Tieu Luan 15 - WCDMA

I HC QUC GIA TP. H CH MINH TRNG H CNG NGH THNG TIN

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TIU LUN

CNG NGH MNG WCDMA

Gio vin hng dn: Th.S Chu Tin Dng

Nhm SV thc hin: 1. L Quc Chung 2. Nguyn Quang Trung 3. V Mai Ph Trng

Nha Trang, 09/2015

TIU LUN CNG NGH MNG WCDMA

1

LI NI U

Nhu cu trao i thng tin l nhu cu thit yu trong cuc sng, trong x hi hin i

ngy nay i hi thng tin cn trao i v mi lnh vc phi m bo cc yu t nh tc

nhanh chng, tin li v chnh xc cao. Vi nhu cu nh vy, ngy nay thng tin

di ng tr thnh mt ngnh cng nghip pht trin nhanh v mnh m. S pht trin

ca th trng vin thng di ng thc y vic nghin cu v trin khai cc h thng

thng tin di ng mi trong tng lai.

Trong tiu lun ca mnh, chng ti xin gii thiu v h thng thng tin di ng

th h ba vi cng ngh WCDMA. Chng ti c gng trnh by tht c ng nhng

vn c bn nht ca cng ngh WCDMA. Tuy nhin, do kin thc c hn nn khng

th trnh khi nhng sai st, cng nh cn nhiu vn cha c gii quyt tha ng.

Chng ti rt mong nhn c s ch bo ca cc thy c gio, s gp v ph bnh ca

cc bn.

Trong thi gian thc hin tiu lun, chng ti nhn c s gip tn tnh

ca thy Chu Tin Dng. Chng ti xin chn thnh cm n!


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MC LC LI NI U .......................................................................................................................................... 1

MC LC................................................................................................................................................. 2

THUT NG V VIT TT ................................................................................................................ 3

I. TNG QUAN H THNG MNG DI NG ............................................................................ 5

1.1. H thng thng tin di ng th h th nht ....................................................................... 5

1.2. H thng thng tin di ng th h th hai ......................................................................... 5

1.3. H thng thng tin di ng th h th ba .......................................................................... 7

1.4. L trnh pht trin t h thng thng tin di ng th h th hai ln th h th ba ....... 7

1.5. Tng quan v mng WCDMA ............................................................................................ 8

1.5.1. Gii thiu cng ngh mng WCDMA ........................................................................ 8

1.5.2. Cc thng s chnh ca mng WCDMA .................................................................... 9

1.5.3. Nhng c im ca mng WCDMA ....................................................................... 10

1.5.4. nh hng ca nhiu ln h thng WCDMA.......................................................... 11

II. CNG NGH DI NG TH H BA WCDMA ...................................................................... 12

2.1. Cu trc mng WCDMA .................................................................................................. 12

2.1.1. Cc thnh phn ca h thng mng WCDMA ........................................................ 12

2.1.2. Kin trc UTRAN ...................................................................................................... 14

2.1.3. Cc giao din v tuyn ca UTRAN ......................................................................... 15

2.2. Cc gii php k thut trong WCDMA ............................................................................ 17

2.2.1. M ha ......................................................................................................................... 17

2.2.2. iu ch BIT/SK v QPSK ........................................................................................ 18

2.3. Tri ph trong WCDMA ................................................................................................... 21

2.3.1. Gii thiu .................................................................................................................... 21

2.3.2. Nguyn l tri ph DSSS ............................................................................................ 22

2.3.3. M tri ph ................................................................................................................. 23

2.4. Truy nhp gi ..................................................................................................................... 24

2.4.1. Tng quan v truy nhp gi trong WCDMA ........................................................... 24

2.4.2. Lu lng d liu gi ................................................................................................ 25

2.4.3. Cc phng php lp biu gi .................................................................................. 26

III. TRIN KHAI MNG 3G WCDMA CA VIETTEL ............................................................ 27

3.1. S dch chuyn t GSM sang WCDMA........................................................................... 27

3.2. Node B ca Viettel .............................................................................................................. 29

3.3. Mt s dch v 3G Viettel cung cp .................................................................................. 29

KT LUN ............................................................................................................................................. 32

TI LIU THAM KHO ..................................................................................................................... 33


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THUT NG V VIT TT

Vit tt Ting Anh Gii thch

2G Second generation H thng thng tin di ng th h 2

3G Third generation H thng thng tin di ng th h 3

AAL2 ATM adaptation layer 2 ATM p ng lp 2

ATM Asynchronous tranfer mode Ch truyn dn bt ng b

BPSK Binary phase-shift keying iu ch pha nh phn

BS Base station Trm c s

BTS Base transceiver station Trm thu pht v tuyn

CDMA Code division multiple access a truy nhp phn chia theo m

CN Core network Mng li

CS Circuit switched Chuyn mch knh

EDGE Enhanced data rate for GSM

evolution

Tc bit tng cng cho GSM

FDMA Frequency Division Multiple

Access

a truy nhp phn chia theo tn s

GGSN Gateway GPRS support node Nt h tr cng GPRS

GMSC Gateway MSC Cng MSC

GPRS General packet radio service Dch v v tuyn gi chung

GPS Global positioning system

communications

H thng nh v ton cu

GSM Global system for mobile H thng thng tin di ng ton cu

HLR Home location register Thanh ghi nh v thng tr

HSCSD Hight speed circuit switched Chuyn mch knh tc cao

IMT-2000 International mobile

communication 2000

Tiu chun vin thng di ng quc t 2000


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ISDN Integrated services digital

network

Mng s liu a dch v

MS Mobile station Trm di ng

MSC Mobile switching center Trung tm chuyn mch di ng

PN Pseudo noise Tp m gi

PS Packet switched Chuyn mch gi

QPSK Quadrature phase-shift keying iu ch pha vung gc

RANAP Radio access network

application part

Phn ng dng ca mng truy cp

RLC Radio link control iu khin lin kt v tuyn

RNC Radio network controller B iu khin mng v tuyn

RNS Radio network subsystem Phn h mng v tuyn

SONET Synchronous optical networking Mng ng b s dng cp quang

SS7 Signalling system 7 Giao thc bo hiu s 7

STM-1 Synchronous transport module

level-1

B truyn ti ng b mc 1

TDMA Time division multiple access a truy nhp phn chia theo thi gian

UE User equipment Thit b ngi dng

UMTS Universal mobile

telecommunication system

H thng vin thng di ng ton cu

UTRAN Universal terrestrial radio

access network

Mng truy nhp v tuyn mt t ton cu

WCDMA Wideband code division

multiple access

CDMA bng rng


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I. TNG QUAN H THNG MNG DI NG

Trong nhng nm gn y,cng ngh khng dy l ch c nhiu chuyn gia quan tm trong lnh vc my tnh v truyn thng. Trong thi gian ny cng ngh ny c rt nhiu ngi s dng v tri qua rt nhiu thay i. Qu trnh thay i th hin qua cc th h:

Th h khng dy th nht l th h thng tin tng t s dng cng ngh a truy cp phn chia theo tn s (FDMA).

Th h th hai s dng k thut s vi cng ngh a truy cp phn chia theo thi gian (TDMA) v phn chia theo m (CDMA).

Th h th ba ra i nh gi s nhy vt nhanh chng v c dung lng v ng dng so vi cc th h trc , v c kh nng cung cp cc dch v a phng tin gi.

1.1. H thng thng tin di ng th h th nht

H thng thng tin di ng th h mt ch h tr cc dch v thoi tng t v s dng k thut iu ch tng t mang d liu thoi ca mi ngi, v s dng phng php a truy cp phn chia theo tn s (FDMA). Vi FDMA, khch hng c cp pht mt knh trong tp hp c trt t cc knh trong lnh vc tn s. S bo hiu ca h thng FDMA kh phc tp, khi MS bt ngun hot ng th n d sng tm n knh iu khin dnh ring cho n. Nh knh ny, MS nhn c d liu bo hiu gm cc lnh v knh tn s dnh ring cho lu lng ngi dng. Trong trng hp s thu bao nhiu hn s lng knh tn s c th, th mt s ngi b chn li khng c truy cp.

Ph tn s quy nh cho lin lc di ng c chia thnh 2N di tn s k tip, v c cch nhau bi mt di tn s phng v. Mi di tn s c gn cho mt knh lin lc. N di k tip dnh cho lin lc hng ln, sau mt di tn phn cch l N di k tip dnh ring cho lin lc hng xung.

c im:

Mi MS c cp pht mt i knh lin lc trong sut thi gian thng tuyn.

Nhiu giao thoa do cc knh ln cn l ng k.

BTS phi c b thu pht ring lm vic vi mi MS.

H thng FDMA in hnh l h thng in thoi di ng AMPS (Advanced Mobile Phone System). H thng di ng ny s dng phng php a truy cp n gin. Tuy nhin h thng khng tha mn nhu cu ngy cng tng ca ngi dng v c dung lng v tc . V th h thng di ng th hai ra i ci thin v c dung lng v tc .

1.2. H thng thng tin di ng th h th hai

Vi s pht trin nhanh chng ca thu bao, h thng thng tin di ng th h th hai

c a ra p ng kp thi s lng ln cc thu bao di ng da trn cng ngh

s.

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Tt c h thng thng tin di ng th h hai s dng phng php iu ch s v

s dng 2 phng php a truy cp:

a truy cp phn chia theo thi gian TDMA.

a truy cp phn chia theo m CDMA.

a truy cp phn chia theo thi gian TDMA:

Ph quy nh cho lin lc di ng c chia thnh cc di tn lin lc, mi di tn lin

lc ny c dng cho N knh lin lc, mi knh lin lc l mt khe thi gian trong chu

k mt khung. Cc thu bao khc nhau dng chung knh nh ci xen khe thi gian, mi

thu bao c cp pht cho mt khe thi gian trong cu trc khung.

c im:

Tn hiu ca thu bao c truyn dn s.

Lin lc song cng mi hng thuc cc di tn khc nhau, trong mt bng tn

c s dng truyn tn hiu t trm gc n cc my di ng v mt bng tn

c s dng truyn tn hiu t my di ng n trm gc. Vic phn chia tn

s nh vy cho php my thu v my pht c th hot ng cng mt lc m

khng can nhiu ln nhau.

Gim s my thu BTS.

Gim nhiu giao thoa.

H thng TDMA in hnh l h thng di ng ton cu GSM. My di ng k

thut s TDMA phc tp hn FDMA. H thng x l s i vi tn hiu trong MS tng

t c kh nng x l khng qu 106 lnh trong 1 giy, cn trong MS s TDMA phi c

kh nng x l 50.106 lnh trong 1 giy.

a truy cp phn chia theo m CDMA:

Trong thng tin di ng CDMA s dng k thut tri ph cho nn nhiu ngi s dng

c th chim cng knh v tuyn ng thi tin hnh cc cuc gi m khng s ly nhiu

ln nhau. Nhng ngi s dng ni trn c phn bit vi nhau nh m tri ph gi

ngu nhin PN, c cp pht khc nhau cho mi ngi s dng.

c im:

Di tn tn hiu rng.

S dng k thut tri ph phc tp.

K thut tri ph cho php tn hiu v tuyn s dng c cng trng rt nh

v chng fading hiu qu hn TDMA v FDMA.

Vic cc thu bao trong cng cell dng chung tn s khin cho thit b truyn dn

n gin v vic thay i, chuyn giao, iu khin dung lng cell thc hin rt

linh hot.


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1.3. H thng thng tin di ng th h th ba

p ng kp thi cc dch v ngy cng phong ph v a dng ca ngi s dng, t

u thp nin 90 ngi ta a ra h thng thng tin di ng t ong th h th ba. H

thng thng tin di ng th h th 3 vi tn gi IMT-2000 a ra cc mc tiu chnh

sau:

Tc truy nhp cao m bo cc dch v bng rng nh internet nhanh hoc

cc dch v a phng tin.

Linh hot m bo cc dch v mi nh nh s c nhn v in thoi v tinh.

Cc tnh nng ny s cho php m rng ng k tm ph sng ca cc thng tin

di ng.

Tng thch vi cc h thng thng tin di ng hin c m bo s pht trin

lin tc ca thng tin di ng.

3G ha hn tc truyn dn ln ti 2.05Mbps cho ngi dng tnh, 38 Kbps cho

ngi dng di chuyn chm v 128Kbps cho ngi dng trn moto. Cng ngh 3G dng

sng mang 5MHz ch khng phi l sng mang 200KHz nh ca CDMA nn 3G nhanh

hn rt nhiu so vi cng ngh 2G v 2,5G. Nhiu tiu chun cho h thng thng tin di

ng th h th ba ITM-2000 c xut, trong hai h thng WCDMA v

CDMA-2000 c ITU chp thun v ang c p dng trong nhng nm gn y.

Cc h thng ny u s dng cng ngh CDMA, iu ny cho php thc hin tiu chun

ton th gii cho giao din thng tin v tuyn.

1.4. L trnh pht trin t h thng thng tin di ng th h th hai ln th

h th ba

m bo ng dng c cc dch v mi v truyn thng my tnh v hnh nh ng

thi m bo tnh kinh t, h thng thng tin di ng th h hai s c chuyn i sang

th h ba. Qu trnh c tng qut trong hnh 1.1

Hnh 1.1 Cc gii php nng cp h thng 2G ln 3G

2G


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L trnh pht trin t GSM ln WCDMA nh sau:

Hnh 1.2 L trnh pht trin t GSM ln WCDMA

K hiu:

GSM: Global System for Mobile Communication: H thng thng tin di ng ton

cu.

HSCSD: Hight Speed Circuit Switched Data: S liu chuyn mch knh tc

cao.

GPRS: General Packet Radio Services: Dch v gi v tuyn chung.

WCDMA: Wideband Code Division Multiple Access: a truy cp phn chia theo

m bng rng.

1.5. Tng quan v mng WCDMA

1.5.1. Gii thiu cng ngh mng WCDMA

WCDMA (Wideband Code Division Multiple Access: a truy cp phn chia theo m bng rng) l mt trong nhng h thng thng tin di ng th h ba, s dng cng ngh CDMA (Code Division Multiple Access: a truy cp phn chia theo m), l mt cng ngh khng dy, s dng k thut tri ph phn tn tn hiu v tuyn trong mt di tn s rng. Trong cng ngh CDMA, nhiu ngi dng chung mt thi gian v tn s. M PN (gi ngu nhin) vi s tng quan cho thp, c n nh cho mi ngi s dng. Ngi s dng truyn tn hiu nh tri ph tn hiu truyn c s dng m PN n nh. u thu to ra mt dy PN nh u pht v khi phc li tn hiu d nh nh vic tri ph ngc cc tn hiu ng b thu c. Cng ging nh TDMA, WCDMA l mt trong nhiu cng ngh ch o mng thng tin di ng hot ng. N cng c bit nh l mt giao din v tuyn hay cng ngh a truy xut. WCDMA l mt giao din v tuyn phc tp v tin tin trong lnh vc thng tin di ng. WDMA c hai ch khc nhau l FDD v TDD. Kh nng lm vic c c hai ch FDD v TDD cho php s dng hiu qu ph tn c cp pht cc vng khc nhau.

FDD (Frequency Division Duplex): l phng php ghp song cng trong truyn dn ng ln v ng xung s dng hai tn s ring bit. FDD ng ln v ng xung s dng hai bng tn khc nhau. H thng c phn b mt cp bng tn ring bit.

TDD (Time Division Duplex): l phng php ghp song cng trong ng ln v ng xung c thc hin trn cng mt tn s bng cch s dng nhng khe thi gian lun phin. TDD cc khe thi gian trong cc knh vt l c chia thnh hai phn: phn pht v phn thu. Thng tin ng xung v ng ln c truyn dn lun phin.

GSM HSCSD GPRS WCDMA

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Hnh 1.3 Phn b tn s FDD v TDD

Kh nng lm vic c 2 ch FDD v TDD cho php s dng hiu qu ph tn c cp pht cc vng khc nhau.

Ba lp c bn ca mng WCDMA:

Lp truy nhp: c to ra bi cc trm gc (node B) v cc b iu khin mng v tuyn khc nhau phn tch v iu khin cc mng v tuyn.

Mng li c hai vai tr chnh:

Gii quyt vic nh hng hay nh tuyn n ni m cuc gi hoc s liu gi n. Phng tin c bn l s dng h thng chuyn mch nh tuyn thng tin qua mt s my ch khc nhau xung quanh mng.

L mt mng ng trc v gii quyt cc chc nng k thut, kh nng truy nhp thun tin ti mng s liu gi khc, cung cp mt giao din vi Internet v phn loi thng tin tnh cc v bo mt.

Lp dch v iu khin cc u tin, cc c tnh v kh nng truy nhp c bn ca thu bao ti cc dch v nng cao lm cho 3G c mt v tr tuyt vi.

1.5.2. Cc thng s chnh ca mng WCDMA

WCDMA l mt phng php a truy xut v tuyn phn chia theo m tri ph trc tip di rng, ngha l cc bit thng tin ca cc ngi dng c tri u ra trn mt di thng rng bng vic nhn d liu ca ngi dng vi cc m ngu nhin (gi l chip) nhn c tri ph trong WCDMA

Tc chip 3.84Mcps c s dng cho ghp di thng sng mang xp x ti 5MHz. Di thng sng mang ca WCDMA rng nh th gn lin vi tc d liu ca ngi dng cao v cn c hiu qu nng cao kh nng phn tp tn s. Cc nh qun l mng c th tng dung lng nh di thng ca sng mang l 5MHz. Khong cch cc


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sng mang c th chn tr nhng khong 200KHz gia khong 4.4 n 5MHz ty thuc vo nhiu gia cc sng mang.

WCDMA cung cp tc kh bin cho cc ngi dng rt cao, hiu theo cch khc chnh l di bng thng theo yu cu cng c cung cp. Mi ngi dng c cung cp mt khung giy c chu k 10ms trong khi tc d liu vn gi nguyn khng i. Tuy nhin dung lng d liu c th thay i t khung nay n khung khc.

WCDMA cung cp hai ch hot ng c bn l FDD v TDD. Trong FDD cc khong tn s sng mang 5MHz c s dng cho sng mang hng ln v hng xung ring r, trong khi TDD ch c mt khong 5MHz c dng cho c hng ln v hng xung.

WCDMA cung cp hot ng bt ng b cho cc trm gc v do khng ging nh h thng ng b IS-95 CDMA, n khng cn thi gian chun trn ton cu GPS.

WCDMA c thit k pht trin nng cp cho chun GSM v vy c th chuyn giao gia mng GSM v mng WCDMA.

Phng thc a truy xut. DS-CDMA.

Phng php ghp song song. FDD/FTD.

ng b trm gc. Hot ng bt ng b.

Tc chip. 3.84Mcps.

di khung. 10ms.

Ghp dch v. a dch v vi yu cu cht lng dch v khc nhau c ghp trn mt kt ni.

a tc . H s tri ph kh bin v a m.

Tch sng Tch sng kt hp nh s dng knh hoa tiu

1.5.3. Nhng c im ca mng WCDMA

Giao din v tuyn trn c s CDMA bng rng to c hi thit k h thng c nhng c tnh p ng nhu cu ca th h th ba. Nhng c im ch yu trong h thng WCDMA l:

Ci thin nhng h thng th h th hai bao gm: ci thin dung lng, ci thin vng ph sng, bao gm c kh nng di chuyn nhng dch v th h th hai sang th h th ba.

Tnh linh hot cao ca dch v bao gm: H tr hot ng khng ng b gia cc trm gc nn trin khai thun li trong nhiu mi trng. H tr mt cch c hiu qu dng hot ng khc chng hn cu trc c bc. S dng k thut tin b nh phi hp anten dn v tch ngi dng. M hnh TDD c thit k hot ng hiu qu trong mi trng khng kt hp.

Ci thin dung lng: rng bng tn ln ca WCDMA lm tng hiu sut vn c trn cc h thng t bo trc do n lm gim fading ca tn hiu v tuyn. Ta bit rng WCDMA s dng iu ch kt hp ng ln, y l tnh nng khng th thc hin c trong cc h thng CDMA t bo. iu khin cng sut chc chn ng xung s c hiu sut hon ho, c bit mi trng trong nh v mi trng ngoi tri c tc thp.


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Ni chung i vi dch v thoi, s ci thin ny l mt bc tin v y l mt trong hai yu t lm tng dung lng cell ca WCDMA.

1.5.4. nh hng ca nhiu ln h thng WCDMA

Trong knh thng tin v tuyn l tng, tn hiu thu c ch bao gm mt tn hiu n

trc tip. Tuy nhin, trong thc t iu l khng th xy ra, tn hiu s b thay i

trong sut qu trnh truyn, tn hiu thu c s l s kt hp ca cc thnh phn khc

nhau: tn hiu suy gim, phn x, nhiu x ca cc tn hiu khc,... WCDMA l h thng

di ng v tuyn nn s b nh hng bi iu . Sau y l m hnh ca cc loi nhiu.

Hnh 1.4 Cc tn hiu a ng

lm gim cc nh hng ca cc loi nhiu trn, trong WCDMA c nhiu loi

k thut x l l: m ha knh, iu ch, tri ph,

Phn ny gii thiu tng quan v cc th h thng tin di ng, c bit l h thng

WCDMA. Trong phn tip theo, chng ta s i su tm hiu v cu trc ca h thng

mng WCDMA v mt s gii php k thut c p dng trn n.

A: khng gian trng

B: phn x

C: khc x

D: tn x


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II. CNG NGH DI NG TH H BA WCDMA

2.1. Cu trc mng WCDMA

2.1.1. Cc thnh phn ca h thng mng WCDMA

H thng WCDMA c xy dng trn c s mng GSM. V mt chc nng c th chia

cu trc mng WCDMA ra lm hai phn: mng li (CN) v mng truy nhp v tuyn

(UTRAN), trong mng li s dng ton b cu trc phn cng ca mng GSM, cn

mng truy nhp v tuyn l phn nng cp ca WCDMA. Ngoi ra hon thin h

thng, trong WCDMA cn c thit b ngi dng (UE) thc hin giao din ngi dng

vi h thng. T quan im chun ha, c UE v UTRAN u bao gm nhng giao thc

mi c thit k da trn cng ngh v tuyn WCDMA, tri li mng li c nh

ngha hon ton da trn GSM. iu ny cho php h thng WCDMA pht trin mang

tnh ton cu trn c s cng ngh GSM.

Hnh 2.1 Cu trc ca WCDMA UMTS

UE (User Equipment)

Thit b ngi dng thc hin chc nng giao tip ngi dng vi h thng. UE

gm hai phn:

Thit b di ng (ME: Mobile Equipment): l u cui v tuyn c s dng cho

thng tin v tuyn trn giao din Uu.

Module nhn dng thu bao (USIM): l mt th thng minh cha thng tin nhn

dng ca thu bao, n thc hin cc thut ton xc thc, lu gi cc kha xc thc

v mt s thng tin thu bao cn thit cho u cui.

UTRAN (UMTS Terestrial Radio Acess Network)


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Mng truy nhp v tuyn c nhim v thc hin cc chc nng lin quan n truy

nhp v tuyn. UTRAN cng cha ng hai thnh phn:

Node B: thc hin chuyn i dng d liu gia cc giao din Iub v Uu. N cng

tham gia qun l ti nguyn v tuyn.

B iu khin mng v tuyn RNC: s hu v iu khin cc ti nguyn v tuyn

trong vng (cc nt B c kt ni vi n). RNC cn l im truy cp tt c cc

dch v do UTRAN cung cp cho mng li CN.

CN (Core Network)

HLR (Home Location Register): l thanh ghi nh v thng tr lu gi thng tin

chnh v l lch dch v ca ngi dng. Cc thng tin ny bao gm thng tin v

cc dch v c php, cc vng khng c chuyn mng v cc thng tin v

cc dch v b sung nh trng thi chuyn hng cuc gi, s ln chuyn hng

cuc gi.

MSC/VLR (Mobile Services Switching Center/Visitor Location Register): l tng

i (MSC) v c s d liu (VLR) cung cp cc dch v chuyn mch knh cho

UE ti v tr ca n. MSC c chc nng chuyn mch cc giao dch. VLR c chc

nng lu gi bn sao v l lch ngi dng cng nh v tr chnh xc ca UE trong

h thng ang phc vu.

GMSC (Gateway MSC): chuyn mch kt ni vi mng ngoi.

SGSN (Serving GPRS support node): c chc nng nh MSC/VLR nhng c

s dng cho cc dch v chuyn mch gi.

Cc mng ngoi

Mng CS: mng kt ni cho cc dch v chuyn mch knh.

Mng PS: mng kt ni cho cc dch v chuyn mch gi.

Cc giao din v tuyn

Giao din Cu: l giao din gia th thng minh USIM v ME. Giao din ny tun

theo mt khun dng chun cho cc th thng minh.

Giao din Uu: l giao din m qua UE truy cp cc phn t c nh ca h

thng v v th m n l giao din m quan trng nht ca UMTS.

Giao din Iu: giao din ny ni UTRAN vi CN, n cung cp cho cc nh khai

thc kh nng trang b UTRAN v CN t cc nh sn xut khc nhau.

Giao din Iur: cho php chuyn giao mm gia cc RNC t cc nh sn xut khc

nhau.

Giao din Iub: giao din cho php kt ni mt nt B vi mt RNC. Iub c tiu

chun ha nh l mt giao din m hon ton.


14

2.1.2. Kin trc UTRAN

Kin trc UTRAN c trnh by trong hnh 2.2. UTRAN cha mt hoc nhiu h thng

mng khng dy con RNS (Radio Network Sub). Mt RNS l mt mng con trong

UTRAN v cha mt RNC v mt hoc nhiu Node B. Cc RNC c th c kt ni vi

nhau thng qua giao din Iur. Cc RNC v Node B c kt ni vi mt giao din Iub.

Hnh 2.2 Kin trc UTRAN

a. Trm gc (Node B)

Trm gc l mt h thng truyn ng ring, l mt phn ca cell. N bao gm mt anten

h thng (c trng cho thp v tuyn), nh trm v thit b v tuyn trm gc. Thit b

v tuyn trm gc bao gm thit b RF (pht - thu, thit b giao tip anten), khi iu

khin v khi cp ngun. Nhng b thu pht trm gc c nhiu phn c bn nh thit b

di ng. Tuy nhin, sng v tuyn trm gc c kt hp bi BSC h thng WCDMA

v nhng khi chc nng nhiu hn ca mt thit b di ng.

Phn thu pht v tuyn c chia thnh my pht v my thu. My pht chuyn

tn hiu thoi hay d liu thnh sng v tuyn RF truyn n thit b di ng, my thu

thc hin ngc li, chuyn sng v tuyn RF thnh tn hiu thoi hay d liu c nh

tuyn n MSC hay mng chuyn mch gi. Phn iu khin ra lnh cho qu trnh chn

v tch thng tin bo hiu.

Khng ging nhng thit b khng dy ngi dng u cui (nh in thoi di

ng, laptop) phn iu khin, pht v thu ca mt im truy nhp c th c phn

nhm vo nhng rack cm thit b, v d: mt rack n c th cha tt c nhng khuch

i RF hay nhng card thoi. Khc vi nhng h thng t ong tng t hay h thng s

phin bn trc y dnh ring mt my thu pht trong mi trm gc cho mt knh iu

khin. H thng WCDMA kt hp c nhng knh iu khin v thoi trn chung trn

mt knh v tuyn vt l.

b. Khi iu khin mng v tuyn RNC

Khi iu khin mng v tuyn l mt khi phi hp t ng (iu khin) trong h thng

WCDMA cho php mt hay nhiu trm thu pht gc lin lc vi mt trung tm chuyn

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15

mch di ng hoc mt h thng thng tin d liu gi. RNC bao gm nhiu c trng

iu khin hn mt trm iu khin gc BSC thng thng.

2.1.3. Cc giao din v tuyn ca UTRAN

Cu trc UMTS khng nh ngha chi tit chc nng bn trong ca phn t mng m ch

nh ngha giao din gia cc phn t logic. Cu trc giao din trnh by trong hnh 2.3

c xy dng trn nguyn tc l cc lp v cc mt phng c lp logic vi nhau, iu

ny cho php thay i mt phn ca cu trc giao thc trong khi vn gi nguyn cc phn

cn li.

Hnh 2.3 M hnh tng qut cc giao din v tuyn ca UTRAN

a. Giao din UTRAN CN, Iu

Giao din Iu l mt giao din m c chc nng kt ni UTRAN vi CN. Iu c hai kiu:

Iu CS kt ni UTRAN vi CN chuyn mch knh v Iu PS kt ni UTRAN vi

CN chuyn mch gi.

Cu trc Iu CS

Iu CS s dng phng thc truyn ti ATM trn lp vt l l kt ni v tuyn, cp

quang hay cp ng. C th la chn cc cng ngh truyn dn khc nhau nh SONET,

STM-1 hay E1 hin thc lp vt l.

Ngn xp giao thc pha iu khin: gm RANAP trn nh giao din SS7 bng

rng v cc lp ng dng l phn iu khin kt ni bo hiu SCCP, phn truyn

Mt phng

ngi dng

mng truyn ti

Mt phng

ngi dng

mng truyn ti

Mt phng iu

khin mng

truyn ti

Mt phng iu khin Mt phng ngi dng


16

bn tin MTP3-b, v lp thch ng bo hiu ATM cho cc giao din mng SAAL-

NNI.

Ngn xp giao thc pha iu khin mng truyn ti: gm cc giao thc bo hiu

thit lp kt ni AAL2 (Q.2630) v lp thch ng Q.2150 nh cc giao thc

SS7 bng rng.

Ngn xp giao thc pha ngi dng: gm mt kt ni AAL2 c dnh trc

cho tng dch v CS.

Cu trc Iu PS

Phng thc truyn ti ATM c p dng cho c pha iu khin v pha ngi

dng.

Ngn xp giao thc pha iu khin: cha RANAP v vt mang bo hiu SS7.

Ngoi ra cng c th nh ngha vt mang bo hiu IP ngn xp ny. Vt mang

bo hiu trn c s IP gm M3UA (SS7 MTP3 User Adaption Layer), SCTP

(Simple Control Transmission Protocol), IP (Internet Protocol) v ALL5 chung

cho c hai ty chn.

Ngn xp giao thc pha iu khin mng truyn ti: pha iu khin mng truyn

ti khng p dng cho Iu PS. Cc phn t thng tin c s dng nh a ch

v nhn dng bo hiu ALL2 ging nh cc phn t thng tin c s dng trong

CS.

Ngn xp giao thc pha ngi dng Iu PS: lung d liu gi c ghp chung

ln mt hay nhiu AAL5 PVC (Permanent Virtual Connection). Phn ngi dng

GTP-U l lp ghp knh cung cp cc nhn dng cho tng lung d liu gi.

Cc lung d liu s dng truyn ti khng kt ni UDP v nh a ch IP.

b. Giao din RNC RNC, Iur

Iur l giao din v tuyn gia cc b iu khin mng v tuyn. Lc u giao din ny

c thit k h tr chuyn giao mm gia cc RNC, trong qu trnh pht trin tiu

chun nhiu tnh nng c b sung v n nay giao din Iur phi m bo 4 chc

nng sau:

H tr tnh di ng c s gia cc RNC.

H tr knh lu lng ring.

H tr knh lu lng chung.

H tr qun l ti nguyn v tuyn ton cu.

c. Giao din RNC Node B, Iub

Cc giao thc trong Iub nh ngha cu trc khung v cc th tc iu khin trong bng

tn cho tng kiu knh truyn ti. Cc chc nng chnh ca Iub:

Thit lp, b sung, gii phng v ti thit lp kt ni v tuyn cho mt UE v chn

im kt thc lu lng.

Khi to v bo co cc c th , Node B, kt ni v tuyn.


17

X l cc knh ring v knh chung.

X l kt hp chuyn giao.

Qun l s c kt ni v tuyn.

2.2. Cc gii php k thut trong WCDMA

2.2.1. M ha

a. M vng

M khi l b m ha chia dng thng tin thnh tng khi tin (message) c k bit. Mi tin

c biu din bng mt khi k thnh phn nh phn u = (u1,u2,,un), u c gi l vect

thng tin. C tng cng 2k vect thng tin khc nhau. B m ha s chuyn vect thng

tin u thnh mt b n thnh phn v = (v1,v2,,vn) c gi l t m. Nh vy ng vi 2k

vect thng tin s c 2k t m khc nhau. Tp hp 2k t m c chiu di n c gi l

mt m khi (n,k). T s R = k/n c gi l t s m, R chnh l s bit thng tin a vo

b gii m trn s bit c truyn. Do n bit ra ch ph thuc vo k bit thng tin vo, b

gii m khng cn nh v c th c thc hin bng mch logic t hp. M vng l mt

tp con ca m khi tuyn tnh.

M vng l phng php m ha cho php kim tra d vng (CRC Cyclic

Redundance Check) v ch th cht lng khung cc khung bn tin.

M ha m vng (n,k) dng h thng gm ba bc:

1) Nhn a thc thng tin u(x) vi xn-k.

2) Chia xn-k.u(x) cho a thc sinh g(x), ta c phn d b(x).

3) Hnh thnh t m b(x) + xn-k.

Tt c ba bc ny c thc hin bng mch chia vi thanh ghi dch (n-k) tng c hm

hi tip tng ng vi a thc sinh g(x).

Nguyn l hot ng:

Bc 1: Cng ng cho thng tin qua mch, k ch s thng tin u0,u1,,un-k c dch

vo mch t thit b u cui nhn trc u(x) vi xn-k. Ngay sau khi thng tin c

a vo mch th n-k ch s cn li trong thanh ghi l nhng con s kim tra chn l.

Bc 2: Ct t ng hi tip bng cch iu khin cho cc cng gi h (khng cho

thng tin qua).

Bc 3: Dch cc con s kim tra chn l v a ra ng truyn. Cc ch s kim tra

ny kt hp vi k ch s thng tin to thnh vect m.

S mch m ha vng:

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18

Hnh 2.4 Mch m ha vng vi a thc sinh g(x) = xn-k+gn-k-1xn-k-1++g2x2+g1x+1

b. M xon

M xon (Convolutional Code) (n,k,m) cng c n u ra, k u vo nh m khi (n,k)

nhng n u ra ca m xon ph thuc khng ch vo k u vo ti thi im m cn

ph thuc vo m khi bn tin trc . M xon (n,k,m) c xy dng bi mch tun

t. Mch ny dng thanh ghi dch m bit lm b nh, cc u ra ca cc phn t nh c

cng vi nhau theo quy lut nht nh to nn chui m, sau cc chui ny c

ghp xen vi nhau to nn chui m u ra.

c. M Turbo

M ha Turbo ch c s dng trong cc h thng thng tin di ng th h th ba khi

hot ng tc bit cao vi yu cu t s li bit BER nm trong khong 10-3 n 10-6.

B m ha Turbo thc cht l b m xon mc ni song song PCCC (Parallel

Concatenated Convolutional Code) vi cc b m ha thnh phn 8 trng thi.

2.2.2. iu ch BIT/SK v QPSK

a. iu ch BIT/SK

Trong mt h thng iu ch BIT/SK (BPSK Binary Phase Shift Keying) cp tn hiu

s1(t) v s2(t) c s dng biu din cc gi tr nh phn. Ta c

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19

() = 2

. cos[2 + () + ]

Trong :

: rng bng thng : nng lng ca mt bit (): gc pha thay i theo tn hiu iu ch, l gc pha ban u () = ( 1), 0 , = 1,2

Mt cp sng sin i pha 180o nh trn gi l mt cp tn hiu i cc.

Hnh 2.5 S nguyn l iu ch BPSK

Lung s tc bit c a qua b chuyn i v tn hiu NRZ (0 1,1 1), sau nhn vi sng mang c tn hiu iu ch BIT/SK.

Chn mt tn hiu l c s trc chun:

1() = 2

. cos(2)

Ta c:

() = . (). 1()

Khong cch gia hai tn hiu:

Hnh 2.6 Khong cch gia hai tn hiu BPSK

Xc sut li trong BPSK:

Lung s

nh phn

2

. cos(2)


20

=1

2 = (

20

)

Vi:

: nng lng ca bit 0: mt xc sut nhiu trng

b. iu ch QPSK

Tn hiu iu ch QPSK c dng:

() = {2

cos(2 + (2 1)

4 + ) , 0

0, < 0; >

Trong :

: nng lng ca mt bit : thi gian mt bit = 2: nng lng pht i trn mt k hiu = 2: thi gian ca mt k hiu : tn s sng mang, : gc pha ban u = 1,2,3,4

Bin i lng gic ta c phng trnh dng tng ng sau:

() = {

2

cos [(2 1)

4] cos(2 . ) , 0

0, < 0; >

Nu ta chn 1 v 2 l cc hm nng lng c s trc giao chun:

1() = 2

sin(2 . ) , 0

2() = 2

cos(2 . ) , 0

Ta c th biu din tn hiu iu ch QPSK bng bn im trong khng gian tn hiu vi

cc ta xc nh nh sau:

= {1 = sin [(2 1)

4]

2 = cos [(2 1)4]} , = 1,2,3,4


21

Quan h ca cp bit iu ch v ta ca cc im tn hiu iu ch QPSK trong khng

gian tn hiu th hin bng sau:

Cp bit vo

0 Pha ca tn hiu QPSK

im tn hiu

Ta cc im tn hiu

1 2 00 4 1 +/2 +/2 01 3

4 2 +/2 /2

11 54

3 /2 /2

10 74

4 /2 +/2

Xc sut li trong QPSK:

, = (20

)

Ta thy xc sut li ca BPSK v QPSK l nh nhau. Tuy nhin, vi QPSK th

hiu sut bng thng gp 2 ln BPSK. Bng thng ca QPSK xp x bng Rb.

2.3. Tri ph trong WCDMA

2.3.1. Gii thiu

Trong cc h thng thng tin vic s dng hiu qu bng tn l vn c quan tm

hng u. Cc h thng c thit k sao cho rng bng tn cng nh cng tt.

Trong WCDMA tng tc truyn d liu, phng php a truy cp kt hp

TDMA v FDMA trong GSM c thay th bng phng php a truy cp phn chia

theo m CDMA hot ng bng tn rng (5MHz) gi l h thng thng tin tri ph. i

vi cc h thng thng tin tri ph (SS: Spread Spectrum) rng bng tn ca tn hiu

c m rng trc khi c pht. Tuy rng bng tn tng ln rt nhiu nhng lc

ny nhiu ngi dng c th dng chung mt bng tn tri ph, do m h thng vn

s dng bng tn c hiu qu ng thi tn dng c cc u im ca tri ph. pha

thu, my thu s khi phc tn hiu gc bng cch nn ph ngc vi qu trnh tri ph

bn pht.

C ba phng php tri ph c bn:

Tri ph dy trc tip DSSS (Direct Sequence Spreading Spectrum): thc hin

tri ph bng cch nhn tn hiu ngun vi mt tn hiu gi ngu nhin c tc

chip cao hn rt nhiu so vi tc bit.

Tri ph nhy tn FHSS (Frequency Hopping Spreading Spectrum): h thng

FHSS thc hin tri ph bng cch nhy tn s mang trn mt tp cc tn s. Mu

nhy tn c dng m ngu nhin. Tn s trong khong thi gian mt chip TC c

c nh khng i. Tc nhy tn c th thc hin nhanh hoc chm, trong h

thng nhy tn nhanh nhy tn thc hin tc cao hn tc bit ca bn tin,

cn trong h thng nhy tn thp th ngc li.


22

Tri ph nhy thi gian THSS (Time Hopping Spreading Spectrum): thc hin

tri ph bng cch nn mt khi cc bit s liu v pht ngt qung trong mt hay

nhiu khe thi gian. Mu nhy tn thi gian s xc nh cc khe thi gian c s

dng truyn dn trong mi khung.

Trong h thng DSSS, tt c ngi dng cng dng chung mt bng tn v pht

tn hiu ca h ng thi. My thu s dng tn hiu gi ngu nhin chnh xc ly ra

tn hiu bng cch nn ph. Cc tn hiu khc xut hin dng nhiu ph rng, cng sut

thp ging tp m. Trong cc h thng FHSS v THSS mi ngi dng c n nh

mt m ngu nhin sao cho khng c cp my pht no dng chung tn s hoc khe thi

gian, nh vy cc my pht s trnh b xung t. Ni cch khc DSSS l kiu h thng

ly trung bnh, FHSS v THSS l kiu h thng trnh xung t. H thng thng tin di

ng cng ngh CDMA ch s dng DHSS nn ta ch xt k thut tri ph DSSS.

2.3.2. Nguyn l tri ph DSSS

Tri ph dy trc tip DSSS thc hin tri ph bng cch nhn tn hiu ngun vi mt

tn hiu gi ngu nhin c tc chip cao hn rt nhiu so vi tc bit.

Tc chip tn hiu gi ngu nhin v tc bit c tnh theo cng thc sau:

= 1

= 1

Trong :

: tc tn hiu gi ngu nhin : tc bit : thi gian mt chip : thi gian mt bit

: thi gian mt bit ca lung s cn pht : chu k ca m gi ngu nhin dng cho tri ph


23

: thi gian mt chip ca m tri ph

Hnh 2.7 Tri ph chui trc tip DSSS

2.3.3. M tri ph

Cc tn hiu tri ph bng rng c to ra bng cch s dng cc chui m gi tp m

PN (Pseudo Noise). M gi tp m cn c gi l m gi ngu nhin do c cc tnh cht

thng k ca tp m trng AWGN (Additive White Gaussian Noise) v c biu hin ngu

nhin, bt nh. Tuy nhin my thu cn bit m ny to bn sao mt cch chnh xc

v ng b vi m c pht gii m bn tin. V th m gi ngu nhin phi hon ton

xc nh.

M gi ngu nhin c to ra bng cc b thanh ghi dch c mch hi tip tuyn

tnh LFSR (Linear Feedback Shift Register) v cc cng XOR.

Hnh 2.8 Mch thanh ghi dch to chui PN

Mt chui thanh ghi dch hi tip tuyn tnh c xc nh bi mt a thc to m tuyn

tnh bc m (m > 0):

() = + 1

1 ++ 1 + 0 (vi = 0 = 1)

: n v tr

Gi s ta np chui gi tr khi u cho thanh ghi dch:

0 = {0(1), 0(2), , 0()}

Gi tr u ra trong (m - 1) xung ng h u tin l:

0 = 0()

1 = 0( 1)

(): l gi tr phn t nh j trong thanh ghi dch xung ng h i

= 0: kha m, = 1: kha ng n b iu ch


24

1 = 0(1)

Ti xung ng h th i (i > m 1) ta c trng thi ca thanh ghi dch:

() = 1( 1) = 2( 2) = = +1(1) (*)

+1(1) = 1. (1) + 2. (2) + + ()

() = 1. (1) + 2. (2) + + ()

p dng cng thc (*), ta c:

() = 1. 1() + 2. 2() + + ()

Gi tr u ra ti xung th i chnh l gi tr phn t nh () ca thanh ghi dch:

= 1. 1 + 2. 2 ++

Hay:

+ = 1. +1 + 2. +2 ++

Tc ca mch nh trn b hn ch v tc do tng thi gian tr trong cc

thanh ghi v cc cng loi tr ng hi tip. hn ch thi gian tr, nng cao tc

ca mch to m ngu nhin ta c th s dng s mch sau:

Hnh 2.9 Mch thanh ghi dch to chui PN tc cao

2.4. Truy nhp gi

2.4.1. Tng quan v truy nhp gi trong WCDMA

Truy nhp gi trong WCDMAcho php cc vt mang khng phi thi gian thc s dng

ng cc knh chung, ring v dng chung. Vic s dng cc knh khc nhau c iu

khin bi b lp biu gi PS (Packet Scheduler). B lp biu gi thng c t RNC

v ti y vic lp biu gi c th thc hin hiu qu cho nhiu , ngoi ra y cng

xem xt cc kt ni chuyn giao mm.

B lp biu gi c cc chc nng chnh sau:

Phn chia dung lng ca giao din v tuyn gia cc ngi dng.

(): l gi tr phn t nh trong thanh ghi dch xung ng h th

= 0: kha m, = 1: kha ng

n b

iu ch


25

Phn chia cc knh truyn ti s dng cho truyn dn s liu ca tng ngi

dng.

Gim st cc phn b gi v ti h thng.

2.4.2. Lu lng d liu gi

Truy nhp gi s dng cho cc dch v khng theo thi gian thc, nhn t quan im giao

din v tuyn n c cc thuc tnh in hnh sau:

D liu gi c dng cm, tc bit yu cu c th bin i rt nhanh.

D liu gi cho php tr ln hn cc dch v thi gian thc. V th d liu gi l

lu lng c th iu khin c xt theo quan im mng truy nhp v tuyn.

Cc gi c th c pht li bi lp iu khin kt ni v tuyn (RLC). iu ny

cho php s dng cht lng ng truyn v tuyn km hn v t l li khung

cao hn so vi cc dch v thi gian thc.

Lu lng gi c c trng bi cc thng s sau:

Qu trnh n ca phin.

S cuc gi n phin.

Thi gian c gia cc cuc gi.

S gi trong mt cuc gi gi.

Khong thi gian gia hai gi trong mt cuc gi gi.

Kch thc gi.

Hnh 2.10 c trng ca mt phin d liu gi


26

2.4.3. Cc phng php lp biu gi

Chc nng lp biu gi l phn chia dung lng giao din v tuyn kh dng gia cc

ngi dng. B lp biu gi c th quyt nh tc bit phn b v thi gian phn b.

Thut ton lp biu gi trong WCDMA c thc hin theo hai phng php: phn chia

theo m v phn chia theo tn s. Trong phng php phn chia theo m, khi c nhu cu

tng dung lng th tc bit phn b cho ngi dng s gim i. Trong phng php

phn chia theo thi gian biu dung lng c dnh cho mt s t ngi theo tng thi

im, nh vy ngi dng c th c tc bit cao nhng ch c th s dng trong thi

gian ngn. Trong trng hp s ngi dng tng th phi i truyn dn lu hn. Thc

t qu trnh lp biu gi l s kt hp ca hai phng php trn.

a. Lp biu phn chia theo thi gian

Khi b lp biu phn chia thi gian phn b cc tc gi, cn xt n hiu nng v

tuyn. Thng thng cc dch v tc bit cao i hi t nng lng bit hn, v th phn

chia theo thi gian c u im l t l thp hn. Ngoi ra thi gian tr trung bnh trong phng php ny l ngn hn so vi phng php phn chia theo m.

Nhc im chnh ca phng php phn chia thi gian l:

Thi gian truyn dn ngn trong khi vic thit lp v gii phng kt ni i hi

thi gian di thm ch n vi khung.

Vic s dng phn b theo thi gian b hn ch bi di tc cao do hn ch cng

sut ca MS ng ln.

Phng php ny s dng cc tc bit cao v to ra lu lng dng cm, iu

ny dn n s thay i ln cc mc nhiu so vi lp biu phn chia theo m.

b. Lp biu phn chia theo m

Trong lp biu phn chia theo m tt c ngi dng c n nh mt knh khi h cn

chng. Nu nhiu ngi dng gi yu cu lu lng th tc bit phi thp hn lp

biu theo thi gian.

Cc u im chnh ca phng php ny l:

Trong lp biu phn chia theo m, vic thit lp v gii phng s gy ra t tn tht

dung lng hn do tc bit thp v thi gian truyn dn lu hn. Do tc bit

thp vic phn b ti nguyn lp biu gi phn chia theo m i hi nhiu thi

gian hn lp biu gi phn chia theo thi gian. iu ny cho php d bo c

mc nhiu.

Lp biu phn chia theo m c th l tnh hoc ng. Trong lp biu tnh, tc

bit c phn b duy tr c nh trong sut thi gian kt ni. Trong lp biu ng,

tc bit c th thay i ph hp vi lu lng gi.

Phng php lp biu ny i hi cc kh nng ca MS thp hn.


27

III. TRIN KHAI MNG 3G WCDMA CA VIETTEL

3.1. S dch chuyn t GSM sang WCDMA

Vi th trng Vit Nam, cng ngh di ng u tin GSM, th h 2G n gin ch cho

php thoi l chnh. Vic nng cp ln cng ngh GPRS vo cui nm 2003 gip ngi

dng bt u lm quen vi nhng ng dng d liu. Cui nm 2007, sau khi ng dng

EGDE, tc c nng cao hn vi nh tc t khong 384kb/s. Nhng tc

thc t vn cn thp khin cc dch v da trn nn d liu khng th pht trin v bng

n mnh nh dch v thoi hin nay. Vi cng ngh WCDMA th h 3G vi tc

2Mbps v HSPA (HSDPA & HSUPA) th h 3.5G vi kh nng truyn ln n

14,4Mbps. y l cng ngh tin tin ang c ng dng rng ri trn th gii vi hn

200 triu thu bao, trn 220 mng thuc 94 quc gia, chim 2/3 thu bao 3G trn ton

cu (GSA, 6/2008).

Khi nng cp ln 3G, cng ngh WCDMA hot ng trn mt k thut truy cp

khc hon ton, l CDMA, do bng tn hot ng s phi tch bit vi GSM.

WCDMA mi knh c tn s l 5MHz, s cn mt di tn 3G mi khc vi tn s ang

hot ng hin nay. S i mi nh vy s cn mt thit b thu pht sng BTS hon ton

mi, c t tn l Node B, cng vi n l mt thit b qun l trm gc (BSC) mi,

tn l iu khin mng v tuyn RNC. Do tnh k tha khi nng cp, h thng mng li

hin hu vn c th c s dng kt ni vi mng v tuyn (Node B v RNC) ca

cng ngh WCDMA.

y, ngoi h thng v tuyn WCDMA (bao gm RNC v Node B) l cn u

t mi, tt c h thng khc s c tn dng li. Hu ht cc nh sn xut tng i hin

nay u c gii php nng cp h thng mng li, truyn dn, c s d liu, h thng

vn hnh,... hin hu h tr c GSM v WCDMA. Nh vy mun ph sng 3G u,

cc nh cung cp dch v s t thit b thu pht sng 3G khu vc v ni v tng i.

Hnh 3.1 Mng 3G UMTS k tha mng li 2G

TIENHighlight


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Tuy nm trn hai thit b khc nhau, s vn hnh ca hai h thng v tuyn GSM

v WCDMA cng s c qun l thng nht, m bo chuyn giao lin mch gia hai

h thng. Cuc gi s vn m bo duy tr khi chuyn bng tn v chuyn cng ngh,

iu ny s xy ra khi ngi dng di chuyn ngoi vng ph sng ca mt cng ngh

hoc b qu ti. Nh tnh lin mch ny, vic s dng bng thng s rt hiu qu c s

iu tit, phn b qua li gia cc cuc gi trn cc bng tn, tc s gim nghn mng,

cc thit b s c tn dng ti a dng chung ti nguyn cho c hai h thng, v vic

u t WCDMA khng cn phi ng lot ton mng.

Hnh 3.2 Kin trc cng tn ti song song hai h thng GSM v WCDMA

Hin nay Viettel trin khai WCDMA theo phng n dn u: u tin ph sng

WCDMA bt u t vng th ri lan ta dn ra, trong khi vn tip tc u t GSM

nng cao dung lng dch v thoi v dch v d liu tc thp GPRS. Cc l do

chn chin lc ny: kh nng pht trin ca GSM v GPRS vn cn cao, cht lng v

dung lng ca GSM v GPRS c vn cn phi u t ci thin phc v khch

hng 2G, mng GSM v s thu bao qu ln, in thoi 2G vn cn nhiu, th trng d

liu di ng ch mi pht trin. Cc thit b u cui a ch GSM/GPRS/WCDMA v


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vy cng s c gii thiu, tip th dn dn, ph thuc vo nhu cu v kh nng ca

khch hng.

3.2. Node B ca Viettel

Viettel trin khai v lp t cc thit b truy nhp v truyn cung cp cc dch v

3G tt nht cho ngi s dng. Vi cu trc Node B nh sau:

Hnh 3.3 Kin trc Node B

c im chnh ca BTS 3900 l:

Cc loi truyn dn E1/T1, FE (cng in v cng quang).

Topo mng: sao, ni tip, cy, vng hoc lai.

Cc ngun ng b: ng b qua giao din Iub, GPS v ng h ni.

Cc loi chuyn giao: chuyn giao mm, chuyn giao mm hn v chuyn giao

cng.

Cc dch v: dch v CS, dch v PS v cc dch v tng hp.

Thc hin cc chc nng: RET, HSDPA, HSUPA.

3.3. Mt s dch v 3G Viettel cung cp

Vi u th tc vt tri ca cng ngh HSDPA 3.5G, dch v 3G Vettel gip ngi

dng tn hng s thoi mi m thoi Video Call, lt web, nghe nhc, chi game

online,... v nhiu dch v tin ch khc nhau nh:

Dch v MobileTV


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Dch v MobileTV cho php ngi dng 3G tip cn cc phng tin gii tr cht

lng cao nh xem cc knh truyn hnh trc tip (liveTV), cc b phim hay cc video

clip theo yu cu (VOD) mi lc mi ni ch vi chic in thoi ha mng 3G. Khch

hng c th s dng dch v thng qua hai phng thc l qua trang WAP ca dch v

hay qua ng dng Client c ci t trc tip trn in thoi.

Cc tnh nng c bn ca dch v bao gm:

Xem cc knh truyn hnh c sc trong nc v nc ngoi.

Xem video theo yu cu vi ni dung phong ph thuc cc lnh vc khc nhau

nh ca nhc, thi s, hi hc, phim,...

Xem lch pht sng ca cc knh trong h thng.

Qun l knh yu thch.

ng k/Hy ng k dch v, cc knh c sc nng cao.

Dch v Mobile Internet

Dch v Mobile Internet 3G l dch v truy nhp Internet trc tip t my in

thoi di ng c s dng SIMCard Viettel;

u im ca dch v Mobile Internet l hot ng trn mng 3G v vy tc truy

cp gp 6 ln so vi EDGE v 8 ln so vi GPRS.

Dch v Vmail

Vmail l dch v gi v nhn email trn in thoi di ng di hnh thc "y

email v ng dng trn in thoi di ng". Thng qua ng truyn data ca mng

Viettel, mi khi c email mi gi n a ch th in t ( ng k nhn v gi), h

thng Vmail s t ng thc hin y trc tip email xung ng dng Vmail c

ci t trn my in thoi di ng.

Cc tnh nng c bn ca Vmail:

Nhn v gi mail qua ng dng thng qua hnh thc Push mail.

Chc nng xem trc vi hu ht cc nh dng file c bn (gif, bmp, doc...).

Nhn file nh km vi dung lng ti a 500 KB, gi file nh km c dung

lng ti a 200KB.

H tr nhiu email khc nhau bao gm: Yahoo, Hotmail, Gmail, local ISP...

H tr hu ht cc my ch email c POP3/IMAP.

H tr hu ht cc mail server c POP3/IMAP.

Dch v Mstore

Mstore l mt kho ng dng dnh cho in thoi di ng c cung cp bi

Viettel. Khch hng c th truy cp vo trang web/wap www.mstore.vn hoc

www.mstore.com.vn t my tnh hoc in thoi di ng xem, ti v gi tng cc ng

dng.

Dch v Imuzik 3G


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Imuzik 3G l dch v m nhc xy dng trn nn tng 3G gip khch hng c th

nghe nhc, xem video clip, ti nguyn bi ht v in thoi (download fulltrack), ti cc

on nhc ch hoc c cc tin tc m nhc trong nc v quc t ngay trn in thoi

di ng ca mnh.

Dch v Game Online

L dch v cung cp game dnh cho in thoi di ng, cho php khch hng

Viettel c th tng tc trc tip vi My ch ni dung (Server) hoc nhiu ngi chi

khc thng qua kt ni 3G (t cht lng ti u) hoc EDGE/GPRS.

Dch v Video Call

Video Call l dch v thoi c hnh cho php cc thu bao khi ang m thoi c

th thy hnh nh trc tip ca nhau thng qua camera ca my in thoi di ng.

Dch v Mobile Broadband

Dch v gip khch hng c th truy nhp Internet bng thng rng t my tnh

thng qua thit b USB HSPA/HSDPA c gn sim 3G Viettel. Khi s dng dch v ny,

thu bao c th truy cp Internet vi tc cao qua sng di ng 3G.


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KT LUN

Trc s bng n v nhu cu truyn thng khng dy c v s lng, cht lng v cc

loi hnh dch v, h thng thng tin di ng th h th ba s dng cng ngh WCDMA

c trin khai rng khp p ng nhu cu ca ngi dng. Tuy nhin trong tng

lai, khi m cng ngh 3G khng p ng c yu cu th cng ngh thng tin di ng

th h th t l gii php tip theo vi tc ln ti 34Mbps. im mu cht trong thng

tin di ng th h th t l thay i phng php a truy cp kinh in bng cc phng

php a truy cp cho hiu sut cao hn nh phng php a truy cp phn chia theo tn

s trc giao (OFDMA), a truy cp phn chia theo c hi (ODMA).

B3G: Broad Band 3G: 3G bng rng

WLAN: Wirless Local Area Network: mng LAN khng dy

BWA: Broad Band Wirless Access: truy nhp khng dy bng rng

Vin cnh thng tin di ng 4G theo kh nng h tr tc chuyn ng v tc

truyn s liu

Vi cc th h di ng tip theo, cht lng dch v cho ngi dng di chuyn vi tc

cao vn c m bo. Vic nng cp cc h thng thng tin di ng l tt yu. Tuy

nhin l mt qu trnh k tha t cc h thng c sn nhm m bo tnh lin tc

v hiu qu kinh t.


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TI LIU THAM KHO

[1] Nguyn Phm Anh Dng, Cng ngh 3G WCDMA UMTS, 2009. [2] Trng Vn Ho, Cng ngh WCDMA v gii php nng cp mng GSM

ln WCDMA, 2007.

[3] Nguyn Vn Su, Tng quan h thng thng tin di ng 3G cng ngh WCDMA v trin khai mng 3G WCDMA ca Viettel, 2010.

[4] Harri Holma, Antti Toskala, WCDMA FOR UMTS HSPA EVOLUTION AND LTE, 5th, 2010.

[5] Reiner Stuhlfauth, UMTS Long Term Evolution (LTE) technology intro + evolution measurement aspects, 2011.

Documents

Tieu Luan 15 - WCDMA