thong tin di dong the he 3 CDMA2000

7/30/2019 thong tin di dong the he 3 CDMA2000

1/94

:http://www.docs.vn :[email protected] (: 0918.775.368

I HC QUC GIA TP.HCM

TRNG H KHTN

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

BO CO TI

H THNG TRUYN THNG

ti: H thng

thng tin di ng th h 3 CDMA2000.

Hc k I

Nm hc 2008-2009
http://www.docs.vn/http://www.docs.vn/mailto:[email protected]:[email protected]://www.docs.vn/mailto:[email protected]


2/94

H thng thng tin di ng th h 3 CDMA2000

A.Phn cng cng vic

I. Yu cu t ra

Tm hiu, gii thiu v h thng thng tin di ng.

Tm hiu cu trc h thng thng tin di ng.

Tm hiu v CDMA2000.

II. Qu trnh thc hin

Trong qu trnh thc hin ti, nhm thc hin lm quen, tm

hiu v nm bt c khi nim v cc thut ng chuyn ngnh h thng

truyn thng.

Nhm cng i su vo tm hiu lch s pht trin ca mng

thng tin di ng cng nh mt s kin trc ca mng thng tin di ng.

Tm hiu su vo kin trc h thng CDMA2000 cng nh cch

thc hot ng ca mng CDMA2000.

Bng phn cng cng vic

Cng vic Ngi thc hin

Tm hiu lch s pht trin, cu trc h thngthng tin di ng.

Tt c cc thnh vin trongnhm

Thc hin phn cu trc Layer. Nguyn Kim Long

Thc hin phn chuyn giao. Nguyn Vn Lim

Thc hin phn hot ng thu pht tn hiu. Thi Hong Hu Ngh

Thc hin phn iu khin cng sut. Nguyn Thnh Phng

Thc hin phn hng pht trin. Hunh Vn Tng

B.Tm hiu v CDMA2000

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I. Tng quan v qu trnh pht trin ca h thng thng tin di

ng

1. Cng ngh tng t OG v 1G

C hai th h trong cc cng ngh di ng c coi l tng t. Cccng ngh ny c gi l 0G v 1G. 1G l cng ngh di ng t ong

(cellular) u tin, cn 0G l cng ngh di ng tin t ong (pre cellular).

Cc thit b u cui s dng trong 0G kh c th gi l thit b di ng. Cc

mu m u tin rt ln v thng c gn vo xe t. Sau , cc thit b

cm tay ra i, nhng 0G b thay th bi th h k tip, 1G.

Kha cnh ch yu phn bit gia 0G v 1G l cng ngh 1G s dngmng t ong (cellullar network). Mt mng t ong l mt mng to nn bi

mt s cc cell. Mi cell ny c phc v bi mt my pht c nh,

thng gi l trm gc. Trn thc t, cng c mt vi v d v vic s dng

mng t ong trong 0G, nhng iu lm nn s khc bit gia 1G v 0G l

1G h tr vic kt ni lin mch khi di chuyn t cell ny sang cell khc.

iu ny c ngha l, khi ngi dng ra khi tm hot ng ca mt trm

gc trong khi ang thc hin cuc gi, nu s dng cng ngh 0G th ngi

dng s b ngt kt ni, trong khi s dng cng ngh 1G ngi dng s

khng nhn thy s ngt qung no. Mt kha cnh khc phn bit 0G v 1G

l cc cng ngh 0G thng l bn song cng (c ngha l vic thu v pht

m thanh khng xy ra ng thi).

Vo nhng nm 1970, cc mng s dng cng ngh 0G b qu ti

nghim trng. Mt chun tng t khc c gii thiu, l 1G. Gingnh 0G, 1G s dng bng tn v tuyn UHF. Vic truyn m thanh c

thc hin m khng c s m ha trn giao din v tuyn. iu ny c ngha

l bt c ai c mt my qut n gin cng c th nghe c cc cuc in

m. Cc c gng ca nh chc trch nhm ngn chn vic xm nhp bt

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hp php ny u khng gii quyt c vn . Bn cnh vic bo v thng

tin c nhn, nhc im ny ca h thng cn a n mt vn khc. Bi

v d liu truyn c gi i m khng m ha, cc k thut bo mt cn

th s d dng l ra cho cc hacker.Hu ht cc cng ngh 1G ch c mt dng bo mt, mt th tc nhn

thc ht sc th s. Th tc ny bao gm vic xc nhn hai s: s nhn dng

di ng MIN v s thu bao in t ESN. Qu trnh xc nhn ny din ra khi

mt thit b di ng bt u lin lc vi h thng. u tin, s en (blacklist)

s c kim tra xem thit b di ng ny c b kha hay khng. Tip theo,

mt bn tin c gi ti HLR thng qua s kt hp ca MIN v ESN. C

hai s ny c truyn khng m ha qua giao din v tuyn. Hacker c th

nghe trm v c th s dng cc s ny to ra cc bn sao bt hp php

m vi chng, cc hacker c th nhn thc thnh cng di dng mt thu

bao khc. Vn cng tr nn trm trng khi nhiu nh cung cp thm ch

khng thc hin vic nhn thc trn cc my di ng do vic thiu ht s

chun ha v cc l do v hiu sut. iu ny gy nn vic s dng tri php

v cng ln trong cc mng di ng.

2. Cng ngh s 2G v 3G

2G ( second generation )

Mc nh du quan trng trong qu trnh pht trin ca cc cng ngh

di ng l s ra i ca x l tn hiu s DSP. Nh c DSP, cht lng thoi

c ci tin ng k v thng tin s khng b nh hng bi mo. Thm

vo , di ph c th c s dng mt cch hiu qu hn hn nh c cc

k thut hp knh. Bi v cc k thut tng t s dng FDMA, ch c mt

ngi dng c th s dng mt tn s xc nh ti bt k thi gian no trong

mt cell. Vi cng ngh 2G, vn ny c gii quyt bng cch s dng

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TDMA v CDMA. Cc k thut ny cho php nhiu ngi dng chia s

cng mt tn s.

Cu trc bo mt cng c nhng bc ci tin ng k. C hai chun

chnh trong 2G: GSM v cdmaOne. C hai chun ny u s dng k thuti hi p ng (challenge response) nhn din ngi dng. Khi thc

hin cuc gi, thit b di ng cn tnh ton mt p ng cho i hi (di

dng mt s ngu nhin) c gi bi mng. p ng ny c tnh ton s

dng mt kha b mt duy nht c lu trn thit b di ng . p ng

ny sau c th c xc nhn bi mng, v n cng lu tr kha b mt

trng vi kha lu ti thit b di ng ca ngi dng. Kha ny sau c

th s dng thit lp vic m ha trn ng truyn qua giao din v

tuyn.

Nhn li nhng vn i vi th h tng t, c th kt lun rng t

nht v mt l thuyt nhng vn ny c gii quyt. Vic truyn dn

c m ha bo v thng tin c nhn ngi dng v s tin cy, mt

phng php nhn thc tt hn c s dng. Trn thc t, li c mt s

vn ny sinh. u tin, cc chun ny c th tin cy c, v mt mt

no , da trn s kh hiu ca cc thut ton ca n. Theo thi gian, b

mt v cc thut ton ny r r, c th d dng chng minh rng cc thut

ton ny tr nn yu t. Th hai, cc chun ny c nhiu khuyt im v

mt giao thc c th s dng nhn thc bt hp php mt my di ng

lu. Mt nhc im na l vic thiu ht trong bo v s ton vn. Khi mt

thit b di ng c nhn thc, nhng khng phi trong mng, mt trmgc gi c th s dng nhn vic nhn thc d liu t mt thu bao

khng r ngun gc.

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3G ( third generation )

Thng tin di ng th h hai mc d s dng cng ngh s nhng v l

h thng bng hp v c xy dng da trn c ch chuyn mch knh nn

khng p ng c nhu cu ca cc dch v mi, thm vo l c qunhiu tiu chun khc nhau, lm cho vic di chuyn ca thu bao gia cc

quc gia ny vi cc quc gia khc gp nhiu kh khn. Chnh v l m

cc t chc vin thng trn th gii thy cn thit phi tp hp li v ra

phng n phi c mt tiu chun thng nht chung cc h thng vin

thng di ng tng lai va p ng c cc yu cu ca thi i mi, va

mang tnh thng nht chung cho cc h thng. Kt qu l IMT 2000 do

ITU R xy dng ra i nhm p ng cc yu cu . IMT 2000 m

rng ng k kh nng cung cp dch v v cho php nhiu phng tin

thng tin c th cng hot ng, t cc phng tin truyn thng cho n

cc phng tin hin i v cc phng tin truyn thng c trong tng

lai. Vo nm 1999, ITU thng qua nm giao din v tuyn s dng IMT

2000. l cc giao din:

IMT DS (Direct Spead) Tri ph trc tip: cn c bit n

vi tn WCDMA hay UTRA FDD v c s dng trong UMTS.

IMT MC (Multi Carrier) a sng mang: cn c gi l

CDMA2000.

IMT TD (Time Division) Phn chia theo thi gian: bao gm

TD CDMA v TD SCDMA, c hai u c chun ha s dng trong

UMTS. IMT SC (Single Carrier) n sng mang: cn c gi l

UWC 136 hoc EDGE.

IMT FT (Frequency Time): cn c gi l DECT.

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Trong nm giao din ny, IMT DS (hay UMTS) v IMT MC (hay

CDMA2000) c coi l hai chun chnh. UMTS c pht trin chu u

v l th h sau ca GSM. CDMA2000 l th h sau ca cdmaOne v c

pht trin M.

Hnh 1: Qu trnh pht trin t cng ngh 2G ln 3G.

II.Tng quan v mng thng tin di ng 3G

1. Gii thiu

3G l thut ng dng ch cc h thng thng tin di ng th h th3 (Third Generation).

3G (third generation technology) l tiu chun truyn thng di ng

bng thng rng th h th 3 tun th theo cc ch nh trong IMT-2000 ca

ITU (T chc vin thng th gii). Chun 3G cho php truyn khng dy d

liu thoi v phi thoi (gi email, hnh nh, video...).

2. Mt s yu cu ca mng thng tin di ng 3G

H thng thng tin di ng ba xy dng trn tiu chun IMT-2000.

Vi cc tiu chun sau:

S dng di tn quy nh Quc T:

ng ln : 1885 2025 MHZ .

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ng xung :2110 2200 MHZ .

L h thng thng tin di ng ton cu cho cc loi hnh thng tin

v tuyn.

Tch hp cc mng thng tin v tuyn v hu tuyn .

Tng tc vi mi loi dch v vin thng .

S dng c trong cc mi trng khc nhau :

Cng s , ngoi ng , v tinh ..

C th h tr c cc dch v khc:

Mi trng o .

m bo cc dch v a phng tin .

D dng h tr cc dch v mi ra .

III. L trnh pht trin ln CDMA2000 t CDMAONE

1. Cc giai on pht trin

Mt trong nhng mc ch ca chun 3G l tng cng s pht trin

ca h thng 2G hin ti, tn dng ti a c s h tng hin c. CDMA2000

l h thng 3G pht trin t h thng CDMA hin ti Bc M l cdmaOne.Chun c quy nh cho CDMA2000 bao gm 2 giai on: 1xRTT v

3xRTT. 1xRTT c coi l giai on I ca CDMA2000 3G v 3xRTT l

giai on II ca CDMA2000 3G.

Giai on th nht c nh ngha l chun c tn 1xRTT. c

hon tt vo thng 7 nm 1999, giai on ny ca CDMA2000 mang tn l

chun TIA theo IS-2000 v mang tn l chun MC-1X theo ITU. 1xRTTcung cp gp i dung lng thoi v thi gian ch so vi IS-95, v cho

php tc d liu ln ti 384 Kbps (theo l thuyt). N hot ng knh

1.25 MHz.

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Giai on th hai ca CDMA2000 l 3xRTT kt hp cht ch cc

kh nng ca 1xRTT, c tc d liu ln ti 2Mbps (theo l thuyt), h tr

tt c cc loi knh (5 MHz, 10 MHz, vv...).

2. 1xEV: 1xEV DO v 1xEV DV1xEV l bc pht trin k tip ca 1x. N da trn cng ngh tc

d liu cao Qualcomm HDR. Cc xu hng dn n s ra i ca 1xEV l:

Trong trnh t pht trin ca CDMA2000 1x, kh nng d liu tc

cao h tr cc dch v da trn nn Internet hin ti v trong tng

lai s tr nn ht sc quan trng.

Di ph s tr thnh mt ti nguyn khan him, lm cho h thng

1.25 MHz tr nn hp dn hn nhiu so vi h thng 5 MHz (3x), ch cn

t c hiu sut tng ng. Nhng nh khai thc v ngi dng s

c li t nhng h thng ny thng qua:

Tc cao v dung lng cao ca h thng truyn dn d liu gi.

Hiu qu s dng di ph cao hn cho chuyn mch gi.

Thoi vi hiu qu s dng di ph cao hn.

S nng cp v linh hot ca h thng CDMA2000 1x tt hn

nhiu so vi h thng 3x trong vic pht trin ln t h thng 2G hin ti.

H thng CDMA2000 1x ti thiu ha tc ng trn cc thit b

trong vng t bo v cc thit b cm tay trong vic cung cp cc dch v d

liu gi tc cao.

t c cc yu cu ca nh khai thc CDMA2000 trong vic

trin khai cc dch v d liu gi tc cao trong sng mang 1.25 MHz,

1xEV s c nh ngha trong hai giai on:

Giai on 1: Ti u ha h thng cho cc dch v d liu gi tc

cao, khng thi gian thc.Dch v d liu gi tc cao hot ng trn

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mt sng mang. Nu thu bao cn thoi hoc cc dch v thi gian thc

khc, h thng 1xEV s s dng CDMA2000 1x thc thi dch v . Mc

ch l nhm lm cho hot ng d hiu i vi ngi dng.

Giai on 2: H thng ng thi h tr d liu gi tc cao vdch v thi gian thc.

Trong cch tip cn tch hp, mc ch l tch hp kh nng ca

giai on mt trn cng mt sng mang, trong khi vn cn kh nng duy tr

dch v d liu gi trn mt sng mang ring bit.

1xEV DO

1xEV-DO l mt chun trong h cc tiu chun v tuyn caCDMA2000 1x. EV-DO l vit tt ca EVolution, Data-Only" (gn y

c sa thnh Evolution, Data Optimized). 1xEV-DO cung cp tc d

liu nhanh gp 10 ln so vi 1xRTT, cng ngh d liu trc ca mng

CDMA. Khng ging nh cc chun 1x khc, 1xEV-DO ch dnh cho d

liu, khng dng cho thoi. N yu cu mt khong ph dnh ring, tch

bit vi mng thoi s dng cc chun nh 1xRTT.

C hai phin bn ca 1xEV-DO: "Release 0" v "Revision A".

Release 0 l phin bn nguyn thy, v l phin bn c trin

khai rng ri u tin. Release 0 cung cp tc d liu ln ti 2.4 Mbps,

trung bnh l 300-600 kbps trong thc t. Tc ny nhanh hn rt nhiu so

vi tc 50-80 kbps cung cp bi 1xRTT. Tc d liu ca Release 0

tng ng vi tc d liu ca 1xEV-DV Revision C.

Revision A tch hp hu ht cng ngh d liu t 1xEV-DV

Revision D, v ci thin ngm ngm. Nhng nng cao ny cho php cc tnh

nng nh VoIP v thoi video.

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Mc d EV-DO v nguyn bn khng c kh nng thoi, Revision A

nhanh cung cp cng ngh VoIP ti mc dch v bng hoc tt hn

so vi cng ngh thoi 1xRTT. y c th l con ng pht trin ca

CDMA nu s pht trin ca 1xEV-DV vn b ngng tr. 1xEV-DO cda trn cng ngh d liu tc cao HDR hoc d liu gi tc cao

HRPD, pht trin bi Qualcomm. Chun quc t gi l IS-856.

1xEV DV

1xEV-DV l mt chun trong h cc tiu chun v tuyn ca

CDMA2000 1x. EV-DV l vit tt ca Evolution, Data and Voice. 1xEV-

DV kt hp c cng ngh tc cao HDR t 1xEV-DO vi chun 1xRTTc trin khai rng ri. N tch hp lin mch vi 1xRTT, cung cp kh

nng tng thch vi cc h thng c v ng thi c thoi v d liu.

C hai phin bn ca 1xEV-DV: "Revision C" v "Revision D"

Revision C cung cp tc d liu cao ch cho chiu xui, c

ngha l tc download s nhanh hn. Chiu ngc ging nh chun

1xRTT.

Revision D cung cp tc d liu cao cho c hai chiu, l tng

cho cc ng dng nh hi thoi video v ti ln cc file dung lng ln.

Revision D cng tch hp vic nhn dng thit b di ng MEID.S pht

trin 1xEV-DV ang b chng li, b cn tr bi 1xEV-DO Revision A v

cng ngh VoIP.

IV. Cng ngh CDMA2000

1. Gii thiu v mng thng tin di ng CDMA2000

Mt trong 2 chun 3G quan trng l CDMA2000, l th h k tip ca

cc chun 2G CDMA v IS-95. Cc xut ca CDMA2000 nm bn ngoi

khun kh GSM ti M, Nht Bn v Hn Quc. CDMA2000 c qun l

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bi 3GPP2, l t chc c lp vi 3GPP. C nhiu cng ngh truyn thng

khc nhau c s dng trong CDMA2000 bao gm 1xRTT, CDMA2000-

1xEV-DO v 1xEV-DV.

CDMA 2000 cung cp tc d liu t 144 kbit/s ti trn 3 Mbit/s.Chun ny c chp nhn bi ITU.

2. Tnh nng

1.2 Loi lu lng

CDMA2000, cng nh cc cng ngh 3G khc, h tr cc loi lu

lng sau ( tc d liu t 9.6 kbps n 2 Mbps).

Thoi truyn thng v VoIP.

Cc dch v d liu.

D liu gi: Cc dch v ny da trn nn IP vi giao thc TCP

hoc UDP ti lp giao vn. Nm trong loi ny l cc ng dng Internet, cc

dch v a phng tin loi H.323 vv...

D liu bng rng m phng knh (circuit-emulated broadband

data): v d nh fax, truy cp dial-up khng ng b, cc dch v a phng

tin loi H.321 ni m audio, video, d liu, iu khin v ch th c

truyn trn m phng knh qua ATM...

SMS ( Short Messaging Service).

Dch v bo hiu.

H thng 3G c d kin cho cc mi trng trong nh v ngoi

tri, cc ng dng b hnh hoc trn xe c, v cc mi trng c nh nh

tng i ni ht v tuyn (wireless local loop). Kch c t bo t vi chcmt (nh hn 50 m i vi picocell) ti vi chc km (hn 35 km cho cc t

bo c ln).

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rng bngH thng CDMA2000 c th hot ng cc rng bng khc

nhau vi mt hoc nhiu sng mang. Trong h thng a sng mang, cc

sng mang cnh nhau phi cch nhau t nht 1.25 MHz. Trong h thng asng mang thc s, mi sng mang thng c rng bng 1.25 MHz v

c phn bit vi sng mang IS-95 bng m trc giao. Tuy nhin, khi ba

sng mang c s dng trong h thng a sng mang, bng thng yu cu

l 5 MHz. cung cp cc dch v d liu tc cao, mt knh n c th

c rng bng danh nh l 5 MHz vi tc chip 3.6864 Mcps ( = 3 x

1.22887 Mc/s). Bng thng BW trong hnh 4, ngoi mt cng sut c th

b qua, ty thuc vo b lc to dng ti bng gc. Nu b lc cosine tng

c s dng, BW = Rc(1 + ), trong Rc l tc chip v l tha s ct

ln (rolloff factor). Nu = 0.25, BW = 4.6 MHz, v do di bo v G =

200 kHz. R rng, mt li th ca bng thng rng hn l n cung cp nhiu

ng hn c th s dng trong b thu a ng tng cng hot

ng ca h thng.

Hnh 2: rng bng trong CDMA2000.

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Cht lng dch v QoS ( quality of service )Bt c lc no, a ng dng cng c th chy trn mt trm di ng

MS. Ngi dng c th yu cu cht lng dch v ty theo ng dng, v

mng c mong i l s m bo cht lng yu cu m khng c s stgim ng k trong QoS quy c vi khch hng.

Cc dch v d liu giCDMA2000 h tr cc dch v d liu gi. T lc khi u, nu c

mt gi gi, ngi dng c gng thit lp cc knh iu khin dng

chung v dng ring s dng phng thc a truy cp phn khe Aloha.

Trong phng thc ny, mt xung nhp tham chiu c s dng to ramt dy cc khe thi gian c di bng nhau. Khi ngi dng c mt gi

cn gi, n c th bt u truyn, nhng ch ti lc bt u ca mt khe thi

gian ch khng phi ti khong thi gian bt k lc no. Lu rng mc d

ngi dng c ng b ha nh xung nhp tham chiu, c mt vi xc

sut rng c th c hai ngi dng hoc nhiu hn c th bt u truyn ti

cng mt thi im. Khi cc knh ny c thit lp, ngi dng c th gi

cc gi tin thng qua knh iu khin dng ring, v c th yu cu mt

knh lu lng hoc mt rng bng thch hp. Mt khi knh lu lng

c cp, ngi dng truyn gi tin, vic bo tr s ng b ha v iu

khin cng sut l cn thit, v vic gii phng knh lu lng ngay sau khi

truyn xong hoc sau mt khong thi gian nht nh. Nu khng cn gi

no gi, knh iu khin dng ring cng c gii phng sau mt

khong thi gian, nhng kt ni lp mng v lp lin kt vn c duy trtrong mt khong thi gian nu c gi mi n th vn s c truyn m

khng b mt thi gian thit lp knh. Ti cui khong thi gian , cc gi

ngn v khng thng xuyn s c gi qua mt knh iu khin dng

chung. Ngi dng c th ngt kt ni ti thi im , hoc tip tc trong

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trng thi v hn, hoc ti thit lp knh iu khin dng ring v knh

lu lng nu c cc gi ln hoc thng xuyn cn gi.

3. Kin trc mng thng tin di ng CDMA2000

Hnh 3: Kin trc c bn ca mng CDMA2000.

1.3 Cc thnh phn ca h thng

Trm di ng MS( Mobile Station): l thit b cho ngi s dngtruy cp vo mng. MS c th l in thoi cm tay, my tnh

Trm thu pht gc BTS( Base Transceiver Station): chu trch

nhim cp pht cc ti nguyn cho cc thu bao. BTS cha cc thit b thu

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pht v tuyn, n l giao din gia mng CDMA2000 v thit b ca ngi

s dng UE (User Equipment).

B iu khin trm gc BSC( Base Station Controller): c nhim

v iu khin cc BTS gn vi n v nh tuyn cc gi n v i t PSDN.Ngoi ra, BSC cn lm nhim v iu khin/qun l chuyn giao.

Trung tm chuyn mch di ng MSC(Mobile Switching Centre):

thc hin vai tr ca chuyn mch trung tm, thit lp v nh tuyn cuc

gi, thu thp thng tin tnh cc, qun l di ng, gi cuc gi ti

PSTN/Internet.

B ghi nh v thng tr HLR (Home Location Register): l c s

d liu lu thng tin v thu bao.

B ghi nh v vng lai VLR (Visitor Location Register): l c s

d liu lu thng tin thu bao ang hot ng trn mt MSC nht nh.

Trung tm nhn thc AC (Authentication Centre): xc nhn thu

bao trc khi cho php cung cp dch v cho thu bao .

IWF (Interworking Function): cho php cc dch v d liu chuyn

mch knh.

Nt dch v d liu gi PDSN (Packet Data Service Node): ch c

mng 3G, cung cp cc dch v d liu chuyn mch gi.

Trung tm nhn thc, trao quyn v thanh ton AAA

(Authentication, Authorization, and Accounting): l mt server cung cp cc

dch v nhn thc, trao quyn v thanh ton cho PSDN, ln lt chuyn cc

dch v kt ni vi mng d liu gi cho ngi dng di ng.

Cc giao thc s dngTrong cu trc mng CDMA2000 trn, c cc giao din gia cc

thnh phn mng c thm vo cung cp cc dch v d liu chuyn

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mch gi. Vic nh ngha cc giao din ny thng c quy nh bi cc

chun. Mt s chun quan trng l:

IS-2000: Cc chun ny quy nh giao din khng trung gia MS

v BSC trong mng CDMA2000. IS-2001: y l phin bn 3G ca IOS (InterOperability

Specification), l chun nh ngha giao din gia BSC v PDSN. N cng

nh ngha giao din gia BSC v MSC, cng nh giao din gia cc BSC

vi nhau nhm qun l di ng.

IS-41: Chun ny, s dng mng 2G, cng vn c s dng

mng 3G. N nh ngha giao din gia MSC, HLR, VLR, v AC, cng

nh giao din gia cc MSC vi nhau.

1.4 Simple internet protocol ( Simple IP )

Simple IP l 1 giao thc truyn nhn gi d liu n gin.

Hnh 4: Mt gi d liu c trao i gia MS v server.

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Nu mt MS c a ch IP l M,v server c a ch IP l S th d liu

c trao i gia MS v server.Khi i t MS n server,gi d liu c a

ch ngun l M v a ch ch l S.V ngc li,khi i t server n MS,gi

d liu c a ch ngun l S,a ch ch l M.Nhc im:Khi MS di chuyn sang mt PSDN khc th c xy ra s

chuyn giao (handoff) gia cc BSC hoc gia cc MSC nhng kt ni s b

ngt.

Mobile internet protocol ( Mobile IP )

y l mt giao thc truyn nhn d liu ng.

Chc nng:Duy tr kt ni khi MS di chuyn t PSDN ny sang mtPSDN khc.

Hnh 5: Gi d liu c gi v nhn khi MS di chuyn.

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Xut hin thm 2 thnh phn mi l home agent (HA) v foreign

agent (FA):

Home agent (HA):Xc nh PSDN m MS di chuyn ti v gi

nhng gi d liu n foreign agent. Foreign agent (FA):Nhn cc gi d liu t MSHA v gi cho

MS ti thi im hin ti.

Khi MS di chuyn t home PSDN n foreign PSDN,gi d liu do

MS gi vn n c server v gi d liu ny mang a ch n l S.Ngc

li,khi server gi xung MS th server vn ly a ch l M.Do gi d liu

c gi ti HA,v HA c nhim v gi ti FA.Cui cng FA s gi cho

MS.

Mobile IP c thm 2 chc nng mi l :

MSregistration with the FA :Khi mt MS di chuyn ti 1 PSDN

khc th MS phi ng k vi FA.Foreign agent s to ra mt a ch tm

thi T.

FAregistration with the HA :Sau khi FA to ra a ch T,FA cn

ng k a ch ny ti MSHA.

T m bo HA gi gi d liu ng cho MS.

4. Cc lp chnh trong CDMA2000

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Hnh 6: Cc lp chnh trong mng CDMA2000.

Lp vt l1.4.2 Gii thiu

Lp vt l chu trch nhim pht v thu cc bit thng qua phng tin

vt l. V phng tin vt l trong trng hp ny l khng trung, nn lp

vt l phi chuyn i bit sang dng sng (iu ch) cho php truyn qua

khng trung. Bn cnh vic iu ch, lp vt l cn thc hin cc chc nngm ha thc hin cc chc nng iu khin li ti mc bit v mc khung.

1.4.3 Knh xui

Cc knh xui trong CDMA2000 chia lm knh bo hiu v knh

ngi dng.Knh bo hiu mang thng tin iu khin.Knh ngi dng

mang d liu.

Knh xui trong CDMA2000

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Knh

bo

hiu

Knh

dng

chung

F-PCH (Paging Channel)

F-QPCH (Quick Paging Channel)

F-CCCH (Forward Common Control Channel)

F-BCCH (Broadcast Control Channel)F-CACH (Common Assignment Channel)

F-CPCCH (Common Power Control Channel)

F-SYNCH (Sync Channel)

F-PICH (Forward Hoa tiu Channel)

F-TDPICH (Transmit Diversity Hoa tiu Channel)

F-APICH (Auxiliary Hoa tiu Channel)F-ATDPICH (Auxiliary Transmit Diversity Hoa tiu

Channel)Knh

chuyn

dng

F-DCCH (Forward Dedicated Control Channel)

Knh ngi dng

F-FCH (Forward Fundamental Channel)

F-SCH (Forward Supplemental Channel)F-SCCH (Forward Supplemental Code Channel)

1.4.4 Knh ngc

Cc knh ngc trong CDMA2000 chia lm knh bo hiu v knh

ngi dng.

Knh ngc trong CDMA2000

Knh

bo hiu

Knh dng chung R-ACH (Access Channel)

R-EACH (Enhanced Access Channel)R-CCCH (Reverse Common Control Channel)

Knh chuyn dng R-PICH (Reverse Hoa tiu Channel)

R-DCCH (Reverse Dedicated Control Channel)R-FCH (Reverse Fundamental Channel)

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Knh ngi dng R-SCH (Reverse Supplemental Channel)

R-SCCH (Reverse Supplemental Code Channel)1.4.5 Chc nng truyn dn ca knh xui

Hnh sau minh ha s n gin ca cc chc nng truyn dn caknh xui ca h thng CDMA2000 n sng mang tri ph trc tip.

n gin, ch c mt s knh xui vt l c a ra trong hnh.

CDMA2000 c hai loi knh lu lng knh c bn v knh ph. Mt s

tc d liu c h tr. Ty thuc vo tc d liu, m xon vi tc

1/2, 3/8, 1/3, hoc 1/4 c th c s dng. C hai loi khung 10 ms v 5 ms

u c h tr. Cc biu tng ca knh I v knh Q c nhn vi cc h

s tch ly (gain factor) cung cp thm mt s iu khin cng sut. Cng

nh trong IS-95, cc t bo c phn tch bi cc lch (offset) ca cc

dy PN khc nhau (chu k ca cc dy PN ny l 215 1 chip). Tuy nhin,

gi y, cc phng php tri ph phc c s dng bng cch, u tin,

thm cc gi tr thc ca dy I v Q trong php cu phng (quadrature)

kt qu tr thnh s phc v sau nhn n vi mt s phc khc S I +jSQ,

trong SI v SQ ln lt l cc PN hoa tiu ca knh I v knh Q. Kt quca php nhn ny l mt i lng phc c cc thnh phn ng pha v

vung pha c biu din gc di ca hnh v.

Vi vic tri ph phc, li ra ca b lc to dng s bng 0 ch vi

xc sut thp, do ci thin hiu qu cng sut.

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Hnh 7: S truyn dn ca knh xui trong CDMA2000.

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1.4.6 Chc nng truyn dn ca knh ngc

Hnh 8: S truyn dn ca knh ngc trong CDMA2000.

S khi chc nng ca knh ngc ca h thng CDMA2000 tri

ph trc tip c biu din trn hnh 6. Trc tin hy xem xt knh c

bn. D liu n trong knh ny c x l theo cch thng thng. Ty

thuc vo tc d liu ngi dng, mt s bit ch th cht lng khung

di dng CRC c thm vo khung. Mt vi bit ui c thm vo

m bo vic hot ng chun xc ca b m ha knh, c th l b m ha

m xon hoc m khi. Biu tng m c lp li, nhng ty thuc vo tc

, mt vi biu tng b xa. Li ra ca b ghp xen (interleaver) c tri

ph vi m Walsh, nh x ti cc biu tng iu ch, v nhn vi cc h stch ly (gain factor), kt qu l bo hiu c gn nhn Afund. Knh ph 1 v

2 v cc knh iu khin c x l cng theo cch , mc d chi tit c

th khc bit trong mt s trng hp. V d nh, s b i cc biu tng

khng c thc hin trn knh iu khin dnh ring. Tng t, knh hoa

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tiu ngc R-PICH, c cc chui bit 0 (c gi tr thc l +1), c x l

khc bi v n khng c m ha thnh m knh, ghp xen theo ghp xen

khi, hoc nhn bi m Walsh. Tuy nhin, mt bit iu khin cng sut

c thm vo knh hoa tiu cho mi nhm iu khin cng sut hoc 16 bitiu khin cng sut trn mt khung. n gin, b qua s lp li ny v

ch yu quan tm n li ra sau khi x l ca cc knh ny l A sub1, Asub2,

Acont, and Ahoa tiu. Knh c bn v knh ph 1 c hp li to ra li ra Q.

Tng t, cc knh cn li c tp hp ring bit, cho li ra I. Ch rng

trong trng hp ny, cc dy knh I v Q to nn bi m ha QPSK l c

lp vi nhau bi v n c to ra t cc knh khc nhau v khng phi bi

vic chia dng d liu ca mt knh thnh hai dng ph. Cc chui I v Q

c tri ph bi m phc di dng SI + jSQ, trong SI v SQ l do ngi

dng nh ngha bi v n c ly t m mt n 42-bit gn cho mi ngi

dng, cc dy PN hoa tiu knh I v knh Q, v m Walsh.

Medium Access Layer ( MAC )

1.4.7 Gii thiu

L giao din gia lp vt l, lp ph LAC v lp trn cng (upper

layer).Lp MAC iu khin vic truy cp ca cc lp cao hn vo mi

trng vt l c chia s bi nhiu ngi s dng.

1.4.8 Phn loi cc thc th chnh

Gm 4 thc th chnh:

Common channel multiplexing sublayer:Lp con hp nht

knh dng chung.

Dedicated channel multiplexing sublayer:Lp con hp nht

knh chuyn dng.

Signaling radio burst protocol (SRBP).

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Radio link protocol (RLP).

1.4.9 Chc nng lp MAC

Hp nht cc knh logic v pha cc knh vt l.

Gii hp nht cc knh vt l thnh cc knh logic. X l cc gi d liu.

X l vic bo hiu trn knh chung.

1.4.10 Data Units

L 1 i lng logic ca thng tin bo hiu v d liu c trao i

gia cc khi chc nng lp MAC, vi lp LAC hay lp Upper.

C 2 loi l:

Payload data unit (PDU) c dng nh r nhng data units

c chp nhn ni cung cp t ni yu cu gi n.

Service data unit (SDU) c dng nh r nhng data units t

ni cung cp gi n ni yu cu.

1.4.11 Primitives

Primitive l mt dng truyn tin gia lp chnh v lp con.Trong

cha thng tin truyn ti v thng tin iu khin.

Hai dng primitive c s dung nhiu nht l:

Request primitives c gi t dch v yu cu n dch v cung

cp.Mt thit b yu cu dng request primitive yu cu s phc v hay

mt ti nguyn.

Indication primitives c gi t dch v cung cp n dch v yu

cu thng bo thng tin m dch v yu cu c thc hin.Mt primitive c th c vit di dng:

Layer/sublayer-Primitive_name.Primitive_Types (Parameters).

Trong :

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Layer/sublayer l tn ca dch v cung cp,ch c th l PHY

(physical layer) hoc MAC (MAC sublayer).

Primitive_name l tn ring bit ca knh.

Primitive_Types l dng primitive nh request hay indication.

Parameters l thng s c mang theo primitive nh kch thc

ca d liu.

V d: Khi lp ph MAC yu cu lp PHY truyn d liu trn knh F-

CCCH,lp ph MAC gi 1 prequest primitive n lp PHY:

PHY-FCCCH.Request (sdu,,num_bits).

1.4.12 Lp con hp nhtBao gm knh chung v knh chuyn dng c nhim v sp xp gia

cc knh vt l v cc knh logic.

S sp xp gia knh vt l v knh logic knh xui.

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Knh logic Knh vt lK hiu Tn K hiu Tnf-csch

f-dsch

f-dtch

Forward

common

signaling

channel

Forward

dedicaded

signaling

channel

Forward

dedicaded traffic

channel

F-SYNCH

F-PCH

F-CCCH

F-BCCH

F-CPCCH

F-CACH

F-DCCH

F-FCH

F-DCCH

F-FCH

F-SCH

Sync channel

Paging channel

Forward

common

control

channel

Broadcast

control

channel

Common

power control

channelCommon

assignment

channel

Forward

dedicated

controlchannel

Forward

fundamental

channel

Forward

dedicated

control

channel

Forward

fundamental

channel

Forward

supplemental

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S sp xp gia knh vt l v knh logic knh ngc.

Knh logic Knh vt lK hiu Tn K hiu Tnr-csch

r-dsch

r-dtch

Reverse

common

signaling

channel

Reverse

dedicaded

signaling

channel

Reverse

dedicaded traffic

channel

R-ACH

R-EACH

R-CCCH

R-DCCH

R-FCH

R-DCCH

R-FCH

R-SCH

Access channel

Enhanced

access channel

Reverse

common

control channelReverse

dedicated

control channel

Reverse

fundamental

channel

Reverse

dedicated

control channel

Reverse

fundamental

channel

Reverse

supplemental

channel

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Khi truyn, lp con MAC s tp hp cc khi d liu thnh cc SDU

v gi xung cho lp vt l truyn i.

Khi nhn, lp con MAC s nhn cc SDU, phn chia thnh cc khi

d liu,v gi ln cc lp cao hn.

Hnh 9: minh ha ng vo v ng ra ca multiflex sublayers.Qu trnh hp cc khi d liu thnh SDU.

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Hnh 10: qu trnh hp khi d liu.

1.4.13 Radio Link Protocol

Chc nng:

Phn pht v nhn cc gi d liu ca ngi dng.

iu khin cch thc di chuyn cc gi d liu trn knh chuyndng.

Pht hin li v thng bo vic truyn li nu d liu nhn b li.

Cc c ch pht hin li:

Positive acknowledgement (ACK) :Nu nhn gi d liu khng c

li th pha nhn s gi tn hiu ACK n pha truyn xc nhn vic nhn

thnh cng.

Negative acknowledgement (NAK): Nu nhn gi d liu c li th

pha nhn s gi tn hiu NAK n pha truyn xc nhn vic nhn cha

thnh cng.

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Retransmission:C nhim v bo cho pha nhn phi truyn li khi

nhn c tn hiu NAK.

Vic phn pht v nhn cc gi d liu c m bo nh cc c ch

ny.

Hnh 11: S phn pht gi d liu.

Qu trnh truyn ngc li gia pha truyn v pha nhn.

Trong :

a1,a2,.a15;b1,b2,,b14 l cc thi im truyn v nhn.

SEQ l cc chui d liu. v d ny SEQ gm 2 bit.

D l khong thi gian delay.

C 4 gi d liu c truyn i vo cc thi im a1,a2,a3,a4.Ti thi

im b1,b2,b3,b4 nhn gi d liu tng ng SEQ 0,SEQ 1,SEQ 2,SEQ

3,SEQ 4.Nhng ti thi im b2 gi d liu b li,khng nhn c.Do

pha nhn gi tn hiu bo li NAK 0 vo thi im b3 v pha truyn yu

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cu gi li.Pha truyn phi i 1 khang thi gian delay D sau mi

truyn tip.

Trong mng CDMA, RPL dng t 8 n 12 bit truyn d liu nn tc

truyn ln ti 2Mbit/s.1.4.14 Signaling radio burst protocol ( SRBP )

iu khin vic x l cc tn hiu bo hiu trn knh bo hiu chung.

Gm c cc knh:F-SYNCH,F-PCH,F-CACH,F-CCCH,F-BCCH,R-

ACH,R-EACH,R-CCCH.

Chc nng:

Tnh ton v pht ra cc thng s cn thit cho vic truyn v nhn

cc tn hiu bo hiu.

Hp cc SDU cho lp vt l truyn i trn cc knh vt l.

Cho php nhn cc SDU t lp vt l gi n lp con LAC.

Hnh 12: cch x l trn knh F-CCCH ti trm gc.

Link Access Control ( Lp LAC )1.4.15 Gii thiu

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L giao thc kt ni d liu,m bo vic phn pht d liu gia lp

upper v lp con MAC mc chnh xc cao nht.

1.4.16 Phn loi lp con trong LAC

Gm c 5 lp con: Authentication sublayer : Lp con xc nhn.

Addressing sublayer : Lp con nh a ch.

Automatic repeat request (ARQ) sublayer : Lp con t ng lp lai

yu cu.

Utility sublayer : Lp con tiu chun ha.

Segmentation and reassembly (SAR) sublayer : Lp con phn chia

v hp li.

Hnh 13: cc lp con trong LAC.

Authentication and addressing sublayer

Xc nhn my di ng ang truy cp vo h thng.

X l thng tin a ch ca my di ng nh s nhn din (Mobile

Identified Number). S xc nhn ch cn thit khi my di ng ln u tin truy cp vo

h thng dng knh bo hiu chung.Sau ,my di ng dng knh chuyn

dng.

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S nh a ch ch cn thit khi my di ng lin lc vi knh bo

hiu chung.

ARQ sublayer

C cc c ch pht hin li,v truyn li khi d liu b li.Do mbo vic phn pht d liu xy ra 1 cch chnh xc nht.

nh r 2 dng phn pht d liu ti lp upper:

Assured delivery:Lp LAC lp li vic gi d liu ti nhng

khong thi gian c nh n khi nhn c tn hiu ACK t pha nhn.Nu

s ln truyn li vt qua s ln truyn nh trc th lp LAC s hy b

vic truyn thm na. Unassured delivery:Lp LAC truyn d liu nhng pha nhn

khng gi li tn hiu ACK.Do lp LAC phi truyn d liu nhiu

ln.pha nhn s pht hin v gi li nhng d liu ging nhau.

Segmentation and Reassembly sublayer (SAR)

Khi truyn, SAR phn chia cc PDU thnh nhng on m lp MAC

c th truyn i.ng thi tnh ra cc bit kim tra chu k d tha (CRC) v

gn vo cc PDU.

Khi nhn,SAR s hp cc on nhn c t lp MAC thnh cc

PDU v gi n cc lp con cao hn.Ngoi ra,SAR kim tra cc bit (CRC)

xc nhn d liu nhn c l ng.

1.4.17 X l cc lp con

1.4.17.1 Bo hiu chung knh xui

Qu trnh ny xy ra trm gc v trm di ng.

Khi trm gc (Base Station-BS) truyn d liu bo hiu chung n

trm di ng (Mobile station-MS) th cc lp con ca LAC s thc hin cc

bc x l nh hnh v.Ch c 4 lp con ca LAC lin quan bi v

authentication sublayer c BS dng xc thc cc my di ng.

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Hnh 14: Qu trnh bo hiu chung knh xui BS.

u tin, upper layer gi n v ti d liu xung cho ARQ, ARQ s

thm vo cc trng xc nhn thch hp nht,v lp con addressing s thm

cc bit nh a ch thch hp nht (a ch ca my di ng). Tip n, mt

phn ca LAC PDU c chuyn ti lp con utility hp nht cc LAC

PDU v thm vo cc chc nng c lin quan. Sau khi nhn cc n v d

liu, lp con SAR tnh ra m CRC v nh km vo n v d liu. Khi dung

lng trn knh vt l sn sng, n s bo hiu cho SAR v SAR s

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truyn cc on PDU xung lp MAC. D liu bo hiu chung knh xui

c truyn trn knh logic f-csch.

Khi MS nhn tn hiu t BS, qu trnh ny xy ra ngc li nh hnh

v sau.

Hnh 15: Qu trnh bo hiu chung knh xui MS.

1.4.17.2 Bo hiu chung knh ngc

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Khi my di ng truyn tn hiu trn knh bo hiu chung n BS th

xy ra cc bc x l nh hnh v sau.Trong tt c cc lp con ca lp

LAC u c s dng.

Hnh 16 :Bo hiu chung knh ngc MS.

My di ng s dng lp con authentication gi m nhn dng

(MIN) n BS. u tin, upper layer gi n v ti d liu (PDU) xung cho

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lp con authentication.Ti y,PDU c thm vo m xc minh. Sau

chuyn xung lp con ARQ,ARQ s thm vo cc trng xc nhn thch

hp nht,v lp con addressing s thm cc bit nh a ch thch hp nht

(a ch ca my di ng). Tip n, mt phn ca LAC PDU c chuynti lp con utility hp nht cc LAC PDU v thm vo cc chc nng c

lin quan.Sau khi nhn cc n v d liu, lp con SAR tnh ra m CRC v

nh km vo n v d liu. Khi dung lng trn knh vt l sn sng,n

s bo hiu cho SAR v SAR s truyn cc on PDU xung lp MAC.D

liu bo hiu chung knh ngc c truyn trn knh logic r-csch.

Khi BS nhn tn hiu t my di ng, qu trnh ny xy ra ngc li

nh hnh v sau.

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Hnh 17 :Bo hiu chung knh ngc BS.

1.4.17.3 Bo hiu chuyn dng knh xui

Hnh v sau minh ha vic x l khi BS truyn d liu bo hiu

chuyn dng n my di ng. Trong trng hp ny ch lin quan n

ARQ,utility,SAR.Cc lp authentication v addressing khng hot ng v

mi my di ng khi nhn d liu trn knh chuyn dng c sn m nhndin (m Walsh), v my di ng khng cn phi xc nhn BS.

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Hnh 18 :Bo hiu chuyn dng knh xui BS.Ti BS, upper layer gi n v ti d liu (PDU) xung cho lp con

ARQ,ARQ s thm vo cc trng xc nhn thch hp nht. Tip n, mt

phn ca LAC PDU c chuyn ti lp con utility hp nht cc LAC

PDU v thm vo cc chc nng c lin quan. Sau khi nhn cc n v d

liu,lp con SAR tnh ra m CRC v nh km vo n v d liu. Khi dung

lng trn knh vt l sn sng, n s bo hiu cho SAR v SAR s

truyn cc on PDU xung lp MAC. D liu bo hiu chuyn dng

knh xui c truyn trn knh logic f-dsch.

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Hnh 19 :Bo hiu chuyn dng knh xui MS.

Hnh sau minh ha vic x l khi my di ng nhn d liu bo hiu

chuyn dng t BS.Ti y,vic x l c thc hin ngc li.

1.4.17.4 Bo hiu chuyn dng knh ngc

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Hnh 20 :Bo hiu chuyn dng knh ngc MS.

Lp con LAC x l tn hiu bo hiu chuyn dng hng ngc

tng t nh knh xui, ch khc ch tn hiu bo hiu chuyn dngtruyn i trn knh r-dsch.

Hnh 21: Bo hiu chuyn dng knh ngc BS.

1.4.18 S tng tc gia lp chnh v lp ph

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Cc primitive c s dng truyn n v d liu v tn hiu iu

khin gia cc lp vi nhau.n v d liu c truyn l mt trong nhng

thng s ca primitive.

1.4.18.1 Khi truyn:

Hnh 22:S tng tc ca cc primitive khi truyn d liu.

Cc primitive c s dng:

L2-Data.Request:c dng khi layer 3 mun gi 1 PDU xung

lp con LAC.

MAC-SDUReady.Request:thng bo cho lp MAC bit vic

truyn PDU sn sng.

MAC-Availability.Indicator:thng bo cho lp LAC bit khong

trng trn knh vt l c sn cho vic truyn.

MAC-Data.Request:thng bo cho lp MAC nhn d liu.

1.4.18.2 Khi nhn:

Cc primitive c s dng:

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MAC-Data.Indication:c dng khi MAC gi cc on PDU

cho SAR,thng bo cho LAC bit d liu c nhn ti MAC v ang

truyn n LAC.

L2-Data.Request:c dng khi LAC gi PDU n layer 3,thngbo cho Upper layer nhn d liu c x l ti LAC.

Hnh 23:S tng tc ca cc primitive khi truyn d liu.

1.5 Upper layer ( Lp trn cng )

1.5.1 Khi bo hiu ( Signaling entity )

Khi bo hiu l khi iu khin hot ng ca h thng

CDMA2000,thi hnh nhng chc nng thit lp,duy tr v kt thc 1 cuc

gi.

Hot ng ca khi bo hiu c th chia thnh 2 kha cnh l trng

thi v chc nng.

1.5.1.1 V mt trang thi v trng thi chuyn

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Khi bo hiu s thc hin vic vo ra cc trng thi chnh v ph

x l 1 cuc gi.

Gm c 4 trng thi l:

Trng thi ban u ca MS (mobile station initialization state).

Trng thi ngh ca MS(mobile station idle).

Truy cp h thng(system access state).

MS iu khin trn knh lu thng(mobile station controls on the

traffic channel).

1.5.1.2 V mt chc nng:

Khi bo hiu iu khin v thc hin nhng nng cn thit cho 1cuc gi.

Nhng chc nng gm c vic ng k,chuyn giao,iu khin cng

sut.

1.5.2 X l cuc gi

Khi bt u gi,my di ng i vo trng thi ban u. trng thi

ban u,my di ng s chn v thu c 1 h thng. Sau khi thu c 1 h

thng my di ng s i vo trng thi ngh,ch nhn c 1 trong 3 s kin

xy ra. l tn hiu trn knh f-csch hay tn hiu khi pht 1 cuc gi hay

tn hiu thc hin vic ng k trn knh r-csch. Nu nhn c mt trong 3

tn hiu trn th my di ng s truy cp vo h thng. Ti y, my di ng

gi tn hiu trn knh r-csch v nhn tn hiu trn knh f-csch. Nu vic pht

ra 1 cuc gi thnh cng th BS s cung cp 1 knh lu thng cho my di

ng. trng thi ny, my di ng s lin lc vi BS thng qua knh lu

thng ny.

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Hnh 24: Cc trng thi xy ra ti my di ng khi thc hin 1 cuc

gi.

Nu my di ng khng th i vo trng thi k tip,n s tr li trng

thi trc hoc kt thc cuc gi.

1.5.2.1 Trng thi ban u

My di ng phi i qua ln lt 4 trng thi con sau thu c 1 h

thng:

Xc nh h thng:my di ng phi chn la mt h thng trong

mt nhm t bo ca mng t ong.

Thu nhn trn knh hoa tiu:my di ng thc hin vic gii iu

ch v ginh c 1 knh hoa tiu xui ca h thng.Vic ny phi cthc hin trong 1 khong thi gian quy nh (15 giy).Nu thnh cng,my

di ng s i vo trng thi con tip theo.Nu khng thc hin c th my

di ng phi quay li trng thi con pha trn.

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Thu nhn trn knh ng b:my di ng phi thu c 1 knh

ng b v tn hiu ng b knh (sync channel message) nh pilot

PN,system time,long code state.Nhng tn hiu ny cho php my di ng

ginh c knh bo hiu chung nh paging channel,forward commoncontrol channel,.Vic nhn tn hiu ng b knh ch xy ra trong 1 giy

i vo trang thi con k tip.Nu khng,my phi tr li trng thi con

trc .

iu chnh ng lc (timing change):my di ng s ng b ha

s iu chnh v m PN ca chnh n vi nhng m khc trong h thng.

1.5.2.2 Trng thi nghMy di ng phi gim st tn hiu gi i trn cc knh paging

channel (F-PCH), quick paging channel (F-QPCH), F-CCCH, F-BCCH.

Gim st trn knh F-PCH

My di ng phi gim st 2 loi tn hiu. l tn hiu c trng

cho tng my di ng v tn hiu lan truyn cho tt c my di ng.

C 2 phng thc gim st l nonslotted v slotted. phng thc

nonslotted,my di ng phi gim st knh F-PCH ti mi thi im.

phng thc slotted,my di ng ch gim st knh F-PCH ti nhng slot

c n nh sn.

Gim st trn knh F-QPCH

Phng thc gim st slotted c im bt li. Khi BS mun gi 1

tn hiu n MS th khng th gi i ngay m phi i ng slot c n

nh sn. Do , MS khng th nhn tn hiu tc th.

Knh F-QPCH c thm vo ci thin im bt li trn.My

di ng ch cn gim st nhng bit cho bit th t trang nn tn t thi gian.

Gim st trn knh F-CCCH v F-BCCH

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Knh F-CCCH c dng truyn cc tn hiu ring bit cho

tng my di ng. Knh F-BCCH c dng truyn tn hiu lan truyn

ca h thng cho ton b my di ng. Ti 2 knh ny, my di ng s dng

2 phng thc gim st l slotted v non slotted.1.5.2.3 Trng thi truy cp h thng

My di ng gi v nhn tn hiu t BS.Nu ch nhn c tn hiu

trn knh F-PCH,th my di ng s gi tn hiu trn knh truy cp.Nu ch

nhn c tn hiu trn knh F-CCCH v knh F-BCCH,th my di ng s

gi tn hiu trn knh truy cp m rng.

Gm c 7 trng thi ph:

Trng thi cp nht thng tin pha trn (Update overhead

information substate).

Trng thi p ng trang (Page respone substate).

Trng thi hon thin vic to ra 1 cuc gi (Mobile station

origination attempt substate).

Trng thi ng k truy cp (Registration access substate).

Trng thi p ng tn hiu theo th t(Mobile station

order/message response substate).

Trng thi truyn tn hiu(Mobile station message transmission

substate).

Trng thi u tin vic truy cp v hy b cc knh c n nh

(Priority access and channel assignment cancel substate).

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Hnh 25:S chuyn giao gia cc trng thi ph trong trng thi truy

cp h thng.

1.5.2.4 Trng thi MS iu khin trn knh lu thng

trng thi ny,mobile trao i thng tin vi BS thng qua knh xui

v knh ngc. Bao gm 3 trng thi ph:

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Trng thi ban u ca knh lu thng: My di ng kim tra vic

nhn knh xui chnh xc hay khng v bt u truyn tn hiu trn knh

ngc.

Trng thi knh lu thng:My di ng tin hnh trao i thng tinngi dng,tn hiu bo hiu vi BS.Thc hin cc chc nng nh gim st

trn knh lu thng,iu khin cng sut,chuyn giao.

Trng thi phng thch:My di ng kt thc cuc gi v tr li

trng thi ban u.

1.5.3 Truyn gi d liu

C ba phng thc truyn gi d liu l phng thc tch cc (ActiveMode), phng thc iu khin s nm gi (Control Hold Mode),v phng

thc ng (Dormant Mode).

Phng thc tch cc

Gi d liu v tn hiu bo hiu chuyn dng c trao i 1 cch

linh hot gia MS v BS.V d khi knh hoa tiu ngc cha c m th

d liu c th truyn i thng qua knh ph.

Phng thc iu khin s nm gi

Gi d liu ca ngi dng khng c trao i gia MS v BS v

knh hoa tiu c ng li chng nhiu nhng knh iu khin chuyn

dng hot ng. H thng duy tr s iu khin lp MAC, iu khin cng

sut,v lu nhng thng s ca cuc gi gi d liu k tip c truyn

ngay lp tc.

Phng thc ng

Khng xy ra s trao i d liu hay tn hiu bo hiu gia MS v

BS.D liu c gi li v cc giao thc tng ng c duy tr.

1.5.4 Thit lp knh

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Khi my di ng nhn 1 cuc gi t BS.

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Khi my di ng thc hin 1 cuc gi.

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Khi my di ng gi gi d liu.

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truyn d liu vi tc cao,BS hay MS s gi tn hiu yu cu

knh b sung.

Khi BS gi tn hiu yu cu knh b sung.

Khi MS gi tn hiu yu cu knh b sung

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5. Hot ng ca h thng thng tin di ng CDMA2000

a truy cp ( Multiple Access )1.5.5 Khi nim

Khi nim a truy cp dng ch s lng ngi c php chia s

chung mt knh truyn. Hai cch truy cp truyn thng l a truy cp theo

tn s ( FDMA) v a truy cp theo khe thi gian ( TDMA).

1.5.6 FDMA ( Frequency Division Multiple Access )

Trong cch truy cp theo tn s, di tn s chia theo khe. Mi ngi

s dng c cp mt khe tn s. S dng FDMA i hi h thng s dng

b lc tt.

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Knh xung.

Knh ln

Hnh 26:M hnh phn chia cc khe tn s.

1.5.7 TDMA ( Time Division Multiple Access )

Trong a truy cp theo thi gian, di tn s khng b chia ra nhng

ngi s dng c cho php s dng di tn s ny trong khong thi gianc cho trc, ti mt thi im, hay ni cch khc l ngi s dng gn

vi mt khe thi gian nht nh. Do TDMA i hi tnh ng b ca

nhng ngi dng.

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Hnh 27: M hnh phn chia cc khe thi gian.

1.5.8 CDMA ( Code Division Mutiple Access )

CDMA( code division multiple access). Phng php a truy cp theo

m ny khc vi 2 cch truyn thng l khng cp tn s hay khe thi giankhi s dng m cp c hai cho ngi s dng mt cch tc thi. s dng

phng php ny ngi ta s dng phng php tri ph (spread spectrum).

Trong trng hp ny, ngi s dng c cp mt on m duy nht c

tc xung clock ln hn rt nhiu so vi tc d liu. Chui PN ny iu

ch d liu ngi dng v kt qu iu ch pha ti ni nhn. Ch nhng my

thu c on m PN ging nhau mi thu c d liu.

Th tc thu v pht tn hiu theo m hnh CDMATn hiu s liu thoi pha pht c m ha, lp, chn v c nhn

vi sng mang c tn s fo v m PN.

Tn hiu c iu ch i qua mt b lc bng thng c rng

bng 1.25Mhz sau pht ra qua sng anten.

u thu sng mang v m PN ca tn hiu thu c t anten c

a n b tng quan qua b lc bng thng rng v s liu thoi c

tch ra ti to nh s dng b tch chn v gii m.

Tri ph1.5.9 Khi nim

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Thng tin tri ph l mt h thng thng tin truyn i cc tn hiu

nh tri ph ca cc tn hiu s liu thng tin c s dng m vi rng

bng ln hn rng bng ca tn hiu thng tin ( cha nhn vi m). Cc

m c lp vi cc tn hiu thng tin, gi tr cc m l -1 v 1 c th tito li ti u thu.

Hnh 28: M hnh nhn ngun tn hiu.

X(t) : d liu.

C(t) : tn hiu tri ph.

M(t) : tn hiu thng tin c truyn i.

Hnh 29: S tn hiu trong qu trnh tri ph.

Hnh v trn biu din qu trnh nhn ca hai tn hiu vo x(t) v c(t)

a ra tn hiu m(t). Nhng bit ca tn hiu tri ph gi l chip. Tb c

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trng cho chu k mt bit d liu, Tc l chu k ca mt chip. Tc chip

1/Tc thng c s dng miu t cho mt h thng tri ph.

Spreading Factor (SF) hay ( Processing Gain (PG) ) c trng cho s

chip cha trong mt bit d liu.PG = SF = Tb/Tc

PG cng cao th cng c nhiu on m c cp cho mt knh tn

s.

1.5.10 Phn loi

C 3 phng php tri ph:

Tri ph chui trc tip( SDSS).

Tri ph nhy tn( FHSS).

Tri ph dch thi gian( THSS).

Trong thc t phng php tri ph chui trc tip thng c s

dng nht.

1.5.11 c im

S dng phng php tri ph c mt s u im:

Mt ph cng sut thp. Khi tn hiu c tri ph thnh di tn

s rng, mt ph cng sut thp do h thng truyn thng khng mt

cht lng.

Chng nhiu.

Bo mt thng tin do khng ai bit m PN ny.

C kh nng truy xut ngu nhin v ngi s dng c th bt u

vic pht tn hiu ti bt k thi im no.

1.5.12 Chui PN ( Pseudo Noise Sequence )

1.5.12.1 Phn loi

Gm 2 loi:

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M trc giao : M Walsh.

M khng trc giao : Chui M , m Gold , m Kasami.

1.5.12.2 Tnh cht

Chui m PN c xy dng t s 2 mc.

Hm tng quan l hm nhn bit mc ging nhau cc chui

PN.Nu hm tng quan c gi tr ln tn hiu chui PN cng ging nhau

v ngc li. t c tn hiu tt hay nhiu thp th gi tr hm tng

quan ny phi nh.

Cc chui PN trc giao nhau khi hm tng quan ny t gi tr

bng 0.Nhng thc t rt kh cc chui trc giao hon ton do trongh thng thng xut hin nhiu gi l nhiu MAI( hay cn gi l nhiu a

truy cp.). Do vn ln trong thit k l lm gim nhiu cp.

1.5.13 Nguyn l tri ph trong CDMA2000

Trong qu trnh a truy nhp theo on m, mi ngi s dng s

c cp on m PN duy nht ti u pht. Chui PN ti u thu d ng

chui ti u pht, sau mt s qu trnh x l s tch ra d liu ca mingi.

1.5.13.1 M hnh ti u pht

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Hnh 30: M hnh tn hiu x l ti u pht.

1.5.13.2 M hnh ti u thu

Hnh 31: M hnh tn hiu x l ti u pht.

1.5.13.3 Cc bc thc hin

Gi s Si(t) l d liu ti u pht, Ci(t) l tn hiu chui m PN. Tnh Vi(t) = Si(t)*Ci(t) .Suy ra dng sng sau khi nhn.

Ng ra ca b gii iu ch :

Tnh R(t) = =

N

i

tCitSi1

)(*)( .

D tm m PN ti u pht , nhn tn hiu m ny vi ng ra b

iu ch.

Ly tch gia R(t) v C(t) ta ly li c tn hiu gii iu ch.

S dng mch tch phn ly li tn hiu d liu ban u.

1.5.13.4 M hnh tng qut tn hiu tri ph

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Hnh 32 : M t cc dng sng xy ra khi thu pht tn hiu.

6. iu khin cng sut

cc h thng thng tin di ng CDMA yu cu quan trng t ra l

tng s lng cc cuc gi ng thi trong cng mt tn s, v tng cht

lng cc cuc gi . Cht lng ca cuc gi s gim nu tn hiu m BS

thu c t my di ng l qu yu, ngc li nu tn hiu m BS thu vo

mnh th cht lng cuc gi l tt, tuy nhin giao thoa gia cc cuc gi

ng thi vi nhau trn cng mt knh s lm cht lng cc cuc gi khc

b gim. Hin tng gn xa: ta c bn di l m hnh mt t bo h thng.

My di ng1 (UE1) c khong cch n BS gn hn khong cch t my ding2 n BS. V trong mt t bo CDMA cc trm hot ng trn mt

ng truyn ging nhau, ch khc PN code. Nn khi m BS nhn c tn

hiu cng lc t my di ng1 v my di ng2 trn cng mt tn s, tn

hiu t my di ng1 s mnh hn tn hiu t my di ng2. Khi phn tch

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tn hiu ti BS t l li bit s tng cao (tn hiu t my di ng2). Thm ch,

tn hiu mnh c th trn, ln tn hiu yu gy kh khn cho BS c th

nhn ra tn hiu yu.

Hnh 33:

khc phc cc vn trn, BS s tnh ton cng sut tn hiu t

cc my di ng, nu vt qu mc ngng BS s gi lnh n cho my di

ng yu cu gim cng sut, sao cho tn hiu m BS nhn c t cc my

di ng khc mnh ngang bng nhau. Tng t, nu tn hiu t my di ng

qu yu, my di ng s gi yu cu n BS tng cng sut ng

truyn.

H thng chun IS2000 c th iu khin cng sut vi tc 800 b/s

trn c hai knh hng ln v knh hng xung. y l tin b rt ln khc

phc c nhc im ca h thng chun IS95, cng mt lc ch c thiu khin cng sut cho mt knh vt l hng ln (tc 50 b/s) hoc

hng xung (tc 800 b/s).

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iu khin cng sut knh hng lnKhi mt my di ng station nhn ng truyn knh hng ln bt

u kt ni vi BS, n lin tc theo di cht kng ng truyn. Nu

ng truyn bt u xu i, my di ng s gi yu cu n BS, qua knhhng xung BS cho php tng cng sut. Nu cht lng ng truyn tr

nn qu tt vt qu cng sut tn hiu trn knh hng ln, my di ng s

gi yu cu BS gim cng sut. L tng, FER l mt ch s tt biu hin

cht lng ng truyn, nhng s tn nhiu thi gian cho my di ng

thu nhn cc bit v tnh ton ra FER. V th mt s cc t l signal/noise

nh l Eb/No c th c s dng nh mt thng s biu hin cht lng

ng truyn knh hng ln.

Nh vy, iu khin cng sut knh hng ln c gii quyt nh

sau:

My di ng lin tc theo di Eb/No trn knh hng ln.

Nu Eb/No qu ln (vt qua ngng), my di ng s yu cu BS

tng cng sut truyn.

Nu Eb/No qu nh (nm di ngng), my di ng s yu cu BS

tng cng sut truyn.

yu cu BS tng hoc gim cng sut my di ng s dng power

control bits (PCBs), l mt chui trong R-PICH. Cn ni thm l PCBs

khng c c ch bo v li, iu gp phn gim tr,( n vn c

gn lin vi cc bit kim tra li - error protected bits) BS s nhanh chng

nhn yu cu v iu chnh cng sut truyn sao cho thch hp.Trn y l m t iu khin cng sut vng trong mch vng kn trn

knh hng ln. Ti y, ta phi gi nh mt ngng Eb/No cho trc

quyt nh tng hoc gim cng sut. Nhng trong mi trng thay i, mi

tng quan gia Eb/No v FER l khng i, v vy ta phi thay i ngng

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Eb/No duy tr mt FER chp nhn c. S thay i ngng Eb/No s

c gii thiu trong outner loop.

C th: theo s bn di, m t mt phn ca inner loop v ton b

outner loop. My di ng nhn ng truyn ln t BS. u tin, n s giiiu ch v c lng FER ca ng truyn. Thng tin v cht lng

ng truyn knh hng ln s c cung cp cho outner-loop. Outner-

loop dng ch s FER ny v t n c lng ra mt ch s Eb/No (estimates)

tnh ton ra mt gi tr Eb/No (setpoint) mi cn thit duy tr FER. Ch

s Eb/No mi ny v ch s Eb/No c lng c so snh vi nhau. Nu

Eb/No c lng ln hn Eb/No setpoint, tng ng vi Eb/No (link) trn

ng truyn ln hn cn thit duy tr ch s FER tt, mt m PCBs(1)

c gi n BS yu cu gim cng sut. Ngc li nu Eb/No c lng

nh hn, tng ng vi Eb/No trn ng truyn nh hn mc cn thit, mt

m PCBs(0) c gi i tng cng sut. M PCBs c gi n v x l

ti BS vi tc 800 b/s.

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Hnh 34:

Hnh 35:

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Ta nn ch outner-loop c th theo di tt c ng truyn knh

hng ln m my di ng nhn c ( knh hng ln c bn, chuyn

dng, b sung ). Nu outner-loop theo di cn c vo F-FCH, outner-loop s

s dng cc thng s Eb/No v FER d on ca F-FCH lm vic. Cnhiu ngun outner-loop ly thng tin u vo nh l:

FPC_FCH_FER or the target frame error rate of the F-FCH.

FPC_FCH_INIT_SETPT or the initial setpoint of the F-FCH.

FPC_FCH_MIN_SETPT or the minimum setpoint of the F-FCH.

FPC_FCH_MAX_SETPT or the maximum setpoint of the F-FCH.

FPC_SCH_FER or the target frame error rate of the F-SCH.

FPC_SCH_INIT_SETPT or the initial setpoint of the F-SCH.

FPC_SCH_MIN_SETPT or the minimum setpoint of the F-SCH.

FPC_SCH_MAX_SETPT or the maximum setpoint of the F-SCH.

1.6 iu khin cng sut knh hng v ( vng mch h )

Khi my di ng di chuyn vng quanh trong mt t bo h thng, s

tiu hao ng dn gia my di ng v BS lin tc thay i. Trong iukhin cng sut mch vng m, my di ng lin tc gim st cng sut thu

c v iu chnh cng sut truyn sao cho ph hp. Lu , iu khin

cng sut mch vng h ch c trn my di ng va khng c trn BS. Trong

chun IS2000 c th iu khin cng sut mch vng h qua 3 loi knh

hng xung:

R-EACH.

R-CCCH.

Knh hng xung ni chung bao gm c R-DCCH, R-FCH, and

R-SCH.

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Trn mi loi knh hng xung, iu khin cng sut mch vng h

qua 2 bc ring bit. u tin my di ng s tnh cng sut truyn knh

hoa tiu (hoa tiu chanel) ca R-PICH, khu ny gn nh lun lun hoc

ng. Bc th hai l tnh cng sut truyn knh m ho (code chanel) caknh hng xung.

Ta c bng sau:

y ta ch i m t iu khin cng sut trn knh hng xung.

Trong qu trnh truyn dn ca knh hng xung (R-DCCH, R-FCH, and

R-SCH), R_PICH cng vn hot ng to s lin kt cht ch, mch lc

cho gii iu ch. cho d hiu, ta i vo m hnh minh ho:

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Hnh 36: iu khin cng sut knh ngc.

Cng sut thu c cng vi nhiu h s iu chnh khc, hot ng

xc nh cng sut truyn ca R_PICH, cng sut truyn ca R_PICH s

quay vng xc nh cng sut truyn ca R_EACH, R_CCCH, v cng

sut truyn knh hng xung.

iu khin cng sut knh hng xung vng mch khp kn iu khin cng sut vng mch khp kn trn knh hng xung,

BS lin tc theo di ng truyn xung v tnh ton cht lng ng

truyn. Nu cht lng bt u gim, BS s gi lnh cho my di ng tng

cng sut thng qua ng truyn knh hng ln. Nu cht lng ng

truyn qu tt, BS s gi lnh cho my di ng gim cng sut. n y th

ta thy n kh ging vi cch iu khin cng sut trn knh hng ln.

Khc ch, iu khin cng sut vng mch khp kn trn knh hng

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xung ch c BS. N cng s dng cc thng s nh Eb/No v FER

nh gi cht lng ng truyn. Ta nn tm hiu c th trn m hnh c

s phn bit.

BS theo di cht lng ng truyn bng ch s Eb/No.

Nu Eb/No qu ln s gi lnh cho my di ng tng cng sut.

Nu Eb/No qu nh s gi lnh cho my di ng gim cng sut.

Ban u BS nhn ng truyn knh hng v t my di ng v gii

iu ch tn hiu, n t c lng mt ch s FER. Thng tin v cht lng

ng truyn s c a n outner-loop. Outner-loop dng FER hin c

v t s Eb/No do n t c lng tnh ton, a ra mt Eb/No setpoint mi

c th duy tr n nh FER. Hai ch s Eb/No mi v c s c so snh. Nu

Eb/No estimate ln hn Eb/No setpoint, c ngha l Eb/No trn ng truyn

qu ln c th duy tr ch s FER tt, mt m PCB(1) s c BS gi i

ra lnh cho my di ng tng cng sut. Ngc li, nu Eb/No estimate nh

hn Eb/No setpoint, BS s gi mt PCBs(0) ra lnh cho my di ng gim

cng sut. PCBs l mt chui trong F-CPCCH, F-DCCH, hoc F-FCH.

PCBs c truyn v x l ti tc cao nht 800 b/s.

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Hnh 37:

M hnh bn di m t qu trnh my di ng nhn cc tn hiu F-

CPCCH, F-DCCH, F-FCH, v gii m PCBs, da vo tng hoc gim

cng sut.

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Hnh 38:

Cht lng truyn dn trong mi trng c nhiu cuc gi ph thuc

vo t s Eb/No, trong Eb l nng lng bit v No l mt nhiu trng

Gauss bao gm nhiu do chnh BS v my di ng gy ra trong qu trnhtruyn v x l tn hiu v nhiu do cc my di ng khc gy ra.

7. Chuyn giao ( Handoff )

1.7 Gii thiu

Trong mt mng in thoi t bo, hand-off l s chuyn tip m bo

cho vic truyn tn hiu t mt trm c s (Base Station) n mt trm c s

k tip theo a l khi ngi dng di chuyn. S chuyn giao c th thc

hin theo hai cch : chuyn giao cng (hard handofff) v chuyn giao mm

(soft handoff). Chuyn giao cng l qu trnh chuyn giao m ch c mt

trm c s (base station) c kt ni vi mobile. Chuyn giao mm cho

php kt ni ng thi hai trm c s cng mt lc vi mobile trong qu

trnh chuyn giao.

Hnh 39: S khc nhau gia chuyn giao mm v chuyn giao cng .

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Trong chun CDMA2000 cc qu trnh nh hng n cht lng h

thng trong s chuyn giao l : soft handoff, idle handoff, access entry

handoff, access handoff, access probe handoff.

1.8 Soft handoff (Chuyn giao mm)Soft handoff l qu trnh m mobile trc tip tc ng ln s chuyn

i knh thng tin gia hai hay nhiu trm (mobile station ). Soft handoff

ch tn ti khi mobile trong trm mobile iu khin vic truyn trng thi

knh (traffic channel state). qun l qu trnh soft handoff, ngi ta dng

cc b (sets): active set, candidate set, neighbor set remaining set.

Thun li ca soft handoff l tnh a dng trong s kt hp vic

truyn thng tin gia hai hay nhiu trm.

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Hnh 40: mi quan h gia cc b trong vic iu khin soft handoff .

1.8.1 Active set (b tch cc)

Active set cha cc pilot(hoa tiu ) ca nhng vng (sector) tc ng

trc tip vo vic chuyn i knh thng tin vi mobile . Active set c nhiu

nht 6 pilot . Nu active set ch c mt pilot th n s khng c ch soft

handoff .Xa pilot (hoa tiu ) t active set : Mi pilot trong active set c mt

handoff drop timer v pilot s chuyn t active set sang neighbor set khi t s

Ec/Io ca pilot nh hn T_DROP v handoff drop timer kt thc.

Thm pilot vo active set : Pilot c thm vo active set lun lun

n t candidate set.

1.8.2 Candidate set

Candidate set cha pilot ca nhng sector c t s Ec/Io lm cho

nhng sector tr thnh handoff candidate, Candidate set cha ti a 10

pilot.

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Xa pilot(hoa tiu ) t candidate set : Mt pilot s t ng b xa khi

candidate set khi Ec/Io ca pilot nh hn T_DROP v handoff drop timer

kt thc (tin n T_TDROP).

Thm pilot vo candidate set : Mobile chuyn mt pilot t active setn candidate set khi:

Handoff drop timer ca pilot khng tin ti c T_TDROP.

Handoff drop timer ca pilot tin ti c T_TDROP, nhng

cng ca pilot ln hn T_DROP.

1.8.3 Neighbor set (b k cn)

Cha nhng pilot c gi t mobile mi Neighbor set cha ti a 40pilot .

Xa pilot t neighbor set: Mobile s t ng chuyn pilot t neighbor

set sang remaining set khi b m ca pilot vt qu

NGHBR_MAX_AGE ,hoc cng ca pilot trong neighbor set ln hn

T_ADD.

Thm pilot vo neighbor set : Pilot chuyn t candidate set n

neighbor set khi handoff drop timer ca pilot tin ti T_TDROP hoc do

pilot c s u tin trong t rong candidate set hoc Mobile s chuyn pilot

t active set n neighbor set khi handoff drop timer ca pilot tin ti

T_TDROP, v cng ca pilot nh hn T_DROP.

1.8.4 Remaining set (b duy tr )

Cha tt c cc pilot c th trong th thng cho tn s mang CDMA

hin thi , n khng cha cc pilot ca active set , candidate set , neighborset . Pilot PN offsets trong b remaining c nh ngha nh s tng i

lng pilot (PILOT_INC).

V D :Nu PILOT_INC =4, th mi sector trong h thng ch c th

truyn pilot vi offset : 0,4,8,12,.

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Xa pilot t remaining set : Khi cng pilot ca remaining set vt

qu T_ADD , mobile s t ng chuyn pilot t remaining set n candidate

set .

Thm pilot vo remaining set: Khi b m ca pilot vt quNGHBR_MAX_AGE, mobile s chuyn mt pilot t neighbor set n

remaining set . Hoc nu xy ra s trn t neighbor set , pilot c u tin t

nht trong neighbor set s b chuyn xung remaining set .

Hnh 41: S chuyn i gia cc b trong soft hadoff.

1.9 Idle handoff (chuyn giao nhn ri)

Idle handoff ch tn ti khi trm mobile trng thi nhn ri. Trong

ch Idle handoff mobile d liu c cha trong bn b c quyn

:active set, neighbor set, private neighbor set (b k cn ring), remaining

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set, v ni dung ca cc b ny khng bao gi trng lp hay chng cht ln

nhau .


B phn chia mobile ch l F-PCH hoc F-CCCH ca nhng b tchcc trn trm c s. Khng ging nh b tch cc dng trong soft hardoff ,

b tch cc ch c mt pilot .

1.9.2 Neighbor set (B k cn)

Cha nhng pilot c tim nng nht cho idle handoff c ch

nh bi danh sch thng bo k tip chung (universal neighbor list mesage),

danh sch thng bo k tip m rng (extended neighbor list message) hoc

nhng danh sch thng bo k tip (neighbor list message). Ging nh

neighbor set trong soft handoff n cng c ti a l 40 pilot .

1.9.3 Private neighbor set (b k cn ring )

Cha nhng pilot c kh nng cao ca handoff trong h thng ring ,

ni dung ca b k tip ring (private neighbor set) c ch nh bi danh

sch k tip ring (private neighbor list message). Private neighbor set cha

ti a l 40 pilot .

1.9.4 Remaining set (B duy tr )

Cha tt c cc pilot c th trong h thng cho tn s mang CDMA

hin thi . Ni dung ca b remaining set trong Idle handoff th cng tng

t nh ni dung ca b remaining set trong Soft handoff .

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Hnh 42:

1.9.5 Idle handoff process(truy xut chuyn giao nhn ri)

Khi trm mobile trnh thi nhn ri , mobile s o cng ca

pilot trong Active set, neighbor set, private neighbor set v remainingneighbor set . Nu t s Ec/Io ca pilot trong neighbor set, private neighbor

set v remaining neighbor set ln hn t s Ec/Io ca pilot trong active set

3db, th mobile s xa nhng pilot yu hn khi active set v ly nhng pilot

mnh hn cho vo active set.

1.10 Access Entry Handoff (Chuyn giao truy xut v nhp

vo )Access Entry Handoff tn ti khi mobile ngng phn chia F-PCH

hoc F-CCCH/F-BCCH ca mt trm c s v bt u kim tra knh tng

ng ca nhng tram c s khc (base station ) .Tm li Access Entry

Handoff tn ti khi trm mobile trng thi nhn ri ( mobile station idle

state ) sang trng thi truy xut h thng (system access state) .

Access entry handoff ch xut hin trong mobile khi mobile nhn

c tin nhn hay lnh m n cn phi p ng li ,tuy nhin n cn ty

thuc vo mobile c th hin access entry handoff hay khng . Mt mobile

xc nh s biu din access entry handoff khi n thc s tun theo quy lut

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ca idle handoff chuyn s phn chia F-PCH hoc F-CCCH/F-BCCH t

trm c s hin ti sang trm c s mi .

Hnh 43:

1.11 Access Handoff ( chuyn giao truy xut )

Access handoff bt u khi mobile chia nhng knh tng ng cho

cc trm khc nhau . Ging nh idle handoff v soft handoff , access

handoff cng lu tr thng tin trong cc b c quyn : active set , neighbor

set ,remaining set .


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Do b tch cc ch cha c duy nht mt pilot nn trong trng thi

truy xut h thng , mn hnh mobile ch l F-PCH hoc F-CCCH ca b

tch cc trong trm c s.

1.11.2 Neighbor set (b k cn)Cha nhng pilot c kh nng cao nht , tim nng nht cho qu trnh

chuyn giao truy xut hoc chuyn giao thm d truy xut (access probe

handoff).Nhng pilot c ch nh bi danh sch k tip chung

(universal neighbor list message), danh sch k tip m rng (extended

neighbor list message )

1.11.3 Remaining set (B duy tr )

Cha tt c nhng pilot c th trong h thng cho tn s mang ca

CDMA hin thi , nhng pilot ny khng c trong b tch cc v b k cn

(neighbor set). Pilot PN offsets trong b remaining c nh ngha nh s

tng i lng pilot (PILOT_INC).

V D :Nu PILOT_INC =4, th mi sector trong h thng ch c th

truyn pilot vi offset : 0,4,8,12,

1.11.4 Access handoff process( qu trnh chuyn giao truy xut )

Mobile ch th hin chuyn giao truy xut khi n trong trng thi

truy xut .

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Hnh 44:

1.12 Access probe handoff (Chuyn giao thm d truy xut)

Access Probe handoff tn ti trong qu trnh mobile truy xut : ngng

gi truy xut thm d ti trm c s hin ti , bt u gi truy xut thm d

ti mt trm c s mi . Mobile c th biu din qu trnh truy xut h thngtrong trang p ng trng thi ph hoc trong trm mobile pht sinh trng

thi ph .

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Hnh 45:

V. Hng pht trin h thng thng tin di ng sau 3G

H thng wireless 3G(Third-generation) to nn nhng kh nng

thng tin mi nh phi hp nhng n lc nghin cu v pht trin t chc,

nhng nh sn xut trang thit b, nhng nh cung cp dch v, v quan

trng nht l nhng tiu chun chung phi hp gia vic t chc v hin

thc nhng bn thit k t nhng nghin cu, to ra nhng tiu chun quc

t.

Nhiu cng ty ang pht trin nhng trang thit b 3G wireless

nhng nh cung cp dch v c th gii thiu cho khch hng trong thi gian

sm nht.

Nhng nh cung cp dch v, nhng nh sn xut cng vi cc phng

nghin cu ang chun b sn sng cho vic tm kim cng ngh sau 3G.

1. HSPDA ( 3.5G )HSDPA (High Speed Downlink Packet Access), gi ng truyn tc

cao, l mt sn phm ca cng ngh 3G cho php cc mng hot ng

trn h thng UMTS c kh nng truyn ti d liu vi tc cao hn hn.

Cng ngh HSDPA hin nay cho php tc download t n 1.8, 3.6, 7.2

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v 14.4 Mbit/giy, v trong tng lai gn, tc hin nay c th c nng

ln gp nhiu ln. Khi , cc mng cung cp c th c nng cp thnh

Evolved HSPA, cho php tc download t n 42 Mbit/giy. Vi nhng

u th vt tri , HSDPA ang tr thnh mt cng ngh c nhiu nhcung cp quan tm pht trin.

HSDPA l mt phng thc truyn ti d liu theo phng thc mi.

y c coi l sn phm ca dng 3.5G. cng ngh ny cho php d liu

download v my in thoi c tc tng ng vi tc ng truyn

ADSL, vt qua nhng cn tr c hu v tc kt ni ca mt chic in

thoi thng thng. y l gii php mang tnh t ph v mt cng ngh v

c pht trin trn c s ca h thng 3G W-CDMA.HSDPA c tc

truyn ti d liu ln ti a gp 5 ln so vi khi s dng cng ngh W-

CDMA. V mt l thuyt, HSDPA c th t tc truyn ti d liu ln ti

8-10 Mbps (Megabit/giy). Mc d c th truyn ti bt c dng d liu no,

song mc tiu ch yu ca HSDPA l d liu dng video v nhc.

HSDPA c pht trin da trn cng ngh W-CDMA, s dng cc

phng php chuyn i v m ha d liu khc. N to ra mt knh truyn

d liu bn trong W-CDMA c gi l HS-DSCH (High Speed Downlink

Shared Channel), hay cn gi l knh chia s ng xung tc cao. Knh

truyn ti ny hot ng hon ton khc bit so vi cc knh thng thng

v cho php thc hin download vi tc vt tri. V y l mt knh

chuyn dng cho vic download. iu cng c ngha l d liu s c

truyn trc tip t ngun n in thoi. Song qu trnh ngc li, tc ltruyn d liu t in thoi n mt ngun tin th khng th thc hin c

khi s dng cng ngh HSDPA. Cng ngh ny c th c chia s gia tt

c cc user c s dng sng radio, sng cho hiu qu download nhanh

nht.Ngoi HS-DSCH, cn c 3 knh truyn ti d liu khc cng c pht

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trin, gm c HS-SCCH (High Speed Shared Control Channel knh iu

khin dng chung tc cao), HS-DPCCH (High Speed Dedicated Physical

Control Channel knh iu khin vt l dnh ring tc cao) v HS-

PDSCH (High Speed Downlink Shared Channel knh vt l chia s ngxung tc cao). Knh HS-SCCH thng bo cho ngi s dng v thng

tin d liu s c gi vo cc cng HS-DSCH.

2. 4G ( fourth generation )

NTT DoCoMo ca Nht ang nghin cu k hoch v h thng

4G(four generation), pht trin nhng k thut cho dch v 4G. Nhiu

ti nghin cu v pht trin Chu u ang nghin cu truyn thng di

sng rng ( nh l nhng tiu chun b mt khng kh, nhng phm vi c

trng ,nhng d phng cho cht lng dch v (QoS) trong IP network,

y s l s tng thch ca 4G.

ng lc pht trin 4G:

Nhng yu cu thc y dch v truyn thng tht ng ngc

nhin.Khi mng li in thoi c gii thiu vo nm 1981,hng nm s

ngi s dng di ng tng 40%, trong khi dch v in thoi tng 5-7%

trong cng k. Hu ht truyn thng tin hin nay trong di ng bao gm

ging ni, nhng i hi truyn thm d liu cng ngy cng cao, xa hn

da trn ng dng sn c ca Internet. iu ny hin nhin v nhng d liu

phc v cho kh nng ca h thng ton cu ca truyn thng u tin

(Global Systems for Mobile Communications )-GSMs ch gii hn trong

nhng tin nhn dch v ngn v nhng d liu truyn tc ch 9.6 Kb/s. Khi nhng yu cu v dch v truyn d liu tng, T chc lp tiu

chun ca Chu u (ETSI) a ra tiu chun GPRS (General Packet Radio

Service) hin nay ang s dung nhiu quc gia trn th gii cung cp

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gi dch v d liu tc 12-20 Kb/s. D bo pht trin ca truyn thng d

liu v ging ni c a ra trong hnh :

Hnh 46:D bo v truyn thng ging ni v d liu.

Mc d y l nhng con s xp x, nhng quan trng cn ch

y l vic truyn thng d liu c trng i s gp i truyn ging nitrong nm 2010 v tng n xp x 24 trong nm 2015. V nu thc vy

truyn thng pht trin vi t l ny th nhng h thng 2G v 3G s khng

cn ph hp thi im . V vy cn thit xem xt li vic phn phi

ph sng m trong truyn thng khng dy th h tip theo.

Ngun gc ca tin on trn l da trn cc dch v truyn thng a

phng tin. Thm ch s c 1 s ng dng truyn thng tng tc vi nhau

lm d liu truyn mt i xng d liu truyn xung nhiu hn d liu

ti ln. Trong 3G, truyn thng a phng tin cho di ng v ng dng

khong 384 Kb/s. Nhiu khch hng s dng dch v a truyn thng vi tc

1.536 hoc 2 Mb/s. Thng thng th khch hng mong mun c cung

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cp ng dch v trong mt mng n nh, mng di ng yu cu cung cp

dch v a truyn thng t tc 2Mb. Tng t nhng ng dng nh mt

on phim, h thng gii tr trong gia nh cn tc truyn d liu 10-20

Mb/s.Tc truyn d liu n nh trong nhng ng dng ca h thng 3Gch t 2Mb/s chnh l l do xem xt h thng 4G. Nu 4G tr thnh hin

thc th chng ta s c nhng c trng v ng dng ca nhng h thng

khc nhau th hin trong hnh sau:

Hnh 47:

ng dng v c trng ca 4G:

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ng dng ca 4G bao gm dch v a phng tin cho

mi trng di ng( nh l giao thng tc cao ,hng khng, v tinh,)

vi tc ln ti 2Mb/s, pht sng nhng CD cht lng cao , quan st t

xa khi vng nh ,nhng on phim, gii tr vi tc 20Mb/s cho nhngng dng phm vi trong gia nh, nhng h thng nh v Mc tiu l

cung cp dch v a phng tin ti mi ngi , mi lc, mi ni. Tc

truyn d liu thng thng ca nhng on video cht lng cao th hin

trong bng sau:

Nhng c trng ca 4G:

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Khng gii hn tc , lin tc , kh nng di ng ton cu khng

ch cho ging ni m cn cho nhng dch v d liu trn khp mi vng v

mng li mi ni c th .

S tng kt gia 3G v 4G cng nh 2G v 4G. H thng tng t c gii thiu M v Chu u vo nm

1981 th ch trong vng 10 nm h thng s c ng dng. 3G c gii

thiu trong nm 2001 v 2002 chnh l l do nhiu kh nng 4G s thay

th vo nm 2010-2012. Thm ch d nhng h thng hin nay khng t

im bo ha th cng cn thit xem xt li s phn b ph sng 4G.

C.Kt lun

I. Nhng kt lun v mng thng tin di ng

Da trn nhng tm hiu trn chng ta nhn thy mng thng tin di

ng pht trin rt mnh m trong nhng nm qua, c rt nhiu cng

ngh mng c nghin cu v a vo s dng p ng nhu cu rtln ca ngi s dng khng ch n thun v mt truyn ti d liu m d

liu cn phi c tc cao cng nh tnh tin cy.

II.Nhng vic thc hin c

Bi bo co gn nh hon thnh cc yu cu ca gio vin hng

dn ra. Vic tm hiu kh chi tit.

Vic tm hiu v ti h thng thng tin ni chung v mng thng

tin di ng CDMA2000 ni ring gip nhm c ci nhn t tng quan n

c th v mt ni dung kh ln nhng rt hay.

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Vic tm hiu su gip nhm lm quen vi nhng khi nim ht

sc mi m c lin quan mt thit vi mt ngnh nghin cu, ng dng rng

ln.

Nhng ti liu, khi nim, thut ng gip nhm t tin hn trong mnhc h thng truyn thng.

III. Nhng vic cha hon thnh

Tuy c gng tm hiu ti liu ting Anh ln ting Vit nhng nhng

vn tm hiu li ht sc rng ln do mt s thut ng chuyn ngnh

vn cha c th dch r ngha.

Do thi gian lm ti bo co c hn nn c mt s phn nhm changhin cu tht su.

TI LIU THAM KHO 3G CDMA Wireless System Engineering, Samuel C.Yang.

WCDMA and CDMA2000, M.R.Karim and M.Sarraf. Spread Spectrum introduction, Jan Meel.

Spread Spectrum application, Jan Meel.

Introduction to CDMA2000, Caroline.

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MC LC

2G ( second generation )..........................................................................................43G ( third generation )..............................................................................................61xEV DO............................................................................................................101xEV DV............................................................................................................11 rng bng..........................................................................................................13

Cht lng dch v QoS ( quality of service )......................................................14Cc dch v d liu gi..........................................................................................14Cc giao thc s dng............................................................................................16Mobile internet protocol ( Mobile IP )..................................................................18Lp vt l..............................................................................................................21Medium Access Layer ( MAC )............................................................................26Link Access Control ( Lp LAC ).........................................................................34a truy cp ( Multiple Access ).............................................................................57Th tc thu v pht tn hiu theo m hnh CDMA...............................................59Tri ph..................................................................................................................59iu khin cng sut knh hng ln....................................................................67

iu khin cng sut knh hng xung vng mch khp kn............................72TI LIU THAM KHO.................................................................................................92

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thong tin di dong the he 3 CDMA2000

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