(02~04)2G (96~01)

MultimediaAnalog Digital

IEEE802.11b

Wireless LAN

HiperLAN2HiperLAN2

IEEE802.11aIEEE802.11a

Wired LAN

Digital Cellular

IMT-2000

(UMTS)

Wireless Multimedia

(IP Based Voice/Video)

High Speed Data/ Stationary Centric

Voice & Video Mobility Centric

Outdoor 5.15-5.35GHz 25-

50Mbps

Indoor 60-65GHz 155-622Mbps

Analog Cellular

Bluetooth

Hnh 4.2Xu hng hi tca cng nghtruy nhp v tuyn

Trn hnh 4.2 m tr hai xu hng pht trin ny, hnh 4.3 nhng xu hng

c miu tvi nhng mc thi gian cth.

2002 2003

IMTIMT--2000

Roadmap

2000Road

map

20052004 2006

Capacity

/Throughput

Peak Data Rate2007 2008 2015

cdma2000 1xEV-DO

cdma2000 1xEV-DO

cdma2000 1x

W-CDMA

HSDPAEnhancement

Harmonization

WLAN 3GInterworking

cdma2000 1x EV-DVEnhancement

OFDM-basedNew

Mobile AccessOFDM-basedNomadic System

4G Network4G Network4G Network

4G Mobile Communications Network

Evolution

cdma2000 1xEV-DV

HSDPA

2010 2013

Mobile GridNetwork/

UbiquitousNetwork

Hnh 4.3Mc lch sca truy nhp v tuyn

4.2.1 Hthng thng tin di ng 2G v nn tng CDMA

GSM


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Hnh 4.4Spht trin ln 4G tcc cng nghWAN

Trong nhng nm u ca thp k1980, hi nghvin thng v bu in chu u(CEPT) a ra nhm di ng c bit vi mc tiu l pht trin chun Pan-Europeancho thng tin tbo s. Dn ny c tn l GSM v h thng thc hin cc chuntng ng, hthng ton cu cho thng tin di ng, cng c vit tt l GSM.

T n nay, cc mng GSM, k cmng GSM theo khi nim gc hoc ccpht trin ca n, pht trin rng khp trn thgii v c nh gi l mt khoch

thnh cng. Cc hthng GSM hot ng di tn khong 900 MHz (GSM-900), 1.8GHz (GSM-1800), hoc 1.9GHz (GSM-1900). GSM-900 l mng t bo GSM png cc vng rng ln v hot ng vi cc u cui ngun ln. GSM sdngTDMA vi tc dliu thp ctrn di 10kbps.

IS-95

Vo cui nhng nm 1980 v u nhng nm 1990, QUALCOMM, Inc. ca SanDiego a ra a truy nhp phn chia theo m CDMA. Cc thnghim v vic chto

mng thnh cng c TIA v EIA chp nhn vi h thng QUALCOMM nhchun tm thi ca h, "TIA/EIA/IS-95 - chun tng thch gia trm gc -trm ding cho hthng di ng tri phbng rng hai ch".

Cc c im kthut ca TIA/EIA/IS-95 c thit lp hthng hot ng

hai chc bn (tng tv s), chai ch trong cng di tn. Khnng hotng hai ch thun tin cho vic chuyn tip tmi trng tng tsang mi

trng s. Mc d tng thch, cc h thng s v tng t kh khc nhau.TIA/EIA/IS-95 htrkthut tri phlin tc trc tip vi cc knh kp bng thng1.25 MHz.

Vic hai hthng sv tng tcng tn ti tc l cc trm di ng hai chctht v nhn cc cuc gi tbt chthng no v ngc li, tt ccc hthng c

EDGE/IS-136HS

HSDPA

Cdma20001x EV

Thhth2(~1998)

Thhth2,5(~2000~)

Thhth3(2002~)

Dliu gitch hp

a phngtinDi ng

Thhth4(~2010~)

GSM

IS-136/CDPD

IS-95A

PDC

7-28.8 kbps

HSCSD/GPRS

IS-136+(PRS)

IS-95B

57-115 kbps

cdma2000(1x)

0.144 ~2 Mbps ~10 Mbps ~100 Mbps/1Gbps

W-CDMA


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tht v nhn cc cuc gi tbt ctrm di ng no. Cc hot ng ngc li nhmiu ttrn yu cu mt sch . Mt trm di ng c thkhi to mt cuc gi vi

h thng CDMA v trong khi cuc gi vn ang trong qu trnh x l, n c thchuyn sang hthng tng t, nu c yu cu.

Mt si mi c a vo hthng CDMA so vi cc hthng tbo ban

u. Chuyn giao mm chnh l mt im mi ngoi ra cn c nhng si mi khcc a ra trng hthng CDMA nh l vic sdng cc bthu hthng nh v

ton cu (GPS) ti cc trm gc. Cc hthng CDMA ban u c sdng vi ccc tnh kthut TIA/EIA/IS-95.

Cc c tnh kthut ca phin bn A c pht trin ln TIA/EIA/IS-94B, trong

cc c tnh mi c lin quan ti truyn d liu tc cao hn, cc thut tonchuyn giao mm, cc kthut iu khin nng lng. Tn CDMA-one c sdng

xc nh hot ng vi cng nghCDMA vi kthut khc.

GPRS

htrmt cch hiu qumt vi loi lu lng to ra bi nhiu loi ng dng,mng tng hp phi cung cp c cc dch vdliu gi. Vi mc tiu y, ba cngnghdliu, c a vo cc hthng v tuyn, xut hin mt xen nhau sdng

cho cc ng dng gi trong cc mng v tuyn: Dch vv tuyn gi chung (GPRS),TIA/EIA/IS-95B, v dliu tc cao (HDR).

Vic a ra GPRS trong mng v tuyn di ng cho php ci thin khnng cahthng GSM sn c, mt sci thin chnh l :

- Sdng chai loi dch vchuyn mch knh v dch vchuyn mch gi.

- Sdng ti nguyn v tuyn tt hn.- Tnh cc da trn dung lng.

4.2.2 Hthng 3G

IMT-2000

Khi nim hthng di ng thhth3 (3G) c a ra bi IMT-2000. Vctli, mt hthng 3G phi cung cp:

- Cc dch va phng tin, trong cc hot ng chknh v gi.

- Cc lnh vc ngi sdng nh t nhn, cng cng, thng mi, dn c, v

cc lnh vc khc.- Cc mng da trn mt t v vtinh.

- Thit bbti c nhn, thit btrn xe c, v bt cu cui c bit khc.


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Hnh 4.5Hthng IMT 2000

Cc c tnh xc nh ca IMT-2000 bao gm:- Mc tng ng cao trong cc thit k trn ton thgii.

- Tnh tng thch ca cc dch vtrong IMT-2000 v cc mng cnh.

- Cht lng cao

- u cui nhc sdng rng ri.

- Khnng ca cc ng dng a phng tin v di rng ca cc dch vv cc

u cui IMT-2000 c thc thc hin nh mng c lp hoc nh mtphn tch hp ca cc mng cnh. Cc h thng 3G cung cp kh nng

modul ho vchai mt dung lng v chc nng.Tri ngc vi QoS cnh trong hthng v tuyn 1G v 2G (c xc nh nh

scgng tt nht), cc hthng 3G cung cp QoS mm do. Cc ng dng ca nv ngi sdng c thc n nh mt QoS mc nh vi cc iu chnh sao cho

thch hp vi QoS mong mun. Cc ti nguyn khi c phn phi ty theo hnglot cc tham s nh cc hin trng QoS cn c bi s thu bao in thoi, ti hthng, cc iu kin truyn, loi lu lng (ci ny tu thuc vo ng dng), v ccyu tkhc.

Tm li, cc mc tiu chnh ca cc mng 3G nh sau:

- Schp nhn ton cu vtp cc chun nng ct cho giao din v tuyn.- Thc y roaming ton cu.

- Htrhiu qudi rng cc dch vdliu bao gm ca phng tin.

Trn thc t, cc hthng 3G c trin khai vi hai mc ch chnh:

- htrcc dch vdliu gi vi tc v cht lng nh cc mng cnh.

- Cung cp truy nhp internet.

Cdma2000 (TIA)- DS-CDMA- MC-CDMA

CDMA I (TTA)

CDMA ng b

W-CDMA (ETSI)W-CDMA (J PN)W-CDMA (USA)CDMA II (TTA)

TD-CDMA (ETSI)TD-SCDMA (CHN)

CDMA cn ng b

UWC-136 (USA)TDMA

ITU

cdma2000

W-CDMA

TD-CDMA

OHG

IMT-2000 CDMA MC (IMT-MC)

IMT-2000 CDMA DS (IMT-DS)

ITU-R TG8/1 (99.11)

IMT-2000 TDMA Single-Carrier(IMT-SC)

IMT-2000 FDMA/TDMA(IMT-FT)

IMT-2000 TDD CDMA (IMT-TC)


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GPP2 & CDMA2000

Giao din v tuyn a sng mang IMT-2000 CDMA c nhc n viCdma2000. N l giao din v tuyn tri phbng rng c thit kt c cc

yu cu ca h thng v tuyn 3G cng nh cc yu cu ca s pht trin ca ccchun h2G TIA/EIA-95-B. Cdma2000 cung cp khnng tng thch ngc li vi

TIA/EIA-95-B. Khnng tng thch ngc cho php c shtng ca cdma2000 htr cc trm di ng TIA/EIA-95-B v cho php cc trm di ng cdma2000 hot

ng c vi cc h thng TIA/EIA-95-B. Cdma2000 xut ra kh nng tngthch ngc vi CdmaOne cung cp vic chuyn giao mm tcc mng 2G ln 3G.

Mt kha cnh quan trng ca khnng tng thch ngc l khnng htrvic baophcc mng Cdma2000 v CdmaOne vi cng ph.

CDMA2000 thc hin cc yu cu truyn dn bng rng theo hai cch khc nhau.Vic truyn dn ln c thsdng hoc k thut tri ph trc tip hoc k thut a

sng mang. Vic thc hin a sng mang i vi ng ln ca Cdma2000 to iu

kin thun li cho thit kchng lp CdmaOne v Cdma2000. Trong vic thc hin asng mang, h thng Cdma2000 Nx1.25 Mhz (vi N=1,3,6,9, hoc 12) c thchng

lp N sng mang lin tc ca CdmaOne, vi N l stc phn tn SR . SR 2 cdng ch1X v SR 3 ch3X, l hai kthut c nh ngha trong cc chunCdma2000.

CDMA2000 cng h trvic sdng li cc chun dch v c ca cdmaOne,nh cc dch vlin quan n thoi, cc dch vdliu, cc dch vtin nhn,Vicchuyn giao y cc cuc gi d liu v thoi tmt h thng ti mt h thng

khc l c im rt hay c htrbi cdmaOne v cdma2000. Khnng thc hin

chuyn giao mm gia h thng cdmaOne v cdma200 cho php cc nh hot ngxy dng dn dn cc mng Cdma2000 khi c nhu cu tng cng dch vv thmdung lng.

4.2.3 WLAN

Cng nghhu tuyn Ethernet c gii thiu vo nm 1970, vi tc 10 Mbps,hn hn tc ca cc cng nghkhng dy khc hin c thi im . Vo nm

1985 FCC cho php pht trin cho thng mi h thng WLAN s dng bng tnISM. Bng tn ISM rt hp dn cc i l cung cp khi khng cn phi c scp

php ca FCC hot ng trong bng tn ny.

Mng v tuyn bng rng u tin, WLAN c xy dng trn c shcc chunIEEE 802.11. Chun IEEE 802.11 u tin c pht hnh vo 1997, chim 83.5MHz

bng thng trong bng tn 2.4GHz khng cp php. N sdng iu chPSK vi triphnhy tn FHSS v tri phchui trc tip DSSS. Tc d liu ln n 2Mbps

c htrvi CSMA/CA, sdng cho truy nhp ngu nhin. Chun u tin cmrng vo 1999 to ra chun 802.11b, hot ng trong cng bng tn nhng ch

sdng DSSS. Cung cp tc knh truyn cc i ln n 11Mbps vi tc d


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liu ngi dng cc i khong 1.6Mbps. Phm vi truyn dn t ti 150m. Kin trcmng trong 802.11b l hnh sao hoc ngang cp, mc d c tnh ngang cp khng

c sdng in hnh. Chun ny c trin khai v sdng rng ri vi cc nhsn xut thit btch hp cc card 802.11b vo cc my tnh xch tay.

Chun 802.11a c hon thnh vo 1999 nh mt smrng ca 802.11b ci

thin tc dliu ca 802.11b. Chun 802.11a chim 300MHz phtrong bng NII5GHz. Thc t, 300MHz phc phn chia thnh ba bng con 100MHz. Mt bng

thp t 5.15-5.25GHz, mt bng gia t 5.25-5.35GHz, mt bng trn t 5.725-5.825GHz. Mi knh chim 20MHz, ngoi trcc phn cui ca bng gia v bngthp l 30MHz. C ba mc cng sut pht cc i c chra l 40mW cho bng thp,200mW cho bng gia v 800mW cho bng cao. Nhng gii hn ny nhm m ch

rng bng thp hu nh chph hp cho cc ng dng trong nh, bng gia cho ngoitri v trong nh cn bng cao cho ngoi tri. iu chv m ha tlbin i cs dng cho mi knh. Cc loi iu ch bin i qua BPSK, QPSK, 16QAM v

64QAM v cc tlm ha xon bin i qua 1/2, 2/3 v 3/4. iu ny dn n tc dliu cc i mi knh l 54MHz. Vi cc hthng trong nh, sng mang 5GHz kthp vi gii hn cng sut trong bng thp gim phm vi ca 802.11a so vi 802.11bv cng kh hn tn hiu xuyn qua cc bc tng v cc vt cn khc. Chun802.11a sdng a truy nhp OFDM thay v FHSS v DSSS.

Chun 802.11g c hon thnh vo 2003, kt hp u im ca 802.11a v

802.11b vi tc d liu ln n 54Mbps trong bng tn 2.5GHz cho phm vi lnhn. Chun ny tip tc tng thch vi 802.11b v thcc im truy nhp 802.11g s

lm vic vi cc b thch ng mng v tuyn 802.11a. Tuy nhin, 802.11g sdng

OFDM, lc iu chv m ha ca 802.11a. Ccc im truy nhp v cc CardLAN u ph hp vi cba chun trnh khng tng thch. Hchun 802.11a/b/gc xem nh l Wi-Fi, cho tin cy v tuyn.

4.2.4 Wimax

Wimax l khnng khai thc lin mng ton cu i vi truy nhp vi ba. Wimax lmt cng ngh khng dy da trn chun 802.16 cung cp cc kt ni bng rng

thng lng cao qua khong cch xa. Cng nghWimax bao gm cc sng vi ba truyn d liu khng dy. Wimax c dng cho mt sng dng nh kt ni bngrng u cui, cc hotspot v cc kt ni tc cao cho cc khch hng kinh doanh.

N cung cp kt ni mng vng thnh thkhng dy MAN vi tc ln ti 70Mbpsv cc trm gc Wimax trung bnh c thbao pht5 n 10km.

Cc chun cnh v di ng u c sdng trong cbng tn cp php vkhng cp php. Tuy nhin min tn scho chun cnh l 2-11GHz trong khi chun

di ng l di 6GHz.

IEEE 802.16 nh ngha cc lp vt l khc nhau:

- Wireless MAN-SC layer


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- Wireless MAN-SCa layer

- Wireless MAN-OFDM Layer

- Wireless MAN-OFDMA Layer

- Wireless HUMAN

Nhng lp vt l c nh ngha chi tit bao gm 5 loi trong hin nay s

dng chyu loi th3 v tht. Hai loi ny da chyu trn nguyn l OFDM vOFDMA

Cc c tnh chnh ca lp vt l ny bao gm:

- HtrTDD v FDD

- TDMA UL

- TDM DL

- iu chkhi thch ng v m ha FEC cho cng UL v DL

- Truyn theo khung ci thin s cn bng (mt chiu) v thc hin c

lng knh qua NLOS v mrng mi trng trtri ph.- K hiu c ng thnh gi.

- M ha son FEC sdng m Reed Solomon v chn Pragmatic TCM

- FEC sdng ty chn BTC v CTC

- Khng sdng FEC ty chn sdng ARQ iu khin li.

- Ty chn tnh phn tp chuyn tip STC.

- Ngoi tr cc yu cu khc, qu trnh truyn tin tng t cho c hngng ln UL v ng xung DL.

Lp vt l v tuyn MAN-OFDM da trn iu chOFDM c thit khotng cho ng truyn trong phm vi khng truyn thng NLOS trong di tn t2-11GHz. Htrsong cng TDD, FDD.

Lp vt l v tuyn MAN-OFDMA: da trn k thut iu ch OFDMA cthit khot ng i vi ng truyn khng trong tm nhn thng NLOS trong

di tn 2-11 GHz. Trong di tn c cp php, hai phng php song cng c sdng l FDD v TDD, FDD SSs c th l bn song cng (H-FDD). Trong di tn

khng cp php, sdng phng php song cng TDD.

4.2.5 Hthng 4G

Ngay ctrc khi cc mng 3G c khai trng v a vo sdng hon ton,nhiu nhm nghin cu khc nhau xem xt n dng tip theo ca cng ngh t

bo, hay cn gi l 4G. Cho n by gi cha c nh dng chung cho 4G, nhng

mng thhmi c thl da trn IP, cung cp tc dliu ln ti 100 Mbps v htrkhnng di dng ton cu. Mt l trnh hng ti mng ny l shi tca cccng nghnh tbo 3G v Wireless LANs (WLANs).


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65/112


CHNG 5

TRUY NHP QUA VTINH

Cng ngh truy nhp v tinh vi u im vphm vi phkt ni ln srt phttrin khi gi thnh sdng dch vthp. Chng 5 gii thiu s lc vcc loi ktni vtinh v mt hthng ang c sdng rng ri Vit Nam, ni dng chnh

ca chng ny bao gm:

q Gii thiu chung

q Hthng VSAT

q Hthng thng tin vtinh IP - STAR


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5.1GII THIU CHUNGMt knh vtinh truyn thng trc tip c thddng hot ng tc dliu

23 Mbps. Tuy nhin, tc phbin nht l khong 400 kbps (dch vDirect PC).Cc h thng hin nay s dng cc qu o a tnh (GEO) cao 22500 dm(khong mt phn mt phn mi khong cch t qu t n mt trng). Khong

cch ln ny lm tng thi gian trca dch vhai chiu tc cc dch vtng tc.Tuy nhin, cc hthng vtinh nhn to thhmi nh hthng vtinh nhn to

Iridium v h thng v tinh nhn to Teledesic sdng cc quo thp hn nhinLEO c thi gian trnhnht v tiu thnng lng my pht nhhn. Mt vn ln ca cc nh cung cp dch vqua hthng thng tin vtinh l gi c.

u im ln nht v c bit ca cc hthng GEO l tm phsng rng. Vtinhnhn to lm cho vng phsng trnn ln nht. Thng tin vtinh hon ton khng

ph thuc vo iu kin a l nh thung lng, ni non, bin c,...Thng tin v tinhphvkhng bnh hng bi khong cch. Mt vtinh nhn to phc vcc im

cch xa nhau hng ngn cy s cng ging vi khi phc vcho hai nh hng xm.iu ny vn ng khi no cc a im phc vca h thng thng tin v tinh vn

cn nm trong tm phsng ca n.

Mt khc hthng thng tin vtinh cng c nhng nhc im trm trng vmtkthut ca n. Cc dch vda vo thng tin c thbmy bay che khut v dnhin

cng c thbcc vtinh c quo thp hn che khut. nh sng mt tri cng cthtc ng ln tn hiu v tn hiu c thbmt mt thi gian khi mt tri i qua sau

cc vtinh trong cc ngy ng ch v hch. Mt vi hiu ng mt tri lm cho bukh quyn phng ln v cc vtinh c quo thp phi chuyn ng u n trnh

khi bkh quyn li ko. Tui thca mt vtinh c xc nh bi lng nhin liun mang theo. Tc ng nhca trng trng phi c cn bng bng vic t nh

ktn la. Khi nhin liu cn kit th vtinh nhn to trnn v dng.

Trngi cui cng ca cc hthng thng tin vtinh l sc mt ca qu nhiuvtinh cng gy ra rc ri. Cc vtr vtinh thun li ca cc vtinh GEO c

chim gi tnhiu nm qua. Tnh hnh cng sxy ra tng ti vi cc v tinhLEO. Dnhin, vic chia nhau di thng hn chgia lng ngi sdng khng lstrthnh mt bi ton nan gii.

C mt vi hthng LEO nh:

- Iridium c 66 vtnh c mc ch ca hthng vtinh nhn to Iridium l

dng cho h thng in thoi di ng cu hnh sdng c thhin trnhnh 5.1

- Teledesic cng gi l Internet trn tri (Internet in the sky) li chchnhm vo dch v truy xut Internet bao gm 288 v tinh nhn to ca

Teledesic c gi thnh xp x9 tdollar.


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CHNG 5 - TRUY NHP QUA VTINH


- Globalstar, mt cng ty con ca hng Loral and Qualcomm c h thng 48v tinh vi gi thnh 2,6 tdollar vi mc ch chnh l dng cho cc ng

dng dliu truyn thng, in thoi v fax.

- Skybridge d kin s phng 64 v tinh vi gi thnh tng cng l 3,5 tdollar.

IridiumGatew ay

Ka-band

Ka-band

L-band

Ka-band

Iridium Satelites

Acronautical

IridiumGatew ay

IridiumTelephone

IridiumPager

TerrestrialSw ittchWirelessCustomers

Hnh 5.1in thoi di ng Iridium

Mt shthng GEO nh :

- H thng Direct PC ca Hu

Documents

Cong Nghe Truy Nhap NGN