N MN HCMn: Thng Tin Di ngGio vin hng dn:Th.S. Nguyn c ThinH v tn SV:Phan Thch Chung + Lu Vn nh + Nguyn Quang Huy + Nguyn Quang V ti: Overview the HSDPA and LTE. Structure of these systems.DANH MC CC K T VIT TT3G : Third Generation3GPP: 3rd Generation Partnership Project16 QAM : 16 Quadrature Amplitude ModulationAMC: Adaptive Modulation and CodingARQ: Automatic Repeat RequestBCCH: BroadCast Control Channel (logic channel)BCH: BroadCast Channel (transport channel)BER: Biit Error RateDCCH: Dedicated Control Channel (logic channel)DPCCH: Dedicated Physical Control ChannelDPCH: Dedicated Physical ChannelDPDCH: Dedicated Physical Data ChannelDTCH: Dedicated Traffic ChannelEDGE: Enhansed Data Rates for GSM EvolutionFDD: Frequency Division Multiple AccessGSM: Global System for Mobile CommunicationsH-ARQ: Hybrid Automatic Repeat RequestHS-DPCCH: Uplink High-Speed Dedicated Physical Control ChannelHS-DSCH: High-Speed Downlink Shared ChannelHS-PDSCH: High-Speed Physical Downlink Shared ChannelHS-SCCH: High-Speed Shared Control ChannelHSPDA: High Speed Downlink Packet AccessITU: Internation Telecommunication UnionMAC: Medium Access ControlMAC-HS: Hight-Speed MACNode-B: Base StationSAW: Stop And WaitTTI: Transmission Time IntervalUMTS: Universal Mobile Telecommunication SystemWCDMA: Wideband CDMA

1.T VN :Thng tin di ng l ngnh cng nghip vin thng pht trin nhanh nht vi con s thu bao di ng t gn vi dn s th gii 7 t ngi. Khi ngun t dch v thoi t tin phc v mt s t ngi di chuyn, n nay vi s ng dng ngy cng rng ri cc thit b thng tin di ng th h ba, thng tin di ng c th cung cp nhiu loi hnh dch v i hi tc s liu cao k c cc chc nng camera, MP3 v PDA. Vi cc dch v i hi tc ngy cng tr nn ph bin th nhu cu v 3G cng nh pht trin n ln 4G ngy cng tr nn cp thit.HSDPA l mt phng thc truyn ti d liu theo phng thc mi. y c coi l dng sn phm 3.5G, cng ngh ny cho php d liu download v my in thoi c tc tng ng vi tc ng truyn ADSL. HSDPA (High Speed Downlink Packet Access), gi ng truyn tc cao, l mt sn phm ca cng ngh 3G cho php cc mng hot ng trn h thng UMTS c kh nng truyn ti d liu vi tc cao hn hn. Cng ngh HSDPA hin nay cho php tc download t n 1.8, 3.6, 7.2 v 14.4 Mbit/giy, v trong tng lai gn, tc hin nay c th c nng ln gp nhiu ln. Khi , cc mng cung cp c th c nng cp thnh Evolved HSPA, cho php tc download t n 42 Mbit/giy. Vi nhng u th vt tri , HSDPA ang tr thnh mt cng ngh c nhiu nh cung cp quan tm pht trin.LTE (vit tt ca cm t Long Term Evolution, c ngha l Tin ha di hn), cng ngh ny c coi nh cng ngh di ng th h th 4 (4G, nhng thc cht LTE mi ch c coi nh 3.9G). 4G LTE l mt chun cho truyn thng khng dy tc d liu cao dnh cho in thoi di ng v cc thit b u cui d liu. N da trn cc cng ngh GSM/EDGE v UMIT/HSPA, LTE nh s dng k thut iu ch mi v mt loi cc gii php cng ngh khc nh lp lch ph thuc knh v thch nghi tc d liu, k thut a anten tng dung lng v tc d liu. Cc tiu chun ca LTE c t chc 3GPP (D n i tc th h th 3) ban hnh v c quy nh trong mt lot cc ch tiu k thut ca Phin bn 8 (Release 8), vi nhng ci tin nh c m t trong Phin bn 9. Dch v LTE thng mi u tin trn th gii c hngTeliaSoneragii thiu OslovStockholm vo ngy 14/12/2009.LTE l hng nng cp t nhin cho cc sng mang vi cc mng GSM/UMTS, nhng ngay c cc nh mng da trn cng nghCDMAnh Verizon Wireless(hng ny khai trng mng LTE quy m ln u tin Bc M vo nm 2010),vhng KDDI Nht cng tuyn b h s chuyn ln cng ngh LTE. Do LTE c d kin s tr thnh tiu chun in thoi di ng ton cu thc s u tin, mc d vic s dng ccbng tnkhc nhau ti cc quc gia khc nhau s yu cu in thoi di ng LTE phi lm vic c cc bng tn khc nhau ti tt c cc quc gia s dng cng ngh LTE.2. GII THIU V CNG NGH HSDPA (3.5G)2.1 Tng quan v HSDPAMc d cng ngh 3G WCDMA hin nay cho php tc c d liu gi ln n 2Mbps. Tuy nhin, cc tiu chun thit k h thng WCDMA c mt s hn ch nh: Khng tn dng cc u th ca d liu gi vn rt ph bin i vi ng trc hu tuyn Thit k dch v 2Mbps hin nay l khng hiu qu v cng cha p ng c nh cu s dng dch v s liu hin nay Khng th x l tc d liu cao ln n 10MbpsDo , R5 tip tc c pht trin khc phc nhng hn ch ny. R5 l s pht trin quan trng ca mng v tuyn 3G k t khi WCDMA c chp nhn l cng ngh mng v tuyn 3G t nm 1997 vi cc tnh nng k thut ca cng ngh HSDPA gm: Tng ng vi CDMA2000 1xEV (HDR) iu ch v m ha thch ng Sng mang tc d liu cao (HDRC) trong bng tn 5MHz 64 QAM h tr tc nh tng ng 7.2 Mbps M Turbo Kh nng sa li gn vi gii hn l thuyt ARQ ghp thch ng T ng thch ng lien tc theo iu kin knh bng cch ghp chn thm thng tin khi cn S dng AMC khi c kt hp vi HARQ nhm ci thin dung lng thng tin khi cn. Cc k thut c s dng cho php HSDPA h tr tc 10 Mbps Trong mt h thng d liu v thoi c tch hp vi ngoi s dng thoi (12.2 Kbps) ti khong 30 Erl/sector v thng lng sector ca d liu vn khong 1 Mbps.HSDPA (High Speed Downlink Packet Access) truy cp gi ng xung tc cao, l gii php mang tnh t ph v mt cng ngh v c pht trin trn c s ca h thng 3G WCDMA, c ti u ho cho cc ng dng d liu chuyn mch gi. Cng ngh HSDPA hin nay cho php tc download t n 1.8 Mbps, 3.6 Mbps, 7.2 Mbps v 14.4 Mbps, v trong tng lai gn, tc hin nay c th c nng ln s dng tt hn. Cc thu bao dch v HSDPA c th nhn email vi tp tin nh km mang dung lng ln, lt web hoc ti v cc tp tin a phng tin hoc vn bn nhanh hn bao gi. Mc d c th truyn ti bt c dng d liu no, song mc tiu ch yu ca HSDPA l d liu dng video v nhc.Khi nim HSDPA c pht trin da trn cng ngh W-CDMA, s dng cc phng php chuyn i v m ha d liu khc. N to ra mt knh truyn d liu bn trong W-CDMA c gi l HS-DSCH (High Speed Downlink Shared Channel), knh chia s ng xung tc cao. Knh truyn ti ny hot ng hon ton khc bit so vi cc knh thng thng v cho php thc hin download vi tc vt tri. V y l mt knh chuyn dng cho vic download. iu cng c ngha l d liu s c truyn trc tip t ngun n in thoi. Song qu trnh ngc li, tc l truyn d liu t in thoi n mt ngun tin th khng th thc hin c khi s dng cng ngh HSDPA. Cng ngh ny c th c chia s gia tt c cc ngi dng c s dng sng radio, sng cho hiu qu download nhanh nht.Ngoi ra HSDPA cn s dng iu ch v m ha thch ng (Adaptive Modulation and Coding), HARD nhanh (Hybrid Automatic Repeat Request), v lp lch gi (Packet Scheduling) nhanh. Nhng tnh nng ny c phi hp cht ch v cho php thch ng cc tham s truyn dn theo mi khong thi gian TTI nhm lin tc hiu chnh s thay i ca cht lng knh v tuyn.2.2 Nhng ci tin quan trng ca HSDPA so vi WCDMATrong WCDMA, iu khin cng sut nhanh nhm gi n nh cht lng tn hiu nhn c (Eb/No) bng cch tng cng sut pht nhm chng li s suy hao ca tn hiu thu c. iu ny s to ra cc gi tr nh trong cng sut pht v tng nn nhiu a truy cp, do s lm gim dung lng ca ton mng. Hn th na, s hot ng ca iu khin cng sut yu cu lun lun phi m bo mt mc d tr nht nh trong tng cng sut pht ca Node B thch ng vi cc bin i ca n. Loi b c iu khin cng sut s trnh c cc hiu ng tng cng sut k trn cng nh khng cn ti d tr cng sut pht ca t bo.Tuy nhin, khng s dng iu khin cng sut, HSDPA yu cu cc k thut thch ng lin kt khc thch ng cc tham s tn hiu pht nhm lin tc bm theo cc bin thin ca knh truyn v tuyn. Mt trong nhng yu cu thch ng lin kt s c cp trong khun kh bi n mn hc ny c gi l iu ch v gii m thch ng - AMC. Vi k thut AMC, iu ch v t l m ha c thch ng mt cch lin tc vi cht lng knh thay cho vic hiu chnh cng sut. truyn dn s dng nhiu m Walsh cng c s dng trong qu trnh thch ng lin kt. S kt hp ca hai k thut thch ng lin kt trn thay th hon ton k thut h s tri ph bin thin trong WCDMA do kh nng thch ng chm i vi s bin thin ca ttruyn dn v tuyn tc cao. Do HSDPA khng cn s dng iu khin cng sut vng kn, phi ti thiu ha s thay i ca cht lng knh v tuyn trong mi khon thi gian TTI, vn ny c thc hin nh vic gim rng ca TTI t 10ms WCDMA xung cn 2ms HSDPA. Vi s b sung k thut HARQ nhanh, n cn cho php pht li mt cch nhanh nht cc block d liu b mt hoc b li v kh nng kt hp vi thng tin mm ln pht u tin vi cc ln pht li sau . thu thp c thng tin v thng tin cht lng knh hin thi cho cc php k thut thch ng lin kt v lp lch gi theo di gim st mt cch lin tc cc iu khin v tuyn hin ti ca thu bao di ng, lp iu khin trung gian MAC th lm nhim v gim st knh nhanh cho php b lp lch gi nhanh v c tnh chia s theo thi gian ca knh HS-DSCH v bn cht c th xem nh phn tp la chn a ngi dng vi nhng li ch to ln i vi vic ci thin thng lng ca t bo. Vic chuyn dch chc nng lp lch n Node B l thay i chnh v kin trc nu so snh vi phin bn R99 ca WCDMA.2.3 Nguyn l hot ng ca HSDPAHSDPA gm cc gii php: Thc hin an xen thi gian truyn dn ngn TTI = 2ms M ha v iu ch thch ng AMC Truyn dn a m, lp vt l tc cao L1 Yu cu lp li H-ARQTrong gii php HSDPA, thit b sp xp gi tin s c chuyn t b iu khin mng v tuyn NC ti Node-B nhm gip ngi s dng d dng truy nhp vo cc chc nng thng k giao din v tuyn. K thut sp xp gi tin tin tin s gip iu chnh c tc d liu ngi s dng sao cho thch hp vi cc iu kin knh v tuyn tc thi.Trong qu trnh kt ni, thit b ngi s dng (UE) s nh k gi mt ch th cht lng knh CQI ti Node-B cho bit tc d liu no (bao gm k thut iu ch v m ha, s lng cc m s dng) m thit b ny c th h tr khi cc iu kin v tuyn hin thi. ng thi, UE gi mt bo co xc nhn (Ack/Nack) ng vi mi gi gip cho Node-B bit c im lp li qu trnh truyn d liu. Cng vi chc nng thng k cht lng knh tng ng cho tng UE trong mt cell, thit b sp xp gi tin s thc hin sp xp cc gi ca cc UE mt cch cng bng.

Hnh 1. Nguyn l lp biu ca Node-B HSDPAVn chng ta cn quan tm l cht lng knh ng truyn ca mi ngi s dng c lp v cch xc nh n. V d nh: t l cng sut k hiu trn tp nhiu (t s Es/No), cht lng b tch UE. Node-B c th c lng tc d liu c h tr cho mi UE bng cch gim st cc lnh iu khin cng sut pht theo chu k mt gi tr ch th cht lng knh (CQI - Channel Quanlity Indicator) c th ca HSDPA trn knh iu khin vt l dnh ring tc cao (HS-DPCCH) ng ln, knh ny cng mang c thng tin bo hiu chp nhn/ khng chp nhn (Ack/Nask) dng gi da trn L1 cho mi knh lin kt. Khi c tnh c cht lng knh, h thng chia s ti nguyn m v cng sut HS-DSCH gia ngi s dng khc nhau.

Hnh 2. X l u tin trong b lp biuLp iu khin truy nhp mi trng (MAC Medium Access Control) c t ti Node-B, do cho php truy nhp nhanh hn ti cc gi tr o lng tuyn kt ni, lp lch gi hiu qu hn v nhanh hn, cng nh c th kim sot cht lng QoS cht ch hn. So snh vi k thut DMA truyn thng, knh HS- DSCH khng thc hin vi iu kin cng sut pht nhanh v h s tri ph c nh. Bng cch s dng k thut m ha Turbo tc thay i, iu ch 16 QAM, cng nh hot ng m m rng, knh HS-DSCH h tr tc d liu nh t 120 Kbps ti hn 10Mbps. Qu trnh iu ch v m ha thch ng c bn c mt di ng khong 20dB, v c m rng hn na s a m kh dng.

Hnh 3. Thch ng ng truyn2.4 Cu trc HSDPA2.4.1 M hnh giao thc HSDPATrong cu trc HSDPA, thit b sp xp cc gi tin s c chuyn t b iu khin nhp mng v tuyn RNC ti Node-B nhm gip ngi s dng d dng truy nhp vo cc chc nng thng k giao din v tuyn. K thut sp xp gi tin tin tin s gip iu chnh c tc d liu ngi s dng sao cho thch hp vi cc iu kin knh v tuyn tc thi.Nu nh tt c cc knh truyn ti theo kin trc R99, chng u chm dt ti RNC th knh HS-DSCH li chm dt ngay ti Node-B nhm mc ch iu khin knh HS-DSCH, lp MAC-HS (lp iu khin truy cp trung gian tc cao), s iu khin cc ti nguyn ca knh ny v nm ngay ti Node-B. Do , cho php nhn cc bn tin v cht lng knh hin thi c th tip tc theo di gim st cht lng tn hiu cho thu bao tc thp. V tr ny ca MAC-HS ti Node-B cng cho php kch hot giao thc HARQ t lp vt l, n gip cho cc qu trnh pht trin li din ra nhanh hn.c bit hn, lp MAC-HS chu trch nhim qun l chc nng HARQ cho mi user, phn phi ti nguyn HS-DSCH gia tt c cc MAC-D thoe s u tin ca chng (v d nh lp lch gi), v la chn khun dng truyn ti thch hp cho mi TTI (v d nh thch ng lin kt). Cc lp giao din v tuyn nm trn MAC khng thay i so vi kin trc Relase 99 bi v HSDPA ch tp trung vo vic ci tin truyn ti ca cc knh logic.Lp MAC-HS cng lu gi d liu ca user c pht qua giao din v tuyn, iu to ra mt s thch thc i vi vic ti u ha dung lng b nh m ca Node-B.2.4.2 Cu trc knhTi nguyn chng ca ngi s dng trong t bo bao gm cc b m ha knh v cng sut pht. Khi nim HSDPA c gii thiu bao gm mt s knh vt l thm vo: Knh vt l chia s ng xung tc cao HS-PDSCH (High Speed Physical Downlink Shared Channel) Knh iu khin vt l HS-DPCCH (HS- Physical Control Channel)2.4.2.1 Knh vt l chia s ng xung tc cao (HS-PDSCH)Trong knh ny thi gian v m ha c chia s gia nhng ngi s dng gn lin vi Node-B. y l c cu truyn ti cho cc knh logic c thm vo: Knh chia s ng xung tc cao HS-DSCH (HS Downlink Shared Channel) Knh iu khin chia s tc cao HS-SCCH (HS Shared Control Channel)Nhng ti nguyn m ha HS-DSCH gm c mt hoc nhiu b m nh hng vi h s phn b c nh SF 16. Phn ln 15 b m ny c th phn b cho nhng yu cu v truyn dn d liu v iu khin. Cc ti nguyn m ha sn sng c chia s ch yu trong min thi gian nhng n c th chia s ti nguyn m ha bng cch dng m ha a thnh phn. Khi c thi gian v b m c chia s , t hai n bn ngi s dng c th chia s ti nguyn m ha trong cng mt TTI.c tnh quan trng ca knh HS-DSCH l tnh linh ng ca ngun c chia s trong khong thi gian rt ngn 2ms. Khi d liu ngi dng c t trn knh HS-DSCH, chng lin tc c gi i khe thi gian 2ms .Ngc li, vi phin bn R99 ca WCDMA cn c thm khong DTX khong truyn gin on nm trn khe DPDCH, n c tc dng lc nhiu trn ng truyn nhng khng th t c tc ln nht. V R99 ra i vi mc tiu chnh l tng dung lng h thng cho cc dch v thoi so vi h thng 2G (GSM) m thi ch cha s t t c nhng yu cu v k vng i vi dichj v s liu v tc h tr d liu cn thp (khong 384 kbps). i vi dch v thoi th chng ta bit, ngun ti nguyn (m, cng sut, nhiu) yu cu truyn dn dch v ny l khng thay i (do tc truyn dn l khng thay i) do iu khin cng sut thc s hiu qu v n gim nhiu MAI lm cho dung lng knh thoi knh thoi m h thng c th p ng trn mt n v ti nguyn v tuyn tng ln.Tuy vy khi trin khai cc dch v s liu (File Tranfer, Internet Access, E-mail, ) chng ta thy rng c th ca nhng dch v ny l yu cu ngun ti nguyn rt ln v trong khong mt thi gian ngn. V d nh nu truy nhp vo mt trang web no th cng mt lc ni dung vn bn v hnh nh ca ni dung trang website cn truyn n my u cui trong mt khong nht nh. Sau khi ni dung trang web download v my u cui th thng thng ngi s dng s xem ni dung v khng truy nhp ti nguyn h thng na. Nhng dch v m yu cu ngun ti nguyn ln v trong khong thi gian ngn nh vy trong k thut ngi ta gi chung mt tn l bursty data service.Vi knh HS-DSCH trong HSDPA th ngi ta cp pht 15 m tri ph vi h s tri 16 dng chung gia cc my trong cng 1 sector. Cc my c cp pht ti nguyn trong tng khong thi gian nht nh (TDM). B scheduler s cp pht ti nguyn: bao nhiu m tri ph, cng sut l bao nhiu ph thuc vo yu cu dch v, trng thi knh ca user .

Hnh 4. Kch thc khi truyn ti ph thuc vo m s nh knh cho QPSK v 16 QAM.Nh hnh v trn, ti khong thi gian u tin User 1 c trng thi knh tt nn b scheduler a ra quyt nh cp pht ti nguyn cho User ny. Khi quyt nh cp pht ti nguyn cho User 1 ny k thut thch ng cng c p dng. nu trng thi knh ca User lc ny tt v nhu cu v tc truyn dn ln th my pht c th dng iu ch 16-QAM hoc m knh vi t l m ln hn truyn dn v User 2 c trng thi knh tt hn nh trn hnh v. Bng vic cp pht ti nguyn ng, kt hp vi k thut thch ng (ACM) chng ta c th thy rng knh truyn dn chng lun c cht lng knh mc tt c th hin ng nt t trn hnh v.Ngoi d liu ngi s dng, Node-B cn thc hin truyn dn bo hiu iu khin nhm thng bo sp xp cho ngi dng k tip. Bo hiu ny c sp xp trong knh iu khin chia s tc cao (HS-SCCH), l knh dng chung cho cc ngi s dng, v n c thc hin bng cch truyn dn hai khe thi gian HS-SCCH TTI. Knh HS-SCCH mang nhng thng tin sau: Mt l ID ca nhng ngi dng c trng UE. Nhim v chnh ca mt l l xc nh ngi dng c phc v trong chu k TTI tip theo. Thng tin lin quan n khun dng truyn ti, m t cc m nh knh, phng thc k thut iu ch c s dng. T l m ha c trch ra t kch c ca block truyn ti v cc tham s khun dng truyn ti khc. Thng tin lin quan HARQ: c th l chu k pht tip theo s l mt block mi hay l mt block c pht li (do c th gp li trc nn yu cu pht li) v thng tin v cc phin bn.Thng tin iu khin ny ch c s dng cho cc UE s c phc v trong chu k tip theo, nh vy knh bo hiu ny l mt knh chia s theo thi gian cho tt c cc user.RNC cng c th ch r cng sut c khuyn ngh cho HS-SCCH ( lch lin quan ti cc bit hoa tiu ca knh DPCH kt hp). Cng sut pht ca HS-SCCH c th l hng s hoc thay i theo thi gian ty theo mt chin lc iu khin cng sut no cho HS-DCCH.2.4.2.2 Knh iu khin vt l tc cao: HS-DPCCHy l knh ng ln, c s dng mang tn hiu bo nhn (ACK) n Node-B trn mi block. N cng c dng ch th Cht lng knh CQI (Channel Quanlity), l yu t s dng trong AMC.Knh HS-DPCCH dng c nh h s phn b 256 v c mt khe cu trc c rng l 2/3 ms. Khe u tin c s dng cho thng tin v HARQ. Hai khe cn li c dnhThng tin v HARQ lun lun c gi khi m knh HS-SCCH gii m chnh xc nhn ng tch sng xung trong khi QCI truyn tn s c iu khin bi thng s k.C 2 khe u hot ng ring bit lp iu khin. V d, trong mt s trng hp, qu trnh lp li ny din ra vi chu k 2ms v hot ng cnh ca t bo khi cng sut hin ti khng chc chn cho qu trnh lp li. Cng sut iu khin t nhng t bo HSDPA cng c th lm gim bt cng sut nhn t knh HS-DPCCH trong qu trnh chuyn giao trong min nh nh thit b u cui lm gim cng sut truyn nu mi t bo hot ng gi mt lnh yu cu.Nh vy l vic khng dng iu khin cng sut m iu khin cp pht ngun ti nguyn s lm cho dung lng h thng tng nh li dng c tnh bin i ca knh fading. R rng bng vic s dng iu khin truyn dn lm thay i cch nhn v fading. Nu trc y chng ta coi l mt nhc im ca mi trng truyn dn h v tm cch trnh, xa b th by gi chng ta li c nh n do chng ta hiu v s dng n ng tnh hung.Dung lng ca h thng thoe phng php ny cng tng nu nh mt thu bao trong sector cng cao v vi nhiu User phn b u tt c cc v tr trong cell th bt c thi im no cng c t nht mt User c trng thi knh cc tt truyn dn vi tc cc ln. tng dung lng ny ngi ta thng nhc n vi tn gi phn tp a ngi s dng Multi-User Diversity. Tuy nhin c ngi s t ra mt cu hi l: Nu b scheduler quyt nh cp pht ti nguyn da trn trng thi knh ca my u cui th s c trng hp c User s c trng hp c User s khng truyn dn c trong mt khong thi gian di v User khc? Thc mc ny hon ton hp l. V n dn n vn cn bng gia dung lng h thng v s tha mn i vi ngi s dng. S tha mn y ngha l khng mt User phi i qu lu mi c truy nhp h thng. t c yu t cn bng ny cc b scheduler c thit k ngoi da trn nguyn tc trn cn phi kt hp vi nguyn tc trn cn phi kt hp vi nguyn tc Round Robin (fist come, fist serve). V mi nh sn xut thit b s c nhng la chn thit k khc nhau ch khng nh sn xut no ging nh sn xut no v bn thn vn ny ch c a ra nguyn l trong 3GPP v 3GPP2 ch khng chun ha thnh mt k thut c bit c th.Mt iu th v khc na cn phi nhc n l khng dng iu khin cng sut m iu khin thu pht c ng lc tt i vi s pht trin ca th trng my u cui. iu ny c th c gii thch nh sau: Khi iu khin thu pht, b lp lch gi da vo nhng thng tin trng thi knh do MS gi v (Channel Quanlity Indicator Channel). M thng th MS s da vo tham s SIR (Signal to Inteference Ratio) yu cu b lp lch cp pht ti nguyn. Do , my di ng cng hin i ngha l kh nng nn nhiu cng ln (ngha l SIR ln) th b lp lch cp pht v iu khin BTS pht vi tc cao hn. Nh vy nu khch hng u t my u cui hin i s c li ch khng phi l h iu hnh hng li nh s dng iu khin cng sut. V vi iu khin cng sut, nu my u cui tt, BTS yu cu MS gim cng sut pht, do nhiu gim v dung lng h thng tng. Khi dung lng tng l li ch ca h iu hnh ch khng phi l li ch ca ngi s dng. Vi li ch thuc v khch hng nh vy c th ni y l yu t kch thch qu trnh tiu th my u cui si ng hn.2.5 Cc k thut s dng trong HSDPA2.5.1 iu ch v m ha thch ng. K thut truyn dn mTrong thng tin di ng, t l tn hiu trn nhiu (SINR) ca tn hiu nhn c ti mt thit b ngi s dng lun bin i trong khong 30 40 dB do fading nhanh v cc c im v a hnh trong mt cell. Nhm ci thin dung lng ca h thng, tc d liu nh, vng ph sng, tn hiu truyn ti ngi s dng c xc nh nhm tnh ton qu trnh thay i cht lng tn hiu thng qua qu trnh x l lin kt thch ng. Theo truyn thng, WCDMA ng dng chc nng iu khin cng sut nhanh cho cc lin kt thch ng. Ngc li, HSDPA lu cng sut pht khng i qua TTI ng thi s dng iu ch thch ng v m ha (AMC) nh mt phng php lin kt thch ng an xen nhm iu khin cng sut ci thin hiu sut ph. i ph vi di ng ca t s tp m trn nhiu Eb/No ti u cui UE, HSDPA thch ng qu trnh iu ch, t l m ha v s m ha nh knh vi cc iu kin v tuyn hin thi. S kt hp ca hai phng php trn gi l: iu ch v M ha thch ng AMCBn cnh QPSK, HSDPA cn kt hp cht ch vi phng thc iu ch 16QAM tng tc d liu ca cc user c phc v vi iu kin v tuyn thch hp. Vic h tr cho QPSK c tnh cht bt buc i vi thng tin di ng, cn i vi 16QAM l mt ty chn cho mng v thit b ngi dng UE.S dng ng thi c 2 phng thc iu ch ny, c bit l phg thc iu ch cp cao 16 QAM, a ra mt s thch thc nht nh i vi phc tp ca b thu u cui, n cn phi xc nh c bin tng ng ca cc k hiu nhn c, trong khi i vi phng php iu ch QPSK truyn thng ch yu cu tch pha tn hiu. Mt b m ha Turbo da trn b m ha Turbo R99 vi t l m ha 1/3, mc d cc t l m ha hiu dng khc trong phm vi (xp x 1/6 n 1/1) cng c th c c bng cc k thut ghp, tch, lp m. Kt qu l to ra mt di di t l m c ti 64 gi tr khc nhau. S kt hp ca mt kiu iu ch v mt t l m c gi l Lc m ha v iu ch.Ngoi k thut iu ch v M ha thch ng AMC, pht a m cng c th coi nh l mt cng c thch ng lin kt. Nu nh user c y cc iu kin knh v tuyn thch hp, Node-B c th li dng iu kin ny bng cch pht nhiu m song song vi nhau, nhm t c thng lng d liu nh kh ln.Vi k thut pht a m, ton b di thng ng AMC c th c tng thm ln mt lng: 10log1015 ~ 12dBsTon b di ng thch ng lin kt do AMC kt hp pht m xp x 30dB.Node-B s xc nh tc truyn dn d liu da trn cc bo co v ch th cht lng knh CQI cng nh cc thng k cng sut cc knh dnh ring. Tc d liu c iu chnh bng cch thay i s iu ch, tc m ha cng nh s lng m ha knh HS-PDSCH. S dng iu ch thch ng v m ha AMC cho php ngi s dng tin gn hn ti Node-B, c th yu cu iu ch vi t l m ha cao hn (chng hn nh iu ch 16QAM vi t l m ha 3/4 )2.5.2 K thut H-ARQKhi vn hnh HSDPA ln cn hiu sut ph cao nht, t l li khi BLER sau ln truyn dn u tin c khuyn ngh trong khong t 10% - 20%. C ch yu cu lp t ng li H-ARQ c ng dng trong gii php HSDPA nhm gim tr v tng hiu sut ca qu trnh ti truyn dn d liu. Thc t, H-ARQ l mt giao thc dng dng v ch SAW (Stop And Wait).

Hnh 5. Nguyn l tng qut HARQ ti Node-BTrong c ch SAW, pha truyn dn lun lun qu trnh truyn dn cc block ang hin hnh cho ti khi thit b ngi s dng hon ton nhn c d liu. tn dng thi gian khi Node-B ch cc bo nhn, c th thit lp N tin trnh SAW-ARQ song song cho thit b ngi dng. Do , cc tin trnh khc nhau truyn dn trong cc TTI ring bit. S tin trnh SAW ARQ song song c thit lp ti a l 8 (N=8), tuy nhin thng thng chn gi tr N t 4 6. Thi gian tr nh nht cho php gia qu tnh truyn d liu gc so vi qu tnh ti truyn dn d liu ln u tin trong HSDPA l 12ms.iu khin H-ARQ lp 1 c t ti Node-B, do vic lu tr cc gi d liu phi bo nhn cng vi chc nng sp xp cc gi ca qua trnh ti truyn dn l khng ph thuc vo RNC. Nh vy s trnh c tr ti truyn dn, ngoi ra cc tr ny s thp hn tr gy ra bi qu trnh ti truyn dn RLC thng thng.K thut HARQ l im khc c bn so vi k thut pht li trong WCDMA bi b gii m UE kt hp cc thng tin mm ca qu tnh pht li ca cng mt block cp bit. K thut ny a ra mt s yu cu v m rng dung lng b nh ca UE, do UE phi lu cc thng tin mm ca nhng ln pht gii m khng thnh cng.

Hnh 6.To ra cc phin bn dCc phng php HARQ nh sau: Kt hp khun (CC: Chase Combining) mi ln pht li ch n gin l s lp li ca cc t m c s dng cho ln pht u tin. u im: Vic truyn v truyn li c gii m ring l (t gii m), tng tnh a dng thi gian, c th tng tnh a dng ng truyn. Nhc im: Vic pht li ton b cc gi s lng ph v bng thng. Tng d (IR: Incremental Reunancy): S pht li bao gm c thng tin s tha b xung v thng tin d tha b cung v thng tin ny c pht km thm nu c li gii m trong ln pht u tin. Tng d c s dng nhn c tnh nng ti a trong bng thng sn sng. Lc ny block c pht la ch bao gm d liu sa cha ca tn hiu gc c truyn i ch khng phi thng tin thc s. Lng thng tin d thm vo c gi i ngy cng tng ln khi qu trnh pht li lp i lp li m bn thu vn nhn b li. u im: Gim bt bng thng / lu lng hu dng ca mt ngi s dng v dng n cho nhng ngi khc. Nhc im: Cc bit h thng ch c gi i khi truyn ln u tin v khng th truyn li, iu lm cho qu trnh truyn li khng th t gii m. V th, nu qu trnh truyn ln u b mt th fading rt ln s tc ng v khng c c hi khi phc li d liu trong hon cnh ny.3. LTE (Long Term Evolution)3.1 Tng quan h thngLTE l mt chun cho cng ngh truyn thng d liu khng dy v l mt s tin ha ca cc chun GSM/UMTS. Mc tiu ca LTE l tng dung lng v tc d liu ca cc mng d liu khng dy bng cch s dng cc k thut iu ch v DSP (x l tn hiu s) mi c pht trin vo u th k 21 ny. Mt mc tiu cao hn l thit k li v n gin ha kin trc mng thnh mt h thng da trn nn IP vi tr truyn dn tng gim ng k so vi kin trc mng 3G. Giao din khng dy LTE khng tng thch vi cc mng 2G v 3G, do n phi hot ng trn mt ph v tuyn ring bit.LTE c hng NTT DoCoMo ca Nht xut u tin vo nm 2004, cc nghin cu v tiu chun mi chnh thc bt u vo nm 2005. Thng 5 nm 2007, lin minh Sng kin th nghim LTE/SAE (LSTI) c thnh lp, lin minh ny l s hp tc ton cu gia cc hng cung cp thit b v hng cung cp dch v vin thng vi mc tiu kim nghim v thc y tiu chun mi m bo trin khai cng ngh ny trn ton cu cng hp cng tt. Tiu chun LTE c hon thnh vo thng 12 nm 2008 v dch v LTE u tin c hng TeliaSonera khai trng Oslo v Stockholm vo ngy 14 thng 12 nm 2009, l kt ni d liu vi mt modem USB. Nm 2011, cc dch v LTE c khai trng th trng Bc M, vi vic hng MetroPCS gii thiu mu in thoi thng minh h tr LTE u tin l Samsung Galaxy Indulge vo ngy 10 thng 2 nm 2011 v tip sau l hng Verizon gii thiu mu in thoi thng minh h tr LTE th hai l HTC ThunderBolt vo ngy 17 thng 3 cng nm. Ban u, cc nh mng CDMA c k hoch nng cp cc tiu chun cnh tranh l UMB v WiMAX, nhng tt c cc nh mng CDMA ln (nh Verizon, Sprint v MetroPCS M, Bell v Telus Canada, au by KDDI Nht Bn, SK Telecom Hn Quc v China Telecom/China Unicom Trung Quc) thng bo h d nh s chuyn ln chun LTE. S tin ha ca LTE l LTE Advanced, c chun ha vo thng 3 nm 2011. Dch v d kin s c cung cp bt u vo nm 2013.c t k thut LTE ch ra tc ti xung nh t 300 Mbit/s, tc ti ln nh t 75 Mbit/s v QoS quy nh cho php tr truyn dn tng th nh hn 5 ms trong mng truy nhp v tuyn. LTE c kh nng qun l cc thit b di ng chuyn ng nhanh v h tr cc lung d liu qung b v a im. LTE h tr bng thng linh hot, t 1,25 MHz ti 20 MHz v h tr c song cng phn chia theo tn s (FDD) v song cng phn chia theo thi gian (TDD). Kin trc mng da trn IP, c gi l Li gi tin ha (EPC) v c thit k thay thay th Mng li GPRS, h tr chuyn giao lin tc cho c thoi v d liu ti trm eNodeB vi cng ngh mng c hn nh GSM, UMTS v CDMA2000. Cc kin trc n gin v chi ph vn hnh thp hn (v d, mi t bo E-UTRAN s h tr dung lng thoi v d liu gp 4 ln so vi HSPA).3.2 c im h thngPhn ln tiu chun LTE hng n vic nng cp 3G UMTS cui cng c th thc s tr thnh cng ngh truyn thng di ng 4G. Mt lng ln cng vic l nhm mc ch n gin ha kin trc h thng, v n chuyn t mng UMTE s dng kt hp chuyn mch knh + chuyn mch gi sang h thng kin trc phng ton IP. E-UTRA l giao din v tuyn ca LTE. N c cc tnh nng chnh sau:Tc ti xung nh ln ti 299.6 Mbit/s v tc ti ln t 75.4 Mbit/s ph thuc vo kiu thit b ngi dng (vi 4x4 anten s dng rng bng thng l 20 MHz). 5 kiu thit b u cui khc nhau c xc nh t mt kiu tp trung vo ging ni ti kiu thit b u cui cao cp h tr cc tc d liu nh. Tt c cc thit b u cui u c th x l bng thng rng 20 MHz.Tr truyn dn d liu tng th thp (thi gian tr i-v di 5 ms cho cc gi IP nh trong iu kin ti u), tr tng th cho chuyn giao thi gian thit lp kt ni nh hn so vi cc cng ngh truy nhp v tuyn kiu c. Ci thin h tr cho tnh di ng, thit b u cui di chuyn vi vn tc ln ti 350 km/h hoc 500 km/h vn c th c h tr ph thuc vo bng tn. OFDMA c dng cho ng xung, SC-FDMA dng cho ng ln tit kim cng sut.H tr c hai h thng dng FDD v TDD cng nh FDD bn song cng vi cng cng ngh truy nhp v tuyn. H tr cho tt c cc bng tn hin ang c cc h thng IMT s dng ca ITU-R. Tng tnh linh hot ph tn: rng ph tn 1,4 MHz, 3 MHz, 5 MHz, 10 MHz, 15 MHz v 20 MHz c chun ha (W-CDMA yu cu rng bng thng l 5 MHz, dn ti mt s vn vi vic a vo s dng cng ngh mi ti cc quc gia m bng thng 5 MHz thng c n nh cho nhiu mng, v thng xuyn c s dng bi cc mng nh 2G GSM v CDMAOne).H tr kch thc t bo t bn knh hng chc m (femto v picocell) ln ti cc macrocell bn knh 100 km. Trong di tn thp hn dng cho cc khu vc nng thn, kch thc t bo ti u l 5 km, hiu qu hot ng hp l vn t c 30 km, v khi ln ti 100 km th hiu sut hot ng ca t bo vn c th chp nhn c. Trong khu vc thnh ph v th, bng tn cao hn (nh 2,6 GHz Chu u) c dng h tr bng thng di ng tc cao. Trong trng hp ny, kch thc t bo c th ch cn 1 km hoc thm ch t hn. H tr t nht 200 u cui d liu hot ng trong mi t bo c bng thng 5 MHz. n gin ha kin trc: pha mng E-UTRAN ch gm cc eNode B H tr hot ng vi cc chun c (v d nh GSM/EDGE, UMTS v CDMA2000). Ngi dng c th bt u mt cu gi hoc truyn d liu trong mt khu vc s dng chun LTE, nu ti mt a im khng c mng LTE th ngi dng vn c th tip tc hot ng nh cc mng GSM/GPRS hoc UMTS dng WCDMA hay thm ch l mng ca 3GPP2 nh cdmaOne hoc CDMA2000). Giao din v tuyn chuyn mch gi. H tr cho MBSFN (Mng qung b n tn). Tnh nng ny c th cung cp cc dch v nh Mobile TV dng c s h tng LTE, v l mt i th cnh tranh cho truyn hnh da trn DVB-H.3.2.1 Cng nh LTEH thng LTE pht trin trn nn tng GSM/UTMS , l mt trong nhng cng ngh tim nng nht cho truyn thng 4G (h thng tin 4G). Kin trc mng mi c thit k vi mc tiu cung cp lu lng chuyn mch gi vi dch v cht lng, tr ti thiu. H thng s dng bng thng linh hot nh vo m hnh a truy cp OFDMA v SC-FDMA. Thm vo , FDD (Frequency DivisionDuplexing) v TDD (Time Division Duplexing), bn song cng FDD cho phpcc UE c gi thnh thp. Khng ging nh FDD, bn song cng FDD khng yu cu pht v thu ti cng thi im. iu ny lm gim gi thnh cho b song cng trong UE. Truy cp tuyn ln da vo a truy cp phn chia theo tn s n sng mang (Single Carrier Frequency Division multiple Access SC-FDMA) cho php tng vng ph tuyn ln lm t s cng sut nh trn cng sut trung bnh thp(Peak-to-Average Power Ratio PAPR) so vi OFDMA. Khi ci thin tc d liu nh, h thng LTE s dng hai n bn ln h s ph cell so vi h thng HSPARelease 6c tnh c bn ca h thng LTE :- Hot ng bng tn : 700 MHz-2,6 GHz.- Tc : DL : 100Mbps( BW 20MHz) UL : 50 Mbps vi 2 anten thu 1 anten pht.- tr : nh hn 5ms- rng BW linh hot : 1,4MHz; 3MHz; 5MHz; 10MHz; 15MHz; 20 MHz. H tr c 2 trng hp di bng ln v bng xung bng nhau hoc khng.- Tnh di ng : Tc di chuyn ti u l 0-15 km/h nhng vn hot ng tt vi tc di chuyn t 15-120 km/h, c th ln n 500 km/h ty bng tn.- Ph tn s: Hot ng ch FDD hoc TDD ph sng t 5-100 km Dung lng 200 user/cell bng tn 5Mhz.- Cht lng dch v: H tr tnh nng m bo cht lng dch v QoS. VoIP m bo cht lng m thanh tt, tr ti thiu thng qua mng UTMSThng s vt l :

3.2.2 Cu trc ca LTES khc nhau gia SAE v LTE

Hnh 7. LTE gives operators the benefits of evolution to a simplified, all IP network architectureTrc tin ta xem s khc nhau v cu trc ca UTMS v LTE. Song song vi truy nhp v tuyn LTE, mng gi li cng ang ci tin ln cu trc tng SAE.Cu trc mi ny c thit k ti u hiu sut mng, ci thin hiu qu chi ph v thun tin thu ht phn ln dch v trn nn IP. Mng truy nhp v tuyn RAN (Radio Access Network): mng truy nhp v tuyn ca LTE c gi l E-UTRAN v mt trong nhng c im chnh ca n l tt c cc dch v, bao gm dch v thi gian thc, s c h tr qua nhng knh gi c chia s. Phng php ny s tng hiu sut ph, lm cho dung lng h thng tr nn cao hn. Mt kt qu quan trng ca vic s dng truy nhp gi cho tt c cc dch v l s tch hp cao hn gia nhng dch v a phng tin v gia nhng dch v c nh v khng dy. C nhiu loi chc nng khc nhau trong mng t bo. Da vo chng, mng c th c chia thnh hai phn: mng truy nhp v tuyn v mng li. Nhng chc nng nh iu ch, nn, chuyn giao thuc v mng truy nhp. Cn nhng chc nng khc nh tnh cc hoc qun l di ng l thnh phn ca mng li. Vi LTE, mng truy nhp l E-UTRAN v mng li l EPC. Mc ch chnh ca LTE l ti thiu ha s node. V vy, ngi pht trin chn mt cu trc n node. Trm gc mi phc tp hn NodeB trong mng truy nhp v tuyn WCDMA/HSPA, v v vy c gi l eNodeB (Enhance Node B). Nhng eNodeB c tt c nhng chc nng cn thit cho mng truy nhp v tuyn LTE, k c nhng chc nng lin quan n qun l ti nguyn v tuyn. Giao din v tuyn s dng trong E-UTRAN by gi ch cn l S1 v X2. Trong S1 l giao din v tuyn kt ni gia eNodeB v mng li. S1 chia lm hai loi l S1-U l giao din gia eNodeB v SAE-GW v S1-MME l giao din gia eNodeB v MME. X2 l giao din gia cc eNodeB vi nhau.

Mng li: mng li mi l s m rng hon ton ca mng li trong h thng 3G, vn ch bao ph min chuyn mch gi. V vy, n c mt ci tn mi : Evolved Packet Core (EPC). Cng mt mc ch nh E-UTRAN, s node trong EPC c gim. EPC chia lung d liu ngi dng thnh mt phng ngi dng v mt phng iu khin. Mt node c th c nh ngha cho mi mt phng, cng vi Gateway chung kt ni mng LTE vi internet v nhng h thng khc. EPC gm c mt vi thc th chc nng.- MME (Mobility Management Entity): chu trch nhim x l nhng chc nng mt bng iu khin, lin quan n qun l thu bao v qun l phin. Gateway dch v (Serving Gateway): l v tr kt ni ca giao tip d liu gi vi E-UTRAN. N cn hot ng nh mt node nh tuyn n nhng k thut 3GPP khc.- P-Gateway (Packet Data Network): l im u cui cho nhng phng hng v mng d liu gi bn ngoi. N cng l Router n mng Internet.- PCRF (Policyand Charging Rules Function): iu khin vic to ra bng gi v cuhnh h thng con a phng tin IP IMS (the IP Multimedia Subsystem) cho mi ngi dng.- HSS (Home Subscriber Server): l ni lu tr d liu ca thu bao cho tt c d liu ca ngi dng. N l c s d liu ch trung tm trong trung tm ca nh khai thc. Cc min dch v bao gm IMS (IP Multimedia Sub-System) da trn cc nh khai thc, IMS khng da trn cc nh khai thc v cc dch v khc. IMS l mt kin trc mng nhm to s thun tin cho vic pht trin v phn phi cc dch v a phng tin n ngi dng, bt k l h ang kt ni thng qua mng truy nhp no. IMS h tr nhiu phng thc truy nhp nh GSM, UMTS,CDMA2000, truy nhp hu tuyn bng rng nh cp xDSL, cp quang, cp truyn hnh, cng nh truy nhp v tuyn bng rng WLAN, WiMAX. IMS to iu kin cho cc h thng mng khc nhau c th tng thch vi nhau. IMS ha hn mang li nhiu li ch cho c ngi dng ln nh cung cp dch v. N v ang c tp trung nghin cu cng nh thu ht c s quan tm ln ca gii cng nghip. Tuy nhin IMS cng gp phi nhng kh khn nht nh v cng cha tht s chn thuyt phc cc nh cung cp mng u t trin khai n. Kin trc IMS c cho l kh phc tp vi nhiu thc th v v s cc chc nng khc nhau.Cu trc LTE lin kt vi mng khc:

Hnh 8. Cu trc h thng cho mng truy cp 3GPP

Hnh 9. Cu trc h thng cho mng truy cp 3GPP v khng phi 3GPP

Hnh 10. Cu trc h thng cho mng truy cp 3GPP v lin mng vi CDMA 20003.2.3 Cc knh s dng trong E-UTRANKnh vt l : cc knh vt l s dng cho d liu ngi dng bao gm:-PDSCH (Physical Downlink Shared Channel) : ph ti c ch (payload)-PUSCH (Physical Uplink Shared Channel) : PUSCH c dng mang d liu ngi dng. Cc ti nguyn cho PUSCH c ch nh trn mt subframe c bn bi vic lp biu ng ln. Cc sng mang c ch nh l 12 khi ti nguyn (RB) v c th nhy t subframe ny n subframe khc. PUSCH c th dng cc kiu iu ch QPSK, 16QAM, 64QAM.-PUCCH(Physical Uplink Control Channel): c chc nng lp biu, ACK/NAK.-PDCCH(Physical Downlink Control Channel): lp biu, ACK/NAK.-PBCH(Physical Broadcast Channel): mang cc thng tin c trng ca cell. Knh logic : c nh ngha bi thng tin n mang bao gm:-Knh iu khin qung b (BCCH) : c s dng truyn thng tin iu khin h thng t mng n tt c my di ng trong cell. Trc khi truy nhp h thng, u cui di ng phi c thng tin pht trn BCCH bit c h thngc lp cu hnh nh th no, chng hn bng thng h thng.-Knh iu khin tm gi (PCCH) : c s dng tm gi cc u cui di ng v mng khng th bit c v tr ca chng cp v v th cn pht cc bn tin tm gi trong nhiu (vng nh v).-Knh iu khin ring (DCCH) : c s dng truyn thng tin iu khin ti/t mt u cui di ng. Knh ny c s dng cho cu hnh ring ca cc u cui di ng chng hn cc bn tin chuyn giao khc nhau.-Knh iu khin a phng (MCCH) : c s dng truyn thng tin cn thit thu knh MTCH.-Knh lu lng ring (DTCH) : c s dng truyn s liu ca ngis dng n/t mt u cui di ng. y l kiu logic c s dng truyn tt c s liu ng ln ca ngi dng v s liu ng xung ca ngi dng khng phi MBMS.-Knh lu lng a phng (MTCH) : c s dng pht cc dch v MBMS.Knh truyn ti : bao gm cc knh sau:-Knh qung b (BCH) : c khun dng truyn ti c nh do chun cung cp. N c s dng pht thng tin trn knh logic.-Knh tm gi (PCH) : c s dng pht thng tin tm gi trn knh PCCH, PCH h tr thu khng lin tc (DRX) cho php u cui tit kim cng sut c quy bng cch ng v ch thc thu PCH ti cc thi im quy nh trc- Knh chia s ng xung (DL-SCH) : l knh truyn ti pht s liu ng xung trong LTE. N h tr cc chc nng ca LTE nh thch ng tc ng v lp biu ph thuc knh trong min thi gian v min tn s. N cng h tr DRX gim tiu th cng sut ca u cui di ng m vn m bo cm gic lun kt ni ging nh c ch CPC trong HSPA. DL-DCH TTI l 1ms.-Knh a phng (MCH) : c s dng h tr MBMS. N c c trng bi khun dng truyn ti bn tnh v lp biu bn tnh. Trong trng hp pht a s dng MBSFN, lp biu v lp cu hnh khun dng truyn ti c iu phi gia cc tham gia pht MBSFN.3.2.4 Giao thc ca LTE (LTE Protocols) LTE chc nng ca RLC c chuyn vo eNodeB, cng nh chc nng ca PDCP vi m ha v chn tiu . V vy, cc giao thc lin quan ca lp v tuyn c chia trc y UTRAN l gia NodeB v RNC by gi chuyn thnh gia UE v eNodeB

Hnh 11. Giao thc UTRAN

Hnh 12. Giao thc ca E-UTRAN

Hnh 13. Phn phi chc nng ca cc lp MAC, RLC, PDCPChc nng ca MAC (Medium Access Control) bao gm:-Lp biu-iu khin u tin (Priority handling)-Ghp nhiu knh logic khc nhau trn mt knh truyn n RLC. Chc nng ca PDCP bao gm:-M ha (ciphering)-Chn tiu 4. KT LUNVi nhng ci tin t ph, HSDPA l mt cng ngh c ch trng pht trin. Trn thc t, th trng ca HSDPA pht trin mnh m giai on khi u, c bit cc nc pht trin, ni c lng khch hng khng l s dng in thoi di ng cht lng cao. L do v nhng chic in thoi HSDPA s c gi thnh cao hn hn nhng chic in thoi thng thng c nhm vo cc th trng nhng nc pht trin thp hn.Do l phin bn nng cp ca WCDMA, HSDPA khng c nhiu kh nng thnh cng ti nhng ni m WCDMA pht trin. Do , thnh cng cui cng ca HSDPA nh mt sn phm ca cng ngh 3.5G s ph thuc rt nhiu vo s thnh cng ca WCDMA vi t cch l mt sn phm ca cng ngh 3G.Cng ngh LTE l mt cng ngh mi, v ang c tip tc nghin cu v trin khai trn ton th gii, vi kh nng truyn ti tc cao kin trc mng n gin , s dng bng tn hiu qu v hon ton tng thch vi cc h thng GSM & WCDMA v da trn mt mng ton IP. LTE c th tr thnh h thng thng tin ding ton cu trong tng lai. V vy vic tm hiu v cng ngh LTE l cn thit v c ngha thc t. ti cp mt cch tng quan v cng ngh LTE, trng tm gm cc phn : Tng quan v h thng di ng 3G Cu trc mng LTE Truy cp v tuyn trong LTE K thut s dng trong LTE5.TI LIU THAM KHO[1] Gio trnh l trnh pht trin thng tin di ng 3G ln 4G TS. Nguyn Phm Anh Dng[2] Kha lun tt nghip v HSPDA ca Nguyn Th Thu Hng HQGHN[3] L trnh trin khai LTE Tp on Vin thng Viettel[4] http://vi.wikipedia.org/wiki/HSDPA[5] http://vi.wikipedia.org/wiki/LTE[6] Harri Holdma and Antti Toskala, HSDPA/HSUPA for UMTS/High Speed Acces Mobile Communication. Wiley. 2006D6--Overview the HSDPA and LTE. Structure of these systems. 44