giao thuc giao dien vo tuyen

8/11/2019 Giao Thuc Giao Dien Vo Tuyen

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TS. Nguyn Phm Anh Dng

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Bi 6GIAO DIN V TUYN 4G LTE

6.1. TNG QUANLTE (Long Term Evolution: pht trin di hn) l tn dnh cho tiu chun

mi do 3GPP pht trn p ng cc yu cu khng ngng tng vtc sliup ng cc dch va phng tin IP. LTE l bc pht trin tip sau ca cch thng 2G v 3G tin n cung cp mc cht lng tng t nh ccmng ha tuyn hin nay.

Cc mc tiu thit kchnh ca LTE bao gm: Hthng phi htrtc nh ng ln l 100Mbps v ng xung l

50Mbps trong bng thng 20 MHz hay tng ng vi cc gi trhiu sutph tn nh l 5bps/Hz ng xung v 2,5bps/Hz ng ln. H thngtham chun c 2 anten trong UE cho ng xung v 1 anten trong UE chong ln

Ti im 5% CDF (xc sut 5% mt thng tin), thng lng trung bnh cangi sdng trn 1 MHz gp 2 n 3 ln R6 HSPA

Hiu sut phtn ng xung gp 3 n 4 ln R6 HSPA v ng ln gp2 n 3 ln R6 HSPA trong mng c ti

Di ng ln n 350km/gi Sdng phlinh hot, ng tn ti vi cc cng nghtrc v gim phc

tp cng nhgi thnh.

Cc yu cu i vi LTE phin bn u c tng kt trong bng 6.1 c sosnh vi HSPA.

HSPA R6 LTEMt CP


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Cc cng nghquan trng nht trong mng truy nhp v tuyn ca LTE lOFDM (Orthogonal Frequency Division Multiplex), n nh ti nguyn ng akch thc (thi gian, tn s) v thch ng ng truyn, truyn dn MIMO(Multiple Input Multiple Output), m ha turbo v HARQ (Hybrid AutomaticRepeat Request) vi kt hp mm.

Trong ch FDD, trn ng xung LTE s dng OFDMA vi truyndn OFDM vi cn trn ng ln LTE s dng SC-FDMA vi truyn dnDFTS-OFDM. Mi k hiu OFDM c pht trn cc sng mang con c bngthng 15 hoc 7,5MHz. Mi khung di 1ms c chia thnh hai khe di 0,5ms vcha mt sk hiu OFDM (14 ch15 KHz v v 12 cho ch7,5kHz ).

Trong LTE, cstruyn dn ng ln v ng xung u c thnnh cc bng tn khc nhau cho cc ngi sdng theo nguyn l FDMA. nnh ny c thc iu chnh ng theo thi gian da trn lp biu. Kiu nnh ny c gi l n nh ti nguyn ng a kch thc (thi gian, tn s).

n nh ti nguyn thun tin, ti nguyn LTE c thc trnh by dng lithi gian-tn s. Phn tnhnht ca li thi gian tn sc gi l phn ttinguyn gm mt sng mang con trong khong thi gian mt k hiu. n vnnh ti nguyn LTE nhnht l khi ti nguyn gm 12 sng mang con trongthi gian mt khe.

Truyn dn a anten l mt trong scc cng nghquan trng nht tc cc mc tiu tc cao cho LTE. Trn ng xung LTE phin bn u htrmt, hai hay bn anten pht trong eNodeB v mt, hai hay bn anten thu trongUE. a anten c th c s dng theo nhiu cch: nhn c phn tppht/thu hay nhn c ghp knh khng gian nhm tng tc s liu bngcch to ra nhiu knh con song khi iu kin cho php. Tuy nhin trn ng lnLTE chhtrmt anten pht tai UE v mt, hai hay bn anten thu ti eNodeB.V thtrn ng ln a anten chc sdng cho phn tp thu. t c ccmc tiu khc nhau.

LTE sdng a anten vi cc cng nghMIMO khc nhau bao gm SU-MIMO (Single-User MIMO: MIMO n ngi sdng), MU-MIMO (Multi-UserMIMO: MIMO a ngi sdng, tin m ha cp hng 1 (Rank-1) vng kn vto bp dnh ring. Cc sSU-MIMO c c tcho cu hnh hai hay bnanten pht trn ng xung htr truyn dn nhiu lp khng gian (ln n

bn lp) cho mt UE. Sphn tp pht c c tcho bn anten pht trnng xung v hai anten pht trn ng ln (phin bn ci tin). SMU-MIMO cho php n nh cc lp khng gian khc nhau cho cc ngi s dngkhc nhau trong cng mt ti nguyn thi gian-tn s. v c htrcngln ln ng xung. Stin m ha vng kn rank-1 c sdng ci thinvng phsng sdng cng nghSU-MIMO da trn tn hiu tham chun chungc th vi vic sdng mt bn tin bo hiu iu khin thng lng thp


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gim chi ph bng thng bsung. Sto bp dnh ring c sdng mrng vng ph s liu khi tch sng s liu da trn tn hiu tham chun ringc htrbi UE.

LTE s dng m ha turbo hiu chnh li cho knh s liu . Trongtrng hp knh chia se ng xung (DL-SCH) bm ha turbo vi t ln m1/3 c sdng cng vi phi hp tc thch ng tlm vi mc mongmhun. Trong mi khung 1ms, mt hoc hai thf m (vi MIMO a tm) cm ha v c pht.

LTE htrHARQ vi kt hp mm. Trong sHARQ, my thu sdngm pht hin li (CRC) kim tra xem ghi thu sau sa li c cha li haykhng. Trong trng hp NACK, gi c pht li. Gi mc li c lu trong bnhm, sau c kt hp vi pht li (hay cc pht) li to nn mt gitin cy hn. LTE s dng kt hp tng phn d (IR: Incremental Redundancy)

trong pht li l cc phin bn phn dkhc nhau ca m turbo.

6.2. CC GIAO THC TRN GIAO DIN V TUYN 4G LTE

Giao din v tuyn c k hiu l LTE Uu (hnh 6.1). Khc vi kin trc3G UMTS, 4G LTE khng sdng RNC v thn phng hn. Cc chc nngtrc y ca RNC c t ngay trong eNodeB c thx l nhanh hn ccthay i trn ng truyn v tuyn nhanh hn. Ngoi ra mng li l mng li gipht trin c xy dng trn nn IP. Giao din v tuyn gia UE v eNodeBc k hiu l LTE Uu.

Hnh 6.1. Kin trc mng 4G LTE

Hnh 6.2 cho thy cc ngn xp giao thc giao din v tuyn trong cc UP(User Plane: mt phng ngi s dng) v CP (Control Plane: mt phng iukhin). Khc vi 3G UMTS, LTE khng c RNC nn tt c cc giao thc u


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c t ti eNodeB. Nhthy trn hnh 1, kin trc ngn xp giao thc v tuyntrong cc mt phng iu khin (CP: Control Plane) t trn xung di bao gmcc lp: RRC (Radio Resource Control: iu khin ti nguyn v tuyn), PDCP(Packet Data Convergence Protocol: giao thc htsliu gi), RLC (Radio LinkControl: iu khin lin kt v tuyn), MAC (Medium Access Control: iu khintruy nhp mi trng) v PHY (Physical: vt l). Ngoi ra ti UE cn c thmNAS (Non Access Stratum: tng khng truy nhp) l tng xl bo hiu lin kttrc tip gia UE v gia UE v EPC (Evolved Packet Core: li gi pht trin)nh: SM (Session Management: qun l phin), EMM (Evolved MobilityManagement: qun l di ng tng cng). Kin trc giao thc mt phng ngisdng (User Plane) c cu trc tng tnhCP, chkhc l khng c lp RRC.

So snh vi m hnh OSI (Open System Interconnection: kt ni hthngm) ta thy RRC nm trong OSI L3 (L3: Layer 3); PDCP, RLC v MAC l ba lpcon ca OSI L2 v PHY nm trong OSI L1.

Hnh 6.2. Ngn xp giao thc giao din v tuyn ca LTE

Hnh 6.3 m tngn gn cc chc nng cbn ca cc lp khc nhau vcch thc tng tc gia cc lp ti pha eNodeB. Cn lu rng cu trc giaothc phn lp trong UE cng tng t.


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Qung bat/t h thng

Tm gi RRC

Mp phng iu khin (CP)Mp phng ngi s dng (UP)

ROHCMt m

ROHCMt m

Phn onARQPCCHBCCH

Phn onARQ

Phn onARQ

Phn onARQ

Ghp knh

Cc knh logic

HARQ HARQ

Cc knh truyn ti

Cc knh vt l

PDCP

RLC

MAC

PHY

RRC

HARQ

X l lp biu/u tin

ROHCMt m

Cc knh mang

Mt mTon vn

ARQ: Automatic Repeate Request: yu cu pht li t ngHARQ: Hybride Automatic Repeate Request: yu cu pht li t ng lai ghpMHK: m ha knhC: iu chROCH: Robust Header Compression: nn tiu bn chc

Cc gi IP ca cc ngi s dng

Hnh 6.3. Cu trc giao thc phn lp ng xung trong eNodeB

Lp trn RRC trn nh hnh 6.3 c nhim vhtrtt ccc thtc bo

hiu gia UE v eNodeB bao gm cc thtc qun l di ng v qun l kt ni.Cc bo hiu tmt phng iu khin ca EPC (Evolved Packet Core: li gi tngcng), chng hn ng k UE v nhn thc, c chuyn n UE qua giao thcSM, MM thng qua RRC mt cch trong sut.

Vai tr chnh ca lp PDCP l nn tiu IP da trn c ch ROHC(Robust Header Compression: nn tiu bn chc) v mt m ha cung cpcc knh mang (RB: Radio Bearer) cho lp thp hn. Mi knh mang tng ngvi mt lung thng tin c th ca mt phng ngi s dng (chng hn: cckhung ting, sliu truyn theo lung, bo hiu IMS ) hay bo hiu mt phngiu khin (chng hn RRC hay bo hiu NAS [Non Access Stratum: tng khngtruy nhp] n tEPC). Do tnh cht c bit, cc lung tin c to bi cc chcnng pht qung b thng tin h thng v tm gi khng c x l ti lpPDCP.

RLC cung cp dch vlp 2 ging nhOSI (m hnh kt ni hthng m)cho lp PDCP nh: phn on sliu gi v ARQ (Automatic Repeate Request:


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yu cu pht li tng) v cchsa li. Ti y RLC thc hin chuyn i mtmt tng lung RRC vo cc knh logic ca lp MAC.

Lp MAC c nhim vghp cc knh logic vo cc knh truyn ti sau khi x l lp biu/u tin i vi cc lung s liu nhn c t lp RLC. Cc

lung c ghp vo mt knh truyn ti c th xut s t mt ngi s dng(mt hay nhiu trng hp ca DCCH v DTCH) hay nhiu ngi sdng (mtsDTCH tcc ngi sdng). MAC cng htrHARQ. Cui cng MAC cungcp cc lung truyn ti cho lp PHY.

Lp PHY thc hin cc chc nng xl tn hiu nhm ha knh, iu chv sp xp cc lung tn hiu ln cc anten v cc phn tti nguyn.

6.3. CC TRNG THI LTE UE

Trong LTE c thc hai bmy trng thi u cui, cc bmy trng thiny khng chc duy tr trong UE m c trong mng (hnh 6.4). Bmy thnht c t ti lp RRC v c duy tr trong eNodeB, bmy thhai ct ti lp MM (Mobility Management: qun l di ng) v c duy tr ti S-GWtrong mng li.

Ti lp RRC c hai trng thi RRC-CONNECTED (RRC kt ni) v RRC-IDLE (RRC ri) ty thuc vo kt ni RRC c c thit lp hay khng.

Trong trng thi RRC-IDLE, UE gim st knh tm gi v pht hin cccuc gi vo, nhn thng tin hthng v thc hin o c cc ln cn cngnhchn/chn li . Trong trng thi ny lp trn c th lp cu hnh DTX c

th UE v UE iu khin di ngTrong trng thi RRC-CONNECTED, UE truyn/nhn sliu n/tmng.

vy, UE gim st cc knh iu khin lin kt vi knh sliu chia sxcnh sliu c c lp biu hay khng v cung cp cht lng knh v thng tinphn hi cho eNodeB. Ngoi ra cng trong trng thi ny, UE thc hin o ccc ln cn v gi bo co o theo cu hnh quy nh bi eNodeB, Khc viWCDMA, c th nhn thng tin h thng t BCCH trong trng thi RRC-CONNECTED. Ti cc lp thp hn, UE c thc lp cu hnh DTX c thUE v c iu khin chuyn giao bi mng.

Ti mc mng li, bmy trng thi MM qun l ba trng thi LTE: Rimng (LTE-Detached), tch cc (LTE-Active) v ri (LTE-Idle):

LTE-Detached. L trng thi trong UE hoc tt ngun hoc btngun nhng khng ng k vi mng. L do c thl cha ng k hocng k tht bi do khng c mng thch hp


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LTE-Idle: u cui ng k vi mng, nhng khng tch cc. Tng ng vi chtiu thcng sut thp. Mng li bit vtr ca UE ti mc TA (vng eo bm). Trong trng hp thit lp dch vhoc dch vc ti tch cc, UE c

thnhanh chng chuyn vo chtch cc (LTE-Active) m khng cn:o Thit lp cc knh mang EPCo m phn li cc thuc ngQoS lin quan

Di ng ca UE tun theo gii thut chn li v v thkhng chu siukhin ca mng.

LTE-Active: L trng thi trong UE thc s tch cc v ang trao i s liu cng

nhbo hiu vi mng UE c mt kt ni RRC c thit lp

Vtr u cui c mng bit c thhn ti mc hin thi v di ngtun theo gii thut chuyn giao do mng iu khin.

Vnguyn tc, UE c th hy ng k t bt k trng thi no ni trn.Trong trng thi LTE-Idle, hy ng k c th tng minh khi UE tt ngunhoc ht in, hoc n tng do UE nm ngoi vng phsng (do khng nhnc cp nht vtr nh k).

Bmy RRC qun l hai trng thi : RRC-Idle:

UE khng c kt ni RRC vi eNodeB (khng c kt ni bo hiu giaUE v eNodeB)

UE thu v gii m thng tin hthng, chv gii m cc bn tin tm gi Di ng da trn chn li do UE thc hin (da trn thng tin hthng) Khng c ngcnh RRC lu trong eNodeB Thtc knh truy nhp ngu nhin (RACH) c sdng khi thit lp kt

ni RRC. RRC-Connected:

UE c kt ni E-UTRAN RRC

UE c ngcnh trong E-UTRAN (C-RNTI: Cell Radio Network Identtityc n nh) eNodeB bit UE thuc no Mng c thpht hoc thu sliu tUE Di ng da trn chuyn giao vi shtrca UE UE o cc ln cn UE bo co kt quo cc ln cn


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Tng ng vi trng thi LTE-Active.

Hnh 6.4. Cc bmy trng thi RRC v MM

Th dvmt chui chuyn i cc trng thi MM c m t trn hnh6.5.

Hnh 6.5. Th dvmt chui chuyn i cc trng thi MM

Hnh 6.5 cho thy mt chui chuyn i trng thi MM bt u tvic UEbt ngun hoc quyt nh ng k vi mng sau khi tm c mt thch hp.Cho n khi cha t c ng k, u cui nm trong trng thi LTE-DETACHED. Sau khi ng k thnh cng n c thtch cc mt knh mang EPS(hoc sdng knh mc nh) ng k IMS. V lu ti trng thi ny cho nkhi xy ra pht hin khng tch cc. Khi ny UE chuyn vo trng thi LTE-IDLEv gii phng kt ni RRC cng vi cc ti nguyn v tuyn, tuy nhin tt ccc


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knh mang EPS c thit lp gia UE v MME vn ginguyn UE c thtrli cc phin tch cc trc y m khng phi m phn li cc thng sphincng vi cc thuc ngQoS. Khi trng thi LTE-IDLE, UE c thkhi ngtch cc truyn MMS: n khi ng chuyn i vo trng thi LTE-ACTIVE.Sau khi truyn song sliu, UE c thtrli trng thy LTE-ACTIVE da trntiu chun pht hin khng tch cc. Trong mi trng hp, sau khi ng k,UE c thnhn c mt phin kt cui ti ngi sdng hoc chuyn vo trngthi LTE- IDLE.

Chuyn i cc trng thi RRC c cho trn hnh 6.6.

Hnh 6.6. Chuyn i trng thi RRC

Hnh 6.7 cho thy kt hp gia chuyn i cc trng thi MM v RRC.

Hnh 6.7. Kt hp gia chuyn i cc trng thi RRC v MMHnh 6.8 cho thy cc yu cu thi gian chuyn i trng thi lin quan n

hot ng bt buc ca E-UTRAN: Chuyn i t trng thi IDLE sang trng thi tch cc khng lu hn

100ms (thi gian ny khng bao gm thi gian cho cc th tc tm gitrong trng hp cc phin kt cui ti my di ng). Tt nhin y khngphi ton bthi gian thit lp cuc gi, m chl thi gian cn thit


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mng v UE chuyn ttrng thi IDLE v trng thi ACTIVE trong mtti nguyn dnh ring c n nh cho truyn dn bo hiu hay sliu cangi sdng

Thi gian chuyn i gia trng thi ACTIVE v STANDBY khng qu50 ms (khng bao hm cc thtc tm gi nu cn thit)

Ktni

Khngktni

Hnh 6.6. Cc yu cu thi gian chuyn i trng thi

6.4. CC KNH TRN GIAO DIN V TUYN 4G LTE

Hnh 6.9 cho thy cc knh logic, cc knh truyn ti, cc knh vt l vsp xp cc knh logic ln cc knh truyn ti, cc knh truyn ti ln cc knh vtl. Thnh 6.9 ta thy cu trc cc knh ca 4GLTE c n gin ha so vi 3G.Tr cc knh iu khin RACH v BCH c sp xp cc knh vt l ring(PRACH/PBCH), tt ccc knh cn li u c sp xp ln knh vt l chia s:PDSCH/PUSCH.

Cc knh iu khin trong mt phng CP bao gm:

BCCH (Broadcast Control Channel: knh iu khin qung b)

PCCH (Paging Control Channel: knh iu khin tm gi)

CCCH (Common Control Channel: knh iu khin chung) MCCH (Multicast Control Channel: knh iu khin a phng)

DCCH (Dedicated Control Channel: knh iu khin ring)

Cc knh lu lng trong mt phng UP bao gm:

DTCH (Dedicated Traffic Channel: knh lu lng ring)

MTCH (Multicast Traffic Channel: knh lu lng ring)


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Hnh 6.9. Cc knh logic, cc knh truyn ti, cc knh vt l v sp xp ccknh logic ln cc knh truyn ti, cc knh truyn ti ln cc knh vt l.

Cc bng 6.1, 6.2, 6.3 tng kt cc chc nng ca cc knh logic, truyn tiv lt l trong LTE.

Bng 6.1. Danh sch cc knh logicNhm knh Knh logic ng dng

CCH (ControlChannel:Knh iukhin)

BCCH (Broadcast ControlChannel: Knh iu khinqung b)

Knh ng xung pht qungb thng tin hthng. Tthng tinny UE bit c: nh khai thcca phc v, cu hnh cc knhchung ca , cch truy nhpmng


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PCCH (Paging ControlChannel: Knh iu khintm gi)

Knh ng xung pht qungb thng tin tm giKnh ny c sdng tm giUE cho phin thng tin kt cui tiUE.

CCCH (Common ControlChannel: Knh iu khinchung)

Knh hai chiu pht thng tiniu khin gia mng v cc UE.c s dng khi khng c ktni RRC hoc khi truy nhp mt mi. Thng thng knh ny cs dng trong giai on sm nhtca qu trnh thit lp thng tin

DCCH (Dedicated ControlChannel: Knh iu khin

ring).

Knh hai chiu im n im pht thng tin iu khin ring

gia UE v mng. c thit lpbi thit lp kt ni ca RRC.Trong ng cnh DCCH, thng tiniu khin chcha bo hiu RRCv NAS. Cc bo hiu lp ngdng(SIP v RTCP) khng cxl bi DCCH.

TCH (TrafficChannel:Knh lulng)

DTCH (Dedicated TrafficChannel: Knh lu lngring)

Knh im n im ring chomt UE truyn s liu cangi s dng cng nhbo hiulp ng dng lin quan n lungs liu. DTCH c th tn ti cng ln ln ng xung

MCCH (Multicast ControlChannel: Knh iu khinkhin a phng)

Knh ng xung im a imc s dng pht thng tiniu khin MBMS.Knh ny chc UE sdng thu MBMS

MTCH Knh ng xung im a imc mng s dng pht lulng tmng n UEKnh ny chc UE sdng thu MBMS


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Bng 6.2. Danh sch cc knh truyn tiTn knh ng dng

BCH (Broadcast

Channel: Knh qungb)

Khun dng truyn ti cnh v c quy nh trc

Pht qung b thng tin hthng E UTRAN trong tonb

PCH (PagingChannel: Knh tmgi)

H tr thu khng lin tc (DRX) cho UE tit kimngun dinPht qung b trong ton bc sp xp ln cc ti nguyn vt l m cc ti nguynny c thc s dng cho cc knh iu khin hoclu lng

MCH (Multicast

Channel: Knh aphng)

Pht trn ton

HtrMBSFN kt hp vi pht MBMS trn nhiu Htrn nh ti nguyn bn cnhDL-SCH (DowlinkShared Channel:Knh chia s ngxung)

truyn ti thng tin iu khin v lu lngHtrHARQH tr thch ng ng truyn ng bng cch thay isiu chv m ha knh v thay i cng sutC thhtrpht qung b trn ton bC th htrto bpHtrcn nh ti nguyn ng ln bn cnhH tr thu khng lin tc (DRX) cho UE tit kim

ngun inHtrpht MBMS

RACH (RandomAccess Channel: knhtruy nhp ngu nhin)

Knh chung ng lnKnh mang thng tin ti thiuC thmt knh ny do va chm

UL-SCH (UplinkShared Channel: knhchia se ng ln)

Knh ng ln c chc nng ging DL-SCHC thhtrto bpH tr thch ng ng truyn ng bng cch thay icng sut v c kh nng c thay i siu chv

m ha knh

Bng 6.3. Danh sch cc knh vt lTn knh ng dng

PDSCH (Physical Knh ng xung


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Downlink SharedChannel: knh vt lchia sng xung)

Mang thng tin DL-SCH, PCHv bo hiu lp cao hniu chQPSK, 16QAM v 64QAM

PDCCH (PhysicalDownlink ControlChannel: knh vt liu khin ngxung)

Knh ng xungThng tin cho UE vn nh ti nguyn ca PCH vDL-SCH, v thng tin HARQ lin quan n DL-SCHMang thng tin cho php lp biu ng lniu chQPSK

PCFICH (PhysicalControl FormatChannel: knh vt l chth khun dng iukhin)

Knh ng xungCh th s lng cc k hiu OFDM s dng choPDCCHiu chQPSK

PHICH (Physical

HARQ IndicatorChannel: knh vt l chthHARQ)

Knh ng xung

Mang HARQ ACK/NACK tr li cho cc truyndn ng lniu chQPSK

PBCH (PhysicalBroadcast Channel:knh vt l qung b)

Knh ng xungKhi truyn ti BCH c sp xp ln bn khung controng khong thi gian 40ms. nh thi 40 ms cpht hin m (khng c bo hiu chra nh thi 40 msnyMi khung con c th t c gii m (C th tchc BCH tmt ln thu nu iu kin truyn sng tt)iu chQPSK

PMCH (PhysicalMulticast Channel: knhvt l a phng)

Knh ng xungMang MCHiu chQPSK, 16QAM v 64QAM

PRACH (PhysicalRandom AccessChannel: knh vt ltruy nhp ngu nhin)

Knh ng lnMang tin ttruy nhp ngu nhinCc tin t truy nhp ngu nhin c to ra t ccchui Zadoff-Chu vi vng tng quan khng, cto ra tmt hoc nhiu chui Zadoff-Chu gc

PUSCH (PhysicalUplink Shared Channel:knh vt l chia sng ln)

Knh ng lnMang UL-SCHiu chQPSK, 16QAM v 64QAM

PUCCH (PhysicalUplink Control Channel:knh vt l iu khin

Knh ng lnMang HARQ ACK/NACK tr li cho cc truyndn ng xung


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ng ln) Mang yu cu lp biu (SR: Scheduling Request)Mang cc bo co CQIiu chBPSK v QPSK

6.5. QUN L DI NG TRONG 4G LTE

6.5.1. Vng eo bm, TA

Vtr ca c MME nhn bit vi chnh xc n vng theo bm (TA:Tracking Area). Khi UE trng thi ri, mi ln chuyn dch tmt TA ny sangmt TA khc n phi thc hin th tc TA thng bo cho MME vTA mi.Kch thc TA phi c chn hp l khng bln qu (dgim ti bo hiutm gi) v khng bnhqu (n trnh thng xuyn bo hiu cp nht v tr).Cng ging nhvng nh tuyn (RA: Routing Area) trong WCDMA/HSPA, TAtrong LTE thng thng bao phvi trm BTS. Khi nim TA c thhin trnhnh 6.10.

Hnh 6.10. Vng theo bm (TA)

6.5.2. Chuyn giao ni LTE

Di ng ca UE ch c iu khin bi chuyn giao khi tn ti RRC. Vkhng c trng thi CELL_PCH nhtrong UTRAN nn di ng da trn UE ch


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c thkhi UE nm trong trng thi RRC-CONNECTED. Cc chuyn giao trongE-UTRAN c xy dng trn cc nguyn tc sau:

1. Cc chuyn giao c mng iu khin. E-UTRAN quyt nh khi no thchuyn giao v chuyn giao n ch no

2.

Chuyn giao theo cc kt quo ca UE. Cc kt quo v cc bo coo c iu khin bi cc thng sdo E-UTRAN cung cp

3. Cc chuyn giao trong UE vi chch khng tn tht bng cch chuynlu lng gia eNodeB ngun v eNodeB gi.

4. Kt ni S1 ca mng li chc cp nht khi chuyn giao v tuyn hon thnh. Cch lm ny c gi l chuyn mch ng truyn mun.Mng li khng iu khin cc chuyn giao.

6.5.2.1. Bo hiu cho chuyn giao

Cc th tc bo hiu c chia thnh ba giai on: chun bchuyn giao(hnh 11), thc hin chuyn giao (hnh 6.12) v hon thnh chuyn giao (hnh 13).

Hnh 6.11. Chun bchuyn giao


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Hnh 6.12. Thc hin chuyn giao

UE eNodeBngun

eNodeBch

MME S-GW

12. Yu cu chuyn mch ng truyn

13. Yu cu cp nht UP

14. Chuyn mch ngtruyn xung

15. Tr li cp nht UP

16. Cng nhn chuyn mch ng truyn

17. Gii phng ti nguyn

18. Gii phng ti nguyn

Hnh 6.13. Hon thnh chuyn giao

6.5.2.2. o chuyn giao

Trc khi UE c thgi bo co kt quo, n phi nhn dng c chbng cch sdng cc tn hiu ng b. UE o mc tn hiu da trn cc tn hiutham chun. Trong khi WCDMA UE cn c knh qung b tm skhung hthng nhm ng btruyn dn ca chuyn giao mm th LTE UE khng cn cknh ny khi o chuyn giao v trongLTE khng c chuyn giao mm.

Khi tha mn iu kin ngng bo co, UE gi cc kt quo chuyngiao n eNodeB.


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6.5.2.3. Chuyn giao gia cc hthng

Cc chuyn giao gia cc RAT c coi l cc chuyn giao gia LTE vGERAN, UTRAN hay cdma2000 cho cc dch vthi gian thc v phi thi gianthc. Chuyn giao gia cc RAT c iu khin bi hthng truy nhp ngun.Hthng ny khi u o v quyt nh chuyn giao. Chuyn giao gia cc RATl chuyn giao ngc trong cc ti nguyn v tuyn c dnh trc trong hthng ch trc khi pht lnh chuyn giao n UE. V hthng GERAN khngh trchuyn giao chuyn giao gi (PHO) nn cc ti nguyn khng c dnhtrc trc khi chuyn giao. Bo hiu c truyn qua mng li v khng c giaodin trc tip gia cc hthng truy nhp v tuyn khc nhau. Chuyn giao giacc RAT ging chuyn giao ni LTE trong trng hp nt li chuyn mch gi bthay i.

Tt ccc thng tin ththng ch c truyn trong sut qua hthngngun n UE. S liu ca ngi sdng c thc truyn tngun n hthng ch trnh mt sliu. y nhanh thtc chuyn giao UE khng cnthit phi bo hiu n mng li. An ninh v QoS context c chuyn tngunn hthng ch.

S-GW c thc s dng nhmt neo di ng trong chuyn giao giacc hthng.

Tng quan chuyn giao gia cc hthng c cho trn hnh 6.14.

Hnh 6.14. Tng quan chuyn giao tLTE n UTRAN/GERAN


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6.6. CU TRC TI NGUYN TRUYN DN TRONG LTE

6.6.1. Li ti nguyn truyn dn trong LTE

Cc ti nguyn trong LTE c cc kch thc thi gian, tn sv khng gian.Kch thc khng gian c o bng lp v c truy nhp bi nhiu anten phtv nhiu anten thu.

Hnh 6.15 thhin cu trc ti nguyn truyn dn khng gian thi gian caLTE trong mt lp (i vi ng truyn dn tmt anten) cho trng hp CPbnh thng.

UL/DL RB

symb SC= N N cc phn

t ti nguy n (RE)

(UL/DL) RBRB SCN N

RB

SCN

= 12

UL/DLsymb

N

UL/DLsymbN

RB

SCN

UL/DLRBN

Hnh 6.15. Cu trc ti nguyn truyn dn khng gian thi gian ca LTE

trong mt lp cho trng hp CP bnh thng

Trong min tn s, n vti nguyn nhnht l phn tti nguyn (RE:Resource Element) gm mt sng mang con trong thi gian mt k hiuOFDM/DFTS-OFDM. Mi sng mang con c rng bng tn bnh thng l 15kHz hoc 7,5KHz. Trong min thi giancc ti nguyn c chia nhthnh cutrc sau: n vln nht ca thi gian l khung v tuyn (Frame) 10ms, n lt


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mnh khung v tuyn li c chia thnh 10 khung con (Subframe) 1ms v mikhung con c chia thnh hai khe (Time Slot) 0,5 ms. Ti mc cao, mi khungc nh sbi SFN (System Frame Number: skhung hthng). SFN c sdng iu khin cc chu k truyn dn khc nhau c thi gian ln hn mtkhung nhcc chu kchngca tm gi v cc chu kbo co trng thiknh.

Mt khi ti nguyn (RB: Resource Block) c nh ngha l RBSCN cc

sng mang con lin tip trong min tn s v ULsymbN k hiu DFTS-OFDM trn

ng ln hay DLsymbN k hiu OFDM trn ng xung trong min thi gian. V

thmt khi ti nguyn bao gm ( )UL RBsymb SCN N cc phn tti nguyn trn ng

ln v ( )DL RBsymb SCN N cc phn tti nguyn trn ng xung trong min thi gian

tn s. Tng qut cho mt khi ti nguyn vt l ng ln (UL) hoc ngxung bao gm

( )

UL / DL RB

SCsymbN N , trong UL/DL

symbN k hiu cho s k hiu DFTS-

OFDM ng ln (UL) hoc sk hiu OFDM ng xung(DL) trong mt khethi gian c di bng 0,5 ms.

Cc thng sca khi ti nguyn RB c cho trong bng 6.4. Tbng 6.4ta thy scc sng mang trong mt khi ti nguyn RBSCN l 12 hoc 24 i vi cctrng hp bng thng sng mang con bng 15 kHz v 7,5KHz. Bng thng sngmang con 7,5kHz ch c s dng cho truyn dn MBSFN (MB SingleFrequency Network). Mi khe bao gm 7 k hiu OFDM trong trng hp diCP bnh thng hoc 6 k hiu OFDM trong trng hp di CP mrng v

c lp cu hnh theo c im ca .Bng 6.4. Cc thng sca khi ti nguyn vt l (RB)Cu hnh RB

SCN DL

symbN (0,5ms)

ng xung

UL

symbN

ng lnCP bnhthng

f=15kHz 12 7 7

CP mrng f=15kHz 12 6 6f=7,5kHz 24 3 Khng p

dng

Theo quy nh sRB ti thiu trong min tn sl 6 (tng ng vi 6x12=72 sng mang con v bng thng truyn dn l 1,08MHz) v sRB cc i trongtrong min tn s l 100 (tng ng vi 100x12=1200 sng mang con v bngthng truyn dn l 18MHz).


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Hnh 6.16 cho thy cu trc ti nguyn khng gian thi gian-tn s caLTE cho trng hp di tin t (CP) bnh thng vi nhiu lp khng gian(truyn dn tnhiu anten).

Tns

Thigian

Hnh 6.16. Li ti nguyn khng gian thi gian-tn s csca LTE (di CP bnh thng) vi nhiu lp khng gian.

Thnh 6.16 ta thy, trong min thi gian cc ti nguyn c chia nhthnh cu trc sau: n vln nht ca thi gian l khung v tuyn (Frame) 10ms,n lt mnh khung v tuyn li c chia thnh 10 khung con (Subframe) 1msv mi khung con c chia thnh hai khe (Time Slot) 0,5 ms. Trong mintn s, cc RE c nhm thnh cc n v 12 sng mang con c bng tn 180kHz to nn mt khi ti nguyn trong min tn s. Trong min khnggian tn s, mt n v12 sng mang con ni trn trong thi gian mt khe di


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0,5ms hp thnh mt khi ti nguyn (RB) trong li ti nguyn khng gian-thigian.

c th n nh khi ti nguyn theo cc phn b cho cc truyn dnphn b, khi nim VRB (Virtual Resource Block: khi ti nguyn o) c sdng cho LTE. Theo khi nim ny cc VRB c sp xp phn bln cc khiti nguyn (RB) thc s cho truyn dn c gi l PRB (Physical ResourceBlock: khi ti nguyn vt l).

Cc thng s truyn dn OFDM/DFTS-OFDM ca LTE c tng kttrong bng 6.5.

Bng 6.5. Cc thng struyn dn OFDM /DFTS-OFDMca LTE .

Bng thng knh[MHz]

1,4 3 5 10 15 20

S khi ti nguyn(RB) trong min tns

6 15 25 50 75 100

S sng mang conc chim

72 180 300 600 900 1200

Kch thcIFFT/FFT, N

128 256 512 1024 1536 2048

Tn s ly mu, fs[MHz]

1,92 3,84 7,68 15,36 23,04 30,72

Smu trn mt khe 960 1920 3840 7680 11520 15360S k hiu OFDMtrn khe (CPngn/di)

7/6

Bnhthng

(4,7/9)x6(5,2/10)x1

(4,7/18)x6(5,2/20)x1

(4,7/36)x6(5,2/40)x1

(4,7/72)x6(5,2/80)x1

(4,7/108)x6(5,2/120)x1

(4,69/144)x6(5,2/160)x1

diCP ((f=15kHz) * M

rng(16,7/32) (16,7/64) (16,7/128) (16,7/256) (16,7/384) (16,67/512)

di

CP (f=7,5kHz)

M

rng

(33.33/1024)x3

* (x/y)z: x l di CP (s), y l smu trong mt CP v z l sk hiu k hiuOFDM.

Quan h gia tn s ly my (fs), kch thc FFT (N), bng thng sngmang con (f) v thi gian ly mu Tsnhsau:

fs= Nxf ; Ts= fs (6.1)


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Hnh 6.17 cho thy cu trc ti nguyn trong mt khe thi gian cho bngthng knh 20MHz vi tn sly mu fs=30,72MHz, Ts=0,0326s v f=15 KHz.

TCP=160.Ts5,2s (khi DFT thnht), 144.Ts4,69s (cc khi DFT cn li).

TCP-e=512Ts16,67s (Tcp-ek hiu cho thi gian CP mrng).

Hnh 6.17. Cu trc khe:Mt khung con bao gm hai khe di bng nhau. Mikhe bao gm su hoc by khi OFDM (ng xung) hoc DFTS-OFDM (ngln) cho trng hp CP bnh thng v CP mrng.

6.6.2. Quy hoch tn scho 4G LTE

Bng 6.6 lit k cc bng tn hin thi c quy nh cho LTE. Hin thic 17 bng cho FDD v 8 bng cho TDD. Mi khi c th, cc quy nh v tuyncho FDD v TDD c duy tr nhnhau m bo stng ng ti a gia haichny.

Ni chung cc c t lp vt l v rt nhiu cc quy nh v tuyn gingnhau i vi cc bng tn ni trn, nhng cng c mt sngoi li vi cc ctv tuyn ca UE. Cc quy nh v tuyn i vi eNodeB trong mt bng tnc nh ngha khng r rng v cc quy nh cho vic thc hin trm gc t hn.Nu xut hin nhu cu, cc bng tn khc c thdrng bsung v chnh hng


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n cc bphn c tch ring ca cc c tv tuyn. Ngoi ra cc phngn tn sca LTE khng phthuc vo ni dung tnh nng pht hnh ca LTE cs(pht hnh R8, R9). Cc phng n tn sny sc bsung trong chngtrnh khung ca pht hnh R9 v vn c thc thc hin vi vic sdng cctnh nng ca R6.

Cc bng s15 v 16 khng sdng cho LTE v chng c sdng trongcc c tca ETSI.

Bng 6.6. Cc bng tn LTEBngLTE

ng ln ng xung Chsong cng

1 1920MHz-1980 MHz 2110 MHz 2170 MHz FDD2 1850 MHz 1910 MHz 1930 MHz 1990 MHz FDD3 1710 MHz 1785 MHz 1805 MHz 1880 MHz FDD

4 1710 MHz 1755 MHz 2110 MHz 2155 MHz FDD5 824 MHz 849 MHz 869 MHz 894 MHz FDD6 830 MHz 840 MHz 875 MHz 885 MHz FDD7 2500 MHz 2570 MHz 2620 MHz 2690 MHz FDD8 880 MHz 915 MHz 925 MHz 960 MHz FDD9 1749,9 MHz 1784,9 Hz 1844,9 MHz 1879,9 MHz FDD10 1710 MHz 1770 MHz 2110 MHz 2170 MHz FDD11 1427,9 MHz 1452,9

MHz1475,9 MHz 1500,9 MHz FDD

12 698 MHz 716 MHz 728 MHz 746 MHz FDD13 777 MHz 787 MHz 746 MHz 756 MHz FDD14 788 MHz 798 MHz 758 MHz 768 MHz FDD17 704 MHz 716 MHz 734 MHz 746 MHz FDD18 815 MHz 830 MHz 860 MHz 875 MHz FDD19 830 MHz 845 MHz 875 MHz 890 MHz FDD33 1900 MHz 1920 MHz 1900 MHz 1920 MHz TDD34 2010 MHz 2025 MHz 2010 MHz 2025 MHz TDD35 1850 MHz 1910 MHz 1850 MHz 1910 MHz TDD36 1930 MHz 1990 MHz 1930 MHz 1990 MHz TDD37 1910 MHz 1930 MHz 1910 MHz 1930 MHz TDD38 2570 MHz 2620 MHz 2570 MHz 2620 MHz TDD39 1880 MHz 1920 MHz 1880 MHz 1920 MHz TDD40 2300 MHz 2400 MHz 2300 MHz 2400 MHz TDD


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15 75 13,520 100 18

Bng thng knh l thng slin quan n tn sv tuyn quy inh pht

xngoi bng (OOB: Out of Band), (chng hn mt npht xph, tld knhln cn: ACLR). Cc bin ca knh v tuyn c nh ngha l cc tn s thpnht v cao nht ca knh mang c phn cch bi bng thng knh: fcBchannel.

6.6.3.2. Sp xp knh tn s

Cc knh ca LTE c sp xp theo mnh ph100 KHz, ngha l tn strung tm phi l mt snguyn ln 100 kHz. So snh vi UMTS sp xp knhthao mnh 200 KHz.

Khong cch gia cc sng mang sphthuc vo kch bn trin khai, kchthc ca khi tn skhdng v cc bng thng knh. Khong cch knh chungia hai sng mang LTE c xc nh nhsau:

Khong cch knh chun= (Bchannel1-Bchannel2)/2 (6.2)

Trong Bchannel1v Bchannel2l cc bng thng ca hai sng mang tng ng.Cng c thiu chnh bng thng chun ti u hiu nng trong mt

kch bn trin khai cth, ngha l phi hp hot ng vi cc sng mang LTE lncn.

6.7. CC TN HIU THAM CHUN TRONG 4G LTE

thc hin gii iu chnht qun cc knh vt l my thu cn c tnh

knh. Cc hthng thng tin di ng sau 3G v 4G u sdng c tnh knh da

trn hoa tiu hay tn hiu tham chun c pht trong lung ghp chung vi cc

k hiu sliu iu ch.

6.7.1. Tn hiu tham chun ng xung

Trong c xung 4G LTE, cc kiu tn hiu tham chun sau y ccung cp:


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Cc RS c th (thng c gi l cc RS chung v chng khdngi vi tt cMS trong mt )

Cc RS c th MS, c sdng nhng trong sliu cho cc MS c th Cc RS c th MBSFN, chng chc sdng cho mng pht qung

b a phng tin n tn (MBSFN: Multimedia Broadcast SingleFrequency Network)

6.7.1.1. Cc tn hiu tham chun c th

Cc tn hiu tham chun c th c c im sau: Khc nhau trong cc ln cn (cc chui tn hiu tham chun khc nhau

hoc cc dch tn tn hiu tham chun khc nhau) Nhnhau cho tt ccc UE tong mt , v thcc UE c thsdng cc

tn hiu tham chun c tnh knh cho cc ca anten khc nhau v sau sdng cc c tnh ny gii iu chnht qun.

6.7.1.1.1. Cc xem xt khi ghp tn hiu tham chun vo min thi gian tn s

Trong 4G LTE, cc k hiu cu thnh cc RS c th trong khng gianhai chiu thi gian-tn sphi tun theo nguyn tc: c tchc ng khongcch t c c tnh sai li trung bnh quan phng ti thiu.

Khong cch cn thit theo thi gian gia hai k hiu c thnhn c datrn tri Doppler cc i (tc cao nht) cn h tr. Trong 4G tc ny l

500km/gi. Dch Doppler l fD=(fcv/c) trong fcl tn ssng mang o bng Hz,v l tc UE o bng m/s v c l tc nh sng (3.108m/s). Nu coi rngfc=2GHz v tc v=500 km/gi, th fD 950Hz. Theo nh l ly mu caNyquist th tn sly mu ti thiu m bo khi phc c knh phi m bokhong cch thi gian:

D symbsymb D

1 12f N

N T 2T f >

giao thuc giao dien vo tuyen

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