Kiến Trúc 3g Wcdma Umts r5 Và r6

KIN TRC 3G WCDMA UMTS R5 v R6

Bc pht trin tip theo ca UMTS l a ra kin trc mng a phng tin IP (hnh 1.11). Bc pht trin ny th hin s thay i ton b m hnh cuc gi. y c ting v s liu c x l ging nhau trn ton b ng truyn t u cui ca ngi s dng n ni nhn cui cng. C th coi kin trc ny l s hi t ton din ca ting v s liu.

Hnh 1.11. Kin trc mng 3GPP R5 v R6

im mi ca R5 v R6 l n a ra mt min mi c gi l phn h a phng tin IP (IMS: IP Multimedia Subsystem). y l mt min mng IP c thit k h tr cc dch v a phng tin thi gian thc IP. T hnh 1.11 ta thy ting v s liu khng cn cc giao din cch bit; ch c mt giao din Iu duy nht mang tt c phng tin. Trong mng li giao din ny kt cui ti SGSN v khng c MGW ring.

Phn h a phng tin IP (IMS) cha cc phn t sau: Chc nng iu khin trng thi kt ni (CSCF: Connection State Control Function), Chc nng ti nguyn a phng tin (MRF: Multimedia Resource Function), chc nng iu khin cng cc phng tin (MGCF: Media Gateway Control Function), Cng bo hiu truyn ti (T-SGW: Transport Signalling Gateway) v Cng bo hiu chuyn mng (R-SGW: Roaming Signalling Gateway).

Mt nt quan trng ca kin trc ton IP l thit b ca ngi s dng c tng cng rt nhiu. Nhiu phn mm c ci t UE. Trong thc t, UE h tr giao thc khi u phin (SIP: Session Initiation Protocol). UE tr thnh mt tc nhn ca ngi s dng SIP. Nh vy, UE c kh nng iu khin cc dch v ln hn trc rt nhiu.

CSCF qun l vic thit lp , duy tr v gii phng cc phin a phng tin n v t ngi s dng. N bao gm cc chc nng nh: phin dch v nh tuyn. CSCF hot ng nh mt i din Server /h tch vin.

SGSN v GGSN l cc phin bn tng cng ca cc nt c s dng GPRS v UMTS R3 v R4. im khc nhau duy nht l ch cc nt ny khng ch h tr dch v s liu gi m c dch v chuyn mch knh (ting chng hn). V th cn h tr cc kh nng cht lng dch v (QoS) hoc bn trong SGSN v GGSN hoc t nht cc Router kt ni trc tip vi chng.

Chc nng ti nguyn a phng tin (MRF) l chc nng lp cu hi nghi c s dng h tr cc tnh nng nh t chc cuc gi nhiu pha v dch v hi ngh .

Cng bo hiu truyn ti (T-SGW) l mt cng bo hiu SS7 m bo tng tc SS7 vi cc mng tiu chun ngoi nh PSTN. T-SGW h tr cc giao thc Sigtran. Cng bo hiu chuyn mng (R-SGW) l mt nt m bo tng tc bo hiu vi cc mng di ng hin c s dng SS7 tiu chun. Trong nhiu trng hp T-SGW v R-SGW cng tn ti trn cng mt nn tng.

MGW thc hin tng tc vi cc mng ngoi mc ng truyn a phng tin. MGW kin trc mng ca UMTS R5 c chc nng ging nh R4. MGW c iu khin bi Chc nng cng iu khin cc phng tin (MGCF). Giao thc iu khin gia cc thc th ny l ITU-T H.248.

MGCF cng lin lc vi CSCF. Giao thc c chn cho giao din ny l SIP.

Tuy nhin c th nhiu nh khai thc vn s dng n kt hp vi cc min chuyn mch knh trong R3 v R4. iu ny cho php chuyn i dn dn t cc phin bn R3 v R4 sang R5. Mt s cc cuc gi thoi c th vn s dng min CS mt s cc dch v khc chng hn video c th c thc hin qua R5 IMS. Cu hnh lai ghp c th hin trn hnh 1.12.

Hnh 1.12. Chuyn i dn t R4 sang R5

1.9. CHIN LC DCH CHUYN T GSM SANG UMTS

Trong phn ny ta s xt chin lc dch chuyn t GSM sang UMTS ca hng Alcatel. Alcatel d kin pht trin RAN t GSM ln 3G UMTS theo ba pht hnh: 3GR1, 3GR2 v 3GR3. Vi mi pht hnh, cc sn phm mi v cc tnh nng mi c a ra.

1.9.1. 3GR1 : Kin trc mng UMTS chng ln

Pht hnh 3GP1 da trn pht hnh ca 3GPP vo thng 3 v cc c t k thut vo thng 6 nm 2000. Pht hnh u ca 3GR1 ch h tr UTRA-FDD v s c trin khai chng ln ln GSM. Chin lc dch chuyn t GSM sang UMTS pht hnh 3GR1 c chia thnh ba giai on c k hiu l R1.1, R1.2 v R1.3 (R: Release: pht hnh). Trong cc pht hnh ny cc phn cng v cc tnh nng mi c a ra. Cc nt B c gi l MBS (Multistandard Base Station: trm gc a tiu chun). Tuy nhin MBS V1 ch n thun l nt B, ch MBS V2 mi thc s a tiu chun v cha cc chc nng ca c nt B v BTS trong cng mt hp my. Tng t RNC V2 v OMC-R V2 c a ra phc v cho c UMTS v GSM.

Hnh 1.13 cho thy kin trc ng tn ti GSM v UMTS c pht trin trong giai on trin khai UMTS ban u (3GR1.1).

Hnh 1.13. Kin trc ng tn ti GSM v UMTS (pht hnh 3GR1.1)

1.9.2. 3GR2 : Tch hp cc mng UMTS v GSM

Trong giai on trin khai UMTS th hai s tch hp u tin gia hai mng s c thc hin bng cch a ra cc thit b a tiu chun nh: Nt B kt hp BTS (MBS V2) v RNC kt hp BSC (RNC V2). Cc chc nng khai thc v bo dng mng v tuyn cng c th c thc hin chung bi cng mt OMC-R (V2). Hnh 1.14 m t kin trc mng RAN tch hp ca giai on hai.

Hnh 1.14. Kin trc mng RAN tch hp pht hnh 3GR2 (R2.1).

1.9.3. 3GR3 : Kin trc RAN thng nht

Trong kin trc RAN ca pht hnh ny c xy dng trn c s pht hnh R5 vo thng 9 nm 2000 ca 3GPP. Trong pht hnh ny RAN chung cho c h thng UMTS v GSM. C UTRA-FDD v UTRA-TDD u c h tr. Giao thc truyn ti c thng nht cho GSM, E-GPRS v UMTS, ngoi ra c th ATM kt hp IP. GERAN (GSM/EDGE RAN) cng s c h tr bi pht hnh ny ca mng. Kin trc RAN ca 3GR1.3 c th hin trn hnh 1.15.

Hnh 1.15. Kin trc RAN thng nht ca 3GR3.11.10. CU HNH A L CA H THNG THNG TIN DI NG 3G

Do tnh cht di ng ca thu bao di ng nn mng di ng phi c t chc theo mt cu trc a l nht nh mng c th theo di c v tr ca thu bao.

1.10.1. Phn chia theo vng mng

Trong mt quc gia c th c nhiu vng mng vin thng, vic gi vo mt vng mng no phi c thc hin thng qua tng i cng. Cc vng mng di ng 3G c i din bng tng i cng GMSC hoc GGSN. Tt c cc cuc gi n mt mng di ng t mt mng khc u c nh tuyn n GMSC hoc GGSN. Tng i ny lm vic nh mt tng i trung k vo cho mng 3G. y l ni thc hin chc nng hi nh tuyn cuc gi kt cui trm di ng. GMSC/GGSN cho php h thng nh tuyn cc cuc gi vo t mng ngoi n ni nhn cui cng: cc trm di ng b gi.1.10.2. Phn chia theo vng phc v MSC/VLR v SGSN

Mt mng thng tin di ng c phn chia thnh nhiu vng nh hn, mi vng nh ny c phc v bi mt MSC/VLR (hnh 1.16a). hay SGSN (1.16b) Ta gi y l vng phc v ca MSC/VLR hay SGSN.

Hnh 1.16. Phn chia mng thnh cc vng phc v ca MSC/VLR v SGSN

nh tuyn mt cuc gi n mt thu bao di ng, ng truyn qua mng s c ni n MSC ang phc v thu bao di ng cn gi. mi vng phc v MSC/VLR thng tin v thu bao c ghi li tm thi VLR. Thng tin ny bao gm hai loi:

Thng tin v ng k v cc dch v ca thu bao.

Thng tin v v tr ca thu bao (thu bao ang vng nh v hoc vng nh tuyn no).

1.10.3. Phn chia theo vng nh v v vng nh tuyn

Mi vng phc v MSC/VLR c chia thnh mt s vng nh v: LA (Location Area) (hnh 1.17a). Mi vng phc v ca SGSN c chia thnh cc vng nh tuyn (RA: Routing Area) (1.17b).

Hnh 1.17. Phn chia vng phc v ca MSC/VLR v SGSN thnh cc vng nh v (LA: Location Area) v nh tuyn (RA: Routing Area)

Vng nh v (hay vng nh tuyn l mt phn ca vng phc v MSC/VLR (hay SGSN) m mt trm di ng c th chuyn ng t do v khng cn cp nht thng tin v v tr cho MSC/VLR (hay SGSN) qun l v tr ny. C th ni vng nh v (hay vng nh tuyn) l v tr c th nht ca trm di ng m mng cn bit nh tuyn cho mt cuc gi n n. vng nh v ny thng bo tm s c pht qung b tm thu bao di ng b gi. H thng c th nhn dng vng nh v bng cch s dng nhn dng vng nh v (LAI: Location Area Identity) hay nhn dng vng nh tuyn (RAI Routing Area Identity). Vng nh v (hay vng nh tuyn) c th bao gm mt s v thuc mt hay nhiu RNC, nhng ch thuc mt MSC (hay mt SGSN).

1.10.4. Phn chia theo

Vng nh v hay vng nh tuyn c chia thnh mt s (hnh 1.18).

Hnh 1.18. Phn chia LA v RA l mt vng ph v tuyn c mng nhn dng bng nhn dng ton cu (CGI: Cell Global Identity). Trm di ng nhn dng bng m nhn dng trm gc (BSIC: Base Station Identity Code). Vng ph ca cc thng c m phng bng hnh lc gic tin cho vic tnh ton thit k.

1.10.5. Mu

Mu c hai kiu: v hng ngang (omnidirectional) v phn on (sectorized). Cc mu ny c cho trn hnh 1.19.

Hnh 1.19. Cc kiu mu

v hng ngang (hnh 1.19a) nhn c t pht x ca mt anten c bp sng trn trong mt ngang (mt phng song song vi mt t) v bp sng c hng chc xung mt t trong mt ng (mt phng vung gc vi mt t). phn on (hnh 1.19b) l nhn c t pht x ca ba anten vi hng pht x cc i lch nhau 1200. Cc anten ny c bp sng dng na s 8 trong mt ngang v trong mt ng bp sng ca chng chc xung mt t. Trong mt s trng hp phn on c th c to ra t pht x ca nhiu hn ba anten. Trong thc t mu c th rt a dng ty vo a hnh cn ph sng. Tuy nhin cc mu nh trn hnh 1.19 thng c s dng thit k cho s ph sng chun.

1.10.6. Tng kt phn chia vng a l trong cc h thng thng tin di ng 3G

Trong cc kin trc mng bao gm c min chuyn mch knh v min chuyn mch gi, vng phc mng khng ch c phn chia thnh cc vng nh v (LA) m cn c phn chia thnh cc vng nh tuyn (RA: Routing Area). Cc vng nh v (LA: Location Area) l khi nim qun l di ng ca min CS k tha t mng GSM. Cc vng nh tuyn (RA: Routing Area) l cc thc th ca min PS. Mng li PS s dng RA tm gi. Nhn dng thu bao P-TMSI (Packet- Temporary Mobile Subsscriber Identity: nhn dng thu bao di ng gi tm thi) l duy nht trong mt RA.

Trong mng truy nhp v tuyn, RA li c chia tip thnh cc vng ng k UTRAN (URA: UTRAN Registration Area). Tm gi khi xng UTRAN s dng URA khi knh bo hiu u cui c thit lp. URA khng th nhn thy c bn ngoi UTRAN.

Quan h gia cc vng c phn cp nh cho hnh 1.20 ( khng c th hin). LA thuc 3G MSC v RA thuc 3G SGSN. URA thuc RNC. Theo di v tr theo URA v trong UTRAN c thc hin khi c kt ni RRC (Radio Resource Control: iu khin ti nguyn v tuyn) cho knh bo hiu u cui. Nu khng c kt ni RRC, 3G SGSN thc hin tm gi v cp nht thng tin v tr c thc hin theo RA.

Hnh 1.20. Cc khi nim phn chia vng a l trong 3G WCDMA UMTS.

1.11. TNG KT

Chng ny trc ht xt tng quan qu trnh pht trin thng tin di ng ln 4G. Nu cng ngh a truy nhp cho 3G l CDMA th cng ngh a truy nhp cho 4G l OFDMA. Sau kin trc mng 3G c xt. Mng li 3G bao gm hai vng chuyn mch: (1) vng chuyn mch cc dch v CS v (2) vng chuyn mch cc dch v PS. Cc pht hnh nh du cc mc quan trng pht trin mng 3G WCDMA UMTS c xt: R3, R4, R5 v R6. R3 bao gm hai min chuyn mch knh v chuyn mch gi trong kt ni gia cc nt chuyn mch gi l TDM (ghp knh theo thi gian). R4 l s pht trin ca R3 trong min chuyn mch knh chuyn thnh chuyn mch mm v kt ni gia cc nt mng bng IP. R5 v R6 h tr cc dch v a phng tin IP hon ton da trn chuyn mch gi. p ng c nhim v ny ngoi min chuyn mch gi, mng c b sung thm phn h a phng tin IP (IMS). Ct li ca IMS l CSCF thc hin khi u kt ni a phng tin IP da trn giao thc khi u phin (SIP Session Initiation Protocol). Ngoi ra IMS vn cn cha chuyn mch mm h tr dch v chuyn mch knh (MGCF). Hin nay mng 3GWCDMA UMTS ang giai don chuyn dn t R4 sang R5 (hnh 1.12). Cui chng trnh by cu trc a l ca mt mng thng tin di ng 3G c cha c vng chuyn mch knh v vng chuyn mch gi.Chng 2

CNG NGH A TRUY NHP CA WCDMA

2.1. GII THIU CHUNG

2.1.1. Mc ch chng

Hiu tng quan tri ph v phng php a truy nhp ca WCDMA Hiu iu khin cng sut, chuyn giao mm v my thu phn tp a ng (RAKE) Hiu cc dng m tri ph v cc s iu ch ca WCDMA2.1.2. Cc ch c trnh by trong chng

Nguyn l tri ph v a truy nhp phn chia theo m

iu khin cng sut

Chuyn giao

My thu phn tp a ng (my thu RAKE)

Cc dng m tri ph v cc s iu cht c s dng cho WCDMA

2.1.3. Hng dn

Hc k cc t liu c trnh by trong chng

Tham kho thm cc ti liu tham kho cui ti liu ging dy ca kha hc

2.2. TRI PH V A TRUY NHP PHN CHIA THEO M

2.2.1. Cc h thng thng tin tri ph

Trong cc h thng thng tin thng thng rng bng tn l vn quan tm chnh v cc h thng ny c thit k s dng cng t rng bng tn cng tt. Trong cc h thng iu ch bin song bin, rng bng tn cn thit pht mt ngun tn hiu tng t gp hai ln rng bng tn ca ngun ny. Trong cc h thng iu tn rng bng tn ny c th bng vi ln rng bng tn ngun ph thuc vo ch s iu ch. i vi mt tn hiu s, rng bng tn cn thit c cng gi tr vi tc bit ca ngun. rng bng tn chnh xc cn thit trong trng hp ny ph thuc v kiu iu ch (BPSK, QPSK v.v...).

Trong cc h thng thng tin tri ph (vit tt l SS: Spread Spectrum) rng bng tn ca tn hiu c m rng, thng thng hng trm ln trc khi c pht. Khi ch c mt ngi s dng trong bng tn SS, s dng bng tn nh vy khng c hiu qu. Tuy nhin mi trng nhiu ngi s dng, cc ngi s dng ny c th dng chung mt bng tn SS (tri ph) v h thng tr nn s dng bng tn c hiu sut m vn duy tr c cc u im ca tri ph.

Mt h thng thng tin s c coi l SS nu:

* Tn hiu c pht chim rng bng tn ln hn rng bng tn ti thiu cn thit pht thng tin.

* Tri ph c thc hin bng mt m c lp vi s liu.

C ba kiu h thng SS c bn: chui trc tip (DSSS: Direct-Sequence Spreading Spectrum), nhy tn (FHSS: Frequency-Hopping Spreading Spectrum) v nhy thi gian (THSS: Time-Hopping Spreading Spectrum). Cng c th nhn c cc h thng lai ghp t cc h thng ni trn. WCDMA s dng DSSS. DSSS t c tri ph bng cch nhn lung s cn truyn vi mt m tri ph c tc chip (Rc=1/Tc, Tc l thi gian mt chip) cao hn nhiu tc bit (Rb=1/Tb, Tb l thi gian mt bit) ca lung s cn pht. Hnh 2.1 minh ha qu trnh tri ph trong Tb=15Tc hay Rc=15Rb. Hnh 2.1a cho thy s n gin ca b tri ph DSSS trong lung s cn truyn x c tc Rb c nhn vi mt m tri ph c tc Rc c lung u ra y c tc Rc ln hn nhiu so vi tc Rb ca lung vo. Cc hnh 2.1b v 2.1b biu th qu trnh tri ph trong min thi gian v min tn s.

Ti pha thu lung y c thc hin gii tri ph khi phc li lung x bng cch nhn lung ny vi m tri ph c ging nh pha pht: x=y(c

x, y v c k hiu tng qut cho tn hiu vo, ra v m tri ph; x(t), y(t) v c(t) k hiu cho cc tn hiu vo, ra v m tri ph trong min thi gian; X(f), Y(f) v C(f) k hiu cho cc tn hiu vo, ra v m tri ph trong min tn s; Tb l thi gian mt bit ca lung s cn pht, Rb=1/Tb l tc bit ca lung s cn truyn; Tc l thi gian mt chip ca m tri ph, Rc=1/Tc l tc chip ca m tri ph. Rc=15Rb v Tb=15Tc.Hnh 2.1. Tri ph chui trc tip (DSSS)

2.2.2. p dng DSSS cho CDMA

Trong cng ngh a truy nhp phn chia theo m da trn CDMA, mt tp m trc giao c s dng v mi ngi s dng c gn mt m tri ph ring. Cc m tri ph ny phi m bo iu kin trc giao sau y:

1. Tch hai m ging nhau bng 1: ci(ci=1

2. Tch hai m khc nhau s l mt m mi trong tp m: ci(cj=ck3. C s bit 1 bng s bit -1 trong mt m ( , trong N l s chip v Ck l gi tr chip k trong mt m

Bng 2.1. cho thy th d s dng b m gm tm m trc giao: c0, c1, , c7. Bng 2.2 v 2.3 cho thy th d khi nhn hai m ging nhau trong bng 1 c 1 v nhn hai m khc nhau trong bng 2.1 ta c mt m mi..Bng 2.1. Th d b tm m trc giao

c0+1+1+1+1+1+1+1+1

c1+1+1+1+1-1-1-1-1

c2+1+1-1-1+1+1-1-1

c3+1+1-1-1-1-1+1+1

c4+1-1+1-1+1-1+1-1

c5+1-1+1-1-1+1-1+1

c6+1-1-1+1+1-1-1+1

c7+1-1-1+1-1+1+1-1

Bng 2.2. Th d nhn hai m ging nhau trong bng 1 c mt

c1+1+1+1+1-1-1-1-1

(((((((((

c1+1+1+1+1-1-1-1-1

c1(c1+1+1+1+1+1+1+1+1

Bng 2.3. Th d nhn hai m khc nhau trong bng 1 c mt m mi trong tp 8 m

c1+1+1+1+1-1-1-1-1

((((((((

c3+1+1-1-1-1-1+1+1

= c2+1+1-1-1+1+1-1-1

Nu ta xt mt h thng gm K ngi s dng c xy dng trn c s CDMA, th sau tri ph cc ngi s dng ny s pht vo khng gian tp cc tn hiu y nh sau:

(2.1)

Ta xt qu trnh x l tn hiu ny ti mt my thu k. Nhim v ca my thu ny l phi ly ra xk v loi b cc tn hiu khc (cc tn hiu ny c gi l nhiu ng knh v trong h thng CDMA chng c pht trn cng mt tn s vi xk). Nhn (2.1) vi xk v p dng quy tc trc giao ni trn ta c:

(2.2)

Thnh phn th nht trong (2.2) chnh l tn hiu hu ch cn thnh phn th hai l nhiu ca cc ngi s dng cn l nhiu ca cc ngi s dng khc c gi l MAI (Multiple Access Interferrence: nhiu a ngi s dng). loi b thnh phn th hai my thu s dng b lc tng quan trng min thi gian kt hp vi b lc tn s trong min tn s. Hnh 2.2 xt qu trnh gii tri ph v lc ra tn hiu hu ch ti my thu k trong mt h thng CDMA c K ngi s dng vi gi thit cng sut pht t K my pht nh nhau ti u vo my thu k. Hnh 2.2a cho thy s gii tri ph DSSS. Hnh 2.2b cho thy ph ca tn hiu tng c pht i t K my pht sau tri ph, hnh 2.2c cho thy ph ca tn hiu ny sau gii tri ph ti my thu k v hnh 2.2d cho thy ph ca tn hiu sau b lc thng thp vi bng thng bng Rb.

Hnh 2.2. Qu trnh gii tri ph v lc tn hiu ca ngi s dng k t K tn hiu.

T hnh 2.2 ta thy t s tn hiu trn nhiu (SIR: Signal to Interference Ratio) l t s gia din tch hnh ch nht c t m trn hnh 2.2.b v tng din tch cc hnh ch nht trng trn hnh 2.2.c: SIR=S1/S2. T s ny t l vi t s Rc/Rb. v th t s Rc/Rb c gi l li x l (TA: Processing Gain).

2.3. IU KHIN CNG SUT

Trong trng hp mt my pht gy nhiu n gn my thu k (n gn nt B chng hn), cng sut ca my pht ny tng cao dn n MAI tng cao, t s tn hiu trn nhiu gim mnh v my thu k khng th tch ra c tn hiu ca mnh. Hin tng ny c gi l hin tng gn v xa. trnh hin tng ny h thng phi iu khin cng sut sao cho cng sut thu ti nt B ca tt c cc UE u bng nhau (l tng). iu khin cng sut trong WCDMA c chia thnh:

iu khin cng sut vng h

iu khin cng sut vng kn

iu khin cng sut vng h c thc hin t ng ti UE khi n thc hin th tc xin truy nhp Nt B (da trn cng sut m n thu c t knh hoa tiu pht i t B), khi ny UE cha c kt ni vi nt ny. Cn iu khin cng sut vng kn c thc hin khi UE kt ni vi nt B. iu khin cng sut vng h li c chia thnh:

iu khin cng sut vng trong c thc hin ti nt B. iu khin cng sut vng trong c thc hin nhanh vi 1500 ln trong mt giy da trn so snh SIR thu vi SIR ch

iu khin cng sut vng ngoi c thc hin ti RNC thit lp SIR ch cho nt B. iu khin cng sut ny da trn so snh t l li khi (BLER) thu c vi t l ch.

2.4. CHUYN GIAO TRONG H THNG CDMA

Thng thng chuyn giao (HO: Handover) c hiu l qu trnh trong knh lu lng ca mt UE c chuyn sang mt knh khc m bo cht lng truyn dn. Tuy nhin trong CDMA khi nim ny ch thch hp cho chuyn giao cng cn i vi chuyn giao mm khi nim ny phc tp hn, ta s xt c th trong phn di y.

C th chia HO thnh cc kiu HO sau:

HO ni h thng xy ra bn trong mt h thng WCDMA. C th chia nh HO ny thnh

HO ni h thng gia cc thuc cng mt tn s sng mang WCDMA

HO gia cc tn s (IF-HO) gia cc hot ng trn cc tn s WCDMA khc nhau

HO gia cc h thng (IS-HO) gia cc thuc hai cng ngh truy nhp v tuyn (RAT) khc nhau hay cc ch truy nhp v tuyn (RAM) khc nhau. Trng hp thng xuyn xy ra nht i vi kiu th nht l HO gia cc h thng WCDMA v GSM/EDGE. Tuy nhin cng c th l IS-HO gia WCDMA v h thng cc h thng CDMA khc (cdma2000 1x chng hn). Th d v HO gia cc RAM l HO gia cc ch UTRA FDD v UTRA TDD.

C th c cc th tc HO sau:

Chuyn giao cng (HHO) l cc th tc HO trong tt c cc ng truyn v tuyn c ca mt UE c gii phng trc khi thit lp cc ng truyn v tuyn mi

Chuyn giao mm (SHO) v chuyn giao mm hn (xem hnh 2.3) l cc th tc trong UE lun duy tr t nht mt ng v tuyn ni n UTRAN. Trong chuyn giao mm UE ng thi c ni n mt hay nhiu thuc cc nt B khc nhau ca cng mt RNC (SHO ni RNC) hay thuc cc RNC khc nhau (SHO gia cc RNC). Trong chuyn giao mm hn UE c ni n t nht l hai on ca cng mt nt B. SHO v HO mm hn ch c th xy ra trn cng mt tn s sng mang v trong cng mt h thng.

Hnh 2.3. Chuyn giao mm (a) v mm hn (b)

Ph thuc s tham gia trong SHO, cc trong mt h thng WCDMA c chia thnh cc tp sau y:

Tp tch cc bao gm cc (on ) hin ang tham gia vo mt kt ni SHO ca UE

Tp ln cn/ tp c gim st (c hai t c s dng nh nhau). Tp ny bao gm tt c cc c gim st/o lin tc bi UE v hin thi khng c trong tp tch cc

Tp c pht hin. Tp ny bao gm cc c UE pht hin nhng khng thuc tp tch cc ln tp ln cn.

SHO l mt tnh nng chung ca h thng WCDMA trong cc ln cn hat ng trn cng mt tn s. Trong ch kt ni, UE lin tc o cc phc v v cc ln cn (do RNC ch dn) trn tn s sng mang hin thi. UE so snh cc kt qu o vi cc ngng HO do RNC cung cp v gi bo co kt qu o n RNC khi thc hin cc tiu chun bo co. V th SHO l kiu chuyn giao c nh gi bi u cui di ng (MEHO: Mobile Estimated HO). Tuy nhin gii thut quyt nh SHO c t trong RNC. Da trn cc bo co kt qu o nhn c t UE (hoc nh k hoc c khi ng bi mt s cc s kin nht nh), RNC lnh cho UE b sung hay loi b mt s khi tp tch cc ca mnh (ASU: Active Set Apdate: cp nht tp tch cc).

2.5. MY THU PHN TP A NG HAY MY THU RAKE

Phainh a ng trn knh v tuyn dn n tn thi v chn lc tn s lm hng tn hiu thu. nh gi hin tng tn thi trn ng truyn v tuyn, ngi ta pht i mt xung hp (xung kim) v o p ng xung ny ti pha thu. p ng ny l bc tranh th hin s ph thuc cng sut ca cc ng truyn khc nhau n my thu vo thi gian tr ca cc ng truyn ny. p ng ny c gi l l lch tr cng sut. Hnh 2.4a cho thy truyn sng a ng v hnh 2.4b cho thy th d v l lch tr cng sut.

Hnh 2.4. Truyn sng a ng v l lch tr cng sut

Chui tn hiu gi ngu nhin c pht i CDMA c thuc tnh l cc phin bn dch thi ca n ti pha thu hu nh khng tng quan. Nh vy mt tn hiu c truyn t my pht n my thu theo nhiu ng khc nhau (thi gian tr khc nhau) c th c phn gii vo cc tn hiu phainh khc nhau bng cch ly tng quan tn hiu thu cha nhiu phin bn dch thi ca chui gi ngu nhin. My thu s dng nguyn l ny c gi l my thu phn tp a ng hay my thu RAKE (hnh 2.5).

Hnh 2.5. My thu RAKE

Trong my thu RAKE nhn c cc phin bn dch thi ca chui ngu nhin, tn hiu thu phi i qua ng tr trc khi c ly tng quan v c kt hp. ng tr bao gm nhiu mt tr c thi gian tr bng thi gian mt chip Tc. My thu dch nh thi bn sao m tri ph tng chip cho tng k hiu thng tin gii tri ph k hiu trong vng mt k hiu v to nn l lch tr cng sut (xem hnh 2.5a). Vi tham kho l lch tr cng sut (bc tranh th hin cng sut v tr ca cc ng truyn) c to ra, my thu chn cc ng truyn c cng sut vt ngng kt hp RAKE trn c s s lng b tng quan, b c tnh knh v b b tr thay i pha (c gi l cc ngn my thu RAKE). Trong trng hp p dng thu phn tp khng gian hay phn tp gia cc on , l lch tr cng sut c to ra cho mi nhnh v cc ng truyn c chn t l lch tr cng sut sut tng hp ca tt c cc nhnh. Trong thc t, v cc tn hiu tri ph gm nhiu ca cc ngi s dng khc v cc tn hiu a ng ca knh ngi s dng, nn gi tr ngng c lp d trn mc cng sut tp m nn v cc ng truyn c SIR hiu dng (c cng sut thu vt ngng) c chn. V MS chuyn ng (hoc mi trng truyn sng thay i khi MS c nh), nn v tr ng truyn (thi gian tr) c kt hp RAKE cng s thng xuyn thay i, my phi nh k cp nht l lch tr ng truyn v cp nht cc ng truyn c kt hp RAKE trn c s l lch mi (qu trnh ny c gi l tm kim ng truyn v n lin quan n tm kim ng truyn kt hp RAKE).

2.6. CC M TRI PH S DNG TRONG WCDMA

Khi nim tri ph c p dng cho cc knh vt l, khi nim ny bao gm hai thao tc. u tin l thao tc nh knh, trong mi k hiu s liu dc chuyn thnh mt s chip nh vy tng rng ph tn hiu. S chip trn mt k hiu (hay t s gia tc chip v tc k hiu) c gi l h s tri ph (SF: Spectrum Factor), hay ni mt cch khc SF=Rs/Rc trong Rs l tc k hiu cn Rc l tc chip. H s tri ph l mt gi tr kh bin, ngoi tr i vi knh chia s ng xung vt l tc cao (HS-PDSCH ) trong HSDPA c SF=16. Thao tc th hai l thao tc ngu nhin ha tng tnh trc giao trong mt m ngu nhin ha c trn vi tn hiu tri ph. M ngu nhin ho c xy dng trn c s m Gold.

Trong qu trnh nh knh, cc k hiu s liu c nhn vi mt m OVSF (Orthogonal Variable Spread Factor: m trc giao h s kh bin) ng b v thi gian vi bin ca k hiu. Trong 3GPP, OVSF (hnh 2.6) c s dng cho cc tc k hiu khc nhau v c k hiu l Cch,SF,k trong SF l h s tri ph ca m v k l s th t m (0(k(SF-1). Cc m nh knh c cc tnh cht trc giao v c s dng phn bit cc thng tin c pht i cng t mt ngun: (1) cc kt ni khc nhau trn ng xung trong cng mt trn ng xung v gim nhiu ni , (2) cc knh s liu vt l ng ln t mt UE. Trn ng xung cc m OVSF trong m b hn ch v th cn c qun l bi RNC, tuy nhin iu ny khng xy ra i vi ng ln.

Cn lu khi chn m nh knh chng khng tng quan vi nhau. Chng hn khi chn m Cch,8,4=+1-1+1-1+1-1+1-1, khng c s dng m Cch,16,8=+1-1+1-1+1-1+1-1+1-1+1-1+1-1+1-1; v hai m ny hon ton ging nhau (tch ca chng bng 1) v chng s gy nhiu cho nhau.

Cc m OVSF ch hiu qu khi cc knh c ng b hon ho ti mc k hiu. Mt tng quan cho do truyn sng a ng c b tr bi thao tc ngu nhin ha b sung. Vi thao tc ngu nhin ha, phn thc (I) v phn o (Q) ca tn hiu tri ph c nhn b sung vi m ngu nhin ha phc. M ngu nhin ha phc c s dng phn bit cc ngun pht: (1) cc khc nhau i vi ng xung v (2) cc UE khc nhau i vi ng ln. Cc m ny c cc tnh cht tng quan tt (trung bnh ha nhiu) v lun c s dng trn vi cc m tri ph nhng khng lm nh hng rng ph tn hiu v bng thng truyn dn.

Hnh 2.6. Cy m nh knh

ng truyn gia nt B v UE trong WCDMA cha nhiu knh. C th chia cc knh ny thnh hai loi: (1) knh ring truyn lu lng v (2) knh chung mang cc thng tin iu khin v bo hiu. ng truyn t UE n nt B c gi l ng ln, cn ng ngc li t nt B n UE c gi l ng xung. Trc ht ta xt tri ph cho cc knh ng ln.

2.7. TRI PH V IU CH NG LN

2.7.1. Tri ph v iu ch cc knh ring ng ln

Nguyn l tri ph cho DPDCH (Dedicated Physical Data Channel: knh s liu vt l ring, knh truyn lu lng ca ngi s dng) v DPCCH (Dedicated Physical Control Channel: knh iu khin vt l ring; knh i cng vi DPDCH mang thng tin iu khin lp vt l) c minh ha trn hnh 2.7.

Mt DPCCH v cc i su DPDCH song song gi tr thc c th c tri ph v pht ng thi. DPCCH lun c tri ph bng m Cc=Cch,256,0, trong k=0. Nu ch mt knh DPDCH c pht trn ng ln, th DPDCH1 c tri ph vi m Cd,1=Cch,SF,k, trong k=SF/4 l s m OVSF v k=SF/4. Ngha l nu h s tri ph SF=128 th k=32. Nu nhiu DPDCH c pht, th tt c DPDCH u c h s tri ph l 4 (tc bit knh l 960kbps) v DPDCHn c tri ph bi m Cd,n=Cch,4,k, trong k=1 nu n({1,2}, k=3 nu n({3,4} v k=2 nu n({5,6}. b tr s khc nhau gia cc h s tri ph ca s liu, tn hiu tri ph c nh trng s bng cc h s khuych i k hiu l (c cho DPCCH v (d cho DPDCH. Cc h s khuych i ny c tnh ton bi SRNC v c gi n UE trong giai on thit lp ng truyn v tuyn hay t li cu hnh. Cc h s khuych i nm trong di t 0 n 1 v t nht mt trong s cc gi tr ca (c v (d lun lun bng 1. Lung chip ca cc nhnh I v Q sau c cng phc vi nhau v c ngu nhin ha bi mt m ngu nhin ha phc c k hiu l Sdpch,n trn hnh 2.7. M ngu nhin ha ny c ng b vi khung v tuyn, ngha l chip th nht tng ng vi u khung v tuyn.

Hnh 2.7. Tri ph v iu ch DPDCH v DPCCH ng ln

Cc nghin cu cho thy mi s pht khng lin tc trn ng ln c th gy nhiu m thanh cho thit b m thanh t gn my u cui di ng. Th d in hnh l trng hp nhiu tn s khung (217 Hz=1/4,615ms) gy ra do cc u cui GSM. trnh hiu ng ny, knh DPCCH v cc knh DPDCH khng c ghp theo thi gian m c ghp theo m I/Q (iu ch QPSK hai knh) vi ngu nhin ho phc. Minh ha trn hnh 2.8 cho thy s iu ch ny cho php truyn dn lin tc ngay c trong cc chu k im lng khi ch c thng tin iu khin lp 1 duy tr hot ng ng truyn (DPCCH) l c pht.

Hnh 2.8. Truyn dn knh iu khin vt l ring ng ln v knh s liu vt l ring ng ln khi c/ khng c (DTX) s liu ca ngi s dng

Nh minh ha trn hnh 2.9, cc m ngu nhin ha phc c to ra bng cch quay pha gia cc chip trong mt chu k k hiu trong gii hn (900. Bng cch ny hiu sut ca b khuch i (lin quan n t s cng sut nh trn cng sut trung bnh) trong UE hu nh khng i khng ph th thuc vo t s ( gia DPDCH v DPCCH.

Hnh 2.9. Chm tn hiu i vi ghp m I/Q s dung ngu nhin ha phc, ( biu din cho t s cng sut gia DPDCH v DPCCH.

DPCCH v cc DPDCH c th c ngu nhin ha bng cc m ngu nhin di hoc ngn. C 224 m ngu nhin ha di ng ln v 224 m ngu nhin ngn ng ln. V c th s dng c hng triu m nn khng cn quy hoch m ng ln. S m ngu nhin cho DPCH (0,., 16777215), cng vi SF thp nht c php ca m nh knh (4, 8, 16, 32, 128 v 256) cho phn s liu c n nh bi cc lp cao hn, chng hn khi thit lp kt ni RRC hoc khi iu khin chuyn giao.

2.7.2. Tri ph v iu ch knh chung ng ln PRACH

Phn ny s trnh by n nh m cho tin t v phn bn tin ca PRACH l mt dng knh chung ng ln.

Tri ph v ngu nhin ha phn bn tin PRACH c minh ha trn hnh 2.10. Hnh 2.10. Tri ph v iu ch phn bn tin PRACH

Phn iu khin ca bn tin PRACH c tri ph bng m nh knh Cc=Cch,256,m, trong m=16.s+15 v s (0((s(15) l ch k tin t v phn s liu c tri ph bng m nh knh Cd=Cch,SF,m, trong SF (c gi tr t 32 n 256) l h s tri ph s dng cho phn s liu v m=SF.s/16.

Phn bn tin PRACH lun lun c tri ph bng m ngu nhin ha di. di ca m ngu nhin ha c s dng cho phn bn tin l 10ms. C tt c l 8192 m ngu nhin ha.

2.8. TRI PH V IU CH NG XUNG

2.8.1. S tri ph v iu ch ng xung

Khi nim tri ph v ngu nhin ha ng xung c minh ha trn hnh 2.11. Ngoi tr cc SCH (knh ng b s xt trong chng 3), mi cp hai bit knh trc ht c bin i t ni tip vo song song tng ng mt k hiu iu ch, sau c t ln cc nhnh I v Q. Sau cc nhnh I v Q c tri ph n tc 3,84Mcps bng cng mi m dnh knh Cch,SF,m. Cc chui chip gi tr thc trn cc nhnh I v Q sau c ngu nhin ha bng m ngu nhin ha phc nhn dng ngun pht nt B, m ny c k hiu l Sdl,n trn hnh 2.11. M ngu nhin ha ny c ng b vi m ngu nhin ha s dng cho P-CCPCH (knh vt l iu khin chung s cp s xt trong cng 3), trong chp phc u tin ca khung P-CCPCH c nhn vi chip s 0 ca m ngu nhin ha ny.

Sau tri ph, mi knh vt l ng xung (tr cc SCH) c nh trng s bng cc h s trng s ring k hiu l Gi nh trn hnh 2.11. P-SCH v S-SCH gi tr phc c nh trng s ring bng cc h s trng s Gp v Gs. Tt c cc knh ng xung c kt hp vi nhau bng cng phc. Chui nhn c sau tri ph v ngu nhin ha c iu ch QPSK.

Hnh 2.11. S tri ph v iu ch cho tt c cc knh vt l ng xung

2.8.2. Cc m tri ph ng xung

Trn ng xung, cng cc m nh knh nh trn ng ln (m OVSF) c s dng. Thng thng mi ch c mt cy m v mi cy m c t di mt m ngu nhin ha dng chung cho nhiu ngi s dng. Theo quy inh, cc m nh knh dng cho P-CPICH (knh hoa tiu chung s cp s xt trong chng 3) v P-CCPCH l Cch,256,0 v Cch,256,1. B qun l ti nguyn trong RNC n nh cc m nh knh cho tt c cc knh khc vi gii hn SF=512 trong trng hp s dng chuyn giao phn tp.

M OVSF c th thay i theo tng khung trn knh PDSCH (knh chia s ng xung vt l s xt trong chng 3). Quy tc thay i nh sau, m (cc m) OVSF c s dng cho kt ni pha di h s tri ph nh nht l m t nhnh cy, m nhnh cy m c ch ra bi h s tri ph thp nht ny. Nu DSCH c sp xp ln nhiu PDSCH song song, th quy tc tng t c p dng, nhng tt cc nhnh m c s dng bi cc m ny tng ng vi h s tri ph nh nht u c th s dng cho n nh h s tri ph cao hn.

2.8.3. Cc m ngu nhin ha ng xung

Trn ng xung ch c cc m ngu nhin ha di l c s dng. C c thy 218-1=262143 m ngu nhin c nh s t 0 n 262142. Cc chui m ngu nhin c k hiu l Sdl,n c cu trc bng cc on ca chui Gold. tng tc qu trnh tm , ch 8192 m trong s 262143 c s dng trong thc t v c ct ngn ly on u 38400 chip ph hp vi chu k khung 10 ms. Nh minh ha trn hnh 2.12, ch c cc m vi n=0,1,, 8191 c s dng. Cc m ny c chia thnh 512 tp. Mi tp gm 16 m (i=015) vi mt m s cp v 15 m th cp. 8 tp (i=07) vi 8x16 m hp thnh mt nhm to nn 64 nhm (j=063).

Hnh 2.12. Cc m ngu nhin ha s cp v th cp

V thng thng mi c nhn dng bng mt m ngu nhin ho s cp, nn qu trnh tm kim cng l qu trnh tm kim m ny. Qu trnh tm kim c th c thc hin theo ba bc sau:

Tm P-SCH (knh ng b s cp) thit lp ng b khe v ng b k hiu

Tm S-SCH (knh ng b th cp) thit lp ng b khung v nhm m

Tm m ngu nhin ha nhn dng 2.8.4. Ghp knh a m ng xung

tng dung lng knh ng xung ta c th s dng s ghp knh a m nh cho hnh 2.13.

S/P: bin i ni tip thnh song songHnh 2.13. Truyn dn a m cho ng xung

2.9. TNG KT

Cc h thng CDMA c xy dng trn c s tri ph chui trc tip (DSSS). Vic s dng tri ph cng vi cc m trc giao cho php nhiu u cui di ng c th dng chung mt tn s. Khi ny tnh trc giao ca cc m v tri ph cho php mt my thu u cui c th d dng tch ra c tn hiu ca mnh. Do s dng chung mt tn s nn c th p dng chuyn giao mm cho CDMA. Trong chuyn giao mm mt my di ng c th kt ni n nhiu trm gc trn cng mt tn s nhng vi m tri ph khc nhau. u im ca chuyn giao mm l khng lm mt cuc gi trong qu trnh chuyn giao mc d n lm gim phn no dng lng v tng thm tnh phc tp h thng. Nhng cng v s dng chung mt tn s nn c th xy ra hin tng gn xa, trong my di ng gn trm gc s gy nhiu cho cc ngi s dng khc. khc phc nhc im ny phi p dng iu khin cng sut nhanh cho CDMA trong my di ng gn trm gc s c iu chnh pht cng sut thp hn my di ng xa trm gc. iu khin cng sut nhanh trong WCDMA c thc hin 1500 ln trong mt giy. Mt c im na ca CDMA l cc m ngu nhin ha mang tnh trc giao kh cao nn cc ng truyn n my thu c tr khc nhau thi gian chip hoc ln hn thi gian ny u c lp vi nhau v v th c th s dng phn tp a ng (hay my thu RAKE) trong CDMA. Nguyn tc ca my thu RAKE l chn mt s ng (mt s ngn) c cng sut thu ln hn ngng, ng chnh pha cc ng ny ri cng cng sut thu ca chng vi nhau. WCDMA s dng hai tng tri ph: (1) tri ph bng m nh knh, (2) tri ph bng m nhn dng ngun pht. M nh knh c xy dng trn c s m h s tri ph trc giao kh bin (OVSF), trong h s tri ph SF=Rs/Rc vi Rs l tc k hiu v Rc l tc chip. M ngu nhin ha c cu trc t m Gold. WCDMA s dng iu ch QPSK cho ng xung v BPSK cho ng ln. gim t s cng sut nh trn cng sut trung bnh ca tn hiu iu ch, ngu nhin ha phc c s dng.

Chng 3

GIAO DIN V TUYN CA WCDMA UMTS

3.1. GII THIU CHUNG

3.1.1. Mc ch chng

Hiu tng quan v WCDMA/FDD Hiu kin trc WCDMA v cc knh ca n Hiu c cc k thut phn tp pht trong WCDMA3.1.2. Cc ch c trnh by trong chng

Kin trc giao din v tuyn ca 3G WCDMA/FDD

Cc thng s lp vt l v quy hoch tn s ca WCDMA/FDD

Cc kiu knh ca WCDMA/FDD

S tng qut ca mt thit b thu pht WCDMA

Cc s phn tp pht c s dng cho WCDMA

Cc s iu ch v chuyn giao trong WCDMA

Cc thng s quan trng my thu v my pht v tuyn ca UE

M ha ting AMR

3.1.3. Hng dn

Hc k cc t liu c trnh by trong chng

Tham kho thm cc ti liu tham kho cui ti liu ging dy ca kha hc

3.2. M U

WCDMA UMTS l mt trong cc tiu chun ca IMT-2000 nhm pht trin ca GSM cung cp cc kh nng cho th h ba. WCDMA UMTS s dng mng a truy nhp v tuyn trn c s W-CDMA v mng li c pht trin t GSM/GPRS. W-CDMA c th c hai gii php cho giao din v tuyn: ghp song cng phn chia theo tn s (FDD: Frequency Division Duplex) v ghp song cng phn chia theo thi gian (TDD: Time Division Duplex). C hai giao din ny u s dng tri ph chui trc tip (DS-CDMA). Gii php th nht s c trin khai rng ri cn gii php th hai ch yu s c trin khai cho cc nh (Micro v Pico). Hin nay mi ch c WCDMA/FDD c trin khai v th trong kha hc ny ta s ch xt WCDMA/FDD

Gii php FDD s dng hai bng tn 5 MHz vi hai sng mang phn cch nhau 190 MHz: ng ln c bng tn nm trong di ph t 1920 MHz n 1980 MHz, ng xung c bng tn nm trong di ph t 2110 MHz n 2170 Mhz. Mc d 5 MHz l rng bng danh nh, ta cng c th chn rng bng t 4,4 MHz n 5 MHz vi nc tng l 200 KHz. Vic chn rng bng ng n cho php ta trnh c nhiu giao thoa nht l khi khi 5 MHz tip theo thuc nh khai thc khc.

Gii php TDD s dng cc tn s nm trong di 1900 n 1920 MHz v t 2010 MHz n 2025 MHz; y ng ln v ng xung s dng chung mt bng tn.

Giao din v tuyn ca W-CDMA/FDD ( n gin ta s b qua k hiu FDD nu khng xt n TDD) hon ton khc vi GSM v GPRS, W-CDMA s dung phng thc tri ph chui trc tip vi tc chip l 3,84 Mcps. Trong WCDMA mng truy nhp v tuyn c gi l UTRAN (UMTS Terrestrial Radio Access Network). Cc phn t ca UTRAN rt khc vi cc phn t mng truy nhp v tuyn ca GSM. V th kh nng s dng li cc BTS v BSC ca GSM l rt hn ch. Mt s nh sn xut cng c k hoch nng cp cc GSM BTS cho WCDMA. i vi cc nh sn sut ny c th ch tho ra mt s b thu pht GSM t BTS v thay vo cc b thu pht mi cho WCDMA. Mt s rt t nh sn sut cn lp k hoch xa hn. H ch to cc BSC ng thi cho c GSM v WCDMA. Tuy nhin a phn cc nh sn sut phi thay th GSM BSC bng RNC mi cho WCDMA.

W-CDMA s dng rt nhiu kin trc ca mng GSM, GPRS hin c cho mng ca mnh. Cc phn t nh MSC, HLR, SGSN, GGSN c th c nng cp t mng hin c h tr ng thi WCDMA v GSM.

Giao din v tuyn ca WCDMA/FDD c xy dng trn ba kiu knh: knh logic, knh truyn ti v knh vt l. Knh logic c hnh thnh trn c s ng gi cc thng tin t lp cao trc khi sp xp vo knh truyn ti. Nhiu knh truyn ti c ghp chng vo knh vt l. Knh vt l c xy dng trn cng ngh a truy nhp CDMA kt hp vi FDMA/FDD. Mi knh vt l c c trng bi mt cp tn s v mt m tri ph. Ngoi ra knh vt l ng ln cn c c trng bi gc pha. Trong phn di y ta trc ht ta xt kin trc giao thc ca giao din v tuyn sau ta s xt giao din v tuyn ca WCDMA/FDD, sau s xt cc knh ny.

3.3. KIN TRC NGN XP GIAO THC CA GIAO DIN V TUYN WCDMA/FDD

Kin trc giao din v tuyn ca WCDMA c cho trn hnh 3.1.

UP: Mt phng ngi s dng

CP: Mt phng iu khin

Hnh 3.1. Kin trc giao thc v tuyn cho UTRA FDD.

Ngn xp giao thc ca giao din v tuyn bao gm 3 lp giao thc:

Lp vt l (L1). c t cc vn lin quan n giao din v tuyn nh iu ch v m ha, tri ph v.v..

Lp lin kt ni s liu (L2). Lp khun s liu vo cc khi s liu v m bo truyn dn tin cy gia cc nt ln cn hay cc thc th ng cp

Lp mng (L3). c t nh a ch v nh tuyn

Mi khi th hin mt trng hp ca giao thc tng ng. ng khng lin nt th hin cc giao din iu khin, qua giao thc RRC iu khin v lp cu hnh cc lp di.

Lp 2 c chia thnh cc lp con: MAC (Medium Access Control: iu khin truy nhp mi trng) v RLC (Radio link Control: iu khin lin kt), PDCP (Packet Data Convergence Protocol: Giao thc hi t s liu gi) v BMC (Broadcast/Multicast Control: iu khin qung b/a phng ).

Lp 3 v RLC c chia thnh hai mt phng: mt phng iu khin (C-Plane) v mt phng ngi s dng (U-Plane). PDCP v BMC ch c mt phng U.

Trong mt phng C lp 3 bao gm RRC (Radio Resource Control: iu khin ti nguyn v tuyn) kt cui ti RAN v cc lp con cao hn: MM (Mobility Management) v CC (Connection Management), GMM (GPRS Mobility Management), SM (Session Management) kt cui ti mng li (CN).

Lp vt l l lp thp nht giao din v tuyn. Lp vt l c s dng truyn dn giao din v tuyn. Mi knh vt l lp ny c xc nh bng mt t hp tn s, m ngu nhin ho (m nh knh) v pha (ch cho ng ln). Cc knh c s dng vt l truyn thng tin ca cc lp cao trn giao din v tuyn, tuy nhin cng c mt s knh vt l ch c dnh cho hot ng ca lp vt l.

truyn thng tin giao din v tuyn, cc lp cao phi chuyn cc thng tin ny qua lp MAC n lp vt l bng cch s dng cc knh logic. MAC sp xp cc knh ny ln cc knh truyn ti trc khi a n lp vt l lp ny sp xp chng ln cc knh vt l.

3.4. CC THNG S LP VT L V QUY HOCH TN S

3.4.1. Cc thng s lp vt l

Cc thng s lp vt l ca WCDMA c cho trong bng 3.1.

Bng 3.1. Cc thng s lp vt l W-CDMA

W-CDMA

S a truy nhpDS-CDMA bng rng

rng bng tn (MHz)5/10/15/20

Mnh ph200 kHz

Tc chip (Mcps)(1,28)/3,84/7,68/11,52/15,36

di khung10 ms

ng b gia cc nt BD b/ng b

M ha sa liM turbo, m xon

iu ch DL/ULQPSK/BPSK

Tri ph DL/ULQPSK/OCQPSK (HPSK)

B m ha thoiCS-ACELP/(AMR)

T chc tiu chun3GPP/ETSI/ARIB

DL: Downlink: ng xung; UL: Uplink: ng ln

OCQPSK (HPSK): Orthogonal Complex Quadrature Phase Shift Keying (Hybrid PSK) = kha chuyn pha vung gc trc giao

CS-ACELP: Conjugate Structure-Algebraic Code Excited Linear Prediction = D bo tuyn tnh kch thch theo m li s cu trc phc hp

3GPP: Third Generation Parnership Project: n ca cc i tc th h ba

ETSI: European Telecommunications Standards Institute: Vin tiu chun vin thng Chu u

ARIB: Association of Radio Industries and Business: Lin hip cng nghip v kinh doanh v tuyn

3.4.2. Quy hoch tn s

Cc bng tn s dng cho WCDMA FDD trn ton cu c cho trn hnh 3.2a.WCDMA s dng phn b tn s quy nh cho IMT-2000 (International Mobile Telecommunications-2000) (hnh 3.2b) nh sau. chu u v hu ht cc nc chu bng tn IMT-2000 l 2(60 MHz (1920-1980 MHz cng vi 2110-2170 MHz) c th s dng cho WCDMA/ FDD. Bng tn s dng cho TDD chu u thay i, bng tn c cp theo giy php c th l 25 MHz cho s dng TDD 1900-1920 (TDD1) v 2020-2025 MHz (TDD2). Bng tn cho cc ng dng TDD khng cn xin php (SPA= Self Provided Application: ng dng t cp) c th l 2010-2020 MHz. Cc h thng FDD s dng cc bng tn khc nhau cho ng ln v ng xung vi phn cch l khong cch song cng, cn cc h thng TDD s dng cng tn s cho c ng ln v ng xung.

UMTS quy nh khai thc song cng phn chia theo tn s l ch tiu chun cho thng tin thoi v s liu. Hot ng ng thi v lin tc ca cc mch in pht v thu l cc thay i ng k nht so vi hat ng ca GSM.Hnh 3.2. Phn b tn s cho WCDMA/FDD. a) Cc bng c th dng cho WCDMA FDD ton cu; b) Bng tn IMT-2000.

Bng tn cho hat ng FDD cho cc bng I, II v III c cho trn hnh 3.3. Bng I (B1) l n nh bng chnh Chu u. Quy nh dnh hai cp pht 60MHz vi khong cch song cng chun 190MHz, tuy nhin quy nh cng cho php song cng kh bin, trong khong cch pht thu nm trong khong 130 n 250MHz. H thng song cng kh bin t ra cc yu cu b sung i vi thit k my pht thu v cc b t tn s my pht v my thu phi hot ng c lp vi nhau. Bng II (B2) ti s dng bng hin c ca h thng thng tin di ng c nhn v d nh s dng M m bo ng tn ti UMTS v GSM. Khong cch song cng ch bng 80MHz i vi bng II v th t ra cc yu cu kh khn hn i vi phn cng ca my thu pht.

Hnh 3.3 Cp pht bng tn WCDMA/FDD

Hnh 3.4 cho thy cp pht bng thng theo u thu ti Vng Quc Anh. Ph tn c chia cho nm nh khai thc nh sau:

Cp php A (Hutchison) nhn cp pht bng kp 14,6 MHz (tng ng 3(5MHz vi bng bo v nh hn)

Cp php B Vodafon) nhn cp pht bng kp 14,8MHz (tng ng 3(5MHz vi bng bo v nh hn)

Cp php C (BT3G) nhn cp pht bng kp 10MHz (2(5MHz) v bng n 5MHz ti 1910 MHz

Cp php D (One2One) nhn cp pht bng kp 10MHz (2(5MHz) v bng dn 5MHz ti 1900MHz Cp php E (Orange) nhn cp pht bng kp (2(5MHz) v bng n 5MHz ti 1905MHz.

Hnh 3.4. Th d cp pht bng tn cho nm nh khai thc ti Vng Quc Anh

Cp pht tn s ca c khc vi cp pht tn s Anh ch, cc 10MHz bng kp c cp pht cho su nh khai thc (6(10MHz), tt c bn knh TDD1 c cp pht (1900 n 1920 MHz) cng vi mt trong s cc knh TDD2 (hnh 3.5).

Hnh 3.5. Cp pht tn s cho su nh khai thc ti c

Ti Vit Nam bng tn 3G c cp pht tn s theo tm khe tn s nh cho trong bng 3.2, trong hai hoc nhiu nh khai thc c th cng tham gia xin cp pht chung mt khe.

Bng 3.2. Cp pht tn s 3G ti Vit Nam

Khe tn s

FDDTDD

BSTx*BSRx**BSTx/BSRx

A2110-2125 MHz1920-1935 MHz1915-1920 MHz

B2125-2140 MHz1935-1950 MHz1910-1915 MHz

C2140-2155 MHz1950-1965 MHz1905-1910 MHz

D2155-2170 MHz1965-1980 MHz1900-1905 MHz

* BSTx: my pht trm gc

** BSRx: my thu trm gc

L do cp pht cc knh 5MHz khc nhau ti cc nc khc nhau l ch cc nh khai thc phi quy hoch m v phi trnh vic s dng cc m gy ra nhiu knh ln cn trong cng mt nc hoc cc nh khai thc khc trong nc lin k. V th cn phi nghin cu quan h gia cc t hp m tri ph v hot ng ca cc knh ln cn.

3.5. CC KNH CA WCDMA

Cc knh ca WCDMA c chia thnh cc loi knh sau y:

Knh vt l (PhCH). Knh mang s liu trn giao din v tuyn. Mi PhCH c mt tri ph m nh knh duy nht phn bit vi knh khc. Mt ngi s dng tch cc c th s dng cc PhCH ring, chung hoc c hai. Knh ring l knh PhCH dnh ring cho mt UE cn knh chung c chia s gia cc UE trong mt .

Knh truyn ti (TrCH). Knh do lp vt l cung cp cho lp 2 truyn s liu. Cc knh TrCH c sp xp ln cc PhCH

Knh Logic (LoCH). Knh c lp con MAC ca lp 2 cung cp cho lp cao hn. Knh LoCH c xc nh bi kiu thng tin m n truyn.

3.5.1. Cc knh logic, LoCH

Ni chung cc knh logic (LoCH: Logical Channel) c chia thnh hai nhm: cc knh iu khin (CCH: Control Channel) truyn thng tin iu khin v cc knh lu lng (TCH: Traffic Channel) truyn thng tin ca ngi s dng. Cc knh logic v ng dng ca chng c tng kt trong bng 3.2.

Bng 3.2. Danh sch cc knh logicNhm knhKnh logicng dng

CCH (Control Channel: Knh iu khin)BCCH (Broadcast Control Channel: Knh iu khin qung b)Knh ng xung pht qung b thng tin h thng

PCCH (Paging Control Channel: Knh iu khin tm gi)Knh ng xung pht qung b thng tin tm gi

CCCH (Common Control Channel: Knh iu khin chung)Knh hai chiu pht thng tin iu khin gia mng v cc UE. c s dng khi khng c kt ni RRC hoc khi truy nhp mt mi

DCCH (Dedicated Control Channel: Knh iu khin ring).Knh hai chiu im n im pht thng tin iu khin ring gia UE v mng. c thit lp bi thit lp kt ni ca RRC

TCH (Traffic Channel: Knh lu lng)DTCH (Dedicated Traffic Channel: Knh lu lng ring)Knh hai chiu im n im ring cho mt UE truyn thng tin ca ngi s dng. DTCH c th tn ti c ng ln ln ng xung

CTCH (Common Traffic Channel: Knh lu lng chung)Knh mt chiu im a im truyn thng tin ca mt ngi s dng cho tt c hay mt nhm ngi s dng quy nh hoc ch cho mt ngi s dng. Knh ny ch c ng xung.

3.5.2. Cc knh truyn ti, TrCH

Cc knh lgic c lp MAC chuyn i thnh cc knh truyn ti. Tn ti hai kiu knh truyn ti: cc knh ring v cc knh chung. im khc nhau gia chng l: knh chung l ti nguyn c chia s cho tt c hoc mt nhm cc ngi s dng trong , cn knh knh ring c n nh ring cho mt ngi s dng duy nht. Cc knh truyn ti chung bao gm: BCH (Broadcast channel: Knh qung b), FACH (Fast Access Channel: Knh truy nhp nhanh), PCH (Paging Channel: Knh tm gi), DSCH (Down Link Shared Channel: Knh chia s ng xung), CPCH (Common Packet Channel: Knh gi chung). Knh ring ch c mt knh duy nht l DCH (Dedicated Channel: Knh ring). Knh truyn ti chung c th c p dng cho tt c cc ngi s dng trong hoc cho mt ngi hoc nhiu ngi c th. Khi knh truyn ti chung c s dng pht thng tin cho tt c cc ngi s dng th knh ny khng cn c a ch. Chng hn knh BCH pht thng tin qung b cho tt c cc ngi s dng trong . Khi knh truyn ti chung p dng cho mt ngi s dng c th, th cn pht nhn dng ngi s dng trong bng (trong bn tin s c pht). Knh PCH l knh truyn ti chung c s dng tm gi mt UE c th s cha thng tin nhn dng ngi s dng bn trong bn tin pht.

Danh sch cc knh truyn ti v ng dng ca chng dc cho bng 3.3.

Bng 3.3. Danh sch cc knh truyn tiKnh truyn ting dng

DCH (Dedicated Channel: Knh ring)Knh hai chiu c s dng pht s liu ca ngi s dng. c n nh ring cho ngi s dng. C kh nng thay i tc v iu khin cng sut nhanh

BCH (Broadcast Channel: Knh qung b)Knh chung ng xung pht thng tin qung b (chng hn thng tin h thng, thng tin )

FACH (Forward Access Channel: Knh truy nhp ng xung)Knh chung ng xung pht thng tin iu khin v s liu ca ngi s dng. Knh chia s chung cho nhiu UE. c s dng truyn s liu tc thp cho lp cao hn

PCH (Paging Channel: Knh tm gi)Knh chung dng xung pht cc tn hiu tm gi

RACH (Random Access Channel)Knh chung ng ln pht thng tin iu khin v s liu ngi s dng. p dng trong truy nhp ngu nhin v c s dng truyn s liu thp ca ngi s dng

CPCH (Common Packet Channel: Knh gi chung)Knh chung ng ln pht s liu ngi s dng. p dng trong truy nhp ngu nhin v c s dng trc ht truyn s liu cm.

DSCH (Dowlink Shared Channel: Knh chia s ng xung)Knh chung ng xung pht s liu gi. Chia s cho nhiu UE. S dng trc ht cho truyn dn s liu tc cao.

Cc knh logic c chuyn thnh cc knh truyn ti nh cho trn hnh 3.6.

Hnh 3.6. Chuyn i gia cc LoCH v TrCH trn ng ln v ng xung

3.5.3. Cc knh vt l

Mt knh vt l c coi l t hp ca tn s, m ngu nhin, m nh knh v c pha tng i (i vi ng ln). Knh vt l (Physical Channel) bao gm cc knh vt l ring (DPCH: Dedicated Physical channel) v knh vt l chung (CPCH: Common Physical Channel). Cc knh vt l c tng kt hnh 3.7 v bng 3.4.

Hnh 3.7. Tng kt cc kiu knh vt l

Bng 3.4. Danh sch cc knh vt l

Tn knhng dng

DPCH (Dedicated Physical Channel: Knh vt l ring)Knh hai chiu ng xung/ng ln c n nh ring cho UE. Gm DPDCH (Dedicated Physical Control Channel: Knh vt l iu khin ring) v DPCCH (Dedicated Physical Control Channel: Knh vt l iu khin ring). Trn ng xung DPDCH v DPCCH c ghp theo thi gian vi ngu nhin ha phc cn trn ng ln c ghp m I/Q vi ngu nhin ha phc

DPDCH (Dedicated Physical Data Channel: Knh vt l s liu ringKhi s dng DPCH, mi UE c n nh t nht mt DPDCH. Knh c s dng pht s liu ngi s dng t lp cao hn

DPCCH (Dedicated Physical Control Channel: Knh vt l iu khin ring)Khi s dng DPCH, mi UE ch c n nh mt DPCCH. Knh c s dng iu khin lp vt l ca DPCH. DPCCH l knh i km vi DPDCH cha: cc k hiu hoa tiu, cc k hiu iu khin cng sut (TPC: Transmission Power Control), ch th kt hp khun dng truyn ti. Cc k hiu hoa tiu cho php my thu nh gi hng ng xung kim ca knh v tuyn v thc hin tch sng nht qun. Cc k hiu ny cng cn cho hot ng ca anten thch ng (hay anten thng minh) c bp sng hp. TPC iu khin cng sut vng kn nhanh cho c ng ln v ng xung. TFCI thng tin cho my thu v cc thng s tc thi ca cc knh truyn ti: cc tc s liu hin thi trn cc knh s liu khi nhiu dch v c s dng ng thi. Ngoi ra TFCI c th b b qua nu tc s liu c nh. Knh cng cha thng tin hi tip hi tip (FBI: Feeback Information) ng ln m bo vng hi tip cho phn tp pht v phn tp chn la.

PRACH (Physical Random Access Channel: Knh vt l truy nhp ngu nhin)Knh chung ng ln. c s dng mang knh truyn ti RACH

PCPCH (Physical Common Packet Channel: Knh vt l gi chung)Knh chung ng ln. c s dng mang knh truyn ti CPCH

CPICH (Common Pilot Channel: Knh hoa tiu chung)Knh chung ng xung. C hai kiu knh CPICH: P-CPICH (Primary CPICH: CPICH s cp) v S-CPICH (Secondary CPICH: CPICH th cp). P-CPICH m bo tham chun nht qun cho ton b UE thu c SCH, P-CCPCH, AICH v PICH v cc knh nay khng c hoa tiu ring nh cc trng hp knh DPCH. Knh S-CPICH m bo tham kho nht qun chung trong mt phn hoc on cho trng hp s dng anten thng minh c bp sng hp. Chng hn c th s dng S-CPICH lm tham chun cho S-CCPCH (knh mang cc bn tin tm gi) v cc knh DPCH ng xung.

P-CCPCH (Primary Common Control Physical Channel: Knh vt l iu khin chung s cp)Knh chung ng xung. Mi c mt knh truyn BCH

S-CCPCH (Secondary Common Control Physical Channel: Knh vt l iu khin chung th cp)Knh chung ng xung. Mt c th c mt hay nhiu S-CCPCH. c s dng truyn PCH v FACH

SCH (Synchrronization Channel: Knh ng b)Knh chung ng xung. C hai kiu knh SCH: SCH s cp v SCH th cp. Mi ch c mt SCH s cp v th cp. c s dng tm

PDSCH (Physical Downlink Shared Channel: Knh vt l chia s ng xung)

AICH (Acquisition Indication Channel: Knh ch th bt)Knh chung ng xung i cp vi PRACH. c s dng iu khin truy nhp ngu nhin ca PRACH.

PICH (Page Indication Channel: Knh ch th tm gi)Knh chung ng xung i cp vi S-CCPCH (khi knh ny mang PCH) pht thng tin kt cui cuc gi cho tng nhm cuc gi kt cui. Khi nhn c thng bo ny, UE thuc nhm kt cui cuc gi th n s thu khung v tuyn trn S-CCPCH

AP-AICH (Access Preamble Acquisition Indicator Channel: Knh ch th bt tin t truy nhp)Knh chung ng xung i cp vi PCPCH iu khin truy nhp ngu nhin cho PCPCH

CD/CA-ICH (CPCH Collision Detection/ Channel Assignment Indicator Channel: Knh ch th pht hin va chm CPCH/n nh knh)Knh chung ng xung i cp vi PCPCH. c s dng iu khin va chm PCPCH

CSICH (CPCH Status Indicator Channel: Knh ch th trng thi CPCH)Knh chung ng xung lin kt vi AP-AICH pht thng tin v trng thi kt ni ca PCPCH

Cc cc knh truyn ti c chuyn thnh cc knh vt l nh trn hnh 3.8.

Hnh 3.8. Chuyn i gia cc knh truyn ti v cc knh vt l

Hnh 3.9 cho thy vic ghp hai knh truyn ti ln mt knh vt l v cung cp ch th li cho tng khi truyn ti ti pha thu.

TFI= Transport Format Indicator: Ch th khun dng truyn ti

TFCI= Transport Format Combination Indicator: Ch th kt hp khun dng truyn tiHnh 3.9. Ghp cc knh truyn ti ln knh vt l

3.5.4. Qu trnh truy nhp ngu nhin RACH v truy nhp gi CPCH

Qu trnh truy nhp ngu nhin RACH v truy nhp gi CPCH c cho trn hnh 3.10a v 3.10b.

Hnh 3.10. Cc th tc truy nhp ngu nhin RACH v truy nhp gi

Cc tr tc truy nhp ngu nhin trn hnh 3.10a nh sau. UE khi xng th tc truy nhp ngu nhin RACH bng cch pht i mt AP (tin t truy nhp). Nu chp nhn (OK), nt B pht AICH (ch th pht hin bt) n UE. Sau UE c th pht bn tin trn knh RACH (knh truy nhp ngu nhin).

Cc th tc truy nhp ngu nhin CPCH nh sau. Da trn thng tin kh dng ca tng knh PCPCH do CSICH thng bo, UE khi xng th tc truy nhp CPCH trn knh cha s dng bng cch pht i mt AP (tin t truy nhp). Nu c nt B chp nhn (OK) UE pht i mt CP (tin t pht hin va chm) thng bo rng n chim knh ny. Cui cng nt B pht i CD/CA-ICH (ch th pht hin va chm v n nh knh) n UE. Sau UE c th pht gi trn knh CPCH (knh gi chung)

3.5.5. Th d v bo hiu thit lp cuc gi s dng cc knh logic v truyn ti

Hnh 3.11 cho thy bo hiu thit lp lp cuc gi s dng knh logic v knh truyn ti. u tin UE s dng knh logic CCCH truyn trn knh truyn ti RACH yu cu ng truyn bo hiu (RRC). RNC tr li bng knh logic CCCH trn knh truyn ti FACH. Sau khi c kt ni RRC, UE s trao i bo hiu vi RNC qua knh logic DCCH trn knh truyn ti DCH. Sau khi nhn c lnh "truyn trc tip" t UE, RNC pht lnh yu cu dch v CM (Connection Management: qun l kt ni) trn giao thc RANAP (Radio Access Application Part: phn ng dng truy nhp mng v tuyn) khi u bo hiu thit lp knh mang lu lng Ty thuc vo yu cu ca UE lnh bo hiu ny c th c chuyn n MSC hoc SGSN (trong trng hp xt l MSC). Sau khi thc hin cc th tc an ninh, cc th tc thit lp knh mang c thc hin.

Hnh 3.11. Bo hiu thit lp cuc gi.

3.6. CU TRC KNH VT L RING

Cu trc knh vt l ring c trnh by trn hnh 3.12. Trong m hnh ny mi cp hai bit th hin mt cp I/Q (mt k hiu) ca iu ch QPSK. T hnh v ta thy, cu trc khung bao gm mt chui cc khung v tuyn, mi khung bao gm 15 khe (di 10 ms, cha 38400 chip) v mi khe cha 2560 chip (di 0,667 ms) bng mt chu k iu khin cng sut (tn s iu khin cng sut l 1500 ln trong mt giy).

Hnh 3.12. Cu trc knh vt l ring cho ng ln v ng xung

Cu trc knh vt l ring ng ln cho mt khe (mt chu k iu khin cng sut) c cho trn hnh 3.12. Thng tin ring lp cao hn bao gm s liu ngi s dng v bo hiu c mang bi DPDCH ng ln v thng tin iu khin to ra bi lp 1 c mang bi DPCCH. DPCCH bao gm cc k hiu hoa tiu quy nh trc (c s dng c tnh knh v tch sng nht qun), cc lnh iu khin cng sut (TPC: Transmit Power Control), thng tin phn hi (FBI: Feedback Information) cho phn tp pht vng kn v k thut phn tp chn trm (SSDT: Site Selection Diversity Technique), TFCI (ty chn). C th khng c, mt hay mt s (nhiu nht l 6) knh DPDCH trn mt lin kt v tuyn, nhng ch c mt DPCCH cho lin kt ny. DPDCH (hoc cc DPDCH) v DPCCH c ghp chung theo m I/Q vi ngu nhin ha phc.

Cu trc knh vt l ring ng xung c m t trn hnh 3.12.Trn ng xung knh ring (DPCH) ng xung bao gm DPDCH ng xung v DPCCH ng xung ghp theo thi gian vi ngu nhin ha phc. S liu ring c to ra ti cc mc cao hn trn DPDCH c ghp theo thi gian vi cc bit hoa tiu, cc lnh TPC v cc bit TFCI (ty chn) c to ra ti lp vt l.

TFCI c th c hoc khng c, nu khng c cc bit TFCI, DTX (pht khng lin tc) c s dng trong trng tng ng.

3.7. S TNG QUT MY PHT V MY THU WCDMA

Hnh 3.13 cho thy s khi ca my pht v tuyn (hnh 3.13a) v my thu v tuyn (3.13b) trong W-CDMA. Lp 1 (lp vt l) b sung CRC cho tng khi truyn ti (TB: Transport Block) l n v s liu gc cn x l nhn c t lp MAC pht hin li pha thu. Sau s liu c m ho knh v an xen. S liu sau an xen c b sung thm cc bit hoa tiu v cc bit iu khin cng sut pht (TPC: Transmit Power Control)), c sp xp ln cc nhnh I v Q ca QPSK v c tri ph hai lp (tri ph v ngu nhin ho). Chui chip sau ngu nhin ho c gii hn trong bng tn 5 MHz bng b lc Niquist cosin tng cn hai (h s dc bng 0,22) v c bin i vo tng t bng b bin i s vo tng t (D/A) a ln iu ch vung gc cho sng mang. Tn hiu trung tn (IF) sau iu ch c bin i nng tn vo sng v tuyn (RF) trong bng tn 2 GHz, sau c a ln khuych i trc khi chuyn n anten pht vo khng gian.

Ti pha thu, tn hiu thu c b khuych i i tp m thp (LNA) khuych i, c bin i vo trung tn (IF) thu ri c khuych i tuyn tnh bi b khuych i AGC (t iu khuych). Sau khuych di AGC tn hiu c gii iu ch c cc thnh phn I v Q. Cc tn hiu tng t ca cc thnh phn ny c bin i vo s ti b bin i A/D, c lc bi b lc Nyquist cosine tng cn hai v c phn chia theo thi gian vo mt s thnh phn ng truyn c cc thi gian tr truyn sng khc nhau. My thu RAKE chn cc thnh phn ln hn mt ngng cho trc). Sau gii tri ph cho cc thnh phn ny, chng c kt hp bi b kt hp my thu RAKE, tn hiu tng c gii an xen, gii m knh (gii m sa li), c phn knh thnh cc khi truyn ti TB v c pht hin li. Cui cng chng c a n lp cao hn. Hnh 3.13. S khi my pht tuyn (a) v my thu v tuyn (b)

3.8. PHN TP PHT

Khi nhiu anten thu c s dng, ta ni my thu s dng phn tp anten thu (Rx). Phn tp Rx c th c s dng ti nt B tng dung lng ng ln v vng ph sng. Do gi thnh v khng gian chim ln, phn tp anten thu khng ph bin ti my u cui. khc phc nhc im ny WCDMA s dng phn tp pht cho my u cui. Tn ti hai k thut phn tp pht WCDMA: Phn tp vng h v phn tp vng kn.

3.8.1. Phn tp vng h

Phn tp pht vng h s dng b m ha c gi l STTD (Space time Transmit Diversity: phn tp pht khng gian thi gian). S my pht v my thu s dng STTD c cho trn hnh 3.14a v 3.14b.

MF: Matched Filter: B lc phi hp

Hnh 3.14. Phn tp pht vng h ca WCDMA

STTD c xy dng trn c s m Alamouti nh sau :

(3.1)

trong ct 1 cha cc k hiu c pht i t anten 1 cn ct 2 cha cc k hiu c pht i t anten 2. Cc k hiu ny l cc k hiu iu ch QPSK (xem hnh 3.15).

Hnh 3.15. B iu ch STTD s dng m khi khng gian thi gian trc giao (O-STBC) 2x2.

3.8.2. Ch vng kn

R3 v R4 s dng hai khi nim phn tp pht vng kn. Trong c hai ch ny, thng tin ng chnh pha c pht trn mt knh hi tip nhanh (tc 1500 bps) cho php chn 4 hoc 16 kh nng trng s bp sng. C hai khi nim ny u c th coi l truyn dn nht qun (to bp thch ng knh) vi s dng cn bng knh v cc chin lc bo hiu hi tip khc nhau. Kin trc my pht v my thu nt B c cho trn hnh 3.16a v 3.16b.Hnh 3.16. Phn tp pht vng kn ca WCDMA

Trong c hai ch trng s pht c la chn theo th tc di y:

u cui o cc knh hoa tiu chung CPICH1 v CPICH2 c pht trn anten 1 v anten 2.

u cui nhn c c tnh knh cho ng truyn h1 v h2

Vect trng s pht cn thit W(w1, w2) c xc nh, c lng t v c gi n BTS trong trng FBI ca knh DCCH.

3.9. IU KHIN CNG SUT TRONG WCDMA

CDMA rt nhy cm vi iu khin cng sut: h thng WCDMA hot ng bnh thng, cn c mt c ch iu khin cng sut tt duy tr t s tn hiu trn nhiu (SIR) ti mc cho php. V nhiu ngi s dng cng truyn ng thi trn cng mt tn s, nn mc nhiu ph thuc vo s lng ngi s dng.

Tn ti hai kiu iu khin cng sut:

1. iu khin cng sut vng h: cho cc knh chung

2. iu khin cng sut vng kn: cho cc knh ring DPDCH/DPCCH v chia s DSCH

iu khin cng sut vng h thng c UE trc khi truy nhp mng v nt B trong qu trnh thit lp ng truyn v tuyn s dng c lng cng sut cn pht trn ng ln da trn cc tnh ton tn hao ng truyn trn ng xung v t s tn hiu trn nhiu yu cu.

iu khin cng sut vng kn c nhim v gim nhiu trong h thng bng cch duy tr cht lng thng tin gia UE v UTRAN (ng truyn v tuyn) gn nht vi mc cht lng ti thiu yu cu i kiu dch v m ngi s dng i hi.

iu khin cng sut vng kn bao gm hai phn: iu khin cng sut nhanh vng trong tc 1500 Hz v iu khin cng sut chm vng ngoi tc 10-100Hz.3.9.1. Th d v iu khin cng sut vng h cho PRACH

Da trn tnh ton ca PC vng h, UE thit lp cc cng sut ban u cho tin t knh truy nhp ngu nhin vt l (PRACH). Trong th tc truy nhp ngu nhin (xem phn 3.5.4), UE thit lp cng sut pht tin t u tin nh sau:

Preamble_Initial_power = CPICH_Tx_power CPICH _RSCP

+ UL_interference + UL_required_CI (3.2)

trong CPICH_Tx-power l cng sut pht ca P-CPICH, CPICH _RSCP l cng sut P-CPICH thu ti UE, CPICH_Tx_power CPICH _RSCP l c tnh suy hao ng truyn t nt B n UE. UL_interferrence (c gi l tng cng sut thu bng rng) c o ti nt B v c pht qung b trn BCH, UL_required_CI l hng s tng ng vi t s tn hiu trn nhiu c thit lp trong qu trnh quy hoch mng v tuyn. 3.9.2. iu khin cng sut vng kn ng ln

S iu khin cng sut vng kn ng ln cc cho trn hnh 3.17.

Hnh 3.17. Nguyn l iu khin cng sut vng kn ng ln

3.9.2.1. iu khin cng sut vng trong ng ln

Phng php iu khin cng sut nhanh vng kn ln nh sau (xem hnh 3.17). Nt B thng xuyn c tnh t s tn hiu trn nhiu thu c (SIR= Signal to Interference Ratio) trn hoa tiu ng ln trong UL DPCCH v so snh n vi t s SIR ch (SIRch). Nu SIRctnh cao hn SIRch th nt B thit lp bit iu khin cng sut trong DPCCH TPC=0 lnh UE h thp cng sut (Ty vo thit lp cu hnh: 1dB chng hn) , tri li n thit lp bit iu khin cng sut trong DPCCH TPC=1 ra lnh UE tng cng sut (1dB chng hn). Chu k o-lnh-phn ng ny c thc hin 1500 ln trong mt giy (1,5 KHz) W-CDMA. Tc ny s cao hn mi s thay i tn hao ng truyn v thm ch c th nhanh hn phainh nhanh khi MS chuyn ng tc thp.

3.9.2.2. iu khin cng sut vng ngoi ng ln

iu khin cng sut vng ngoi thc hin iu chnh gi tr SIRch nt B cho ph hp vi yu cu ca tng ng truyn v tuyn t c cht lng cc ng truyn v tuyn nh nhau. Cht lng ca cc ng truyn v tuyn thng c nh gi bng t s bit li (BER: Bit Error Rate) hay t s khung li (FER= Frame Error Rate). L do cn t li SIRch nh sau. SIR yu cu (t l vi Ec/N0) chng hn l FER=1% ph thuc vo tc ca MS v c im truyn nhiu ng. Nu ta t SIRch ch cho trng hp xu nht (cho tc cao nht) th s lng ph dung lng cho cc kt ni tc thp. Nh vy tt nht l SIRch th ni xung quanh gi tr ti thiu p ng c yu cu cht lng. thc hin iu khin cng sut vng ngoi, mi khung s liu ca ngi s dng c gn ch th cht lng khung l CRC. Nu kim tra CRC cho thy BLERctnh> BLERch th SIRch s b gim i mt nc bng (SIR, tri li n s c tng ln mt nc bng (SIR. L do t iu khin vng ngoi RNC v chc nng ny thc hin sau khi thc hin kt hp cc tn hiu chuyn giao mm.

3.9.3. iu khin cng sut vng kn ng xung

iu khin cng sut vng kn c minh ha trn hnh 3.18. UE nhn c BLER ch t lp cao hn do RNC thit lp cng vi cc thng s iu khin khc. Da trn BLER ch nhn c t RNC, n thc hin iu khin cng sut vng ngoi bng cch tnh ton SIR ch cho iu kin cng sut vng kn nhanh ng xung. UE c tnh SIR ng xung t cc k hiu hoa tiu ca DL DPCCH . c tnh SIR ny c so snh vi SIR ch. Nu c tnh ny ln hn SIR ch, th UE thit lp TPC=0 trong UL DPCCH v gi n n nt B, tri li n thit lp TPC=1. Tc diu khin cng sut vng trong l 1500Hz

Hnh 3.18. Nguyn l iu khin cng sut vng kn ng xung

3.10. CC KIU CHUYN GIAO V CC S KIN BO CO TRONG WCDMA

Chuyn giao l qu trnh c thc hin khi UE c kt ni v tuyn duy tr cht lng truyn dn. Trong WCDMA c th c chuyn giao cng hoc chuyn giao mm.

3.10.1. Chuyn giao cng

Chuyn giao cng (HHO: Hard Handover) ca WCDMA cng ging nh ca GSM. UE ch ni n mt nt B. Khi thc hin HO n mt nt B khc, kt ni n nt B c c gii phng.

Tt c cc kt ni s dng knh FACH (knh khng s dng iu khin cng sut v dnh cho cc gi ngn) hay DSCH (knh ph hp nht cho cc dch v chuyn mch gi) u s dng HHO.

Ngoi ra HHO s dng cho:

HO gia cc h thng (gia UTRAN v GSM)

HO gia cc tn s sng mang khc nhau ca UTRAN

3.10.2. Chuyn giao mm/ mm hn

Chuyn giao mm (hoc mm hn) s dng nhiu kt ni t mt UE n nhiu nt B. Danh sch cc nt B tham gia vo kt ni vi UE trong chuyn giao mm/mm hn c gi l tp tch cc. C th quy nh c kch thc cc i ca tp tch cc. Thc cht chuyn giao l qu trnh trong mt (on ) hoc c kt np vo tp tch cc hoc b loi ra khi tp tch cc. nh k hoc ti cc s kin bo co (s kin 1A, 1B v 1C chng hn), SRNC nhn c kt qu o t UE a ra quyt nh chuyn giao. Sau khi quyt nh chuyn giao, SRNC gii bn tin lp li cu hnh lin kt v tuyn c ng b n cc nt B lin quan v ng thi gi bn tin RRC v lp li cu hnh knh vt l n UE cc nt B ny v UE thc hin chuyn giao. Chuyn giao mm cho php tng s ng truyn thu c trn ng xung v ng ln nh vy tng t s tn hiu trn nhiu (SIR: Signal to Interference Ratio): Ec/I0 (Ec l nng lng chip cn I0 l mt ph cng sut nhiu) v lng tng ny c gi l li chuyn giao. S tng qut SHO c cho trn hnh 3.19.

R1a, R1b l di bo co cho cc s kin 1a v 1b c thit lp bi RNC; H1a, H1b l hng s tr c quy nh cho cc s kin 1a v 1bHnh 3.19. Th d v gii thut SHO

Trong th d trong trn hnh 3.19 ta s dng cc s kin bo co 1A, 1B v 1C. T hnh 3.19 ta thy:

Lc u. Ch c 1 v 2 nm trong tp tch cc

Ti s kin A. (Ec/I0)P-CPICH1 > (Ec/I0)P-CPICH3- (R1a-H1a/2) trong (Ec/I0)P-CPICH1 l t s tn hiu trn nhiu knh hoa tiu ca 1 mnh nht, (Ec/I0)P-CPICH3 l t s tn hiu trn nhiu knh hoa tiu ca 3 nm ngoi tp tch cc, R1a l hng s di bo co (do RNC thit lp), H1a l thng s tr s kin v (R1b-H1a/2) 1 ca s kt np cho s kin 1A. Nu bt ng thc ny tn ti trong khong thi gian (T th 3 c kt np vo tp tch cc

Ti s kin C. (Ec/I0)P-CPICH4 > (Ec/I0)P-CPICH2 +H1c, trong (Ec/I0)P-CPICH4 l t s tn hiu trn nhiu ca 4 nm ngoi tp tch cc v (Ec/I0)P-CPICH2 l t s tn hiu trn nhiu ca 2 ti nht trong tp tch cc, H1c l thng s tr s kin 1C. Nu quan h ny tn ti trong thi gian (T v tp tch cc y th 2 b loi ra khi tp tich cc v 4 s th ch ca n trong tp tch cc Ti s kin B. (Ec/I0)P-CPICH1 < (Ec/I0)P-CPICH3- (R1b+H1b) trong (Ec/I0)P-CPICH1 l t s tn hiu trn nhiu knh hoa tiu ca 1 yu nht trong tp tch cc, (Ec/I0)P-CPICH3 l t s tn hiu trn nhiu ca 3 mnh nht trong tp tch cc v R1b l hng s di bo co (do RNC thit lp), H1b l thng s s tr v (R1b+H1b) l ca s loi cho s kin 1C. Nu quan h ny tn ti trong khong thi gian (T th 3 b loi ra khi tp tch cc3.11. CC THNG S MY THU V MY PHT V TUYN CA UE

Cc thng s my thu v my pht quan trng trong phn v tuyn ca UE c cho trong bng bng 3.2.Bng 3.2. Cc thng s my thu v my pht v tuyn quan trng cho phn v tuyn ca UE Cc thng s chung

Tn s cng tcBng tn I: 2110-2170 MHz

Bng tn II: 1930-1990 MHz

Bng tn III: 1805-1880 MHz

Phn cch song cng chunBng tn I: 190 MHz

Bng tn II: 80 MHz

Bng tn III: 95 MHz

Cc thng s my thu

nhyBng tn 1: -117dBm

Bng tn II: -115dBm

Bng tn III: - 114dBm

Cc thng s my pht

Cng sut pht cc ai v chnh xcLoi 1: +33dBm +1/-3dB

Loi 2: +27dBm +1/-3dB

Loi 3: +24dBm +1/-3dB

Loi 4: +21dBm (2dB

iu khin cng sut pht vng hBnh thng: (9dB

Cc ai: (12dB

3.12. AMR CODEC CHO W-CDMA

B m ho ting a tc thch ng (AMR CODEC: Adaptive Multirate Codec) c coi l cng ngh vt tri cc cng ngh m ho ting khc. V th n c chn l s m ho ting cho 3GW-CDMA UMTS. N cung cp 8 ch m ho t 12,2 bps n 4,75kbps. Trong s cc ch ny, 12,2kbps, 7,4 kbps v 6,7 kbps c chung mt gii thut vi cc s m ho ting c tiu chun ho cc tiu chun ca cc vng khc trn th gii. AMC CODEC cho php la chn tc ty theo cht lng knh truyn sng. Nu cht lng tt, tc cao nht (12,2kbps) c chn. Nu ng truyn xu, mt trong s cc tc thp hn c la ty thuc vo cht lng ng truyn.

AMR cng quy nh cc cng ngh ngoi vi cn thit cho thng tin di ng. Hai tu chn c cung cp l gii thut VAD (pht hin tch cc ting) v DTX (pht khng lin tc. Ngoi ra cng nh ngha cc yu cu cho che du li khi xy ra li. Chng hn ni suy cc thng s m ho nh khuch i bng m, h s d on ngn hn cng c nh ngha theo s chuyn i trng thi do li gy ra.

3.13. TNG KT

Trc ht chng ny trnh by ngn xp giao thc ca giao din v tuyn v cc knh logic, knh truyn ti, knh vt l c to nn giao din ny. Sau chng trnh by cc thng s lp vt l v quy hoch tn s ca WCDMA. Ti Vit- Nam bng I c chia lm bn khe v c phn cho 4 nh khai thc. Ngn xp giao thc c chia thnh hai loi: mt trong mt phng C-Plane truyn bo hiu v mt trong mt phng U-Plane truyn lu lng. Tip theo cu trc ca cc knh ny c trnh by c th. Cc knh c chia thnh hai loi: knh iu khin, bo hiu v knh truyn lu lng. WCDMA l giai on pht trin u ca 3G WCDMA UMTS v th vic thit k cc knh truyn lu lng vn tp trung ln dch v chuyn mch knh vi knh c s dng cho dch v ny l DPCH. Tuy nhin cc knh dung c chuyn mch gi cng bt u c ch trng. DSCH (Knh chia s ng xung), RACH, FACH v CPCH c s dng cho mc ch ny. Cc knh RACH, FACH v CPCH c s dng truyn nhanh cc gi nh, cn knh DSCH c s cng vi knh DPCH trong thi im gi ln hn kh nng truyn ca knh DPCH. ng xung s dng s iu ch QPSK kt hp vi m ha knh kim sot li. M ha kim sot li c thc hin hai lp: (1) m ha pht hin li CRC, (2) m ha sa li. Cc m sa li c th l m xon hoc m turbo. WCDMA s dng phng php tri ph chui trc tip vi tc chip Rc=3,84Mcps. Tri ph c thc hin ti hai thao tc vi hai m: m nh knh v m nhn dng ngun pht. Khc vi GSM, 3G WCDMA s dng c phn tp pht ln phn tp thu ti nt B. Cc s ny c th nm trong ch vng h hoc vng kn. m bo t s tn hiu trn nhiu yu cu, hai s iu khin cng sut c s dng cho WCDMA: iu khin cng sut vng h v vng kn. iu khin cng sut vng h c p dng khi khi UE bt u truy nhp mng. iu khin vng kn c s dng khi UE kt ni vi nt B. iu khin cng sut vng kn bao gm iu khin cng sut vng trong nhanh vi tc 1500 ln trong mt giy v iu khin cng sut vng ngoi chm vi tc 10-100 ln trong mt giy. WCDMA c th s dng chuyn giao cng hoc mm. Chuyn giao mm ch c thc hin trn cng mt tn s v trong cng mt h thng Cui chng mt s thng s v thng tin quan trng lin quan n my thu v my pht v tuyn ca UE cng nh CODEC thoi cho WCDMA cng c trnh by.Chng 4

TRUY NHP GI TC CAO (HSPA)

4.1. GII THIU CHUNG

4.1.1. Mc ch chng

Hiu kin trc ngn xp giao thc giao din v tuyn HSDPA Hiu c cc s lp biu (Scheduler) v HARQ p dng cho HSPA Hiu c kin trc HSDPA v cc knh ca n Hiu c kin trc HSUPA v cc knh ca n Hiu c chuyn giao trong HSDPA4.1.2. Cc ch c trnh by trong chng

Tng quan HSPA

Kin trc giao din v tuyn ca HSPA

HSDPA

HSUPA

Chuyn giao HSDPA

4.1.3. Hng dn

Hc k cc t liu c trnh by trong chng

Tham kho cc ti liu tham kho nu cn

4.2. TNG QUAN TRUY NHP GI TC CAO (HSPA)

4.2.1. M u

Truy nhp gi tc cao ng xung (HSDPA: High Speed Down Link Packet Access) c 3GPP chun ha ra trong R5 vi phin bn tiu chun u tin vo nm 2002. Truy nhp gi ng ln tc cao (HSUPA) c 3GPP chun ha trong R6 v thng 12 nm 2004. C hai HSDPA v HSUPA c gi chung l HSPA. Cc mng HSDPA u tin c a vo thng mi vo nm 2005 v HSUPA c a vo thng mi vo nm 2007. Cc thng s tc nh ca R6 HSPA c cho trong bng 4.1.Bng 4.1. Cc thng s tc nh R6 HSPA

HSDPA (R6)HSUPA (R6)

Tc nh (Mbps)14,45,7

Tc s liu nh ca HSDPA lc u l 1,8Mbps v tng n 3,6 Mbps v 7,2Mbps vo nm 2006 v 2007, tim nng c th t n trn 14,4Mbps nm 2008. Trong giai on u tc nh HSUPA l 1-2Mbps trong giai on hai tc ny c th t n 4-5,7 Mbps vo nm 2008.

HSPA c trin khai trn WCDMA hoc trn cng mt sng mang hoc s dng mt sng mang khc t c dung lng cao (xem hnh 4.1).

Hnh 4.1. Trin khai HSPA vi sng mang ring (f2) hoc chung sng mang vi WCDMA (f1).

HSPA chia s chung h tng mng vi WCDMA. nng cp WCDMA ln HSPA ch cn b sung phn mm v mt vi phn cng nt B v RNC.

Lc u HSPA c thit k cho cc dch v tc cao phi thi gian thc, tuy nhin R6 v R7 ci thin hiu sut ca HSPA cho VoIP v cc ng dng tng t khc.

Khc vi WCDMA trong tc s liu trn cc giao din nh nhau (384 kbps cho tc cc i chng hn), tc s liu HSPA trn cc giao din khc nhau. Hnh 4.2 minh ha iu ny cho HSDPA. Tc nh (14,4Mbps trn 2 ms) ti u cui ch xy ra trong thi im iu kin knh truyn tt v th tc trung bnh c th khng qu 3Mbps. m bo truyn lu lng mang tnh cm ny, nt cn c b m lu li lu lng v b lp biu truyn lu lng ny trn h tng mng.

Hnh 4.2. Tc s liu khc nhau trn cc giao din (trng hp HSDPA)

4.3. KIN TRC NGN XP GIAO THC GIAO DIN V TUYN HSPA CHO S LIU NGI S DNG

Hnh 4.3 cho thy kin trc giao din v tuyn HSDPA v HSUPA cho s liu ngi s dng. Mt phng bo hiu khng c th hin trn hnh 4.3 (trong mt phng ny bo hiu c ni n RLC sau c a ln DCH hay HSDPA hoc HSUPA). S liu t cc dch v khc nhau c nn tiu IP ti PDCP (Packet Data Convergence Protocol). MAC-hs (High Speed: tc cao) thc hin chc nng lp biu nhanh da trn nt B.

i vi HSDPA chc nng MAC mi (MAC-hs) c t trong nt B x l pht li nhanh da trn HARQ (Hybrid Automatic Repeat Request: yu cu pht li t ng lai ghp), lp biu v u tin.

i vi HSUPA chc nng MAC mi (MAC-e) c t trong nt B x l pht li nhanh da trn HARQ, lp biu v u tin. Ti UE chc nng MAC-e mi c s dng x l lp biu v HARQ di s iu khin ca MAC-e trong nt B. Chc nng MAC mi (MAC-es) c t trong RNC sp xp li th t gi trc khi chuyn ln cc lp trn. S sp xp li ny l cn thit, v ca chuyn giao mm c th dn n cc gi t cc nt B khc nhau n RNC khng theo th t.

MAC-hs: High Speed MAC: MAC tc cao

MAC-e: E-DCH MAC: MAC knh E-DCH, MAC-es: thc th MAC knh E-DCH sp t li th t

Hnh 4.3. Kin trc giao din v tuyn HSDPA v HSUPA cho s liu ngi s dng

Hnh 4.4 cho thy cc chc nng mi trong cc phn t ca WCDMA khi a vo HSPA.

Hnh 4.4. Cc chc nng mi trong cc phn t ca WCDMA khi a vo HSPA.

4.4. TRUY NHP GI TC CAO NG XUNG (HSDPA)

HSDPA c thit k tng thng lng s liu gi ng xung bng cch kt hp cc cng ngh lp vt l: truyn dn kt hp pht li nhanh v thch ng nhanh c truyn theo s iu khin ca nt B.

4.4.1 Truyn dn knh chia s

c im ch yu ca HSDPA l truyn dn knh chia s. Trong truyn dn knh chia s, mt b phn ca tng ti nguyn v tuyn ng xung kh dng trong (cng sut pht v m nh knh trong WCDMA) c coi l ti nguyn chung c chia s ng theo thi gian gia cc ngi s dng. Truyn dn knh chia s c thc hin thng qua knh chia s ng xung tc cao (HS-DSCH: High-Speed Dowlink Shared Channel). HS-DSCH cho php cp pht nhanh mt b phn ti nguyn ng xung truyn s liu cho mt ngi s dng c th. Phng php ny ph hp cho cc ng dng s liu gi thng c truyn theo dng cm v v th c cc yu cu v ti nguyn thay i nhanh.

Cu trc c s thi gian v m ca HS-DSCH c cho trn hnh 4.5. Ti nguyn m cho HS-DSCH bao gm mt tp m nh knh c h s tri ph 16 (xem phn trn ca hnh 4.5), trong s m c th s dng lp cu hnh cho HS-DSCH nm trong khong t 1 n 15. Cc m khng dnh cho HS-DSCH c s dng cho mc ch khc, chng hn cho bo hiu iu khin, cc dch v MBMS hay cc dch v chuyn mch knh.

Hnh 4.5. Cu trc thi gian-m ca HS-DSCH

Phn di ca hnh 4.5 m t n nh ti nguyn m HS-DSCH cho tng ngi s dng trn c s TTI=2ms (TTI: Transmit Time Interval: Khong thi gian truyn dn). HSPDA s dng TTI ngn gim tr v ci thin qu trnh bm theo cc thay i ca knh cho mc ch iu khin tc v lp biu ph thuc knh (s xt trong phn di).

Ngoi vic c n nh mt b phn ca tng ti nguyn m kh dng, mt phn tng cng sut kh dng ca phi c n nh cho truyn dn HS-DSCH. Lu rng HS-DSCH khng c iu khin cng sut m c iu khin tc . Trong trng hp s dng chung tn s vi WCDMA, sau khi phc v cc knh WCDMA, phn cng sut cn li c th c s dng cho HS-DSCH, iu ny cho php khai thc hiu qu tng ti nguyn cng sut kh dng.

4.4.2. Lp biu ph thuc knh

Lp biu (Scheduler) iu khin vic dnh knh chia s cho ngi s dng no ti mt thi im cho trc. B lp biu ny l mt phn t then cht v quyt nh rt ln n tng hiu nng ca h thng, c bit khi mng c ti cao. Trong mi TTI, B lp biu quyt nh HS-DSCH s c pht n ngi (hoc cc ngi) s dng no kt hp cht ch vi c ch iu khin tc (ti tc s liu no).

Dung lng h thng c th c tng ng k khi c xt n cc iu kin knh trong quyt nh lp biu: lp biu ph thuc knh. V trong mt , cc iu kin ca cc ng truyn v tuyn i vi cc UE khc nhau thay i c lp, nn ti tng thi im lun lun tn ti mt ng truyn v tuyn c cht lng knh gn vi nh ca n (hnh 4.6). V th c th truyn tc s liu cao i vi ng truyn v tuyn ny. Gii php ny cho php h thng t c dung lng cao. li nhn c khi truyn dn dnh cho cc ngi s dng c cc iu kin ng truyn v tuyn thun li thng c gi l phn tp a ngi s dng v li ny cng ln khi thay i knh cng ln v s ngi s dng trong mt cng ln. V th tri vi quan im truyn thng rng phainh nhanh l hiu ng khng mong mun v rng cn chng li n, bng cch lp biu ph thuc knh phainh c li v cn khai thc n.

Chin lc ca b lp biu thc t l khai thc cc thay i ngn hn (do phainh a ng) v cc thay i nhiu nhanh nhng vn duy tr c tnh cng bng di hn gia cc ngi s dng. V nguyn tc, s mt cng bng di hn cng ln th dung lng cng cao. V th cn cn i gia tnh cng bng v dung lng.

Hnh 4.6. Lp biu ph thuc knh cho HSDPA

Ngoi cc iu kin knh, b lp biu cng cn xt n cc iu kin lu lng. Chng hn, s v ngha nu lp biu cho mt ngi s dng khng c s liu i truyn dn cho d iu kin knh ca ngi s dng ny tt. Ngoi ra mt s dch v cn c cho mc u tin cao hn. Chng hn cc dch v lung i hi c m bo tc s liu tng i khng i di hn, trong khi cc dch v nn nh ti xung khng c yu cu gt gao v tc s liu khng i di hn.

Nguyn l lp biu ca HSDPA c cho trn hnh 4.7. Nt B nh gi cht lng knh ca tng ngi s dng HSDPA tch cc da trn thng tin phn hi nhn c t ng ln. Sau lp biu v thch ng ng truyn c tin hnh theo gii thut lp biu v s u tin ngi s dng.

Hnh 4.7. Nguyn l lp biu HSDPA ca nt B4.4.3. iu khin tc v iu ch bc cao

iu khin tc c coi l phng tin thch ng ng truyn cho cc dch v truyn s liu hiu qu hn so vi iu khin cng sut thng c s dng trong CDMA, c bit l khi n c s dng cng vi lp biu ph thuc knh.

i vi HSDPA, iu khin tc c thc hin bng cch iu chnh ng t l m ha knh v chn la ng gia iu ch QPSK v 16QAM. iu ch bc cao nh 16QAM cho php t c mc s dng bng thng cao hn QPSK nhng i hi t s tn hiu trn tp m (Eb/N0) cao hn. V th 16 QAM ch yu ch hu ch trong cc iu kin knh thun li. Nt B la chn tc s liu c lp cho tng TTI 2ms v c ch iu iu khin tc c th bm cc thay i knh nhanh.

4.4.3.1. M ha knh HS-DSCH

Do m ha turbo c hiu nng vt tri m ha xn nn HS-DSCH ch s dng m ha turbo. Nguyn l tng qut ca b m ha turbo nh sau (hnh 4.8a). Lung s a vo b m ha turbo c chia thnh ba nhnh, nhnh th nht khng c m ha v cc bit ra ca nhnh ny c gi l cc bit h thng, nhnh th hai v th ba c m ha v cc bit ra ca chng c gi l cc bit chn l 1 v 2. Nh vy c mt bit vo th c ba bit ra, nn b m ha turbo ny c t l m l r=1/3. T l ny c th gim nu ta b bt mt s bit chn l v qu trnh ny c gi l c l (hnh 4.8b).

Hnh 4.8. M ha turbo v c l

4.4.3.2. iu ch HS-DSCH

HS-DSCH c th s dng iu ch QPSK v 16-QAM. Chm tn hiu QPSK v 16QAM c cho trn hnh 4.9.

iu ch QPSK ch cho php mi k hiu iu ch truyn c hai bit, trong khi iu ch 16QAM cho php mi k hiu iu ch truyn c bn bit v th 16QAM cho php truyn tc s liu cao hn. Tuy nhin t hnh 4.9 ta thy khong cch gia hai im tn hiu trong chm tn hiu 16QAM li ngn hn khong cch ny trong chm tn hiu QPSK v v th kh nng chu nhiu v tp m ca 16QAM km hn QPSK.

Hnh 4.9. Chm tn hiu iu ch QPSK, 16-QAM v khong cch cc tiu gia hai im tn hiu

4.4.3.3. Truyn dn thch ng trn c s iu ch v m ha knh thch ng

Truyn dn thch ng l qu trnh truyn dn trong tc s liu c thay i ty thuc vo cht lng ng truyn: tc ng truyn c tng khi cht lng ng truyn tt hn, ngc li tc ng truyn b gim. thay i tc truyn ph hp vi cht lng knh, h thng thc hin thay i s iu ch v t l m nn phng php ny c gi l iu ch v m ha thch ng (AMC: Adaptive Modulation and Coding). Chng hn khi cht lng ng truyn tt hn, h thng c th tng tc truyn dn s liu bng cch chn s iu ch 16QAM v tng t l m bng 3/4 bng cch c l, tri li khi cht lng truyn dn ti hn h thng c th gim tc truyn dn bng cch s dng s iu ch QPSK v khng c l gim t l bng 1/3. 4.4.4. HARQ vi kt hp mm

HARQ vi kt hp mm cho php u cui yu cu pht li cc khi thu mc li, ng thi iu chnh mn t l m hiu dng v b tr cc li gy ra do c ch thch ng ng truyn. u cui gii m tng khi truyn ti m n nhn c ri bo co v nt B v vic gii m thnh cng hay tht bi c 5ms mt ln sau khi thu c khi ny. Cch lm ny cho php pht li nhanh chng cc khi s liu thu khng thnh cng v gim ng k tr lin quan pht li so vi pht hnh R3.

Nguyn l x l pht li HSDPA c minh ha trn hnh 4.10. u tin gi c nhn vo b nh m ca nt B. Ngay c khi gi c gi i nt B vn gi gi ny. Nu UE gii m tht bi n lu gi nhn c vo b nh m v gi lnh khng cng nhn (NAK) n nt B. Nt B pht li c gi hoc ch phn sa li ca gi ty thuc vo gi thuth kt hp gi ti UE. UE kt hp gi pht trc vi gi c pht li v gii m. Trong trng hp gii m pha thu tht bi, nt B thc hin pht li m khng cn RNC tham gia. My di ng thc hin kt hp cc pht li. Pht theo RNC ch thc hin khi xy ra s c hot ng lp vt l (li bo hiu chng hn). Pht li theo RNC s dng ch cng nhn RLC, pht li RLC khng thng xuyn xy ra.

Hnh 4.10. Nguyn l x l pht li ca nt B

Khng nh HARQ truyn thng, trong kt hp mm, u cui khng loi b thng tin mm trong trng hp n khng th gii m c khi truyn ti m kt hp thng tin mm t cc ln pht trc vi pht li hin thi tng xc sut gii m thnh cng. Tng phn d (IR) c s dng lm c s cho kt hp mm trong HSDPA, ngha l cc ln pht li c th cha cc bit chn l khng c trong cc ln pht trc. IR c th cung cp li ng k khi t l m i vi ln pht u cao v cc bit chn l b sung lm gim tng t l m. V th IR ch yu hu ch trong tnh trng gii hn bng thng khi u cui gn trm gc v s lng cc m nh knh ch khng phi cng sut hn ch tc s liu kh dng. Nt B iu khin tp cc bit c m ha s s dng pht li c xt n dung lng nh kh dng ca UE.

Cc hnh 4.11 cho thy th d v s dng HARQ s dng m turbo c s t l m r=1/3 cho kt hp phn d tng. Trong ln pht u gi bao gm tt c cc bit thng tin cng vi mt s bit chn l c pht. n ln pht li ch cc bit chn l khc vi cc bit chn l c pht trong gi trc l c pht. Kt hp gi pht trc v gi pht sau cho ra mt gi c nhiu bit d sa li hn v v th y l s kt hp phn d tng.

Hnh 4.11. HARQ kt hp phn d tng s dng m turbo

4.4.4. Kin trc

T cc phn trn ta thy rng cc k thut HSDPA da trn thch ng nhanh i vi cc thay i nhanh trong cc iu kin knh. V th cc k thut ny phi c t gn vi giao din v tuyn ti pha mng, ngha l ti nt B. Ngoi ra mt mc tiu quan trng ca HSDPA l duy tr ti a s phn chia chc nng gia cc lp v cc nt ca R3. Cn gim thiu s thay i kin trc, v iu ny s n gin ha vic a HSDPA vo cc mng trin khai cng nh m bo hot ng trong cc mi trng m khng phi tt c cc u c nng cp bng chc nng HSDPA. V th HSDPA a vo nt B mt lp con MAC mi, MA-hs, chu trch nhim cho lp biu, iu khin tc v khai thc giao thc HARQ. Do vy ngoi tr cc tng cng cho RNC nh iu khin cho php HSDPA i vi cc ngi s dng, HSDPA ch yu tc ng ln nt B (hnh 4.12).

Hnh 4.12. Kin trc HSDPA

Mi UE s dng HSDPA s thu truyn dn HS-DSCH t mt ( phc v). phc v chu trch nhim lp biu, iu khin tc , HARQ v cc chc nng MAC-hs khc cho HSDPA. Chuyn giao mm ng ln c h tr trong truyn dn s liu ng ln s thu c t nhiu v UE s nhn c cc lnh iu khin cng sut t nhiu .

Di ng t mt h tr HSDPA n mt khng h tr HSDPA c x l d rng. C th m bo dch v khng b gin on cho ngi s dng (mc d ti tc s liu thp hn) bng chuyn mch knh trong RNC trong ngi s dng c chuyn mch n knh dnh ring (DCH) trong khng c HSDPA. Tng t, mt ngi s dng c trang b u cui c HSDPA c th chuyn mch t knh ring sang HSDPA khi ngi ny chuyn vo c h tr HSDPA.

Cu trc knh tng th ca HSDPA kt hp WCDMA c cho trn hnh 4.13.

Hnh 4.13. Cu trc knh HSDPA kt hp WCDMA

Di y ta tng kt chc nng ca cc knh trong HSDPA:

1. HS-DSCH (High Speed- Downlink Shared Channel) l knh truyn ti c sp xp ln nhiu knh vt l HS-PDSCH truyn ti lu lng gi chia s cho nhiu ngi s dng, trong mi HS-PDSCH c h s tri ph khng i v bng 16. Cu hnh cc i ca HS-DSCH l 15SF16 (tng ng vi tc nh khi iu ch 16QAM v t l m 1/1 l 14,4Mbps). Cc ngi s dng chia s HS-DSCH theo s knh vt l HS-PDSCH (s m vi SF=16) v khong thi gian truyn dn TTI=2ms.

2. HS-SCCH (High Speed-Shared Control Channel) s dng h s tri ph 128 v c cu trc thi gian da trn mt khung con c di 2ms bng di ca HS-DSCH. Cc thng tin sau y c mang trn HS-SCCH:

S m nh knh

S iu ch

Kch thc khi truyn ti

Gi c pht l gi mi hay pht li (HARQ) hoc HARQ theo RNC RLC

Phin bn d

Phin bn chm tn hiuKhi HSDPA hot ng trong ch ghp theo thi gian, ch cn lp cu hnh mt HS-SCCH, nhng kho HSDPA hot ng trong ch ghp theo m th cn c nhiu HS-SCCH hn. Mt UE c th xem xt c nhiu nht l 4 HS-SCCH ty vo cu hnh c lp bi h thng.

3. HS-DPCCH (High Speed- Dedicated Physical Control Channel) ng ln c h s tri ph 256 v cu trc t 3 khe 2ms cha cc thng tin sau y:

Thng tin phn hi (CQI: Channel Quality Indicator: ch th cht lng knh) bo cho b lp biu nt B v tc s liu m UE mong mun

ACK/NAK (cng nhn v ph nhn) cho HARQ

4. DPCCH (Dedicated Physical Control Channel) i cng vi HS-DPCCH ng ln cha cc thng tin ging nh R3.5. F-DPCH (Fractional- Dedicated Physical Channel) ng xung c h s tri ph 256 cha thng tin iu khin cng sut cho 10 ngi s dng tit kim ti nguyn m trong truyn dn gi4.4.5. HSDPA MIMO

MIMO l mt trong tnh nng mi c a vo R7 tng cc tc s liu nh thng qua truyn dn lung. Ni mt cch cht ch, MIMO (Multiple Input Multiple Output) l mt cch th hin tng qut s s dng nhiu anten c pha pht v pha thu. Nhiu anten c th c s dng tng li phn tp v v th tng t s sng mang trn nhiu ti my thu. Tuy nhin thut ng ny thng c s dng biu th truyn dn nhiu lp hay nhiu lung nh l mt phng tin tng tc s liu n mc cc i c th trong mt knh cho trc. V th MIMO hay ghp knh khng gian c th nhn nhn nh l mt cng c ci thin thng lng ca ngi s dng u cui ging nh mt b khuch i tc s liu. V bn cht, ci thin thng lng ca ngi s dng u cui mt mc nht nh s dn n tng thng lng h thng.

Cc s MIMO c thit k khai thc mt s thuc tnh ca mi trng truyn sng v tuyn nhm t c cc tc s liu cao bng cch pht i nhiu lung s liu song song. Tuy nhin t c cc tc s liu cao nh vy, cn m bo t s tn hiu trn nhiu cao tng ng ti my thu. V th ghp knh khng gian ch yu c p dng cho cc nh hn hay vng gn vi nt B, ni m thng thng t s tn hiu trn nhiu cao. Trong trng hp khng th m bo t s tn hiu trn nhiu cao, nhiu anten thu m UE c nng lc MIMO c trang b c th c s dng cho phn tp thu cho mt lung pht n. V th mt UE c nng lc MIMO s m bo tc s liu cao hn ti bin trong cc ln so vi mt UE tng ng ch c mt anten.

HSDPA MIMO h tr truyn dn hai lung. Mi lung c x l lp vt l nh nhau (m ha, tri ph v iu ch ging nh trng hp HSDPA mt lp). Sau m ha, tri ph v iu ch, tin m ha tuyn tnh da trn cc trng s phn hi t UE c s dng trc khi lung s c sp xp ln hai anten (hnh 4.14).

Hnh 4.14. S MIMO 2x2

S trn cng c th hot ng trong ch truyn dn mt lung. Trong trng hp ny ch c mt lung s liu l c m ha v c truyn ng thi trn c hai anten ging nh trng hp phn tp pht vng kn ca WCDMA. S MIMO vi hai ch ny c gi l D-TxAA (Dual Transmit Adaptive Array: dn thch ng pht kp). Trong mi trng di ng thc t ch hai lung c s dng khi UE gn trm gc (ng truyn c cht lng tt) v mt lung c s dng khi UE xa trm gc (ng truyn c cht lng xu).

Vic a vo MIMO s nh hng ch yu ln qu trnh x l lp vt l; nh hng ln lp giao thc l nh v cc lp trn ch yu nhn MIMO nh l mt tc s liu cao hn.

4.4.6. Tng tc nh bng vic s dng MIMO v iu ch bc cao 16QAM/64QAM

Bng 4.2 cho thy qu trnh tng tc nh HSDPA bng vic s dng MIMO kt hp vi iu ch bc cao 16QAM/64QAM i vi cc loi u cui UE khc nhau.Bng 4.2. Cc loi u cui HSDPA khc nhauTh loiS miu chMIMOT l m haTc bit nh (Mbps)Pht hnh ca 3GPP

125QPSK-3/41,8R5

5/6516QAM-3/43,6R5

7/81016QAM-3/47,2R5

91516QAM-3/410,1R5

101516QAM-Gn 1/114,0R5

131564QAM-5/617,4R7

141564QAM-Gn 1/121,1R7

151516QAM2x25/623,4R7

161516QAM2x2Gn 1/128R7

4.5. TRUY NHP GI TC CAO NG LN (HSUPA)

Ct li ca HSUPA cng s dng hai cng ngh c s nh HSDPA: lp biu nhanh v HARQ nhanh vi kt hp mm. Cng ging nh HSDPA, HSUPA s dng khong thi gian ngn 2ms cho TTI ng ln. Cc tng cng ny c thc hin trong WCDMA thng qua mt knh truyn ti mi, E-DCH (Enhanced Dedicated Channel: knh ring tng cng).

Mc d s dng cc cng ngh ging HSDPA, HSUPA cng c mt s khc bit cn bn so vi HSDPA v cc khc bit ny nh hng ln vic thc hin chi tit cc tnh nng:

Trn ng xung, cc ti nguyn chia s l cng sut v m u c t trong mt nt trung tm (nt B). Trn ng ln, ti nguyn chia s l i lng nhiu ng ln cho php, i lng ny ph thuc vo cng sut ca nhiu nt nm phn tn (cc nt UE)

Trn ng xung b lp biu v cc b m pht c t trong cng mt nt, cn trn ng ln b lp biu c t trong nt B trong khi cc b m s liu c phn tn trong cc UE. V th cc UE phi thng bo thng tin v tnh trng b m cho b lp biu

ng ln WCDMA v HSUPA khng trc giao v v th xy ra nhiu gia cc truyn dn trong cng mt . Tri li trn ng xung cc knh c pht trc giao. V th iu khin cng sut quan trng i vi ng ln x l vn gn xa. E-DCH c pht vi khong dch cng sut tng i so vi knh iu khin ng ln c iu khin cng sut v bng cch iu chnh dch cng sut cho php cc i, b lp biu c th iu khin tc s liu E-DCH. Tri li i vi HSDPA, cng sut pht khng i ( mc nht nh) cng vi s dng thch ng tc s liu.

Chuyn giao c E-DCH h tr. Vic thu s liu t u cui ti nhiu l c li v n m bo tnh phn tp, trong khi pht s liu t nhiu trong HSDPA l phc tp v cha chc c li lm. Chuyn giao mm cn c ngha l iu khin cng sut bi nhiu gim nhiu gy ra trong cc ln cn v duy tr tng tch ngc vi UE khng s dng E-DCH

Trn ng xung, iu ch bc cao hn (c xt n hiu qu cng sut i vi hiu qu bng thng) c s dng cung cp cc tc s liu cao trong mt s trng hp, chng hn khi b lp biu n nh s lng m nh knh t cho truyn dn nhng i lng cng sut truyn dn kh dng li kh cao. i vi ng ln tnh hnh li khc; khng cn thit phi chia s cc m nh knh i vi cc ngi s dng khc v v th thng thng t l m ha knh thp hn i vi ng ln. Nh vy khc vi ng ln iu ch bc cao t hu ch hn trn ng ln trong cc v m v v th khng c xem xt trong pht hnh u ca HSUPA. 4.5.1. Lp biu

i vi HSUPA, b lp biu l phn t then cht iu khin khi no v ti tc s liu no mt UE c php pht. u cui s dng tc cng cao, th cng sut thu t u cui ti nt B cng phi cng cao m bo t s Eb/N0 (Eb=Pr/Rb, Pr l cng sut thu ti nt B cn Rb l tc bit c pht i t UE) cn thit cho gii iu ch. Bng cch tng cng sut pht, UE c th pht tc s liu cao hn. Tuy nhin do ng ln khng trc giao, nn cng sut thu t mt UE s gy nhiu i vi cc u cui khc. V th ti nguyn chia s i vi HSUPA l i lng cng sut nhiu cho php trong . Nu nhiu qu cao, mt s truyn dn trong , cc knh iu khin v cc truyn dn ng ln khng c lp biu c th b thu sai. Tri li mc nhiu qu thp cho thy rng cc UE b iu chnh thi qu v khng khai thc ht ton b dung lng h thng. V th HSUPA s dng b lp biu cho php cc ngi s dng c s liu cn pht c php s dng tc s liu cao n mc c th nhng vn m bo khng vt qu mc nhiu cc i cho php trong .

Nguyn l lp biu HSUPA c cho trn hnh 4.15.

Hnh 4.15. Nguyn l lp biu HSUPA ca nt B

Khc vi HSDPA, b lp biu v cc b m pht u c t ti nt B, s liu cn pht c t ti cc UE i vi ng ln. Ti cng mt thi im b lp biu t ti nt B iu phi cc tch cc pht ca cc UE trong . V th cn c mt c ch thng bo cc quyt nh lp biu cho cc UE v cung cp thng tin v b m t cc UE n b lp biu. Chng trnh khung HSUPA s dng cc cho php lp biu pht i t b lp biu ca nt B iu khin tch cc pht ca UE v cc yu cu lp biu pht i t UE yu cu ti nguyn. Cc cho php lp biu iu khin t s cng sut gia E-DCH v hoa tiu c php m u cui c th s dng; cho php ln hn c ngha l u cui c th s dng tc s liu cao hn nhng cng gy nhiu nhiu hn trong . Da trn cc kt qu o c mc nhiu tc thi, b lp biu iu khin cho php lp biu trong tng u cui duy tr mc nhiu trong ti mc quy nh (hnh 4.16).

Trong HSDPA, thng thng mt ngi s dng c x l trong mt TTI. i vi HSUPA, trong hu ht cc trng hp chin lc lp biu ng ln c th thc hin lp biu ng thi cho nhiu ngi s dng. L do v mt u cui c cng sut nh hn nhiu so vi cng sut nt B: mt u cui khng th s dng ton b dung lng mt mnh.

Hnh 4.16. Chng trnh khung lp biu ca HSUPA

Nhiu gia cc cng cn c iu khin. Thm ch nu b lp biu cho php mt UE pht ti tc s liu cao trn c s mc nhiu ni chp thun c, nhng vn c th gy nhiu khng chp nhn c i vi cc ln cn. V th trong chuyn giao mm, phc v chu trch nhim chnh cho hat ng lp biu, nhng UE gim st thng tin lp biu t tt c cc m UE nm trong chuyn giao mm. Cc khng phc v yu cu tt c cc ngi s dng m n khng phc v h tc s liu E-DCH bng cch pht i ch th qu ti trn ng xung. C ch ny m bo hot ng n nh cho mng.

Lp biu nhanh cung cp mt chin lc cho php kt ni mm do hn. V c ch lp biu cho php x l tnh trng trong nhiu ngi s dng cn pht ng thi, nn s ngi s dng s liu gi tc cao mang tnh cm c cho php ln hn. Nu iu ny gy ra mc nhiu cao khng th chp nhn c trong h thng, th b lp biu c th phn ng nhanh chng hn ch cc tc s liu m cc UE c th s dng. Khng c lp biu nhanh, iu khin cho php c th chm tr hn v phi dnh mt d tr nhiu trong h thng trong trng hp nhiu ngi s dng hot ng ng thi.

4.5.2. HARQ vi kt hp mm

HARQ nhanh vi kt hp mm c HSUPA s dng vi mc ch c bn ging nh HSDPA: m bo tnh bn vng chng li cc sai li truyn dn ngu nhin. S c s dng ging nh i vi HSDPA. i vi tng khi truyn ti c pht trn ng ln, mt bit c pht t nt B n UE thng bo gii m thnh cng (ACK) hay yu cu pht li khi truyn ti thu b mc li (NAK).

im khc bit chnh so vi HSDPA bt ngun t vic s dng chuyn giao mm trn ng ln. Khi UE nm trong chuyn giao mm, ngha l giao thc HARQ kt cui ti nhiu . V th trong nhiu trng hp s liu truyn dn c th c thu thnh cng ti mt s nt B nhng li tht bi ti cc nt B khc. Nhn t pha UE, iu ny l , v t nht mt nt B thu thnh cng s liu. V th trong chuyn giao mm tt c cc nt B lin quan u gii m s liu v pht ACK hoc NAK. Nu UE nhn c ACK t nht t mt nt B, UE coi rng s liu c thu thnh cng.

HARQ vi kt hp mm c th c khai thc khng ch m bo tnh bn vng chng li nhiu khng d bo c m cn ci thin hiu sut ng truyn tng dung lng v (hoc) vng ph. Cc bit c m ha b sung ch c pht khi cn thit. V th t l m sau cc ln pht li c xc nh theo t l m cn thit cho iu kin knh tc thi. y cng chnh l mc tiu m thch ng tc c gng t c, im khc chnh l thch ng tc c gng tm ra t l m ph hp trc khi pht.

4.5.3. Kin trc

hot ng hiu qu, b lp biu phi c kh nng khai thc cc thay i nhanh theo mc nhiu v cc iu kin ng truyn. HARQ vi kt hp mm cng cho li t cc pht li nhanh v iu ny gim chi ph cho cc pht li. V th hai chc nng ny phi c t gn giao din v