THIT K MN HC THNG TIN DI NG I.Lch s pht trin h thng thong tin di ng: Lch s pht trin gn lin vi cc h thng truyn dn v tuyn Hnh thc u tin l cc my b m gn trn cc xe cnh st M V sau m rng cho cc khch hang c yu cu Sau nng cp thnh h thng thong tin : c trm pht sng ln ,cao phc v 1 vng rng:s dng k thut a truy nhp phn chia theo tn s(FDMA) H thng thong tin di ng th h u tin(1G): l cc h thng tng t ch yu cho thoi, dung lng thp , cht lng km 1G: AMPS v NAMPS M v Bc M E-TACS v NMT chu u JTACS v NTACS Nht Bn H thng thong tin di ng th h 2(2G GSM): thng tin di ng s S dng k thut TDMA hoc CDMA kt hp vi FDMA Dch v 2G: thoi ,SMS, MMS(hn ch) Chuyn mch trong 2G: chuyn mch knh H thng thng tin di ng th h 3(3G UMTS): S dng k thut W-CDMA Dch v 3G: thoi,SMS,MMS,internet Chuyn mch trong 3G UMTS: chuyn mch knh + chuyn mch gi

II.H thng thng tin di ng GSM GSM:The Globe system for Mobile Telecommunication H THNG THNG TIN DI NG TON CU GSM c pht trin t nm 1982 khi cc nc Bc u gi ngh n CEPT quy nh mt dch v vin thng chung Chu u bng tn 900 MHz. H thng GSM s dng kt hp phng php a truy nhp phn chia theo thi gian (TDMA) v phn chia theo tn s (FDMA), trong mi trm di ng truy nhp vo mng c cp pht mt cp tn s v mt khe thi gian. Nm 1991, h thng thng tin di ng GSM u tin c a vo thng mi ha s dng bng tn 900 MHz. Nm trong di tn 890- 960 MHz, vi rng bng 25 MHz c b tr nh sau: fu= 890 + 0.2*n (MHz) fd= fu + 45 (MHz) vi: n= 0,1,2, , 124

Bao gm 125 knh nh s t 0 n 124, trong s dng 200KHz dnh cho khong bo v gia di tn dnh cho ng ln v ng xung. GSM s dng phng php a truy nhp TDMA, nn mi tn s chia thnh 8 khe thi gian. Nm 1990, tng sc cnh tranh, Anh Quc a ra yu cu v phin bn mi ca GSM s dng bng tn 1800MHz. Ti nhiu quc gia, h thng GSM 1800 c a vo s dng nh mt phng php nhm tng dung lng h thng GSM 900, cng nh tng s nh phc v. Bng tn s dng trong DCS 1800 l: 1710 1785 MHz ng ln 1805 1880 MHz ng xung m bo cc quy nh v tn s bn ngoi bng phi c mt khong bo v gia cc bin ca bng (200KHz). V th, DCS 1800 c 374 tn s v tuyn bt u t 1710.2MHz. Mi mt knh tn s v tuyn c t chc thnh cc khung TDMA c 8 khe thi gian. Mi khe thi gian c di 0.577ms.

1.Cu trc h thng GSM:

MSC: Mobile Switching Center : Trung tm chuyn mch di ng Chuyn mch cuc gi iu khin cuc gi Giao tip vi mng PSTN, ISDN Qun l di ng MS thng qua giao din v tuyn Thc hin chuyn giao gia cc BTS Trm gc BSC: l 1 trm thu pht sng c nh trong h thng thng tin di ng.BSC bao gm cc knh v tuyn v cc anten thu pht Chc nng BSC: Chuyn mch v iu khin cc BTS Khi to cc kt ni

Qun l ti nguyn v tuyn BTS:thc hin cc chc nng sau: Thu pht v tuyn iu ch, gii iu ch M ha gii m ting MS: Mobile Station MS=SIM + ME VLR: (Visitor Location Registers): b nh v tm tr: lu tr cc thng tin v thu bao trong vng phc v ca MSC HLR: Visitor Location Registers : b nh v thng tr:thc hin kim tra tnh hp l trong ca MS v cc dch v phc v AUC: Authentication Center : Trung tm nhn thc thu bao Qun l cc thng tin nhn thc v mt m lien quan n tng thu bao da trn mt kha b mt Ki EIR: Equipment Identity Register :c s d liu lu tr s IMEI ca ME 2.Mng t bo v cc khi nim c bn dng trong thng tin di ng: 2.1:Mng t bo:(mng t ong) Lm th no vi tn s c cp pht c gii hn phi phc v 1 s lng thu bao ln v khng ngng tng ln?? Gii php: chia nh din tch c th ti s dng tn s Mi vng phc v s c chia thnh cc vng nh c gi l cc cell.Mi cell c 1 anten thu pht hay cn gi l trm BTS Cell : l 1 hnh lc gic u c cnh l R

Din tch cell: S=

2.2.S dng li tn s: l vic mt tn s hoc mt nhm tn s c s dng ng thi cc cell khc nhau trong h thng. Cc cell s dng li tn s c gi l cc cell ng knh.Cc cell ny phi cch nhau mt khong ln trnh nhiu ng knh. Mc ch :Nhm lm tng dung lng ca h thng do ti nguyn tn s cp pht cho h thng l c hn trong khi s thu bao khng ngng tng ln Vic xc nh cc cell ng knh theo cng thc: N = i2 + ij = j2, vi i, j >= 0 V d : vi N=3 ta v c cc cell ng knh nh sau:

2.3.Cluster/ Cluster size: Cluster: 1 nhm gm cc cell k nhau m ton b bng tn ca h thng c s dng Cluster s c s dng li trong ton mng Cc knh tn s s c ti s dng trong cc cluster Mi 1 cell trong 1 cluster s c cp 1 nhm cc knh s dng trong vng phc v Cluster size: s cell trong 1 cluster c gi l cluster size(N) N = i2 + ij = j2, vi i, j >= 0 Theo cng thc th N mang cc gi tr v d nh:

Vic la chn N ph thuc vo thc t mng v s dng hiu qu ti nguyn tn s 2.3.Phn chia tn s:

V sao phi phn chia tn s? Trong thc t vic phn b lu lng khng ng u gia cc cell v mt a l,v mt dn c nn t ra yu cu phi phn chia tn s sao cho hp l gia cc cell trong cng 1 cluster.Vic phn chia hp l tn s s s dng hiu qu ti nguyn tn s, trnh lng ph ti nguyn v tng cht lng ca ton mng Phn chia tn s gm 3 loi: FCA (Fixed channel assignment) l hnh thc phn knh c nh trong ton b bng tn c chia u v gn c nh cho cc cell trong cluster. DCA (Dynamic Channel Assignment) l hnh thc phn knh ng trong cc cell trong mt cluster s dng chung mt ti nguyn tn s chung (common pool). CP ny c iu khin v qun l bi MSC. Cc cell khi c nhu cu s dng knh lu lng s c MSC cung cp theo nhu cu ca cell trong gii hn bng tn ca h thng. Khi c mt yu cu knh lu lng mt cell, MSC s cp mt knh trong CP cho cell , v knh c cp ny c gi trong sut thi gian m thoi. Khi cuc gi kt thc, knh ny s c gii phng v tr v cho CP. HCA ( Hydrid channel assignment) l hnh thc phn knh kt hp gia phn knh ng v phn knh c nh. Bng tn h thng c chia thnh 2 phn: BW = BW1 + BW2 Trong : BW1 l bng tn s dng hnh thc phn knh c nh BW2 l bng tn s dng hnh thc phn knh ng 2.4.Tch cell: Trong thc t, khi s thu bao trong 1 cell tng vt qu dung lng thit k ban u,mng s khng p ng c cc dch v dn n tc nghn cuc gi,mt kt niKhi gii php s c a ra l tch cell

Vic tch cell p dng cho vng c mt thu bao cao Vic tch cell s lm tng dung lng ca h thng 2.5.Ch s GoS:( Grade Of Service) Ch s GoS l xc sut cuc gi khng thnh cng trn tng s cc cuc gi kt ni

GoS=

T NC / N C !

Tk 1

NC

k

/ k!

Trong : NC: l s knh phn b trong mt cell T : Tng lu lng ca mt cell III.Thit k h thng GSM 1. . S cell thc t ti thiu cn lp t m bo yu cu dch v Kch thc ca 1 cell nh hnh v di y:

khu vc c din tch:X*Y=120*15(km2) Khi sp xp cell theo chiu di(X=120 km2 ) ta c s cell: 120/2.598= 46.189 (cell) Ta chn 47 cell Khi sp xp cell theo chiu rng(Y=15 km2 ) ta c s cell: 15/(1.5*1.5)= 6.66 (cell) Ta chn 7 cell Vy ta c s cell thc t cn lp t cho vng l: Ncell= 47*7 + 3 = 332 (cell)

2.Mu s dng li tn s N tt nht cho nm u tin Din tch ca 1 cell:

S cell

3 3 * R 2 3 3 *1,5 2 5,845 (km2 ) 2 2

S cell l thuyt l:

N cell

S 120 * 15 307 .9(cell ) S cell 5,845

Ta chn Ncell = 308 cell S ngi s dng mng trong nm u tin: U = 10,000,000*0.6 = 6,000,000 (ngi) Lu lng tng ca ton mng: T = 0.08 * 6,000,000 = 480,000 (erl) Lu lng ca 1 cell: Tcell = T/ Ncell = 480,000 / 308 = 1558.44 (erl) Ta c Tcell = 1558.44 v GoS= 0.015 nn theo bng Erlang B ta c: S knh trong 1 cell: Ccell = 1573 knh H thng GSM 1800 c 374 knh vt l kt hp vi TDMA nn ta c 374*8=2992 knh lu lng Mu s dng li tn s: N= = 1.9 < 3

Mu s dng li tn s N=1.9