CG MỀM TRONG WCDMA

8/3/2019 CG MM TRONG WCDMA

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NG I: TNG QUAN V MNG THNG TIN DI NGS pht trin ca mng di ng H thng di ng tng t th h u tin 1980 bt u k nguyn mng in thoi di ng t bo, v t

n thng di ng tri qua nhng thay i ng k v pht trin ln v mt kinhm.Hnh I.2 cho thy s tin trin ca mng di ng.hng di ng th h u tin s dng phng thc truyn tng t icc dch v thoi. Nm 1979, h thng di ng u tin trn th gii c a dng 600 knh hai chiu trn ph tn 30 MHz bng tn 800 MHz, vi khongknh l 25 kHz. 2 nm sau, k nguyn di ng t bo hng ti Chu u. 2

bin nht ca h thng tng t l Nordic Mobile Telephones (NMT) v Totaless Communication Systems (TACS).Nm 1981, h thng NMT-450 cng mi ho bi NMT Scandinavia. H thng hot ng di tn 450 MHz vMHz vi bng thng tng cng l 10 MHz. TACS, c ra mt ti Anh vo nm2, hot ng ti tn s 900 MHz vi bng tn dnh cho mi ng l 25 MHz v

thng mi knh l 25 kHz. TACS c m rng trin khai vo nm 1985. NgoiT v TACS, mt s h thng tng t khc cng c gii thiu vo nm 1980ton Chu u. V d, c, h thng di ng t bo C-450 , hot ng ti bng50 MHz v 900 MHz (sau ny) , c trin khai vo thng Chn nm 1985. Tt c

h thng ny cung cp kh nng chuyn vng v chuyn giao nhng mng di ngo li khng cho php lin kt ni gia cc quc gia. y l mt trong nhng kh

khng th trnh khi ca mng di ng th h u tin. Ti Hoa K, mng ini di ng AMPS (Advanced Mobile Phone System) c a ra vo nm 1982.hng c phn b mt bng thng 40 MHz trong di tn t 800 n 900 MHz. 1988, AMPS c b sung thm 10 MHz bng thng v gi l ph m rng

anded Spectrum (ES).2 H thng di ng th h th 2 v giai on 2 +hng di ng th h th 2 c gii thiu vo cui nhng nm 1980.Ccv d liu tc thp cng nh cc dch v thoi truyn thng c h tr. Cc

hng ny s dng k thut truyn dn s ch khng phi truyn dn tng t. Doso vi h thng di ng th h th nht, hiu sut ph ca th h th 2 cao hn,v d liu v kh nng chuyn vng tt hn. Chu u, h thng ton cu dnh

truyn thng di ng c tn gi l GSM (Global System for Mobilemunications) c trin khai cung cp mt tiu chun mang tnh thng nht.

vo hot ng bi Nippon Telephone and Telegraph (NTT) Tokyo, Japan.H thng


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u ny cho php cc dch v khng c ng ni ra khi Chu u bng phngchuyn vng quc t. H thng GSM sm nht hot ng bng tn 900 MHz

bng thng tng cng l 50 MHz. Sut trong qu trnh pht trin hn 20 nm, cngGSM lin tc c ci tin cung cp cc dch v tt hn trn th trng.


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ng cng ngh mi tin tin hn c bit n nh l h thng th h 2,5 (2,5G)c pht trin da trn nn tng ca h thng GSM gc. Cho n nay, nh l mthng di ng ln nht trn ton th gii, GSM l cng ngh ca s la chn ti190 quc gia vi khong 787.000.000 thu bao.

h I.1 S pht trin ca mng di ng

Hoa K, c 3 dng pht trin ca h thng di ng t bo s. H thngtin, c gii thiu vo nm 1991, l IS-54 (North America TDMA Digitalular), trong c mt phin bn mi h tr cc dch v b sung (IS 136) c

thiu vo nm 1996. Trong , IS-95 c trin khai vo nm 1993. S um truyn thng lin bang M Federal Communications Commision (FCC) cngu gi mt khi ph mi trong di tn 1900 MHz (PCS), cho php GSM 1900vo th trng M. Nht Bn, h thng Personal Digital Celluar (PDC), ban

c bit n nh l JDC (Japanese Digital Cellular) bc u c nh nghanm 1990. Dch v thng mi c bt u bi NTT vo nm 1993 bng00 MHz v nm 1994 bng tn 1,5 GHz. Bng I.1 cho thy cc thng s kt ca bn h thng di ng s th h th hai in hnh.


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IS-136 IS-95 PDCa truy xut TDMA TDMA CDMA TDMA

ch

KQPSKent /4-DQPSKent 8-PSK

/O-QPSK

QPSK

ng knh 200 kHz 30 kHz 1.25 kHz 25 kHz bit 270.833 kbit/s 48.6 kbit/s(/4-DQPSK)bit/s(8-PSK)8 Mchip/s 42 kbit/si khung 4.615 ms 40 ms 20 ms 20 mse/khung 8/16 6 1 3/6tnung))15/935 9601785/1805-18801990/1850-191049/869-894

1990/1850-191049/869-8941990/1850-

26/910 9561453/1477-

d liuhp ti a)D: 57.6: 115.2-182.4

6+: 43.2 IS 95A: 14.4B: 115.2

uyn giao Cng Cng Mm Cng

LE I.1 Cc thng s k thut ca h thng s th h th 2

y nay, h thng di ng t bo s th h th hai vn chim u th trong cng nghip di ng trn ton th gii. Tuy nhin, h ang tin trin theo hng

hng th h th ba (3G) v nhng nhu cu v lu lng di ng v s xut hin caoi hnh dch v mi. Cc h thng mi, chng hn nh l HSCSD (High Speeduit Switched Data), GPRS (General Packet Radio Service), v IS 95B, thngc gi chung l th h 2,5 (2,5G).CSD, GPRS v EDGE tt c u da trn nn tng ca h thng GSM ban

HSCSD l s ci tin u tin ca giao tip v tuyn GSM: n b cc khe thiGSM cho ra mt tc d liu ti a v mt l thuyt l 57,6 Kbit/s ( 4it/s). HSCSD cung cp c 2 loi hnh dch v i xng v bt i xng v nc trin khai tng i d dng. Tuy nhin, HSCSD khng d dng v mt gi c

tranh.HSCSD, GPRS l bc pht trin tip theo ca giao tip v tuyn GSM.

i b cc khe thi gian, th 4 s m ho knh mi c xut. GPRS cungalways on cc gi d liu chuyn mch gi vi bng thng ch c s dng khihit. V vy, GPRS cho php GSM truy xut Internet vi hiu sut ph cao bngs dng cc khe thi gian khc nhau gia cc User. V mt l thuyt, GPRS c


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h tr tc d liu ln ti 160 Kbit/s (hin ti GPRS cung cp 40 Kbit/s). TrinGPRS khng d dng nh l HSCSD v mng li cn phi c nng cp tt.

GE s dng cu trc v tuyn GSM v khung TDMA nhng vi mt s ch mi, 8QPSK, thay v GMSK, qua tng gp 3 ln so vi GSM thng quas dng cng mt bng thng. EDGE kt hp vi GPRS s cung cp tc dcho mi User ln n 384 Kbit/s. H thng di ng th h th 3 v cao hn na

hng thng tin di ng chuyn t th h 2 sang th h 3 qua mt giai ong gian l th h 2,5 s dng cng ngh TDMA trong kt hp nhiu khe hocu tn s hoc s dng cng ngh CDMA trong c th chng ln ph tn ca thai nu khng s dng ph tn mi, bao gm cc mng c a vo s dngGPRS, EDGE v CDMA2000-1x. th h th 3 ny cc h thng thng tin di

g c xu th ho nhp thnh mt tiu chun duy nht v c kh nng phc v tcit ln n 2 Mbit/s. phn bit vi cc h thng thng tin di ng bng hp hincc h thng thng tin di ng th h 3 gi l cc h thng thng tin di ng bng.u tiu chun cho h thng thng tin di ng th h 3 IMT-2000 c trong 2 h thng W-CDMA v CDMA2000 c ITU chp thun v a

hot ng trong nhng nm u ca nhng thp k 2000. Cc h thng ny ung cng ngh CDMA, iu ny cho php thc hin tiu chun ton th gii chodin v tuyn ca h thng thng tin di ng th h 3.

W-CDMA (eband Code Division Multiple Access nng cp ca cc

hng thng tin di ng th h 2 s dng cng ngh TDMA nh: GSM, IS-136.MA2000 l s nng cp ca h thng thng tin di ng th h 2 s dngngh CDMA: IS-95.


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h I.2 L trnh pht trin t 2G n 3Gcu i vi h thng thng tin di ng th h 3:

ng tin di ng th h th 3 xy dng trn c s IMT-2000 c a vov t nm 2001. Mc ch ca IMT-2000 l a ra nhiu kh nng mi nhngng thi bo m s pht trin lin tc ca thng tin di ng th h 2.

c ca th h th ba c xc nh nh sau:4 Kb/s i vi vng ph sng rng.Mb/s i vi vng ph sng a phng.

c tiu ch chung xy dng h thng thng tin di ng th h ba (3G):

dng di tn quy nh quc t 2GHz nh sau:ng ln : 1885-2025 MHz.ng xung : 2110-2200 MHz.h thng thng tin di ng ton cu cho cc loi hnh thng tin v

tuyn:ch hp cc mng thng tin hu tuyn v v tuyn.

ng tc vi mi loi dch v vin thng.dng cc mi trng khai thc khc nhau: trong cng s,ngoi

ng trn xe, v tinh.th h tr cc dch v nh:


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i trng thng tin nh o (VHE: Virtual Home Environment

c s mng thng minh, di ng c nhn v chuyn mngcu.m bo chuyn mng quc t.m bo cc dch v a phng tin ng thi cho thoi, s liun mch theo knh v s liu chuyn mch theo gi.dng h tr cc dch v mi xut hin.u trc mng thng tin di ng th h th 3 UMTS

hng W-CDMA c xy dng trn c s mng GPRS. V mt chc nngh chia cu trc mng W-CDMA ra lm hai phn : mng li (CN ) v mng truy

v tuyn (UTRAN ), trong mng li s dng ton b cu trc phn cng cag GPRS cn mng truy nhp v tuyn l phn nng cp ca W-CDMA. Ngoi raon thin h thng, trong W-CDMA cn c thit b ngi s dng (UE) thc hindin ngi s dng vi h thng. T quan im chun ha, c UE v UTRAN

bao gm nhng giao thc mi c thit k da trn cng ngh v tuynDMA, tri li mng li c nh ngha hon ton da trn GSM. iu ny cho

h thng W-CDMA pht trin mang tnh ton cu trn c s cng ngh GSM.

trc ca UMTS

(User Equipment)

t b ngi s dng thc hin chc nng giao tip ngi s dng vi h thng.gm hai phn :


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t b di ng (ME : Mobile Equipment) : L u cui v tuyn c s dngthng tin v tuyn trn giao din Uu.dule nhn dng thu bao UMTS (USIM) : L mt th thng minh cha thnghn dng ca thu bao, n thc hin cc thut ton nhn thc, lu gi cc khathc v mt s thng tin thu bao cn thit cho u cui.

RAN

MTS Terestrial Radio Access Network)

g truy nhp v tuyn c nhim v thc hin cc chc nng lin quan n truyv tuyn. UTRAN gm hai phn t :t B : Thc hin chuyn i dng s liu gia cc giao din Iub v Uu. N cng

m gia qun l ti nguyn v tuyn.iu khin mng v tuyn RNC : C chc nng s hu v iu khin cc ti

yn v tuyn trong vng (cc nt B c kt ni vi n). RNC cn l im truyt c cc dch v do UTRAN cung cp cho mng li CN.

(Core Network)R (Home Location Register) : L thanh ghi nh v thng tr lu gi thnghnh v l lch dch v ca ngi s dng. Cc thng tin ny bao gm : Thng tin

c dch v c php, cc vng khng c chuyn mng v cc thng tin v dch sung nh : trng thi chuyn hng cuc gi, s ln chuyn hng cuc gi.SC/VLR (Mobile Services Switching Center/Visitor Location Register) : L

i (MSC) v c s d liu (VLR) cung cp cc dch v chuyn mch knhUE ti v tr ca n. MSC c chc nng s dng cc giao dch chuyn mch knh.

R c chc nng lu gi bn sao v l lch ngi s dng cng nh v tr chnh xcUE trong h thng ang phc v.

MSC (Gateway MSC) : Chuyn mch kt ni vi mng ngoi.SN (Serving GPRS) : C chc nng nh MSC/VLR nhng c s dng cho

dch v chuyn mch gi (PS).GSN (Gateway GPRS Support Node) : C chc nng nh GMSC nhng ch

v cho cc dch v chuyn mch gi.mng ngoing CS : Mng kt ni cho cc dch v chuyn mch knh.ng PS : Mng kt ni cho cc dch v chuyn mch gi.

giao din v tuynao din CU : L giao din gia th thng minh USIM v ME. Giao din nytheo mt khun dng chun cho cc th thng minh.

ao din UU : L giao din m qua UE truy cp cc phn t c nh ca hg v v th m n l giao din m quan trng nht ca UMTS.


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ao din IU : Giao din ny ni UTRAN vi CN , n cung cp cho cc nh khaikh nng trang b UTRAN v CN t cc nh sn xut khc nhau.

ao din IUr : Cho php chuyn giao mm gia cc RNC t cc nh sn xutnhau.

ao din IUb : Giao din cho php kt ni mt nt B vi mt RNC. IUb cchun ha nh l mt giao din m hon ton.

thng thng tin di ng th h tip theo:

hng thng tin di ng th h 3 sang th h 4 qua giai on trung gian l

h 3,5 c tn l mng truy nhp gi ng xung tc cao HSDPA. Th h 4 lngh truyn thng khng dy th t, cho php truyn ti d liu vi tc ti a

g iu kin l tng ln ti 1 cho n 1.5 Gb/giy. Cng ngh 4G c hiu ln tng lai ca cc thit b khng dy. Cc nghin cu u tin ca NTToMo cho bit, in thoi 4G c th nhn d liu vi tc 100 Mb/giy khi din v ti 1 Gb/giy khi ng yn, cho php ngi s dng c th ti v truyn lnnh ng cht lng cao. Chun 4G cho php truyn cc ng dng phng tin

n thng ph bin nht, gp phn to nn cc nhng ng dng mnh m cho ccg khng dy ni b (WLAN ) v cc ng dng khc.h 4 dng k thut truyn ti truy cp phn chia theo tn s trc giao

DM, l k thut nhiu tn hiu c gi i cng mt lc nhng trn nhng tn s

nhau. Trong k thut OFDM, ch c mt thit b truyn tn hiu trn nhiu tn slp (t vi chc cho n vi ngn tn s). Thit b 4G s dng my thu v tuynnhn bi phn mm SDR (Software - Defined Radio) cho php s dng bngg hiu qu hn bng cch dng a knh ng thi. Tng i chuyn mch mngh dng chuyn mch gi, do , gim tr thi gian truyn v nhn d liu.

Tng quan v cng ngh CDMA Nguyn l tri ph (CDMA)thng truyn thng s c thit k ti a ho dung lng s dng.T

yn tc dung lng knh ca Shannon c biu din (1.1), hin nhin rngg lng knh c th c tng ln bng cch tng bng thng knh.

(1.1)

g

ng thng (Hz),

ung lng knh (bit/s),

ng sut tnv

ng sut nhiu.Do , i vi mt t s S/N c th (Signal to Noise:SNR), dung lng s c tng ln nu bng thng s dng truyn thng tin

c tng ln.CDMA l mt cng ngh tri ph ca tn hiu bng hp thnh tn hiurng trc khi truyn.CDMA thng c gi l Spread-Spectrum Multiple

ess (SSMA).og.2


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ca bng thng truyn v bng thng d liu c gi l li x l Gpg c gi l h s tri ph):

oc (1.2)

g Bt l bng thng truyn, Bi l bng thng ca tn hiu mang thng tin,bng thng RF v R l tc thng tin d liu.T s S/N lin quan n t s

N0, trong Eb l nng lng ca 1 bit, v N0 l mt ph cng sut nhiu, iudn n:

(1.3)

vy, i vi yu cu Eb/N0 c nh, li x l cao th t s S/N phi nh.g h thng CDMA u tin IS 95, bng thng truyn l 1,25 MHz. Trong hg WCDMA, bng thng truyn l khong 5 MHz.g CDMA, mi User c gn mt chui m duy nht (m tri ph) c

ng tri tn hiu bng hp thnh tn hiu bng rng trc khi c truyn i.vi my thu, do bit c chui m i vi mi User nn n c th gii m phci d liu ban u.

2 Tri ph v gii tri phri ph v gii tri ph l nhng hot ng c bn nht ca h thng

CDMA, c a ra hnh I.3. D liu ngi dng y c gi s l iu chK vi tc chui bit l R. Nguyn l tri ph l nhn mi bit d liu ngi dngmt chui m chu k n bit, c gi l chips. y, n=8, do h s tri ph l liu sau khi tri ph c tc l 8 R v n c cng dng ngu nhin ging nh tri ph.S gia tng tc d liu bng h s 8 tng ng vi s m rng phs dng ca tn hiu d liu ngi dng. Tn hiu bng rng sau s c

n i thng qua mt knh v tuyn n u cui nhn.


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H: L Trung Hiu Lp 05VTA1 Trang 15

h I.3 Tri ph v gii tri phg gii tri ph, tn hiu cao tn nhn c t my thu s c nhn tr li

mt chui m ging ht nh trong qu trnh tri ph.Nh c hin th trn hnh,u ngi dng ban u c phc hi hon ton. a truy xutmng truyn thng di ng l mt h thng a ngi dng, trong mt sg ln ngi s dng cng chia s chung mt ti nguyn vt l truyn v nhng tin.Kh nng a truy xut l mt trong nhng thnh phn c bn. Vic tri phiu c truyn cho mt tnh kh thi v a truy xut ca h thng CDMA. Hnha ra ba cng ngh a truy xut khc nhau l : CDMA, TDMA, FDMAh I.4 Cc cng ngh a truy xut

ng FDMA (Fequency Devision Multiple Access), cc tn hiu ca cc Usernhau c truyn trong mi knh khc nhau vi mt tn s iu ch khc nhau.g TDMA (Time Division Multiple Access), tn hiu ca cc User khc nhau c

n trong cc khe thi gian khc nhau. Vi hai cng ngh trn, s User ti a c ths cc knh vt l ng thi l c nh. Tuy nhin, trong CDMA, tn hiu ca cckhc nhau c truyn trn cng mt bng tn ti cng mt thi gian. Mi tnca User ny nh l nhiu i vi tn hiu ca User khc v do dung lng ca

hng CDMA c mi lin quan cht ch n cp nhiu: khng c s lng ti a


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nh, do , dung lng gii hn mm c a vo s dng. Hnh I.5 a ra mt v cch 3 User c th truy xut ng thi trong mt h thng CDMA.u thu, User 2 thc hin gii tri ph tn hiu thng tin ca n tr li dngiu bng hp, nhng cc User khc khng lm c. iu ny l bi mi tngcho gia m ca User ch nh v m ca cc User khc l rt nh: mch d ch

ng sut ca tn hiu ch nh v mt phn nh tn hiu t cc User khc vog bng thng thng tin.li x l, cng vi bn cht bng rng ca qu trnh x l a ra nhngch ca h thng CDMA, nh l dung lng mm v hiu sut ph cao.nhin, tt c nhng li ch ny i hi vic s dng chuyn giao mm v

khin cng sut cht ch trnh tn hiu ca mt User che khut tn hiu cakhc.iu khin cng sut v chuyn giao mm s c gii thch chi tit hn

phn sau.h I.5 Nguyn l a truy xut tri ph4 Cc c im chnh ca cng ngh WCDMADMA (Wideband CDMA) l cng ngh thng tin di ng th h ba giptc truyn nhn d liu cho h thng GSM bng cch dng k thut CDMAng bng tn rng thay th cho TDMA. Trong cc cng ngh thng tin di ng

h ba th WCDMA nhn c s ng h ln nht nh vo tnh linh hot ca lp trong vic h tr cc kiu dch v khc nhau c bit l dch v tc bit thpung bnh.

DMA c cc c im c bn sau :h thng a truy cp phn chia theo m tri ph trc tip, c tcit ln cao (ln n 2 Mbps).c chip 3,84 Mcps vi rng sng mang 5 MHz, do h tr d liu cao em li nhiu li ch nh li a phn tp.


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tr tc ngi s dng thay i lin tc. Mi ngi s dngcp mt khung, trong khung tc d liu gi c nh

ng tc c th thay i t khung ny n khung khc.tr hai m hnh v tuyn FDD v TDD. Trong m hnh FDDmang 5 MHz s dng cho ng ln v ng xung, cn trong

hnh TDD sng mang 5 MHz chia x theo thi gian gia ngv ng xung.CDMA h tr hot ng khng ng b ca cc trm gc, do ng pht trin cc trm gc va v nh.CDMA s dng tch sng c tham chiu n sng mang da trn

hoa tiu, do c th nng cao dung lng v vng ph.CDMA c thit k d dng nng cp hn cc h thng CDMAtch sng a ngi s dng, s dng anten thng minh nngdung lng v vng ph.CDMA c thit k tng thch vi GSM m rng vng ph

v dung lng ca mng.p vt l mm do d thch hp c tt c thng tin trn mt sngg.s ti s dng tn s bng 1tr phn tp pht v cc cu trc thu tin tin.

c im chnh ca W_CDMA l h thng khng cho php trong bng TDD

lin tc cng nh khng to iu kin cho cc k thut chng nhiu cc ming lm vic khc nhau.hng thng tin di ng th h ba WCDMA c th cung cp cc dch v vi bit ln n 2 Mbps. Bao gm nhiu kiu truyn dn nh truyn dn i xng vng i xng, thng tin im n im v thng tin a im. Vi kh nng , cchng thng tin di ng th h ba c th cung cp d dng cc dch v mi nh:thoi thy hnh, ti d liu nhanh, ngoi ra n cn cung cp cc dch v a

ng tin khc.Qun l ti nguyn v tuyn (RRM: Radio Resource Management) RRM trong mng di ngo Resource Management (RRM) trong mng 3G c trch nhim ci thin

s dng cc ngun ti nguyn giao tip khng gian.Cc mc tiu ca RRM c thc tm tt nh sau:m bo QoS i vi cc ng dng khc nhau.

Duy tr vng ph sng theo k hoch.i u ho dung lng h thng.


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g mng 3G, tin phn b (pre-allocating) ti nguyn v qu kch thcr-dimensioning) mng l khng kh thi bi v khng d on trc c s cnv cc yu cu khc nhau ca cc dch v khc nhau. V vy, qun l ti nguyn

uyn bao gm 2 phn: cu hnh ti nguyn v tuyn v ti cu hnh. Cu hnh tiyn v tuyn c trch nhim phn b ti nguyn mt cch hp l khi c cc yumi vo h thng mng n nh v khng ri vo tnh trng qu ti. Nhng, sghn c th xy ra trong mng 3G bi v tnh di ng ca ngi dng, ti cu hnhguyn v tuyn chu trch nhim phn b li ti nguyn trong mng khi ti tng

hoc tt nghn bt u xut hin. N c trch nhim iu chnh li h thng qu ticch nhanh chng v iu khin tr li ti mc tiu.

2 Chc nng ca RRMn l ti nguyn v tuyn c th c chia thnh cc chc nng l iu khin

sut, chuyn giao, iu khin thm nhp v iu khin ti. Hnh I.6 th hin ccin hnh ca RRM trong mng WCDMA.

h I.6 Cc v tr in hnh ca RRM trong mng WCDMA

iu khin cng sut (Power Control)u khin cng sut l mt yu t cn thit trong tt c cc h thng di ngcc vn v pin v cc l do an ton, nhng trong h thng CDMA, iu khin

sut l iu cn thit bi bn cht nhiu c gii hn trong h thng CDMA.g GSM, iu khin cng sut chm (tn s xp x 2 Hz) c trinTrong IS-95 iu khin cng sut nhanh vi tn s 800 Hz c h tr ng

nhng ng xung, mt vng iu khin cng sut tng i chm (xp x 50iu khin cng sut truyn i.Trong WCDMA, iu khin cng sut nhanh vi 1,5 kHz c h tr trong c 2 ng ln v ng xung. iu khin cngnhanh v cht ch l mt trong nhng kha cnh quan trng ca h thngDMA.


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l do s dng iu khin cng sut l khc nhau i vi ng ln vng xung. Cc mc tiu ca iu khin cng sut c th c tm tt nh sau:

Khc phc hiu ng gn xa ng lni u ho dung lng h thng bng cch iu khin nhiui a ho tui th pin ca u cui di ng

h I.7 cho thy vn gn xa hng ln. Cc tn hiu t cc MS (mobileon) khc nhau c truyn i ng thi trn cng mt bng tn trong h thngDMA. Nu khng c iu khin cng sut, tn hiu n t mt MS gn BS nht th chn cc tn hiu t cc MS khc ang xa hoc rt xa BS (Base station).g trng hp xu nht mt MS cng sut qu cao c th chn ton b cc MS

g mt cell. Gii php a ra l s dng iu khin cng sut m bo rng cciu n t cc u cui khc nhau c cng mt cng sut v SIR (Signal-to-ference Ratio) khi chng n trm gc BS.

h I.7 Hiu ng gn xa (iu khin cng sut hng ln)

ng xung, khng c vn gn xa trong vin cnh mt MS nh hngnhiu MS khc.iu khin cng sut c trch nhim b nhiu inter-cell m ccdi ng phi chu, c bit l ranh gii gia cc cell gn nhau nh trong hnh I.8.na, iu khin cng sut hng xung c nhim v gim thiu nhiu tng

gi tr QoS cho php.


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h I.8 B nhiu inter-cell (iu khin cng sut hng xung)

g hnh I.8, mobile 2 phi chu nhiu inter-cell nhiu hn mobile 1. Do ,p ng cng mt mc tiu cht lng, phn cng sut thm vo cn thit phic phn b cho cc knh hng xung gia BS v mobile 2.

kiu iu khin cng sut trong h thng WCDMA l: iu khin cngvng h, iu khin cng sut vng ng v iu khin cng sut vng ngoi.

u khin cng sut vng hu khin cng sut vng h c s dng ch FDD UMTS dnh cho

lp cng sut ban u cho di ng.Trm di ng c tnh suy hao ng truyntrm gc v trm di ng bng cch s dng mt mch iu khin li t ngC:Automatic Gain Control) o cng tn hiu nhn c.Theo c tnh suyng truyn , trm di ng c th quyt nh cng sut truyn hng ln. iun cng sut vng h c hiu qu trong h thng TDD bi v hng ln v hngng l i ng, nhng n khng phi rt hiu qu cho h thng FDD bi cc knhng ln v hng xung hot ng cc di tn khc nhau v fading Rayleigh ng ln v ng xung l c lp nhau. V vy, iu khin cng sut vng h chnh xc khng cao.V l l do ti sao n ch c s dng nh l thit lpsut ban u trong h thng FDD.

u khin cng sut vng knu khin cng sut vng kn, cng cn c gi l iu khin cng suth trong h thng WCDMA, c nhim v iu khin cng sut truyn ca MSng ln) hoc ca trm gc (hng xung) chng li fading ca knh v tuynp ng SIR mc tiu thit lp bi vng ngoi. Ly v d, hng ln, trm gc soSIR nhn c t MS vi SIR mc tiu. Nu SIR nhn c ln hn mc tiu, truyn mt lnh TPC 0 n MS thng qua knh iu khin c ch nh

ng xung. Cn nu SIR nhn c nh hn mc tiu, BS s truyn mt lnh TPCn MS.Bi v tn s ca iu khin cng sut vng kn l rt ln nn n c th b

ng nhanh cng nh fading chm.Mt v d khc hng xung, MS s cn c vo


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nhn c t BS v s iu khin cng sut t trm gc, n s iu khin cngpht ca n mt cch thch hp.

u khin cng sut vng ngoiu khin cng sut vng ngoi l cn thit duy tr cht lng ca truyng ti mc yu cu bng cch thit lp gi tr mc tiu cho iu khin cng sut

g kn. N nhm mc ch cung cp cht lng yu cu l khng xu v khngTn s ca iu khin cng sut vng ngoi in hnh l t 10-100 kHz. Hnh I.9hin cc thut ton chung ca iu khin cng sut vng ngoi.

h I.9 Thut ton chung ca iu khin cng sut vng ngoiu khin cng sut vng ngoi so snh cht lng thu c vi cht lng

cu. Thng thng cht lng c nh ngh a nh l mt BER (Bit Error Rate)FER (Fame Error Rate) mc tiu nht nh. Mi quan h gia SIR mc tiu vlng mc tiu ph thuc vo tc di ng v cu hnh a ng. Nu chtg nhn c l tt, iu c ngha l SIR mc tiu hin ti cao m boyu cu. gim thiu khong tha, SIR mc tiu s c gim. Tuy nhin, nulng thu c xu hn cht lng yu cu, SIR mc tiu cn phi c tng lnm bo yu cu v QoS.iu khin chuyn giao (Handover control)yn giao l mt phn cn thit ca cc h thng truyn thng di ng tTnh di ng l nguyn nhn dn n nhng bin ng v cht lng ng dn

mc nhiu trong h thng di ng t bo, i khi i hi mt User c th phi

i trm gc dch v ca n. V s thay i ny c gi l Chuyn Giaondover). Phn sau s trnh by chi tit hn v vn ny.iu khin thm nhp (Admission control)u ti giao tip khng gian c php tng qu mc th vng ph sng cas gim xung di gi tr mong mun ( cn c gi l t bo th) v QoS ca

kt ni ang tn ti s khng th m bo. L do ca hin tng t bo th l vng nhnt hn chtyu cuSaiSIR mc tiu Gim SIR mc tiu


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nh gii hn nhiu ca h thng CDMA. Do , trc khi nhn mt kt ni mi,khin thm nhp cn phi kim tra rng vic nhn kt ni mi s khng hi sinh

ng ph sng mc tiu hoc QoS ca cc kt ni tn ti. iu khin thm nhphp nhn hoc t chi mt yu cu thit lp mt ng bao truy xut v tuyng mng truy xut v tuyn. Chc nng ca iu khin thm nhp c t RNC,m c th thu c thng tin ti ca nhiu Cell.thut iu khin thm nhp c tnh s tng ln ca ti thit lp ng

trong mng truy xut v tuyn. c tnh ti c a vo trong c 2 hng ln vng xung. ng bao yu cu ch c th c chp nhn nu iu khin thm

trong c 2 hng chp nhn n, ngc li n s b t chi bi nhiu thm vog l qu mc.chung, cc chin lc iu khin thm nhp c th c chia thnh 2 loi

: chin lc iu khin thm nhp da trn cng sut bng rng v chin lckhin thm nhp da trn s lng a vo.

h I.10 a ra iu khin thm nhp da trn cng sut bng rng.

h I.10 ng cong ti

i s dng mi s khng c chp nhn nu kt qu mi ca mc nhiucao hn gi tr ngng:

(1.4)

::

ldoldtotalldoldtotal

dmideject


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tr ngng ging nh l mc tng ln nht ca nhiu hng ln v c thc thit lp bi quy s hoch mng v tuyn.ng chin lc iu khin thm nhp da trn s lng a vo, mt Usercu mi s khng c chp nhn vo mng truy xut v tuyn nu kt qu mii tng cao hn gi tr ngng:

(1.5)

lu rng chin lc iu khin thm nhp c p dng ring r chong ln v hng xung, cc chin lc iu khin thm nhp khc nhau c th

c s dng trong mi hng.iu khin Ti (iu khin tc nghn)nhim v quan trng ca chc nng qun l ti nguyn v tuyn l chcrng h thng khng b qu ti v vn n nh. Nu h thng ng mc tiu, vkhin thm nhp lm vic tt th tnh trng qu ti s him khi xy ra. Tuy nhin,

g mng di ng, tnh trng qu ti mt vi ni l khng th trnh khi bi tiyn v tuyn khng th c phn b trc trong mng. Khi gp phi tnh trngti th iu khin ti (cng c gi l iu khin tc nghn) s tr li h thngcch nhanh chng v iu khin tr li tnh trng ti mc tiu, c nh ngha quy hoch mng v tuyn. Cc cng vic iu khin ti gim bt hoc cnti c lit k bn di:

chi cc lnh cp ngun hng xung nhn c t MS.Gim t s Ec/N0 mong mun hng ln c s dng bi iu khin cng sut

h hng ln.hay i kch c vng chuyn giao mm cha nhiu User hn.huyn giao n mt sng mang WCDMA khc.(inter-frequency handover)huyn giao n mng chng lp khc(mng UMTS hoc mng GSM khc)

Gim tc bit ca ngi s dng thi gian thc, v d m ho thoi AMR.Gim lu lng d liu gi vo (dch v khng thi gian thc).

t cuc gi trong cch iu khin.cng vic u tin trong danh sch l 2 thao tc nhanh c thc hin trong2 thao tc c th t trong 1 khe thi gian,vi tn s 1,5 kHz v cung cp u

cho cc dch v khc nhau. Gii php th 3, thay i kch c vng chuyn giaom c bit hu dng trong mng gii hn hng xung v s c tho lun r hnc chng sau.thao tc iu khin ti khc c trng chm hn.Chuyn giao inter-uency v chuyn giao inter-system c th khc phc tnh trng qu ti bng cchldoldtotalldoldtotal

midect

:


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bng ti.Thao tc cui cng l rt User thi gian thc (thoi hoc User d liun mch knh) gim ti. Cng vic ny ch c a vo nu ti ca ton bg vn rt cao ngay c khi a vo cc thao tc iu khin ti khc gim quGiao tip khng gian WCDMA v s gia tng d kin ca lu lng khng thithc trong mng th h th 3 a ra mt s la chn ln v cc thao tc c th

tnh trng qu ti, v v vy vic gim ti bng cch thc hin rt User thi gianl rt him khi.


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NG II: CHUYN GIAO TRONG H THNG 3G WCDMA

Tng quan v chuyn giao trong mng di ngg mng di ng cc thu bao c th truy nhp dch v khi ang di chuynni cch khc mng di ng cung cp tnh t do cho thu bao trong mt phm dig nht nh. Tuy nhin, tnh t do ny mang n s khng chc chn trong hg di ng. Tnh di ng ca cc thu bao l nguyn nhn dn n nhng bin ngg c cht lng ng dn v mc nhiu, i khi i hi rng mt thu bao chi thay i trm gc dch v ca n. V thao tc ny c gi l chuyn giao

ndover:

yn giao l mt thnh phn thit yu i ph vi tnh di ng ca thuN m bo tnh lin tc ca cc dch v khng dy khi thu bao di ng din qua cc ranh gii t bo.

ng h thng di ng t bo th h th nht nh AMPS, chuyn giao l tngn gin. Trong h thng di ng th h th 2 nh GSM v PACS th chuyn giaoc a ln mt mc cao hn nhiu hnh thc bao gm cc gii thut c sg. Phc tp hn, cc th tc quyt nh chuyn giao v x l tn hiu c tchtrong nhng h thng ny v s tr hon quyt nh chuyn giao cng c gim

u ng k. T lc cng ngh CDMA c gii thiu, mt tng khc c ci tin qu trnh chuyn giao, l chuyn giao mm v y l cng vic

g tm trong lun n ny. Cc kiu chuyn giao trong h thng 3G WCDMAkiu chuyn giao khc nhau trong mng di ng WCDMA. l:

yn giao trong cng mt h thng ( Intra-system HO )yn giao trong cng h thng c th c chia thnh chuyn giao cng tn chuyn giao khc tn s. Chuyn giao cng tn s xut hin gia cc cell thuc

sng mang WCDMA. Chuyn giao khc tn s xut hin gia cc cell hot ngcc tn s sng mang khc nhau.

yn giao ngoi h thng ( Inter-system HO )yn giao ngoi h thng xut hin gia cc Cell thuc 2 cng ngh truyv tuyn (RAT) khc nhau hoc cc ch truy xut khc nhau. Trng hp

c mong i thng gp nht trong kiu th nht l gia h thng WCDMA vM/EDGE. Chuyn giao gia cc h thng CDMA khc nhau cng thuc kiu

n giao ny. Ly mt v d v chuyn giao gia cc ch truy xut khc nhau a UTRA FDD v UTRA TDD.

yn giao cng ( Hard Handover:HHO )


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yn giao cng l mt th loi ca cc th tc chuyn giao, trong tt ckt ni c ca mt trm di ng c gii phng trc khi mt kt ni mi clp. i vi cc knh yu cu thi gian thc th n c ngha l ngt mt kt nica knh, cn i vi cc knh khng yu cu thi gian thc th HHO c ngha l

ng tn hao. Chuyn giao cng c th t trong kiu chuyn giao cng tn s hoctn s.

yn giao mm ( SHO ) v chuyn giao mm hn ( Softer HO )yn giao mm l chuyn giao gia hai BS khc nhau, cn chuyn giao mml chuyn giao gia t nht 2 sector ca cng mt BS. Trong sut qu trnh chuyn

mm, MS giao tip mt cch tc th vi hai (chuyn giao hai ng) hoc nhiuca cc BS khc nhau thuc cng RNC (Intra-RNC) hoc cc RNC khc nhaur-RNC). Trn ng xung my di ng nhn hai tn hiu vi t s kt hp ln ng ln, knh m ho di ng c pht hin bi c hai BS (chuyn giao hai

ng), v c gi n RNC cho vic la chn kt hp. Hai vng iu khin cngtch cc tham gia vo qu trnh chuyn giao mm, mi vng cho mt BS. Trongng hp chuyn giao mm hn, MS c iu khin t nht bi hai sector ca cngdo RNC khng c tham gia v ch c mt vng iu khin cng sut tchChuyn giao mm v mm hn ch s dng mt sng mang, do chng l cctrnh chuyn giao trong cng mt tn s.

h II.1 cho thy mt vi vin cnh ca cc loi chuyn khc nhau.

h II.1 Cc vin cnh ca cc kiu chuyn giao khc nhau2 Cc mc tiu ca chuyn giaoyn giao c th c bt u trong 3 cch khc nhau l: bt u t thudi ng, bt u t mng v h tr thu bao.


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t u t thu bao: thu bao thc hin cc php o v cht lng, latrm gc tt nht, v chuyn mch, vi s iu phi ca mng. Kiun giao ny thng c kch hot bi cc lin kt km cht lng

c o t thu bao.t u t mng: Trm gc thc hin cc php o v bo co v RNC t nh c nn chuyn giao hay khng. Ngoi iu khin ng dn vn, chuyn giao bt u t mng cn c thc hin bi nhng l dohn, v d nh iu khin s phn phi lu lng gia cc Cell.

ng hn nh chuyn giao v l do lu lng c iu khin bi trm(TRHO). Nu ti ca Cell ngun vt qu mc cho php, v ti caCell ln cn thp hn mt mc cho php khc, th khi Cell ngun s

hp vng ph sng ca n, chuyn giao mt s lu lng n Cell lnV vy, t l chn tng th c th gim, dn n vic s dng ti

yn Cell tt hn.H tr thu bao: y mng v thu bao u thc hin cc php o. Thubo co cc kt qu o lng t nhng trm gc gn v mng shin quyt nh c nn chuyn giao hay khng.mc tiu ca chuyn giao c th c tm tt nh sau:m bo tnh lin tc ca cc dch v khng dy khi cc thu bao di

g di chuyn qua cc ranh gii ca Cell.Gi QoS c yu cuGim ti a mc nhiu ca ton h thng

huyn vng gia cc mng khc nhauhn phi ti t cc khu vc im nng.(Cn bng ti)yu t c th c s dng khi xng qu trnh chuyn giao c l:lng ng dn (hng ln hoc hng xung), s thay i dch v, thay i tc

v cc l do lu lng hoc s can thip ca O&M (Operation and Maintenance). Cc th tc v php o chuyn giaotc chuyn giao c th c chia thnh ba giai on: o lng, quyt nh

hc hin, c minh ho trong hnh II.2.g giai on o lng chuyn giao, cc thng tin cn thit thc hint nh chuyn giao c o. hng xung, trm di ng thc hin cc php o

o t s Ec/I0 ca knh hoa tiu chung (CPICH: Common Pilot Channel) ca Cellv ca n v cc Cell ln cn. i vi mt s loi chuyn giao no , cc phphc l ht sc cn thit. Ly v d trong mng bt ng b nh UTRA FDDDMA), thng tin nh thi tng i gia cc Cell cn c o iu chnhthi truyn trong chuyn giao mm cho php 1 s kt hp cht ch my thu


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e. Tuy nhin, vic truyn dn t cc trm gc khc nhau s rt kh kt hp vbit l hot ng iu khin cng sut trong chuyn giao mm s b tr hon thm.

h II.2 Cc th tc chuyn giaog giai on quyt nh chuyn giao, cc kt qu o lng c so snh vi

ng c xc nh trc v sau n quyt nh c bt u thc hin chuynhay khng. Cc gii thut chuyn giao khc nhau s c cc iu kin kch hot

nhau.g giai on thc hin, qu trnh chuyn giao c hon thnh v cc thngn quan cng c thay i tu theo cc kiu chuyn giao khc nhau. V d, trongon thc hin ca chuyn giao mm, khi trm di ng vo hoc ri b trng thin giao mm th mt trm gc mi s c a vo hoc gii phng, cc ci tcc c cp nht v cng sut ca mi knh tham gia vo qu trnh chuyn giao

m c iu chnh.Chuyn giao mm (SHO)yn giao mm c gii thiu bi cng ngh CDMA. So vi tiu chunn giao cng th chuyn giao mm c mt s u im li th hn. Tuy nhin, nc nhng nhc im nh s phc tp v s tiu th ngun ti nguyn b sung.

quy hoch tng ph Chuyn giao mm (soft handover overhead) l mt trongng thnh phn c bn ca vic quy hoch v ti u ho mng v tuyn. Trong phns trnh by cc nguyn l c bn ca chuyn giao mm.

ng thng tin cn thit quyt nhn giao.(vd: Ec/I0 ca knh CPICH cach v v cc Cell ln cn,thng tinhi tng i gia cc Cell.iu chunn giaothnh qu trnh chuyn giao.ht cc thng s lin quan.

on o lngon quyt nhon thc hin


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Nguyn l ca chuyn giao mm

yn giao mm khc vi qu trnh chuyn giao cng truyn thng. Vin giao cng, mt quyt nh xc nh c thc hin chuyn giao hay khngn giao v trm di ng ch truyn thng vi mt trm gc ti thi gian . Cn

chuyn giao mm, mt quyt nh c iu kin c thc hin quyt nh cn giao hay l khng. Tu thuc vo nhng thay i ca cng tn hiu knh

tiu t 2 hoc nhiu trm gc tham gia vo qu trnh, mt quyt nh tt nht cuis c thc hin truyn thng vi mt v ch mt trm gc m thi. V iu

thng xy ra sau khi chc chn rng tn hiu n t trm gc c chn mnh

tn hiu n t cc trm gc khc. Trong chu k chuyn tip ca qu trnh chuynmm, trm di ng truyn thng ng thi vi tt c trm gc ang kt ni vi

S khc nhau gia chuyn giao cng v chuyn giao mm ging nh s khc nhaucc cuc thi bi tip sc v chy tip sc. Chuyn giao cng xy ra ti mt imgian, trong khi chuyn giao mm ko di trong mt chu k thi gian.h II.3 a ra qu trnh c bn ca chuyn giao cng v chuyn giao mm

ng hp 2 ng). Gi s c mt u cui di ng bn trong chic xe hi din t Cell 1 n Cell 2, BS1 l trm gc ban u ca trm di ng. Trong khi din, trm di ng o ng thi cng tn hiu knh hoa tiu nhn c t ccgc ln cn. Vi chuyn giao cng a ra hnh II.3(a), vic kch hot c m

n gin nh sau:

ilot_Ec/I0)2 (pilot_Ec/I0)1 > D v BS1 l BS dch vHandover to BS2

Do not handover

ng t_Ec/I0)1

t_ Ec/I0)2

lt l t s Ec/I0 knh hoa tiuc t BS1 v BS2; D l s d tr tr.


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h II.3 S so snh gia chuyn giao cng v chuyn giao mmdo gii thiu s d tr tr D trong gii thut chuyn giao cng l trnhng ca hin tng -ponghin tng m khi trm di ng di chuyn

g v ngoi bin gii ca Cell, th qu trnh chuyn giao cng thng xut hin.i tnh di ng ca thu bao, hin tng fading ca knh v tuyn cng lm chong -pongng tr nn nghim trng hn. Bng vic gii thiu s d tr

D, tc ng ca ping-pong s gim nh hn bi khi trm di ng s khngn giao ngay n trm gc tt hn. S d tr cng ln th tc ng ca hin tngg-pong cng gim. Tuy nhin, nu s d tr ln th iu cng ng ngha vi hon tng. Hn na, trm di ng cng gy thm nhiu i vi cc Cell ln cnc kt ni cht lng km sut trong thi gian tr hon. Do , i vi chuyncng th s d tr tr D l kh quan trng. Khi qu trnh chuyn giao cng xut kt ni lu lng ban u vi BS1 s b rt trc khi thit lp mt kt ni mi

BS2 v cng v l do m ta ni chuyn giao cng l mt qu trnh Break beforee c ngha l ngt trc khi ni.ng trng hp chuyn giao mm, c a ra hnh II.3(b), trc khit_ Ec/I0)2

qut_Ec/I0)1cn iu kin kch hot chuyn giao mmc tho mn th trm di ng s vo trng thi chuyn giao mm v mt kt ni mic thit lp. Trc khi BS1 b rt (iu kin rt chuyn giao c tho mn) th

di ng s truyn thng ng thi vi c

vy, khng ging nhn giao cng, chuyn giao mm l mt qu trnh ni trc ngt sau hay ngi

n gi l make before break. Cho n nay, mt s thut ton c xut


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chuyn giao mm v cc tiu chun khc nhau c s dng trong cc thutkhc nhau.trnh chuyn giao mm l khng ging nhau trong cc hng truyn khc. Hnh II.4 minh ho cho iu . hng ln, trm di ng truyn tn hiu n

ng gian thng qua ngten ng hng ca n. Hai trm gc ang kt ni vi n cnhn c tn hiu mt cch ng thi bi h s ti s dng tn s ca mt trongng h thng CDMA. Sau , nhng tn hiu ny s c truyn thng ti RNC hin kt hp la chn. Khung no tt hn s c chn v khung kia s b b i.

, hng ln, khng c knh b sung cn thit h tr cho qu trnh chuynmm.

h II.4 Nguyn l chuyn giao mm (trng hp 2 ng)

ng xung, c 2 BS s cng truyn cc tn hiu ging nhau n trm dig, v khi trm di ng nhn thy chng th n c th kt hp mt cch d dng cciu ny. Thng thng, chin lc kt hp t l ti a s c s dng cungmt li ch b sung c gi l phn tp a dng. Tuy nhin, h tr cho qu

chuyn giao hng xung th cn t nht mt knh hng xung b sung (SHOng). Knh hng xung b sung ny tc ng n cc User khc ging nhu b sung trong giao tip khng gian. V vy, h tr cho qu trnh chuyn giao

m hng xung th yu cu phi c thm ti nguyn. V kt qu l, hng

ng, hiu sut ca qu trnh chuyn giao mm ph thuc vo s cn bng gia hn tp a dng (macrodiversity) v s tiu th ngun ti nguyn b sung.

2 Thut ton chuyn giao mmt ton c mt tm nh hng ln n hiu sut ca qu trnh chuyn giao

m. Hnh II.5 a ra thut ton chuyn giao mm ca IS-95A (cng cn c gi lt ton CDMAone c bn)


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h II.5 Thut ton chuyn giao mm ca IS-95Ag hnh

he Active set (Tp tch cc): l danh sch cc Cell m hin ang kt nirm di ng.The Candidate set (Tp ng c): l danh sch cc Cell m hin khng

c s dng trong kt ni chuyn giao mm, nhng cc gi tr Ec/I0pilot ca chng l mnh c b sung vo tp tch cc.

The neighbouring set ( Tp ln cn): l danh sch cc Cell m tram dig o lng lin tc, nhng cc gi tr Ec/I0 knh pilot ca chngng mnh b sung vo tp tch cc.g IS-95A, ngng chuyn giao l mt gi tr Ec/I0 c nh nhn c thoa tiu. N rt d thc hin, nhng li gp nhiu kh khn khi phi i mt vi

ng thay i ti ng. Da trn thut ton IS-95A, nhiu bin i ca thut tonaOne vi tnh nng ng hn ngng c nh c xut cho h thng IS-v cdma2000.g WCDMA s dng cc thut ton phc tp hn, c minh ho nh trnII.6


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h II.6 Thut ton chuyn giao mm WCDMA

t ton chuyn giao mm WCDMA c th c m t nh sau:

u.c 1 v 2 nm trong tp tch cc

s kin A/I0)P-CPICH3 > (Ec/I0)P-CPICH1 - (R1a-H1a/2)

g (Ec/I0)P-CPICH1 l t s tn hiu trn nhiu knh hoa tiu camnh nht, (Ec/I0)P-CPICH3 l t s tn hiu trn nhiu knh hoaca 3 nm ngoi tp tch cc v R1a l hng s di bo co (do

C thit lp, H1a/2 l thng s tr v (R1a-H1a/2) l ca s kt nps kin 1a. Nu bt ng thc ny tn ti trong khong thi gian T3 c kt np vo tp tch cc

s kin C

/I0)P-CPICH4 > (Ec/I0)P-CPICH2 +H1c/2, trong I0)PCPICH4 l t s tn hiu trn nhiu ca 4 nm ngoi tp tchv (Ec/I0)PCPICH2 l t s tn hiu trn nhiu ca 2 ti nht trongch cc, H1C l thng s tr. Nu quan h ny tn ti trong thi gianv tp tch cc y th 2 b loi ra khi tp tch cc v 4 s thca n trong tp tch cc

s kin B/I0)P-CPICH1 < (Ec/I0)P-CPICH3- (R1b+H1b/2)

g (Ec/I0)P-CPICH1 l t s tn hiu trn nhiu knh hoa tiu cayu nht trong tp tch cc, (Ec/I0)P-CPICH3 l t s tn hiu trn

u ca 3 mnh nht trong tp tch cc, R1b hng s di bo co (doC thit lp), H1b/2 l thng s tr v (R1b+H1b/2) l ca s loi cho


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n 1B. Nu quan h ny tn ti trong khong thi gian T th 3 bra khi tp tch ccng thut ton WCDMA, ngi ta s dng ngng tng i ch khng sg ngng tuyt i. So vi IS-95A, li ch ln nht ca gii thut ny l s biutham s mt cch d dng, v nh c cc gi tr ngng tng i nn khng yu

bt k mt s thay i tham s no i vi cc khu vc c nhiu cao v thp.ht cng vic trong lun n ny u da trn thut ton chuyn giao mm

MDA. c im ca chuyn giao mm

i chuyn giao cng truyn thng th chuyn giao mm cho thy nhng um r rng hn, v d nh l loi b hin tng ping pong v lm cho ngn dn lin tc hn, khng b gy khc. Khng c hin tng ping pong ca l s lng ti trn mng bo hiu thp hn v vi chuyn giao mm cng s

ng b mt d liu do s ph v truyn dn tm thi (xy ra trong chuyn giaog).i l do x l tnh di ng ca thu bao, cn c mt l do khc na thcchuyn giao mm trong CDMA; l s dng n nh mt c ch gim nhiuc thc hin cng vi iu khin cng sut). Hnh II.7 a ra 2 vin cnh. vinth nht (hnh a), iu khin cng sut c s dng. vin cnh th 2 (hnh b),khin cng sut v chuyn giao mm u c h tr. Gi s rng trm di ngdi chuyn t BS1 n BS2. Ti v tr ang xt, tn hiu nhn c t BS2 mnh

t BS1 iu ny c ngha l BS2 tt hn BS1.


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h II.7 Gim nhiu hng ln bng cch s dng SHOnh (a), vng iu khin cng sut lm tng cng sut truyn ca trm dig m bo QoS hng ln khi trm di ng di chuyn ra xa trm gc dch vn (BS1). hnh (b), trm di ng ang trong trng thi chuyn giao mm v c 2gc truyn thng mt cch ng thi vi trm di ng, cc tn hiu thu c sau

c trm gc truyn thng ti RNC thc hin kt hp. hng ln, vic ktla chn c s dng trong chuyn giao mm, khung no mnh nht s c

v khung yu hn s b xo b i. Bi v BS2 tt hn BS1 nn t c cngQoS mong mun th yu cu cng sut truyn ca trm di ng hnh (b) phihn so vi hnh (a). V vy, nhiu gp vo h thng bi trm di ng hng lnp hn bi qu trnh chuyn giao mm lun lun gi cho trm di ng lin kt vit nht. hng xung th c v phc tp hn, mc d t l kt hp ti a ra li v phn tp a dng nhng cng cn thit phi h tr thm knh hng

ng b sung vo qu trnh chuyn giao mm.h tm tt cc c im chnh ca chuyn giao mm nh sau:

u imm hin tng ping-pong, t dn ti gim tng ph v s lng

n mng bo hiu


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uyn dn lin tc, khng xy ra gin on sut trong qu trnh chuyn

mm.ng c s d tr tr, dn ti tr hon thp hn.m nhiu hng ln, dn n: cht lng truyn thng tt hn cho mt

ng ngi dng nht nh ng thi tng s lng ngi dng vimt Qos yu cu.

c rng buc v thi gian trn mng t hn, iu ny c ngha l thi

xp hng c c mt knh mi t BS mong mun s di hn,cho xc sut chn v rt cuc gi gim i.

Nhc imc tp hn trong vic thc hin qu trnh chuyn giao cngn phi b sung thm ngun ti nguyn mng hng xung ( ti

yn v m v cng sut )


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NG III : PHN TCH HIU SUT CP NG DN VP H THNG

Phn tch hiu sut cp ng dn Phn tch nhiu hng xung

g quan cp trong chng 1, cc h thng CDMA l cc h thng gii hnu v do vic nh gi nhiu l mt trong nhng th tc c bn phn tch hg CDMA. Nhiu tng c tri nghim bi trm di ng c th c chia thnh 2 l : nhiu trong cng mt Cell(intra-Cell) v nhiu gia cc Cell khc(inter-Cell).ng ln, xt mt trm di ng no th nhiu intra-Cell n t tt cng trm di ng khc c phc v bi cng mt trm gc; i vi nhiu inter-th bao gm tt c nhng tn hiu thu c t tt c cc trm di ng trong ccln cn khc ngoi tr Cell dch v ca trm di ng. Do , hng ln, nhiun quan n vic phn phi ti trong mng ch khng lin quan n v tr cah trm di ng .

h III.1 Nhiu hng lnng xung, c a ra trn hnh III.2, nhiu intra-Cell ca mt trm dig no n t chnh trm gc dch v ca n: loi nhiu ny l do mt mt phn

trc giao gia cc User do hiu ng a ng. WCDMA s dng cc m trc giaonhau hng xung i vi cc User ring bit v khng c bt k mt s lann a ng no cng nh khng c nhiu intra-Cell khi tnh trc giao vn cn.ng thng, tnh trc giao nm gia 0,4 n 0,9 (trng hp l tng l bng 1).u intra-Cell trong thc t bao gm mt phn cng sut ca cc knh iu khing v cc knh lu lng hng xung i vi cc User khc trong cng mt Cell.u inter-Cell l cng sut nhn c ca trm di ng t tt c cc trm gc ln

khc ngoi tr trm gc dch v ca n. Bi v trong ch FDD WCDMA, cc

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