TNG QUAN H THNG GSM Phn 1:Gii thiuPhn ny gii thiu cc c tnh ca cc h thng cell th h u, th h th hai. Ni dung phn ny bao gm: Mng v tuyn cell Cc c tnh ca cc h thng cell th h u Cc c tnh ca cc h thng cell th h th hai v cc h thng phi GSM Cc h thng cell trn th gii v s phn b thu bao

GII THIU CC H THNG CELL

Mng v tuyn cellCc c tnh ca mng v tuyn di ng Mng v tuyn di ng hnh thnh theo cu trc t bo nn cn c tn gi l mng v tuyn cell. Mi cell l vng ph ca 1 anten. V th hnh dng ca cell ph thuc vo kiu anten v cng sut pht ca tng trm gc. Dng anten thng s dng l anten v hng pht ng hng v anten c hng tp trung cng sut pht theo hng nht nh S lng tn s trong mng l hu hn. Do , s dng hiu qu ti nguyn v tuyn ta cn s dng li tn s cc BTS khc nhau Tnh di ng gia cc cell thc hin c nh vo chuyn giao (gii thiu c th chng 8).

Hnh 1.1-Mc thi gian ra i ca cc th h mng

H thng cell th h th nhtCc c tnh ca h thng cell th h th nht: Gii thiu rng ri u nm 1980 S dng k thut iu ch tng t Dng kiu a truy xut phn chia theo tn s Ch dng cho thai Khng c kh nng roaming vi mng ngoi Khng an ton trn giao din v tuyn

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TNG QUAN H THNG GSMCc chun mng th h th nht AMPS (Analogue Advanced Mobile Phone System): theo chun Bc M dng bng tn 800Mhz. TACS (Total Access Communications System): chun Hoa K da trn AMPS dng bng tn 900Mhz. NMT(Nordic Mobile Telephony System): theo chun Bc u dng bng tn 450Mhz v 900Mhz. C-450: theo chun c dng bng tn 450Mhz JTACS: theo chun Nht dng bng tn 900Mhz Quy hach cell cho mng th h th nht Macrocellular: t v tr cao cho vng ph ln, anten trn mi nh Hach nh tn s: i vi cc mng s cell nhiu hn s tn s th cn phi hach nh cho tn s Cell kch thc ln, vng ph 30km Chuyn giao cng: Mi MS ti 1 thi im ch c kt ni ti duy nht 1 cell Cell c hnh dng lc gic

Hnh 1.2- S phn b tn s gia cc cell trong mng v tuyn cell.

H thng cell th h th haiCc c tnh h thng cell th h th hai Gii thiu rng khp trong nhng nm 1990 Dng iu ch s Dng nhiu k thut a truy cp khc nhau S dng ph v tuyn hiu qu hn Truyn thai v d liu chuyn mch mch tc thp C kh nng roaming quc t An tan trn giao din v tuyn Tng thch vi ISDN

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TNG QUAN H THNG GSMTrong khi nhng h thng th h u dng kin trc cell v ti s dng li tn s th cc h thng s vn pht trin quan dim ny v dng thm cc thng s cell a lp (cc microcell v macrocell). Ti s dng tn s cht hn do nhiu trong truyn dn s gim. Cc c tnh ca mng CDMAOne Nhng mng u tin nm 1996 Bt ngun t giao din v tuyn Qualcomm IS-95 a truy cp phn chia theo m Mng li ANSI-41 Tc chip l 1.2288Mcps Cc c tnh D-AMPS/PDC TDMA(D-AMPS) Dng TDMA/FDMA Phn ln c dng Bc v Nam M Hach nh ging mng GSM Mng core ANSI-41 PDC Dng TDMA/FDMA Phn ln c dng chu Hach nh ging mng GSM

S pht trin ca GSM v cc c tnhCu trc cell Mc ch ca h thng cu trc cell l s dng tn s sn c mt cch hiu qu Cu trc cell cho php ti s dng tn s trong mng Vic hach nh thng s ti s dng tn s l phn chnh ca thit k h thng Hach nh GSM Cc thng s chnh cn quan tm khi hach nh mng Vng ph Dung lng Cht lng Cc thng s ty chn yu cu khi hach nh mng Cu trc cell phn bc(macrocell/microcell) Nhy tn Truyn khng lin tc iu khin cng sut Phn tch dung lng thu bao: dung lng gii hn bi s TRX

S phn b thu bao trong cc h thng cell

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TNG QUAN H THNG GSM

Hnh 1.3-S phn b thu bao ng vi cc th h mng di ng

Hnh 1.4-S phn b thu bao di ng trn th gii

Cc c tnh ca mng 2.5G iu ch s Thai v d liu chuyn mch mch tc va K thut roaming 2G An tan trn giao din v tuyn Da trn cc chun u th tn ti trong mng 2G nh GSM v CDMAOne Tc d liu c tng cao

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TNG QUAN H THNG GSM

Phn 2:

TNG QUAN V KIN TRC MNG

2.1 Cc s nhn dng trong mng GSM 2.1.1 IMEI-International Mobile Equipment IdentityIMEI (International Mobile Equipment Identity) l s nhn dng thit b di ng quc t, dng phn bit tng my TD. Khng th c hai TD cng mang mt s IMEI. Thng thng, s IMEI do mt s t chc cung cp cho nh sn xut TD. IMEI c lu trong AuC, my, EIR. EIR dng s ny nhn dng thit b di ng bi ly cp v ngn cm truy cp vo mng S IMEI lun gm 15 ch s theo dng:

TAC(Type Approval Code) c 6 ch s 2 ch s u cho bit t chc no cung cp s IMEI cho nh sn xut TD. Bn ch s k tip c gi l Mobile Equipment Type Identifier, dng nhn dng dng (model) TD FAC (Final Assembly Code) dng xc nh xut x ca sn phm SNR (Serial Number) s xri ca sn phm Spare cho s dng trong tng lai V d: Nu IMEI l 350893-30-952659-2 :s u 35 cho bit do t chc BABT cp, c sn xut ti Hn Quc(30).

2.1.2 IMSI-International Mobile Subscriber IdentityIMSI l s nhn dng thu bao di ng quc t dng phn bit cc thu bao di ng tan cu. N c dng cho bo hiu trong mng, c lu trong SIM, HLR v VLR ang phc v S IMSI lun gm 3 phn:

MCC(Mobile Country Code): M nc di ng(Vit Nam l 452) MNC(Mobile Network Code): M nh cung cp mng di ng(Viettel l 04) MSIN(Mobile Station Identification Number): s nhn dng thu bao di ng

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TNG QUAN H THNG GSM2.1.3 TMSI-Temporary Mobile Subscriber IdentityTMSI l s nhn din thu bao di ng tm thi. S ny c gi tr trong tng LA, c cp mi cho MS mi khi thc hin IMSI attach, hay khi cp nht v tr do MS chuyn sang LAI khc. S ny c s dng tm gi MS trn giao din v tuyn, c thay i sau tng cuc gi hay theo chu k trnh cho MS b theo di bng cch nghe ln tn hiu gi trn ng v tuyn. Ch khi khng th gi c bng TMSI th mng mi tm gi MS bng IMSI. TMSI c lu trong VLR v trong SIM. TMSI bao gm 4 octet. Mi nh iu hnh mng c th chn cu trc TMSI

2.1.4 LAI-Location Area IdentityMng PLMN s c chia thnh nhiu vng nh gi l LA(Location area). Mi vng nh ny s c 1 s nhn dng v s ny gi l LAI. LAI c broadcast u n bi cc BTS trn knh BCCH. Cng dng ca LAI l dng tm gi v cp nht v tr cho thu bao Cu trc nh sau:

LAC(Location Area Code):16 bit cho php 65536 vng nh c xc nh trong 1 PLMN

2.1.5 MSISDN-Mobile Station ISDN Numbery l s thc ca 1 thu bao khi lin lc vi thu bao ta s gi s ny .MSISDN l s m t thu bao di ng trong mng PSTN. Khi 1 my c nh gi cho 1 my di ng trong bo hiu vi tng i c nh th a ch ca my b gi chnh l s MSISDN v tng i c nh s cn c vo s iu khin kt ni ti mng di ng(GMSC-HLR) ca my b gi. Cu trc nh sau :

CC(Country Code) : M nc NDC(National Destination Code):M mng SN(Subscriber Number): S thu bao

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TNG QUAN H THNG GSMVD:84 98 8000345 2.1.6 MSRN-Mobile Station Roaming NumberMSRN l 1 s tm thi c cp bi VLR c dng nh tuyn cuc gi gia 2 thu bao thuc 2 mng khc nhau(GMSC-MSC) hay 2 thu bao thuc 2 MSC khc nhau Cu trc gm 3 phn:

2.1.7 CI-Cell IdentifierCI l s nhn dng cell dng nhn dng cc cell khc nhau trong 1 mng PLMN

2.1.8 BSIC-Base Station Identity CodeBSIC l m dng phn bit cc cell khc nhau khi cc cell ny c cng tn s BCCH. Hai cell c tn s BCCH ging nhau th BISC phi khc nhau Cu trc nh sau:

NCC(Network Color Code) 3 bit tng ng t 0 n 7 BCC(Base Station Color Code) 3 bit tng ng t 0 n 7

2.1.9 CGI-Cell Global IdentityCGI c dung nhn dng cc cell ring bit trong cng mt LA. Nhn dng cell thc hin bng cch cng CI vi LAC. CI c chiu di ti a l 16 bit. CGI bao gm:

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TNG QUAN H THNG GSM

2.2 Tng quan kin trc mngSw itching S ystem SS AUC

V LR O ther netw orks B ase S tation S ystem

H LR

EIR

GM SC

MSC

B SSBSC N MC and OMC

S ignaling transm ission Call connections and signaling transm issionBTS

MS

Mng GSM hnh thnh t 3 phn: Mobile Station (MS) Base Station Sub-system (BSS) : Gm 1 BSC v nhiu BTS Network and Switching Sub-system (NSS) : gm MSC v VLR, HLR, EIR, AUC

2.2.1 MS-Mobile StationMS l thit b thu pht c nhn do ngi ng k thu bao trc tip s dng bao gm: Thit b di ng : ME Mobile equipment. Module nhn dng thu bao: SIM Subscriber Identity Module. SIM ct gi thng tin v thu bao, mng bao gm: S IMSI, kha nhn thc, thut tan kim tra nhn thc, bo mt TMSI, LAI, danh sch cc tn s c dng cho vic chn cell Module nh s danh b, tin nhn ME c phn bit bi s IMEI Cn c vo cng sut pht ti a ca MS m ta phn MS thnh cc lp nh sau:

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TNG QUAN H THNG GSM

Nhng thit b di ng u cui dng trong mng GSM thng l class 3 v 4 i vi bng tn 900 , class 1 v 2 i vi bng tn 1800(DCS). Nhng class khc dng cho nhng thit b lp t c nh hay lp trn xe

2.2.2 BSS-Base Station Subsystem 2.2.2.1 BTS-Base TransceiverBTS gm c Cc TRX c chc nng pht v nhn tn hiu Cc thit b iu khin v x l tn hiu Cc cp feeder v anten Hin nay 1 BTS gm c 3 anten t theo 3 hng khc nhau. Mi anten ti ra mt vng ph sng nh gi l cell. Nhiu cell to thnh 1 LA. Ty theo lai thit b BTS m cho php 1 cell c th c ti a bao nhiu TRX Chc nng ca BTS l to ra vng hat ng cho MS

2.2.2.2BSC-Base Station ControllerBSC thc hin cc chc nng chnh sau: Cp pht knh v tuyn Qun l ti nguyn v tuyn Duy tr cuc gi nh gim st cht lng, iu khin cng sut pht ca MS hay BTS, iu khin chuyn giao iu khin 1 hay nhiu BTS

2.2.2.3Topo mng BSSGm cc topo sau:

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TNG QUAN H THNG GSM Dng chui(Chain): chi ph r, d thc hin nhng nu lin kt b h s tc ng n nhiu BTS

Dng vng(Ring): an tan nh bo v nu lin kt h nhng kh hn cho vic m rng

Dng sao(star): y l cu hnh ph bin cho nhng h thng GSM u tin. Chi ph t v mi BTS u c lin kt ring vi BSC, 1 lin kt b h khng tc ng n BTS khc

Cc BTS c lin kt n BSC theo 1 trong nhng topo chun. Cc lin kt vt l c th l vi ba, cp quang hay ng.

2.2.3 NSS-Network Switching SubsystemNSS gm cc thnh phn sau: Mobile Switching Centre (MSC) Visitor Location Register (VLR) Home Location Register (HLR) Authentication Centre (AuC) Equipment Identity Register (EIR) Gateway MSC (GMSC) Nhng thnh phn ny c kt ni bng mang SS7

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2.2.3.1 MSC-Mobile Switching CentreMt MSC l 1 tng i thc hin chc nng: Chuyn mch, iu khin v ghi li cuc goi Giao din vi PSTN, ISDN, PSPDN Qun l tnh di ng Qun l 1 phn ti nguyn v tuyn nh handover gia cc BSC Thng tin tnh cc Mt MSC qun l nhiu BSC nn vng qun l ca MSC l tan b vng ph ca cc BTS thuc quyn qun l ca cc BSC

2.2.3.2VLR-Visitor Location RegisterVLR l 1 c s d liu phc v cho cc thu bao m hin thi ang nm trong vng phc v ca 1 MSC. Mi MSC trong mng s kt hp vi 1 VLR nhng 1 VLR c th phc v nhiu MSC. Nhng hin nay th mi VLR c tch hp trong 1 MSC. Mt MS di chuyn trong vng phc v ca 1 MSC c iu khin bi VLR kt hp vi MSC . Thng tin trn VLR cp nht t ng Khi di chuyn sang vng mi, MS thc hin cp nht v tr. Nu vng mi ny cn trong phm vi qun l ca MSC-VLR c th ch cn cp nht s LAI mi(v tr mi) ca MS trn VLR. Nu v tr mi thuc phm vi qun l ca 1 MSC-VLR khc th VLR mi phi ly thng tin ca MS t HLR v HLR cng s yu cu VLR c xa thng tin v MS. Sau VLR mi mi cp nht s LAI ca MS. Do VLR ch ct thng tin tm v s b mt khi MS di chuyn sang vng mi hay MS ri mng qu lu Thng tin ct trong VLR bao gm: IMSI MSISDN MSRN

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TNG QUAN H THNG GSM TMSI LAI Nhng thng s dch v cng thm Trng thi ca thu bao(tt, bt..)

2.2.3.3HLR-Home Location RegisterHLR l 1 c s d liu m nhim vic qun l cc thu bao di ng. Mt mng PLMN c th c 1 hay nhiu HLR ty thuc vo s lng thu bao di ng, dung lng ca thit b v s t chc ca mng Thng tin ct trong HLR gm: IMSI MSISDN a ch MSC-VLR Cc dch v cng thm MSRN Thng tin thu bao Nhng gii hn dch v Cng vi AuC, HLR kim tra tnh hp l ca thu bao Lu :VLR cho bit MS thuc LAI no nhng HLR ch cho bit MS thuc vng qun l ca MSC-VLR no

2.2.3.4AUC-Authentication CentreAuC c kt hp vi HLR, cha kha nhn thc ca cc thu bao ng k trong HLR Kha ny c dng to ra: D liu c dng nhn thc 1 MS c quyn truy nhp vo mng hay khng Mt kha c dng mt m thng tin trn ng v tuyn gia MS v mng Nhng th tc c dng cho nhn thc v m ha s c miu t y hn chng an tan trong GSM

2.2.3.5GMSC-Gateway Mobile Switching CentreGMSC l 1 thit b nh tuyn lu lng trong 1 mng di ng n ch n GMSC truy cp HLR ca mng tm xem thu bao di ng c gi thuc MSCVLR no Mt MSC ring bit c th ng vai tr nh 1 GMSC Nh iu hnh mng c th dng 1 hay nhiu GMSC GMSC nh tuyn cuc gi gia cc MSC hay gia MSC vi mng ngai

2.2.3.6EIR-Equipment Identity RegisterEIR l 1 c s d liu lu tr cc s IMEI. Trong c 3 danh sch: Danh sch trng l nhng s IMEI c php kt ni vi mng

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TNG QUAN H THNG GSMDanh sch xm l nhng s IMEI ca ME c quyn s dng dch v mng nhng di tm gim st ca mng Danh sch en l nhng s IMEI ca cc ME b nh cp hay l 1 ME khng c ng dng trong mng GSM. Nhng u cui ny s khng c php kt ni vo mng ME c th c phn lai thuc danh sch trng, en hay xm cho bit trng thi ca MS y l 1 thit b ty chn. N c th c dng bi nh iu hnh mng iu khin truy nhp n mng cho php, gim st hay ngn cm(i vi thit b b nh cp) kt ni mng.

2.3

Cc giao din trong mng GSM

2.3.1 Giao din Ay l quan n: giao din gia MSC v BSS ca n. Giao din ny c dng mang thng tin lin Qun l BSS X l cuc gi Qun l tnh di ng

2.3.2 Giao din Abisy l giao din gia BSC v BTS h tr nhng dch v cung cp cho thu bao. Giao din ny cng cho php iu khin thit b v tuyn v cp pht tn s v tuyn trong BTS.

2.3.3 Giao din By l giao din gia MSC v VLR. Dng trong cc trng hp sau: Bt c khi no MSC cn d liu lin quan n 1 MS ang nm trong vng phc v ca n, n s truy vn VLR

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TNG QUAN H THNG GSM Khi 1 MS thc hin 1 th tc cp nht v tr vi 1 MSC, MSC s nhc nh VLR ca n ct gi thng tin lin quan Khi 1 thu bao kch hat 1 dch v cng thm c bit no hay b sung 1 vi d liu v 1 dch v, MSC s yu cu (thng qua VLR) HLR ct gi cc thng tin b sung ny v HLR cp nht cho VLR nu c yu cu

2.3.4 Giao din Cy l giao din gia MSC v HLR. GMSC phi truy vn HLR ly thng tin nh tuyn cho 1 cuc gi hay 1 tin nhn n thu bao

2.3.5 Giao din Dy l giao din gia VLR v HLR. Giao din ny c dng trao i d liu lin quan n v tr thu bao v qun l thu bao. Dch v chnh ca 1 thu bao di ng l thit lp hay nhn cuc gi trong 1 mng. h tr dch v ny, cc thanh ghi v tr phi trao i d liu vi nhau Khi MS di chuyn sang MSC khc, VLR thng bo cho HLR bit v tr ca MS v cung cp cho n (khi thit lp cuc gi) s roaming ca MS . HLR gi cho VLR tt c thng tin h tr dch v ca MS . HLR sau yu cu VLR c hy b thng tin v tr ca MS Vic trao i thng tin c th xy ra khi: MS yu cu 1 dch v c th no MS mun thay i vi thng tin thu bao Mt thng tin ca thu bao c b sung bi cc phng tin qun tr

2.3.6

Giao din E

y l giao din gia cc MSC. Khi 1 MS di chuyn t 1 MSC ti 1 MSC khc trong 1 cuc gi. Mt th tc chuyn giao phi c thc hin dy tr cuc gi. V mc ch cc MSC phi trao i d liu khi to 1 knh MSC mi v gii phng knh MSC c Sau khi chuyn giao thnh cng cc MSC s trao i thng tin truyn bo hiu giao din A nu cn thit. Khi 1 tin nhn c truyn gia MS v trung tm dch v nhn tin(Short Message Service Centre-SC), giao din ny c dng truyn bn tin gia MSC phc v MS v MSC ni vi trung tm dch v nhn tin

2.3.7 Giao din Fy l giao din c dng gia MSC v EIR trao i d liu, EIR c th xc nh tnh trng MS thng qua s IMEI

2.3.8

Giao din G

y l giao din gia cc VLR. Khi 1 MS di chuyn t vng phc v ca VLR ny sang vng phc v ca VLR khc th tc cp nht v tr s xy ra. Th tc ny nhm ly li thng s IMSI v cc thng s nhn thc t VLR c

2.3.9 Giao din Umy l giao din gia MS v BSS

2.3.10 Giao din H

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TNG QUAN H THNG GSMy l giao din gia HLR v AuC. Khi HLR nhn 1 yu cu cung cp d liu cho nhn thc v mt m cho 1 MS, HLR khng gi d liu yu cu, HLR s yu cu d liu t AuC. Giao thc ny c dng truyn d liu trn giao din ny

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TNG QUAN H THNG GSM

Phn 3: GIAO DIN V TUYN3.1 Gii thiuGiao din v tuyn l giao din gia u cui di ng (MS) v trm thu pht gc (BTS) m n c truy nhp. 3.2 Cp pht ph tn trong GSM 3.2.1 Ph trong thng tin di ng Ph v tuyn l mt ti nguyn gii hn Cc di tn ang s dng trong thng tin di ng

Ton b ph v tuyn c chia thnh cc bng tn nh VHF, UHFbng tn UHF c s dng trong thng tin di ng. Cp pht tn s Cc yu t chn bng tn s dng: V tr Mc cng sut Loi iu ch Bng thng Cc t chc qui nh v cp pht tn s trn th gii: ITU (International Telecomunication Union) ESTI (European Telecommunications Standards Institute) RA (Radiocommunications Agency) ti Hoa k Chi ph chnh ban u cho cc nh khai thc mng l tm c licence s dng mt phn bng tn v tuyn. Phng php cp pht bng tn hot ng khc nhau trong cc

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TNG QUAN H THNG GSMnc, nhng c th c u gi hoc chn trc tip nh hot ng bi t chc chnh ph. 3.2.2 Ph GSM c bn Ph P-GSM (Primary GSM)

GSM s dng phn chia tn s song cng (FDD), mi knh ng ln v xung hot ng mt tn s khc nhau. Do , c 2 bng tn c cp cho GSM, cch nhau 20MHz. Bng tn u tin c cp trong GSM (P-GSM): Bng tn 890MHz n 915MHz cho ng ln (uplink) t MS n BTS Bng tn 935MHz n 960MHz cho ng xung (downlink) t BTS n MS Mi bng tn c chia thnh mt s sng mang, mi sng mang c bng thng 200KHz. Do c 125 sng mang cho mi bng tn ln, xung. Trong , mt knh c dng nh knh bo v, iu ny lm gim s knh cn 124 knh. Hai tn s n nh cho mi cp knh cch nhau 45MHz. Mi cp tn s c nhn dng bi mt s ARFCN (Absolute Radio Frequency Channel) Tnh ton tn s knh ng ln v xung: Cc tn s uplink: Ful (n) = 890 MHz + (0,2 MHz) n Cc tn s downlink: Fdl (n) = Ful (n) + 45 MHz n = ARFCN vi 1 n 124 3.2.3 Ph E-GSM (Extended-GSM)

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TNG QUAN H THNG GSM

E-GSM cp thm 10MHz ca bng thng ti u cui ca bng tn ng ln v xung. Cc bng tn nh sau: ng uplink: 880MHz n 915MHz ng downlink: 925MHz n 960MHz Kt qu: Thm 50 cp sng mang (cc knh 10MHz/200KHz) Gim khong cch bng thng gia bng tn ng ln v ng xung t 20MHz xung10MHz. Tng kch thc bng tn ng ln v xung t 25MHz ln 35MHz Cp dy sng mang tn s v tuyn mi t 975-1023. Sng mang tn s v tuyn 0 trong P-GSM chuyn t bng bo v thnh mt sng mang tn s v tuyn c gi tr. Cc knh tn s v tuyn ng ln v xung trong E-GSM c tnh nh sau: Cc tn s uplink: Ful (n) = 890 MHz + (0,2 MHz) n (0