MT S KHI NIM C BNV THNG TIN V TUYN CONCEPTs OF WIRELESS COMMUNICATION SYSTEM Ths. H c TB Mn Vin ThngKhoa in-in TTrng i Hc Bch Khoa TP. H Ch Minh

Tp.HCM 9-2006

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NI DUNGKhi nim v nguyn l c bn1Mng thng tin t bo234Khi nim lu lngKhi nim iu khin cuc gi5Can nhiu v dung lng HT

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Khi nimChc nng c bn ca mt h thng TT di ng:

Thit lp kt ni d liu (Data connection) gia 2 thu bao hoc gia thu bao di ng v mt nh cung cp dch v.Cc thu bao c th di ng c (Mobility).H tr chc nng nh v cho cc thu bao.m bo thu bao lun c kt ni vi mt trm thu pht sng gc (BTS) trong mng thng tin t bo (Cellular Network).

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Nguyn l truyn thng di ngMSCMS1MS2BTS1BTS2

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S mng CDMA 2000 1X (Exp.) BTSBSCBTSBTSBTSBSCIWFAAAInternetHADCNPDSN(FA)SMSCHLR/AuCMSC/VLRVMSRadio Access Network RANPacket Core Network PCNCircuit Core Network CCNWIN/PPSMSMS

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P.T. truyn sng ban u tng thit k ban u:Mt h thng v tuyn c th phc v kt ni cho mt khu vc rng ln:

Antenna kh caoCS pht lnNhng khng p dng k tht ti s dng ti nguyn v tuyn.Dung lng h thng hn chS dng ph tn s km hiu qu.

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Khi nim ti s dng tn s* Khi nim:* Khi nim ti s dng (Re-use) tn s trong T.T. t bo:Nng cao dung lng h thngTrnh tt nghn trong thng tinTit kim, s dng hiu qu ti nguyn v tuyn

* Thc hin:Thay th 1BTS cng sut pht ln thnh nhiu BTS cng sut b hn.Mi BTS ch ph sng cho mt vng vi phm vi nh hn.Cc vng ph sng ny c b tr st nhau v gi l cc t bo thng tin (Communication Cell).

Mi BTS c gn mt nhm tn s (f1,f2).Cc BTS k cn s dng cc nhm tn s khc nhau (f1,f2; f3,f4)Ti s dng nhm tn s Cell ny cho cc Cell khng k cn

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Khi nim ClusterKhi nim Cluster:

L nhm cc Cell gn nhau v c tn s hon ton khc nhau:

Tng s cc tn s c trong Cluster bng vi tng tn s c c trong ton h thngn: s Cell trong mt Cluster gi l kch thc ca Cluster.

H s ti s dng tn s RGSMCDMA

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Khi nim ClusterCc Cluster khc nhau c t ti cc v tr a l khc nhau trn ton min ph sng. thun tin cho vic qui hoch, qun l v pht trin mng, Cell c dng hnh lc gic.V c bn, c 2 cch t trm BTS: Ti tm ca Cell (antenna v hng) Ti gc ca 3 Cell k nhau (Antenna c hng).

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Khi nim cell v clusterCell hnh lc gic nn cc Cluster xp st nhau:

Di tn s dng trong mt cell bng 1/n tng tn s s dng trong ton b h thng.Nu n nh, kch thc Cell khng i S Cluster tng ln dung lng HT tng, nhng nhiu ng knh tng.Ngc li, nu n ln t Cluster v nhiu ng knh b.Cn thit k N nh m bo dung lng h thng cng nh cht lng thng tin

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Khi nim mng T.T. t boM hnh chia vng ph sng thnh cc cell/cluster: M hnh khi nim v mng thng tin t bo:

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Cu trc h thng TT t boVi mi trm gcPh sng mt phn ca mng bng mt trm v tuyn gc.c cp pht mt hoc nhiu sng mang2. Kt ni Duplex gia thu bao MS vi trm gc3. Mt MSC c th qun l nhiu BS.4. MSC c th l Gateway kt ni vi cc h thng V.T. khc.Cu trc h thng T.T v tuyn t bo

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Khi nim vng ph sngTrn thc t, vng ph sng ca mt Cell c hnh dng ph thuc vo a hnh (Footprint).

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M hnh mng t bo thcMt v d v vng ph sng trn thc t ca mt mng thng tin di ng PLMN:

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Khi nim .K. cuc giMS thc hin trao i tin v lin lc vi BTS thng qua cp tn s:Hng ln (Reverse)Hng xung (Forward)C 4 loi knh c bn:Reverse Control Channel RCCReverse Voice Channel RVCForward Control Channel FCCForward Voice Channel FVCKnh iu khin thit lp cuc gi v chuyn n knh thoi ri. Nhn v pht cc thng tin thit lp cuc gi, yu cu dch v. c gim st bi cc thu bao.MSC

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Mi Cell u c knh iu khin.Khi m my, MS qut tm cc knh iu khin, chn knh mnh nht v gim st knh .Khi MS c gi, MSC gi yu cu tm kim thu bao c gi ti tt c BTS. T BTS tip tc tm kim thu bao c gi thng qua knh iu khin xung FCC.Khi TB c gi nhn c tin, n xc nhn, gi ti BTS qua knh RCC. BTS chuyn bn tin ny n MSC.

iu khin cuc gi

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MSC iu khin BTS kt ni cuc gi n trn mt knh thoi ri. ng thi BTS bo hiu cho MS tin hnh kt ni trn knh thoi ri ny.Tip n, BTS truyn tn hiu chung cho MS chung.Trong qu trnh gi, MSC iu chnh cng sut ca MS ti u thu/pht tn hiu.MSC iu khin BTS chuyn giao cuc gi khi MS i ra khi vng ph sng (Hand-off). iu khin cuc gi

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Khi MS thit lp cuc gi, MS gi s nhn dng ca n v s cn gi n BTS thng qua knh RCC.BTS nhn thng ip ny v gi tip n MSC.MSC phn tch yu cu, xem s cn gi thuc mng PSTN hay mng di ng:a) PSTN, MSC nh tuyn cuc gi n tng i ca mng PSTN.b) PLMN, MSC pht tin qung b n tt c cc BTS, tm kim TB c gi v kt ni vi TB ny.

iu khin cuc gi

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Khi nim Hand-offYu cu v c im ca Hand-Off:

Hand Off m bo cuc gi lin tc khi MS di chuyn t Cell ny sang Cell khc.MSC chuyn cuc gi n mt knh v tuyn thuc mt BTS mi.Yu cu cho Hand Off lun cao hn yu cu thit lp cuc gi.Hand Off khng c nhn bit bi ngi s dng.Mc cng sut thu ti u ti BTS c ch nh tin hnh Hand-off, thng: -90~ -100(dBm), ty thuc cc h thng khc nhau. = PRhandoff PRminimum usable khng qu ln hoc qu nh

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Handoff trong h thng 1 & 2GC s ca vic Hand-Off cc h thng 1G v 2G:

H thng 1G, cng trng o bi BTS v c gim st bi MSC.BTS o cng trng ca cc MS trong Cell thng qua o tn hiu ca cc knh thoi.ng thi mt Receiver khc ca BTS chu trch nhim o cng trng ca tt c cc MS thuc BTS xung quanh.Da vo gi tr o c, MSC quyt nh l tin hnh Hand-Off hay khng ? Thng th = 6 ~12 dB.Cc h thng 2G, vic Hand Off c s tr gip ca MS.MS lun o cng sut t BTS phc v v o cng sut t BTS k cn, gi v MSC.Khi cng sut t BTS k cn cao hn cng sut t BTS phc v, Hand off xy ra. Thng th = 1 ~ 6 dB.Khi MS di chuyn sang mt Cell khc (thuc MSC khc) gi l Intersystem Hand Off.

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Tin trnh x l Hand-offPilot Strength(Ec/Io)Cell ACell BMoving Direction of MSAdd point Drop point Handoff RegionCell ACell BHAND-OFF CALL PROCESSINGBTS-ABTS-B

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Cc dng Hand-off c bnScope of Hand-off: Intra-BS, Intra-MSC Handoff Inter-BS, Intra-MSC Handoff Inter-BS, Inter-MSC Handoff

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Khi nim lu lng (Traffic)Mi User c cp mt tn s khi c yu cu thoi v gii phng khi kt thc. Do h thng ch c th phc v mt s lng ln thu bao vi s lng knh gii hn (Traffic and Grade of Service).Lu lng (Traffic) c n v l Erlang. Mt Erlang (1Erl) c ngha l lu lng c truyn ti bi mt knh m n hon ton c s dng trong sut thi gian thc hin o lu lng truyn qua knh .Cng thc v lu lng cn thit cho mt User:

Trong : : Tn sut thc hin cuc gi (s cuc/n v tgian) H : Thi gian trung bnh thc hin cuc giTng lu lng cn thit cho U users l:

S lng knh trong mt Cell phi ln hn hoc bng A.

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Cp Dch V - GOSKhi nim Grade of Service (GOS): kh nng tt nghn h thng vo gi cao im (BH: Busy Hour).GOS t l vi nhng cuc gi khng th lin lc c v cc knh ang b chim ht. GOS: tiu chun i vi cht lng chuyn mch (1%)Cng thc tnh ERLANG_B: Th hin quan h gia kh nng nghn GOS, s knh C v lu lng A:

tin s dng, da vo bng kt qu gii bi tm s knh cn phc v khi bit GOS v lu lng cn truyn.

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Bng tham chiu tnh Erlang_B

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V d tnh ton s knhV d tnh ton s knh cn thit phc v 100 Users, vi mc phc v GOS=2%. Lu lng trung bnh cho mi ngi s dng l 30m Erl

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Khi nim Channel Usage

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K thut TrunkingTng quan v Trunking measured traffic representative traffic expected traffic at target future required channel without margin raw trafficinterval, valuesaverage, peakstatistical analysistraffic forecastseasonal variationErlang-B expected traffic / routenetworkconfiguration required channel with marginMarginu t hiu qu1Giao tip trong h thng li : MSC E1 PortGiao tip trong truyn dn: E1 PortDung lng truyn dn kt ni (in., ext.)m bo cht lng dch v2Mc QoS thi im thngMc QoS khi c s c h thngMc QoS cho cc d liu bt thngMc ch Trunking8 required E1/Route

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Can nhiu v dung lng HT

Gi thit tnh ton nhiu ng knh CCI

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Khi nim Reuse DistanceReuse distance, D:

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Tnh ton s Cell trong Cluster

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Khi nim Sector ha

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Khi nim Sector ha

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Ni dung cn nm btKhi nim chung v cc h thngThng tin v tuynPhn tch c iu khin cuc giTrong h thng di ngPhn tch c c ch chuyn giaoCuc gi Hand-offPhn tch v tnh ton c lu Lng cn thit trong h thng thng tinCan nhiu v dung lng h thng

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Phn tip theoChngMt1. Cc khi nim6. Thit k h thng T.T.D.2. M hnh truyn sng3. FDMA, TDMA, CDMA. OFDMA5. K thut tri phV h thng CDMA4. H thng GSM (TDMA)