LI GII THIU

S ra i ca in thoi di ng t bo vo nhng nm 1980 m ra mt vin cnh ht sc sng sa cng vi s pht trin nh v bo ca khoa hc k thut cng ngh thng tin nh u mt bc nhy vt trong thng tin lin lc. Thng tin di ng t lu tr thnh mt phng tin hu hin v thun tin cho ngi s dng trong sut hn hai thp k qua cc th h: in thoi di ng th 1 (analog) v th 2 (digital) vi rt nhiu loi h thng hot ng theo nhiu nguyn tc khc nhau c ng gp to ln vo s pht trin ca loi ngi. Cc th h tip theo ca thng tin di ng ang c pht trin mnh m. Vi s ra i ca cc th h th 3 (3G) loi ngi ngy cng tin ti gn vic bin c m thnh hin thc l tin hnh lin lc bt c u v bt k nc no. T nhiu nm tr li y thng tin di ng t bo loi GSM (mt h thng thng tin s) c trin khai trn phm vi rng vic nghin cu tm hiu v in thoi di ng do vy l mt vn cn thit v cp nht. H thng thng tin di ng t bo s GSM l mt h thng tiu chun quc t do ITU-T khuyn ngh y l h thng c xy dng trn c s ci tin cc tiu chun giao thc ca ISDN v l h thng c s ho ton b t thu bao tr i a vo sn xut khai thc k thut trc c hng trm khuyn ngh ra i gii quyt hng lot cc vn ln nh. Trong thi gian hc tp ti khoa in t vin thng trng i hc dn lp ng vi s tn tnh ch bo ca cc thy c trong khoa cng vi kin thc c trau ri nn em chn ti khai thc H Thng Thng Tin 3G tm hiu r hn v h thng thng tin di ng. Mi kin thc thu thp c trong thi gian hc tp ti khoa in t vin thng v trong qu trnh thc tp em trnh by tng hp trong bo co thc tp ny nhng v thi gian cn hn hp kin thc chuyn mn cn hn ch nn khng th chnh khi nhng thiu st em rt mong c s gp ca cc thy c v cc bn b trong khoa. Em xin chn thnh cm n thy H Quang Huy nhit tnh trc tip hng dn v cc thy c bn b trong khoa in t vin thng gip em hon thnh quyn Bo co thc tp tt nghip ny. H Ni thng 1 nm 2005.

PHN I TNG QUAN V MNG IN THOI DI NG GSM GII THIU CHUNG

H thng thng tin di ng l h thng truyn thng tin chuyn giao tin tc di dng ting ni (thoi ) s liu vn bn (fax).vi c im l ngi s dng dch v thng tin di ng c th lun mang theo thit b u cui bn mnh khi cn m bo lin lc thng sut khc vi thu bao c nh thu bao di ng c th gi nhn mi cuc gi bt c ni no trong vng ph sng ca mng di ng vi mi trng truyn dn gia thu bao v mng di ng l sng v tuyn. CHNG I - CC TH H THNG TIN NI CHUNG

1.1. Lch s pht trin ca thng tin di ng:

Qu trnh pht trin ca thng tin di ng c bt u bng pht minh th nghim v sng in t ca Hertz v in bo v tuyn ca Macorni vo cui th k 19 qua cc th nghim ca cc nh bc hc cho thy l thng tin v tuyn c th thc hin gia cc my thu v pht xa nhau v di ng vo thi k ny thng tin v tuyn ch yu s dng m Morse cho n nm 1928 h thng thng tin v tuyn truyn thanh mi c thit lp v c dng trong ngnh cnh st. n nm 1933 s cnh st Bayone, NewJersey mi thit lp c mt h thng thoi v tuyn di ng tng i hon chnh u tin trn th gii sau qun i cng dng thng tin di ng trin khai chin u c hiu qu. Cc dch v di ng trong i sng nh cnh st, cu thng, cu ho, hng khng hng hi..cng s dng thng tin di ng cc hot ng ca mnh c thun li. Hi cc thit b in thoi di ng rt cng knh nng hng chc kg y tp m v rt tn ngun do dng cc n in t tiu th ngun ln cng tc trong di tn thp do s dng bng tn VHF cc thit b ny lin lc c vi khong cch vi chc dm cht lng thng tin rt km l do c tnh truyn dn sng v tuyn dn n tn hiu thu c l mt t hp nhiu thnh phn ca tn hiu c pht i khc nhau c v bin , pha v tr tng vc t ca cc tn hiu ny lm cho ng bao tn hiu thu c b thng ging mnh v nhanh khi trm di ng tin hnh mc thu tn hiu thng b thay i ln v nhanh lm cho cht lng m thoi suy gim trng thy cho n nhng nm 1950- 1960 cc khi nim t ong cc k thut tri ph iu ch s v cc cng ngh v tuyn hin i khc c bit n nhng ch c s dng dng l cc sa i thch ng ca cc h thng iu vn. Cc h thng in thoi di ng u tin ny t tin li v dung lng thp so vi cng ngh hin nay. Cui cng cc h thng in thoi t ong iu tn song cng s dng k thut a truy nhp phn chia theo thi gian (FDMA: Frequency Division Multiple Access) xut hin vo nhng nm 1980 ngi ta nhn thy rng cc h thng t ong

tng t khng th p ng c nhu cu ngy cng tng vo th k sau nu khng loi b c cc hn ch c hu ca h thng ny nh: - Phn b tn s rt hn ch, dung lng thp. - Ting n kh chu v nhiu xy ra khi my di ng chuyn dch trong mi trng pha dinh a tia. - Khng p ng c cc dch v mi hp dn i vi khch hng. - Khng cho php gim ng k gi thnh ca thit b di ng v c s h tng. - Khng m bo tnh b mt ca cc cuc gi. - Khng tng thch gia cc h thng khc nhau. Gii php duy nht loi b hn ch trn l phi chuyn i sang s dng k thut thng tin s cho thng tin di ng cng vi cc k thut a truy nhp mi. H thng thng tin di ng s s dng k thut a truy nhp phn chia theo thi gian (TDMA: Time Division Multiple Access) u tin trn th gii c ra i Chu u v c tn gi l GSM (Group Special Mobile ). Ban u h thng ny c gi l (nhm c trch di ng) theo tn gi ca mt nhm c CEPT (Conference of European Postal and Telecommunication administrantions). Hi ngh cc c quan qun l vin thng v bu chnh Chu u c ra nghin cu tiu chun sau tin cho vic thng mi ho GSM c gi l H thng thng tin di ng ton cu (GSM : Gobal System for Mobile Communications) GSM c pht trin t nm 1982 khi cc nc Bc u gi ngh ti CFPT (Conference of European Postal And Telecommunications). quy nh mt dch v vin thng chung Chu u bng tn 900 MHz vo nhng nm 1982- 1985 ngi ta nu ln vic xy dng mt h thng s hay tng t bng rng hay hp. Nm 1985 h thng s c quyt nh thng 5 -1986 gii php TDMA bng hp c la chn. Vi cc gii php trn 13 nc k vo bin bn ghi nh MOU ( Memorandum Of Understanding) thc hin cc ghi nh nh vy m ra mt th trng di ng c tim nng ln . Tt c cc hng khai thc k MOU ha s c mt h thng GSM vn hnh vo ngy 1- 7 -1991 v c mt s nc cng b kt qu ph sng cc vng rng ln ngay t u trong khi th mt s nc bt u phc v bn trong v bn ngoi th . vit nam h thng thng tin di ng s GSM c a vo hot ng t nm 1993 hin nay ang c cng ty VMS v GPC khai thc rt hiu qu. M h thng AMPS (American Mobile Phone System) tng t s dng phng thc FDMA c trin khai vo nhng nm 1980 nhng cc th trng di

ng chnh nh NewYork, Los angeles, Chicago. Do ngi s dng ln pht sinh cc vn v dung lng lin hip cng nhip vin thng TIA (Telecommunications Industry Association) c chin lc nng cao h thng ny thnh h thng s chuyn ti h thng TDMA (Time Division Multiple Access) v k hiu l IS 95. Cui nhng nm 1980 vic kho st khch hng cho thy cht lng ca AMPS (American Mobile Phone System) tt hn h thng IS 95 dn ti vic cc hng ca M lnh nht vi h thng TDMA. Duy nht ch cn mt hng l AT&T vn s dng h thng TDMA nhng hng ny pht trin ra mt phin bn mi gi l IS 136 hay AMPS s: D AMPS ( Digital American Mobile Phone System) Khng ging nh IS 95 GSM t c cc thnh cng ny l ch cc nh pht trin GSM dm thc hin mt hy sinh tm kim cc th trng Chu u v Chu h khng tng thch giao din v tuyn gia GSM v AMPS nh vy cc hng Ericsson v Nokia tr thnh cc hng dn u c s h tng v tuyn v b li sau cc hng Motorola v Lucent. Vi tnh trng trn to c hi cho cc nh nghin cu M v h tm ra h thng thng tin di ng s mi l cng ngh a truy nhp phn chia theo m CDMA (Code Division Multiple Access) cng ngh ny s dng k thut tri ph v c ng dng ch yu trong qun s nm 1985 cng ty thng tin Qualcom (Qualcom Communications) c thnh lp v pht trin cng ngh CDMA cho thng tin di ng v nhn c nhiu bng pht minh trong lnh vc ny. Lc ny cng ngh ny c n nhn mt cch d dt do quan nim truyn thng v v tuyn l mi cuc thoi i hi mt knh v tuyn ring n nay cng ngh ny tr thnh cng ngh thng tr Bc M. Qualcom a ra phin bn CDMA u tin c gi l IS 95 Cc mng CDMA thng mi c a vo khai thc ti Hn Quc, Hng kng Achentina, Braxin, Chile, Trung Quc, c, Ixraen, Peru, ....Thi lan mi c th nghim v mi y l Nht Bn. Vit Nam tng cng ty bu chnh vin thng cng c k hoch th nghim CDMA, nm 1993 Nht Bn NTT a ra tiu chun thng tin di ng s u tin ca nc ny l JPD (Japanese Personal Digital Cellular System) gi l h thng t ong s Nht Bn. tng dung lng cho cc h thng thng tin di ng tn s ca cc h thng ny ang c chuyn vng t (800 900) MHz vo vng (1,8- 1,9)MHz. Mt s nc a vo s dng c hai tn s song song vi s pht trin ca cc h thng thng tin di ng t ong ni trn cc h thng thng tin di ng hn ch cho mng ni ht s dng my cm tay khng dy s (digital cordless phone) cng c nghin cu pht trin hai h thng in hnh cho hai loi thng tin ny l DECT(Digital Enhanced Cordless Telecommunications) c gi l Vin thng

khng dy s tng cng v h thng PHS (Personal Handy Phone) gi l h thng my in thoi cm tay c nhn . Cng c a vo thng mi ho. Ngoi cc h thng thng tin mt t cc h thng thng tin di ng v tinh Global star v Iridium cng c a vo thng mi ho trong nm 1980. Nh vy s kt hp gia cc h thng thng tin di ng ni trn s to ra mt h thng thng tin c nhn (PCS : Personal Communications System) cho php mi c nhn c th thng tin mi thi im v bt c ni no h cn.

1.2. Mt s h thng thng tin di ng: 1.2.1. Thng tin di ng th h I: Cc h thng thng tin di ng t ong th h mt bao gm : AMPS : dch v in thoi di ng tin tin. NAMPS : AMPS bng hp. TACS : H thng truy nhp ton b. ETACS : TACS m rng . NMT450 : H thng in thoi di ng bc u s dng bng tn 450 MHz. NMT900 : H thng in thoai di ng bc u s dng bng tn 900MHz. NMT : H thng do NNT pht trin.

H thng thng tin di ng th h ny t tin li, dung lng thp. Cc h thng thng tin di ng th h I s dng k tht a truy nhp phn chia theo tn s xut hin vo nhng nm 1980. Nhng do nhu cu ca ngi s dng tng th h thng ny khng p ng c nhu cu ca ngi s dng vi mt s l do sau: * Do phn b tn s hn ch, dung lng mng thp . * Hin tng ting n gy kh chu v nhiu xy ra khi my di ng trong mi trng pha inh a tia. * Khng p ng c cc dch v mi hp dn khch hng. * Chi ph cho cc dch v cao v thit b lp t tn km.

* Khng m bo tnh an ton thng tin. * Tnh tng thch gia cc h thng rt km. loi b c nhng hn ch trn cn phi chuyn sang s dng k thut thng tin s cho di ng. 1.2.2. H thng thng tin di ng th h II: H thng thng tin di ng t ong th h th II bao gm :
-

IS- 54B TDMA. IS 136 TDMA. IS 95 CDMA. GSM H thng thng tin di ng ton cu. PCM Mng thng tin c nhn. CT- 2 in thoi khng dy. DECT Vin thng khng dy s tin tin.

- PDC H thng t ong c nhn. - Thng tin di ng th h II s dng 2 cng ngh a truy nhp phn chia theo thi gian v phn chia theo m (TDMA v CDMA ). Hin nay cc h thng thng tin di ng ang giai on chuyn t th h 2 sang th h 3. * Mt s u th ca th h II:
1.

Cc dch v mng mi v ci thin cc dch v ca ngi s dng s hiu chuyn mch knh tc cao (HSCSD), dch v v tuyn gi a nng (GPKS) v s liu 14,4 Kb/s. Cc cng vic lin quan n cc dch v in thoi nh Codec ting ton tc ci tin (EFC), Codec a tc thch ng v khai thc t do u cui cc Codec ting. Cc dch v b xung nh: Chuyn hng cuc gi, hin th tn ch gi, chuyn giao cuc, v cc dch v cm gi mi.

2.

3.

4.

Ci thin lin quan n dch v bn tin ngn (SMS): Mc ni cc SMS, m rng bng ch ci, m rng tng tc gia cc SMS. Cc cng vic lin quan n cng vic tnh cc: Cc dch v tr tin trc, tnh cc nng v h tr cho u tin vng gia nh.

5.

6. Tng cng cng ngh SIM.

7. 8.

Dch v mng thng minh nh : CAMEL. Cc ci thin chung nh: Chuyn mch CTSM-AMPS, cc dch v nh v, tng tc vi cc h thng thng tin di ng v tinh v h tr nh tuyn ti u.

Thng tin di ng s th h II xy dng theo tiu chun GSM, IS95. Cc yu cu v dch v mi ca cc h thng thng tin di ng nht l cc dch v truyn s liu i hi cc nh khai thc phi a ra c cc h thng thng tin di ng mi. Trong bi cnh ITU a ra n tiu chun ho h thng thng tin di ng th h 3 vi tn gi IMT- 2000. 1.2.3. H thng thng tin di ng th h III: H thng thng tin di ng th h III l th h thng tin cho cc dch v di ng truyn thng c nhn a phng tin. Hp th in thoi s c thay th bng bu thip in t c lng ghp vi hnh nh v cc cuc thoi thng thng trc dy s c b xung cc hnh nh tr thnh thoi c hnh. * u im ca h thng thng tin di ng th h III: 1 . Tc truy nhp cao m bo cc dch v bng rng nh truy cp Internet nhanh hoc cc dch v a phng tin. 2 . Linh hot m bo cc dch v mi nh nh s v c nhn ton cu v in thoi v tinh. Cc tnh nng ny s cho php s dng ng k cc dch v ca cc h thng thng tin di ng. 3. D dng tng thch vi cc h thng thng tin di ng hin c m bo s pht trin lin tc ca thng tin di ng. phn bit gia th h III vi cc th h khc th th h III c gi l th h bng rng. 1.3. Mt s loi hnh dch v trong thng tin di ng:

in thoi di ng ln u tin xut hin ti M n c nhng u im hn hn so vi in thai c nh ngi dng c th trao i thng tin vi nhau bt c ni no trong vng ph sng. Ngy nay in thoi di ng c dng ph bin v rng ri trn th gii.Sau y l mt s cc loi hnh in thoi:

1.3.1. in thoi ko di: in thoi khng dy thay vic i dy in thoi ti nh thu bao i vi in thoi c nh bng mt h thng v tuyn h thng ny cn c mt thit b u cui cm vo cm ca ng dy thu bao (gi l my m) v mt my in thoi khng dy (gi l my con). *C hai loi my khng dy: + Loi th nht ch yu dng xch tay m khng cn thit phi i dy trong phng. + Loi th hai ch yu dng xch tay d dng cm my in thoi (my con) i li trong mt vng gii hn. *H thng in thai khng dy ny c hai phng thc thm nhp: + Thm nhp n knh : Bng mt knh v tuyn c nh n nh cho tng my in thoi khng dy v thit b u cui km theo. + Thm nhp a knh : p ng bi cnh pht trin ca k thut m trc ht l lnh vc in thoi t h thng thm nhp a knh tr thnh phng hng chnh h thng ny s dng a knh v tuyn c dng cho ton b h thng v bt c my in thoi khng dy no trong h thng thm nhp ti mi thi im. 1.3.2. Thng tin di ng ng st: Thng tin di ng ng st bao gm c in thoi v tuyn s dng cho kinh doanh v in toi cng cng ho xa v m bo an ton cng cng v tng hiu qu dch v giao thng ng st in thoi v tuyn kinh doanh c s dng ci thin cc dch v du lch.

*Thng tin di ng ng st s dng hai loi h thng tiu biu: + V tuyn ho xa: c s dng cho vic iu hnh v giao tip gia cc thnh vin ca ho xa on. +V tuyn ho xa on: c s dng giao tip gia ngi li tu vi nhn vin kim sot v thng tin khn cp gia ho xa on v nhn vin iu hnh nh ga v thng tin bo hiu hay giao tip gia cc nhn vin lin quan n iu vn tu. 1.3.3. My nhn tin :

H thng my nhn tin c cc ph d hn bt c loi hnh dch v di ng no v ti trm gc th ch cn c my pht ngi ta thc hin bin i dng tin nhanh thnh chui s liu iu ch di tn my pht. Trm gc ti trm di ng th ch cn mt my thu thc hin thu tn hiu cao tn gii iu ch di tn to thnh chui s liu v a vo hin th trn mn hnh tinh th lng nhng n c nhc im l khng thc hin chao i trc tip thng tin vi nhau c v lng tin nhn th hn ch. 1.3.4. Thng tin di ng hng hi: Thng tin an ton v khn cp cho vic cu h trn bin v thng tin o hng l khng th thiu c i vi cc tu thuyn v l loi thng tin di ng hng hi c nht cc tn s 500KHz cho m Morse, 2182KHz v 156,800KHz cho thoi c n nh chung cho lin lc khn cp trn ton th gii v tnh mng con ngi nn cc tn s ny c quc t bo v ngoi ra cn c h thng bo cnh o hng v thng bo ng v ring bit s dng bo hiu Morse bng tn HF (4- 22) Mhz cho cc tu thuyn ngoi khi cc h thng ny hot ng trn ton cu di s qun l quc t phc v cho vic tm kim v cu h trn bin. Thng 3 1973 ngi ta a vo s dng mt h thng u ni chuyn mch t ng dng bng tn 250Mhz i vi tu thuyn ngoi khi hay thay i v tr h thng ny cho php u ni chuyn mch t ng nh i vi in thoi c nh bng phng php duy tr mt File thng tin nh v cho mi tu pha chuyn mch. Thng 111988 mt h thng mi vi iu khin chung ra i trung tm chuyn mch v trung tm iu khin ca h thng mi ny c kt hp vi h thng in thoi di ng bng tn 800Mhz gim gi thnh h thng thng nht vic vn hnh v khai thc. 1.3.5. Thng tin di ng hng khng : Thng tin di ng hng khng c s dng lin lc v iu khin cc my bay cung cp cc thng tin thi tit cho chng m bo an ton v trng t cho hot ng ca cc chuyn bay ni a v quc t thng tin gia cc my bay va trung tm iu khin c thc hin qua mt trm gc t sn bay hoc c lp trn chuyn bay. Thng tin di ng hng khng s dng cc bng tn HF(2 22)Mhz v VHF (118 138) MHz trong bng tn VHF thng tin tm nhn thng t ti 400 Km cho nn cc nh doanh nghip, quc phng khai thc trit bng tn ny s dng sao cho thng tin di ng c s dng mt cch hiu qu nht. Cc cng ty my bay s dng bng tn ny lin lc, hng dn vn chuyn hng ho, hng dn nhanh cho khc hng. N c s dng gia mt trm gc v cc trm di ng hoc gia cc trm di ng ci thin hiu qu cc dich v. Cc tn s thu trong bng tn 400Mhz c n nh cho mi thit b mng thng tin s dng mt h thng n cng tng t FM vi khong cch knh l 12,5Khz.

CHNG II. MNG THNG TIN DI NG GSM Vi mc ch to ra mng thng tin di ng ton cu th t nm 1983 chu u thnh lp ra mt nhm nghin cu tiu chun v thng tin di ng cc tiu chun th c a ra cc khuyn ngh t nm 1987 1990 n nm 1992 mng GSM u tin trn th gii c a vo hot ng hin nay ang tn ti trn a s cc nc. Cc c tnh k thut. 2.1 c im ca mng GSM: Mng GSM c cc c im sau: + p ng c nhiu dch v tin ch cho cc thu bao c v thoi v truyn s liu (ghp vi my tnh) . + M ho tn hiu thoi vi tc bt thp c th ghp xen nhiu knh thoi n vo mt lung bt chun. + iu khin ng trong vic cp pht knh lin lc do lm tng kh nng s dng hiu qu tn s. + p dng k thut m ho knh v m ho ngun lm tng kh nng sa sai. + C kh nng tng thch vi cc dch v mng sn c nh mng thoi cng cng mng chuyn gi (s liu ) cng cng mng s a dch v cc mng di ng mt t khc nh cc giao din thit k. + lnh hot (tin ch cho ngi s dng )khi s dng cc my u cui. c tnh tn s: GSM s dng hai di tn + Bng ln (uflink ) : lm vic di tn ( 890 915) Mhz. V c th m rng dn( 882 915 )Mhz. + Bng xung (downlink) : lm vic di tn t ( 935 915 )Mhz. V c th m rng n ( 927 960 )Mhz. Mi bng ln hoc xung c chia thnh 124 knh sng mang. Mi sng mang c rng bng tn l 200Khz Mi mt cp (ln xung )cch nhau 45Khz Bng tn ln dng cho MS pht v BTS pht Bng tn xung dng cho MS thu v BTS thu

Tn s cng cao th hiu sut my pht cng thp dn n nng lng tiu tn cng nhiu. * Ngoi bng tn ny ngoi ra cn c bng tn 1800Mhz n cng c chia thnh hai bng: + Bng ln (1710 - 1785)Mhz + Bng xung ( 1805 1880)Mhz c tnh cu chc t bo: GSM l mng di ng t ong dng hai loi BTS (Base Transceiver Station) trm thu pht gc. BTS ng hng (dng angten ng hng) to ra mt t bo hnh trn. BTS nh hng (dng angten nh hng) to ra cc d qut gim cc vng chng ln v cc vng trng khi ph sng ngi ta to ra cc lc gic u . Cc t ong c gi l cc lc gic u c xp kn vo nhau. Cc dch v trong GSM * Dch v thoi: + Chuyn hng cuc gi v. + Chuyn hng cuc gi khi thu bao di ng b bn.

+ Chuyn hng cuc gi khi ch lu. + Chuyn hng cuc gi khi i phng ri mng. + Chuyn hng cuc gi khi tc nghn ng v tuyn. + Cm tt c cc cuc gi ra. + Cm tt c cc cuc gi quc t. + Cm tt c cc cuc gi n. + Cm tt c cc cuc gi n khu vc quy nh. + Gi cuc gi. + Chuyn giao cuc gi. + Hon thnh cuc gi n thu bao bn. + in thoi hi ngh. + Thng bo cc ph ... *Dch v truyn s liu : +Truyn dn s liu theo phng thc truyn s liu mnh gi. +Truyn bn tin ngn. 2.2. Cu trc h thng v a l ca mng GSM: 2.2.1. Cu trc h thng: Mt h thng di ng bao gm nhiu phn t vt l, chung c th l cc b phn ring r hay t cng vi cc phn t logic khc. Tuy nhin cc phn t ny phi tng tc vi nhau kt hp hot ng. tng tc, cc bn tin phi c pht i trn cc giao din gia hai phn t. Nu hai b phn chc nng tch bit v nu giao din c chun ho th cc nh cung cp dch v c th mua sn phm t cc nh sn xut khc nhau. Tuy nhin vn cha th m bo hot ng tt v tiu chun lin kt ny c th khng bao hm c tt c cc kha cnh khai thc.

Cc phn t chnh ca m hnh tham kho :

ISDN PSPDN CSPDN PSTN PLMN

SS

AUC VLR HLR MSC OMS BSC BTS MS EIR

MSCG BSS

Tn tt ca cc khi trn hnh v: AUC: Authentication center (trung tm nhn thc) VLR: Visiting Location Register (thanh ghi nh v tm tr ) MSC: Mobile Serviser Switching Center ( trung tm chuyn mch cc dch v di ng) HLR :Home Location Register(thanh ghi nh vi thng tr) OMC: Operation and Maintenance Center (trung tm khai thc v bo dng) BTS:Base Transceiver Station (trm thu pht gc) MS: Mobile Station(trm (my) di ng) BSC:Base Transceiver Controllek (b iu khin trm gc) MSCG: Gateway (cng MSC ) MSC: Mobile Servicer Swiching Center (trung tm chuyn mch cc dch v di ng)

SS: Swiching Subsystem (h thng con chuyn mch) BS: Base station (trm gc) EIR: Equipment Identity Register(thanh ghi s nhn din phn cng trm di ng) * Cu hnh h thng GSM c chia thnh 3 h thng con: - H thng chuyn mch SS bao gm cc chc nng chuyn mch chnh ca mng GSM. Chuyn mch cc d liu cn thit cho s liu ring ca thu bao v qun l di ng, thu bao qun l trao i thng tin gia nhng ngi s dng mng GSM vi nhng ngi s dng mng vin thng khc. - H thng trm gc BS: Thc hin gim st theo ng ghp ni v tuyn thc hin u ni gia cc MS vi tng i c th chuyn mch ni b hay chuyn mch gia cc thu bao khc. * Cc chc nng chnh ca BS: + iu khin thay i tn s v tuyn tn s ca cc ng ghp ni cng vi s thay i cng sut. + iu khin thu pht v tuyn. + M ho thoi v m ho knh phi hp tc truyn i. + Qun l chuyn giao . + Bo mt knh v tuyn. 2.2.2 . Trung tm khai thc v bo dng mng : H thng khai thc OS thc hin khai thc v bo dng tp trung cho mng thng tin di ng. Khai thc l cc hot ng cho php nh khai thc mng theo di hnh vi ca mng nh: Ti ca h thng, mc chn, s lng chuyn giao (handover) gia hai , nh vy nh khai thc c th gim st c ton b cht lng ca dch v m h cung cp cho khch hng v kp s l cc s c. Khai thc cng bao gm vic thay i cu hnh gim nhng vn xut hin thi im hin thi, chun b tng lu lng trong tng lai, tng vng ph sng. Vic thay i mng c th thc hin mm qua bo hiu (chng hn thay i thng s chuyn giao thay i bin gii tng i gia hai ) hoc thc hin cng i hi s can thip ti hin trng ( chng hn b xung thm dung lng truyn dn hay lp t mt trm mi ). h thng vin thng hin i khai thc c thc hin bng my tnh v c tp trung mt trm. Bo dng c nhim v pht hin, nh v v sa cha cc s c hng hc n c mt s quan h vi khai thc. Cc thit b mng vin thng hin i c kh nng

t pht hin mt s s c thng qua t kim tra. Trong nhiu trng hp ngi ta d phng cho thit b thit b s c c th thay th bng thit b d phng s thay th ny c th thc hin t ng. Ngoi ra vic gim nh s c c th thc hin bi ngi khai thc bng iu khin t xa. Bo dng cng bao gm c cc hot ng ti hin trng nhm thay th thit b b s c. H thng khai thc v bo dng c th c xy dng trn nguyn l TMN mng qun ly mng vin thng. Khi ny mt mt h thng khai thc v bo dng c kt ni n cc phn t mng vin thng ( cc MSC, BSC, HLR v cc phn t mng khc tr BTS v truy nhp n BTS ) mt khc h thng ng vai tr giao tip ngi v my. H thng ny thng c gi l OMC trung tm khai thc v bo dng. 2.2.3. Thit b h tr AUX: * Qun l thu bao v trung tm nhn thc : Qun l thu bao gm cc hot ng qun l ng k thu bao. Nhim v u tin l nhp v xo thu bao khi mng. ng k thu thu bao cng c th phc tp, bao gm nhiu dch v v cc tnh nng b xung. Nh khai thc phi truy nhp c tt c cc thng s ni trn. Mt nhim v quan trng khc ca khai thc l tnh cc cc cuc gi. Cc ph phi c tnh v gi n thu bao. Qun l thu bao mng thng tin di ng ch lin quan n HLR v mt s thit b OS ring chng hn mng ni HLR vi cc thit b giao tip ngi my cc trung tm giao dch vi thu bao. Vic qun l thu bao c thc hin thng qua mt kho nhn dng b mt duy nht cho tng thu bao. AUC qun l cc thng tin nhn thc v m lin quan n tng c nhn thu bao da trn kho b mt ny AUC c th c t trong HLR hay MSC hay c lp vi c hai. Kho ny cng c lu gi vnh cu v b mt trong b nh ca MS. GSM b nh ny c dng SIM- CARD c th rt ra v cm li c. 2.2.4 Qun l thit b di ng. EIR : Qun l thit b di ng c thc hin bi b ng k nhn dng thit b EIR. EIR lu gi tt c cc d liu lin quan n trm di ng MS. EIR c ni n MSC qua ng bo hiu kim tra s c php ca thit b. Mt thit b khng php s b cm. 2.2.5. Trm di ng MS : MS l thit b duy nht m ngi s dng c th thng xuyn nhn thy ca h thng. MS c th l thit b t trong t hay thit b xch tay. Loi thit b nh gn cm tay s l thit b ph bin nht. Ngoi vic cha cc chc nng v tuyn chung v s l cho giao din v tuyn MS cn phi cung cp cc giao din vi ngi s dng (nh micro, loa, mn hin th, bn phm qun l cuc gi ) hoc giao din vi mt s thit b khc ( nh giao din vi my tnh c nhn ,fax) Hin nay ngi ta ang c gng sn xut cc thit b u cui gn nh u ni vi trm di ng.

Vic la chn cc thit b u cui hin m cho cc nh sn xut. Chc nng chnh ca cc thit b u cui gm: Thit b u cui TE thc hin cc chc nng khng lin quan ti mng di ng, FAX, my tnh. Kt cui trm di ng MT thc hin cc chc nng lin quan n truyn giao din v tuyn. B thch ng u cui (TAF) lm vic nh mt ca ni thng thit b u cui vi kt cui di ng tun theo tiu chun ISDN u ni u cui cn thit b u cui li c giao din u cui modem. 2.2.6. Trm thu pht gc BTS: Mt BTS bao gm cc thit b pht thu, anten v x l tn hiu c th cho giao din v tuyn. C th coi BTS l TRAU. TRAU l thit b m qu trnh m ho v gii m ting c th ring cho h thng di ng c tin hnh, y cng thc hin thch ng tc trong trng hp truyn s liu. TRAU l mt b phn ca BTS nhng cng c th t n cch xa BTS v thm tr trong nhiu trng hp n t gia BSC v MSC. 2.2.7. B iu khin trm gc BSC : BSC c nhim v qun l tt c giao din v tuyn thng qua cc lnh iu khin t xa ca BTS v MS. Cc lnh ny ch yu l cc lnh n nh, gii phng knh v tuyn v qun l chuyn giao ( handover). Mt pha BSC c ni vi BTS cn pha kia ni vi MSC. Trong thc t BSC l mt tng i nh c kh nng tnh ton ng k vai tr ch yu ca n l qun l cc knh giao din v tuyn v chuyn giao. Mt BSC trung bnh c th qun l ti vi chc BTS ph thuc vo lu lng ca cc BTS ny. BTS cng c th kt hp chung vi BSC vo mt trm gc. 2.2.8. Trung tm chuyn mch cc dch v di ng MSC: h thng thng tin di ng chc nng chuyn mch chnh thc c thc hin bi MSC, nhim v chnh ca MSC l iu phi vic thit lp cuc gi n cc ngi s dng mng thng tin di ng. Mt mt MSC giao din vi BSAC, mt khc n giao din vi mng ngoi. MSC lm nhim v giao din vi mng ngoi c gi l MSC cng (GMSC: Gate MSC ). Vic giao din vi mng ngoi m bo thng tin cho cc ngi s dng mng thng tin di ng i hi cng thch ng IWF (IWF: Inter Wking Function- cc chc nng tng tc ). Mng thng tin di ng cng cn giao din vi mng ngoi s dng cc kh nng truyn ti ca mng ny cho vic truyn ti s liu ca ngi s dng hoc bo hiu gia cc phn t ca mng. Chng hn mng thng tin di ng c th s dng mng bo hiu knh chung s 7 (C7), mng ny m bo hot ng tng tc gia cc phn t trong mt hay nhiu mng thng tin di ng. MSC thng l mt tng i ln iu khin v qun l mt s cc

b iu khin trm gc (BSC). Mt tng i MSC thch hp cho mt vng th v ngoi c dn c vo khong mt triu ngi(vi mt thu bao trung bnh ). kt ni MSC vi mt s mng khc cn phi thch ng cc c im truyn dn ca mng thng tin di ng vi cc mng ny. Cc thch ng ny c gi l cc chc nng tng tc (IWF: Inter Working Funtion). IWF bao gm mt thit b thch ng giao thc truyn dn. N cho php kt ni vi cc mng: PCDN(Packet Switched Public Data Network- mng s liu cng cng chuyn mch gi) hay CSPDN (Circui Switched Public Data Network mng s liu cng cng chuyn mch knh), n cng tn ti khi cc mng khc ch n thun l PSTN (Public Switched Telephone Network- mng s lin kt a dch v). IWF c th c thc hin trong cng chc nng MSC hay c th thit b ring. trng hp hai giao tip gia MSC v IWF c m. 2.2.9.Cng MSC GMSC : Mng thng tin di ng c th cha nhiu MSC, VLR, HLR thit lp mt cuc gi t mng ngoi n ngi s dng thng tin di ng, trc ht cuc gi phi c nh tuyn n mt tng i cng c gi l GMSC m khng cn bit n hin thi thu bao ang u. Cc tng i cng c nhim v ly thng tin v v tr ca thu bao v nh tuyn cuc gi n tng i ang qun l thu bao thi im hin ti (MSC tm tr ). vy trc ht cc tng i cng phi da trn s in thoi danh b ca thu bao tm ng HLR cn thit v hi HLR ny. Tng i cng c mt giao tip vi cc mng ngoi thng qua giao tip ny lm nhim v cng kt ni cc mng ngoi vi mng thng tin di ng. Ngoi ra tng i cng ny cng c giao din bo hiu s 7 c th tng tc vi cc phn t khc ca mng thng tin di ng. V phng din kinh t khng phi bao gi tng i cng ng ring m n thng c kt hp vi MSC. 2.2.10. B ghi nh v thng tr HLR : * C kh nng qun l hng trm ngn thu bao do n l c s d liu quan trng trong GSM lu tr cc thng tin c nh v tm thi ca cc thu bao m khng ph thuc vo v tr hin ti cc s liu l: +S liu nhn dng thu bao. +Lu s nhn dng chuyn giao . +S cc dch v c quyn s dng ca thu bao . +S liu nhn dng tm thi. +Trng thi thu bao ng k. 2.2.11.B ghi nh v tm tr VLR:

B ghi nh v tm tr thng c kt hp trong phn cng ca MSC v l c s d liu th 2 ca mng MS. VLR c kt ni mt chiu hay nhiu chiu vi MSC v lu gi tm thi s liu thu bao (ch cc thu bao thuc quyn qun l ca MSC ) lu gi v v tr cc thu bao ni trn khi mt MS di chuyn vo vng qun l ca MSC th cc thng tin nh v thu bao s c cp nht vo VLR gm c : + Nhn dng vng nh v. + Trng thi ri hay bn ca thu bao. + S nhn dng tm thi thu bao. + S chuyn giao. *Thanh ghi nhn dng thit b EIR : Thanh ghi ny bo v mng di ng khi s truy nhp bt hp php bng con s nhn dng thu bao. *AUC trung tm nhn thc c chc nng cung cp cho HLR cc thng s nhn thc v cc kho mt m dng cho tng thu bao. B kho m gm c: +Mt khu. +S kho mt. + S ngu nhin. Khi ng k thu bao kho nhn thc s my dnh ring cho thu bao ny s c lu tr trong qu trnh ho mng khi thit lp cuc gi khi chuyn mng phi nhn thc xem thu bao c phi ca mnh hay khng. 2.3. Cu hnh a l ca mng GSM:

Mng thng tin di ng Vng phc v MSC/ VLR Vng ng v Cell()

GMS C

 gip cho vic nh tuyn cc cuc gi gia cc thu bao trong mng gia cc mng vi nhau th mng GSM phn cp a l. Vng phc v ca cc mng GSM c th l 1 hay nhiu quc gia, l vng a l c ph sng bi cc mng di ng tun theo tiu chun GSM. + Vng phc v mng GSM l vng ph sng mt mng di ng, mt t, tiu chun GSM thng l lnh th quc gia hoc mt phn. Cc mng ny c lin kt vi nhau qua cc ca cng. + Vng phc v MSC/ VLR: l vng phc v ca mt MC thc hin vic u ni qun l tt c cc thu bao hin thi c mt trong vng. Vng phc v c th trng hoc khng trng vi vng tnh cc. + Vng nh v : Vng phc v MSC c chia thnh nhiu vng phc v l mt vng MS c th di chuyn t do m khng cn cp nht v tr vi cc MS qun l n khi c tn hiu tm gi mng s pht tn hiu trong mt vng nh v mt vng nh v c th c qun l mt hoc mt vi BSC. Mi vng nh v c th chia ra mt hoc vi , mi c ph sng bi cc my thu, pht trm gc c th t mt BTS hoc mt phn BTS. t bo (cell) Vng nh v c chia thnh mt s nh mi (cell) c ph sng bi mt trm thu pht gc BTS t ti n c nhim v nh tuyn cho mt cuc gi t MS n BTS trong mt c thc hin bi lin lc trc tip gia BTS ca v MS. 2.4. V tuyn trong mng di ng GSM: Mng GSM lm vic vi hai di tn cng tc (900)MHz v 1800Mhz. y l di tn s cng tc cao. + c im kch thc linh kin nh, h thng anten b. + Cch truyn sng : Truyn thng ( do nh hng nhiu n nhiu mi trng ) sng truyn thng ph thuc vo vt che chn. Ph thuc di tn ln v thc hin iu ch tn hiu th cht lng tn hiu tt hn. - Kh nng nh hng anten tt dn n vic chia s d dng.

c tnh truyn sng trong thng tin v tuyn di ng l tn hiu thu c my thu b thay i so vi tn hiu c pht i c v tn s bin v tr cc thay i ny lm cho cht lng thng tin km i rt nhiu. Nhiu lc tn hiu my thu b mt hon ton n mang tnh ngu nhin v ph thuc vo hng lot cc yu t khc nhau nh a hnh khong cch lin lc, di tn, kh quyn, tc truyn tin. Tc di chuyn ca trm di ng cng sut pht ... Tuy nhin v c bn ca nh hng truyn sng c chia mt cch vn tt nh sau: + Hiu ng dopple. + Tn hao ng truyn. + Pha inh a ng. + Tri tr. * Truyn sng trong thng tin di ng trong khng gian t do: Trng hp ch c hai tia sng thng khng c phn x, khc x ch c tn hao do cng xa ngun bc x th vng bc x cng ln. o tn hao : Tn hao = R : c ly bc x. : Bc sng bc x.

*Truyn sng trong vng hai tia: - C hai ng i khc nhau do s sai pha ti im thu x tnh c tng cng in trng (c th b trit tiu hoc tng ln). - Ngoi tia nhn thng cn c tia phn x t mt t (trng hp ph sng dc theo quc l, cc vng nng thn) hai tia sng i trn cc qung ng khc nhau nn c s sai pha khc nhau ti cc im thu. Nu sai pha bng nhau hoc l n = 360 th chng ng pha dn n bin tng cng s ln. - Nu gc sai pha l 180 th chng ngc pha nhau dn n bin tng cng bng khng. - Cc trng hp cn li bin s thng ging. * Truyn sng trong vng nhiu tia:

* y l trng hp ph sng cho cc vng th nhiu vt che chn ngoi tia truyn thng cn c v s cc tia phn x do cc vt che chn rt nhiu trng hp khng c tia nhn thy. in trng tng cng l tp hp nhiu tia sng c sai pha khc nhau to ra hin tng pha inh nhanh khi cc tia ln cng in trng tng cng s tim cn vi mt gi tr khng i . Pha inh do cng in trng trong thng tin di ng (E)

Cng in trng trong khng gian t do :E E =

Gp: tng ch ca anten pht ( khuch i ca anten ). Pp : cng sut my pht trm gc. d : c ly

Nh vy E khng ph thuc vo cao anten thu pht n ph thuc vo cng sut my pht v suy hao ca h thng (m bn thn my pht v s di chuyn) khng ph thuc vo nhy my thu .

Cng in trng trong vng truyn sng hai tia. E=E

L= E : cng in trng trong khng gian t do r : h s ph x t mt t : lch pha gia 2 tia ti im thu : gc hp bi gia hai tia . - Cng in trng khi truyn sng 2 tia khng nhng ph thuc vo cng sut suy hao ca thit b v mi trng m cn ph thuc vo cao ca anten kh nng phn x t mt t v s sai khc pha gia hai tia sng

* Cng in trng trong vng truyn sng nhiu tia .

-Tnh in trng tng cng ca tia nhn thng v mt tia phn x v coi l mt tia nhn thy cc tia khc cng lm tng t v coi trong thc t ngi ta thng tnh n 5 tia. *Tia nhn thng : E =E =d -d+ r : h s phn x ca tia 1 (t s gia bin tia sng phn x ti tia nhn thy). d : di ca tia phn x (c ly theo ng phn x). * Tng t nh vy ta c tia th 2: E =E Vi

Hiu ng dopple:

Khi cc my thu pht c c ly thay i lin tc trong mt phin lm vic th tn s cng tc s b bin i ( tn s cng tc chnh l tn s my pht ). Trong vng ph sng dc quc l khi trm di ng t trn t th tc thay i so vi phm vi ph sng l ng k th ta phi tnh n hiu ng dopple.

f =f +f f = f .cos ; f = c = 3.10 m/s ( tc nh sng ) v : vn tc ca trm di ng f : f ca my thu Khi ta xt mc tiu sng th i t BS n MS to ra vi mt t mt gc , do hiu ng dopple tn s sng mang ca tn hiu b dch chuyn ( dch tn dopple) f ph thuc vo tc dch chuyn MS gc , c ly lin lc cang xa gc cng nh , mt di tn cng t. gim nh hng ca hiu ng dopple th thay i bng cch dng cao cc ct anten pht chia nh li (lm d nh li ). Tri tr:

Cc bt truyn t BS n MS lun tr mt on trong thi gian l d . Trong di ng do truyn sng nhiu tia qung ng i ca cc tia l khc nhau thi im cc bt n im thu s khc nhau gy ra tri tr D . Nu D ln gy ra xuyn nhiu gia cc du my thu s nhn bit nhm khc phc th D < T , Tc bt : R = >

Hin tng tri tr : Vn tc bt phi ph thuc vo tri tr gii php trong thng tin di ng trnh xuyn nhiu gia cc du phi gim tc thc hin ghp xen. Tn hao ng truyn : -Tn hao ng truyn l hin tng suy gim mc in thu so vi mc in pht trong khng gian truyn sng t do mc in trung bnh ca tn hiu thu gim dn theo bnh phng khong cch t my pht ti my thu do cng sut tn hiu trn mt n v din tch ca mt cu song gim dn theo bnh phng khong cch gia anten thu v pht trong thng tin di ng trong mi trng kh quyn gn mt t do hp th ca mi trng truyn do che khut ... tn hao ng truyn c th ln hn rt nhiu tn hao trong iu kin truyn sng trong khng gian t do tn hao ng

truyn phi thuc tn s bc x, a hnh, tnh cht mi trng, mc di ng ca cc chng ngi, cao ca anten, loi anten... Trong thng tin v tuyn t bo trong nhiu trng hp tn hao ng truyn tun theo lut m 4 tc l t l vi lu tha 4 ca khong cch. V nguyn tc tn hao ng truyn hn ch kch thc t bo v c ly lin lc, song trong nhiu trng hp, ta c th li dng tnh cht tn hao ca ng truyn phn chia hiu qu cc t bo cho php ti s dng tn s mt cch hu hiu lm tng hiu qu s dng tn s. 2.5. K thut trong thng tin di ng: 2.5.1. K thut TDMA: Trong thng tin TDMA nhiu ngi s dng mt sng mang v trc thi gian c chia nhiu khong thi gian nh dnh cho nhiu ngi s dng sao cho khng c s chng cho. TDMA c chia thnh TDMA bng rng v TDMA bng hp, M v Nht s dng TDMA bng hp cn Chu u s dng TDMA bng rng, nhng c hai h thng ny c coi nh l s tng hp ca FDTM v TDMA v thc t ngi s dng dng cc knh c n nh c v tn s v khe thi gian trong bng tn.

Ngi s dng1 Khe thi gian1 Khe thi gian 2

Ngi s dng 2 Khe thi gian 3 Khe thi gian 4

Ngi s dng 3 Khe thi gian 5 Khe thi gian 6

2.5.2. K thut GSM: GSM l h thng thng tin ca Chu u tng thch vi h thng bo h s 7. Chng s dng h thng TDMA vi cu trc khe thi gian to nn s linh hot trong truyn in thoi, s liu v thng tin iu khin. H thng GSM s dng bng tn:

( 890 - 960) Mhz cho bng ln ( t MS n BS ). ( 935 - 960 ) Mhz cho bng xung ( t BS n MS ) . * Cu trc khung ca h thng di ng GSM:

0 1 2 3

.................
1 sie khung bag 51 a u n khung(6,12s)

2047
1 sie khung bag 26 a u n khung(6,12s)

0 1 2 3 ......... 50
1 a khung bag 26 n khung(120s)

0 1 ......... 24 25
1 a khung bag n

0 1 .......... 24 25

0 1 2 3 ......... 50

0 1 2 3 4 5 6 7
1 khung TDMA bag 8 khe thgian (4,615ms) n i

2.5.3. K thut CDMA: L thuyt v CDMA c xy dng nhng nm 1980 v c p dng trong thng tin qun s t nm 1960 cng vi s pht trin cng ngh bn dn v l thuyt thng tin vo nm 1980 CDMA c thng mi t phng php thu GRS v Ommi Trasc, phng php ny c xut trong h thng t ong ca Qual Comm M vo nm 1990. Trong thng tin CDMA nhiu ngi s dung chung thi gian v tn s, m PN ( tp m gi ngu nhin ) vi s tng quan cho thp c n nh cho mi ngi s dng, ngi s dng truyn tn hiu nh tri ph tn hiu truyn c s dng PN c n nh, u thu to ra mt gi ngu nhin nh u pht v khi phc tn hiu d nh nh s tri ph ngc cc tn hiu ng b thu c. 2.5.4. Tri ph: * H thng tri ph trc tip DS : Direct Sequency

H thng DS l l s iu ch cc dy m c iu ch thnh dng sng trc tip, h thng ny c dng tng i n gin v chng khng yu cu tnh n nh nhanh hoc tc tng hp tn s cao. * Nguyn l : Nguyn l ca phng php DS CDMA cho hnh v :

Si(t)

Tn hie so u To o c bit Rb= 1/Tb e(t) M i(t) L PF

Tn hie so u lie u c khophu i c U(t) V(t) Bo pha tch n

Ci(t) Bo o ma ta

cos(w) Ci(t)

2cos(w) C(t) Bie oma n i

C(t) Bo o ma ta

To o c chp Rc=1/Tc

Tb
Mi(t) t

Ci(t)

Mi(t).Ci(t)

Tn hie so c u khophu i c

Bn tin ca tn hiu s cn pht Mi(t) dng m NRZ lng cc vi Mi(t) =

1 c

a nn vi chui m Ci(t) c to ra mt b to chui c, hai gi ngu nhin PRBS tc ca bn tin gi l tc bt Rb, Rb nh hn nhiu so vi tc ca chui m c gi l tc chp Rc. Mi lung s ca mi knh s c b to m, to ra mt chui PRBS tng ng Ci(t) c di L, mi bt c lu ca chui m Tb = TxL, Ci(t) c tc cao hn nhiu so vi Rb = 1/Thun Chu ca tn hiu s cn pht do ph ca tn hiu gi ngu nhin rng hn nhiu ph ca tn hiu s cn pht. Do ph rng v cng sut pht khng thay i nn tn hiu PRBS c bin rt thp. * c tnh ca tn hiu DS: iu ch DS l iu ch 2 pha. Dy m c a vo b iu ch cn bng c u ra l sng mang. RF iu ch 2 pha, sng mang c lch pha 180 0 gia pha 1 v pha 0 theo dy m. Tn hiu thu c khuyn i v nhn vi m ng b lin quan ti u pht v u thu, khi nu cc m ti u pht v u thu c ng b sng mang c tch pha ln hn 1800 v sng mang c khi phc cc sng mang bng tn hp ny i qua b lc bng thng c thit k ch cho cc sng mang iu ch bng gc i qua.

 rng bng RF ca h thng DS nh hng n hot ng h thng mt cch cch trc tip nu bng l 2KHz th li s l gii hn l 20 KHz. 2.5.5.iu ch QPSK ( Quadrature Phase Shift Keying): Sau khi c tri ph bi 2 chui PN hoa tiu vung gc 2 lung I v Q c khc pha 900 c a hai b lc bng thng v c iu ch kho chuyn pha 4 trng thi. Tn hiu sau iu ch QPSK c xc nh theo cng thc sau: S(t) = A. cos ( 2Iifct + t ) Trong : - fc: tn s sng mang - A : bin sng mang c iu ch xc nh theo cng thc sau: A= - : Pha ca sng mang c iu ch = ar tg ( )

Quan h gia cc trng thi pha ca tn hiu QPSK v cc k thut I, Q I 0 1 1 1 Q 0 0 1 0 /4 3/4 5/4 7/4

S s b iu ch QPSK:

+ 1
-1

TCxo Bo chuye n song song 90 Lo c Keh n QPSK

+ 1 -1

PHN II
CHNG III: TNG QUAN V H THNG THNG TIN DI NG TH H 3 3.1. Yu cu chung i vi mt h thng thng tin di ng th h 3: H thng TTD th h 3 c xy dng c s tiu chun chung ca IMT 2000 ( Vin thng di ng quc t 2000). Cc tiu ch chung xy dng IMT 2000 nh sau: 3.1.1. S dng di tn quy nh quc t 2 GHZ nh sau: ng ln: 1885 2025 MHZ ng xung: 2110 2200 MHZ 3.1.2. L h thng TTD ton cu cho cc loi hnh thng tin v tuyn: + Tch hp cc mng thng tin hu tuyn v v tuyn. + Tng tc vi mi loi dch v vin thng. 3.1.3. S dng cc mi trng khai thc khc nhau: + Trong cng s. + Ngoi ng. + Trn xe. + V tinh. 3.1.4. C th h tr cc dch v nh: + Mi trng thng tin nh o trn c s mng thng tin, di ng c nhn v chuyn mng ton cu. + m bo chuyn mng quc t. + m bo cc dch v a phng tin ng thi cho thoi, s liu chuyn mng theo knh v s liu chuyn mng gi. 3.1.5. D dng h tr cc dch v mi xut hin: Mi trng hot ng ca IMT 2000 c chia lm 4 vng vi cc tc bt Rb phc v nh sau:

Vng 1: Trong nh , pico, Rb 2 Mbps. Vng 2: Thnh ph, micro, Rb 384 Kbps. Vng 2: Ngoi , macro, Rb 144 Kbps. Vng 3: Ton cu, Rb = 9,6 Kbps. 3.2. Gii thiu v h thng thng tin di ng th h 3 (3G): T thp nin 90, Lin minh Vin thng Quc t bt tay vo vic pht trin nn tng chung cho cc h thng thng tin di ng. Kt qu l mt sn phm c gi l Thng tin di ng ton cu 2000 (IMT - 2000). Con s 2000 c ngha l sn phm ny s c mt vo khong nm 2000, nhng thc t phi chm n 2, 3 nm. IMT 2000 khng ch l mt dch v, n p ng c m lin lc t bt c ni u v bt c lc no. c nh vy IMT 2000 to iu kin thch hp cc mng mt t hoc v tinh. Hn th na, IMT 2000 cng cp ti Internet khng dy, hi t cc mng c nh v di ng (chuyn vng), cc tnh nng a phng tin di ng, hot ng xuyn mng v lin mng. Nh ni, h thng 3G cn phi hot ng trn mt di ph rng v cung cp c cc dch v thoi, d liu, a phng tin. i vi mt thu bao hot ng trn mt siu nh (picocell), tc d liu c th ln n 2,048 Mbps. Vi mt thu bao di ng vi tc chm hot ng trn mt cc nh (microcell), tc d liu c th t ti 384 Kbps. Vi mt ngi dng di ng trn phng tin giao thng hot ng trn mt ln (macrocell), tc d liu c th t ti 144 Kbps. T GSM ln 3G Con ng n 3G duy nht ca GSM l CDMA bng thng rng, Chu u. WCDMA c gi l h thng vin thng di ng ton cu (UMTS). Trong cu trc dch v 3G, cn c bng thng rt ln v nh th cn nhiu ph tn hn. Hoa K, FCC cha th nhanh chng phn b bt c ph no cho cc dch v 3G. Hoa K c khong 190 Mhz ph tn phn b cho cc dch v v tuyn di ng trong khi phn cn li ca Th gii ch c phn b 400 Mhz. V th c th tin rng s pht trin 3G Hoa K s rt khc vi phn cn li ca Th gii.

 n 3G c l cn phi i qua giai on 2,5G. Ni chung 2,5G bao gm tt c cc cng ngh sau: D liu chuyn mch gi tc cao (HS CSD), dch v v tuyn ni chung (GPRS), tc d liu nng cao cho s pht trin GSM hay ton cu (EDGE). * HSCSD l phng thc n gin nht nng cao tc . Thay v mt khe thi gian (Ts), mt trm di ng c th s dng mt s khe kt ni d liu. Trong cc ng dng thng mi hin nay, thng thng s dng ti a 4Ts, 1Ts c th s dng hoc tc 9,6 Kbps. y l cch khng tn km nhm tng dung lng d liu ch bng cch nng cp phn mm ca mng. Nhng nhc im ln nht ca n l cch s dng ti nguyn v tuyn. Bi y l hnh thc chuyn mch knh, HSCSD ch nh vic s dng cc Ts mt cch lin tc, thm ch ngay c khi khng c tn hiu trn ng truyn. * Gii php tip theo l GPRS v dng nh l gii php c nhiu nh cung cp dch v la chn. Tc d liu ca n c th ln ti 115,2 Kbps bng vic dng 8Ts. N c quan tm l v h thng chuyn mch gi, do n khng s dng ti nguyn v tuyn mt cch lin tc m ch thc hin khi c thng tin cn gi i. GPRS c bit thch hp vi cc ng dng phi thi gian thc nh email v lt Web. Trin khai h thng ny th tn km hn h thng HSCSD. Mng ny cn cc thnh phn mi cng nh cn sa i cc thnh phn hin c nhng n c xem l bc i cn thit tin ti tng dung lng, dch v. Mt mng GMS m khng c kh nng GPRS th s khng tn ti lu trong tng lai. Vit Nam, qu IV nm nay vinaphone v Mobiphone cng trin khai GPRS.. * Bc tip theo l ci tin GSM thnh tc d liu nng cao cho s pht trin GMS hay ton cu (EDGE), tng tc d liu ln ti 384 Kbps vi 8Ts thay v 14,4 Kbps cho mi Ts, EDGE t ti 48 Kbps cho mi Ts. tng ca EDGE l s dng phng php iu ch mi c gi l 8 PSK. EDGE l mt phng thc nng cp hp dn i vi mng GSM v n ch yu cu mt phn mm nng cp trm gc. N khng thay th hay ni ng hn cng tn ti vi phng php iu ch kho dch ti thiu Gausian (GMSK), c s dng trong GSM, nn cc thu bao c th s dng my di ng c ca mnh nu khng cn c cung cp cht lng dch v tt

hn. Xt trn kha cnh k thut, cng cn gi li GMSK. Nu EDGE c s dng cng vi GPRS th s kt hp ny c gi l GPRS nng cp (EGPRS), cn s kt hp ca EDGE v HSCSD c gi l ECSD. WCDMA thc s l mt dch v v tuyn bng thng rng s dng bng tn 5 Mhz t c tc d liu ln ti 2 Mbps. Rb 384 Kbps. Hin ti c Chu u v Nht Bn u ang th nghim hoc trin khai WCDMA v cng ngh ny ang tin trin nhanh trn con ng thng mi ho. T IS 95 n CDMA 2000 CDMA khng th chuyn ngay sang 3G v khng c ph tn trn th trng Hoa K. Trn th trng Hn Quc th nghim CDMA2000 trn ph tn 3G ca mnh. Cng nh i vi GSM, Hoa K v phn cn li ca th gii c nhng con ng khc nhau i ti 3G. CDMA2000 c cu trc theo cch cho php nhiu mc dch v 3G trn knh IS 95 1,25 Mhz truyn thng. Cc dch v ny l CDMA2000 1xRTT (mt thi c gi l cng ngh truyn dn v tuyn kch thc knh IS - 95). Vi cng sut 3G ti a, CDMA2000 s dng mt knh 3,75 Mhz, ln gp 3 ln knh truyn thng, gi l 3xRTT. H thng 1xRTT s dng mt s iu ch hiu qu hn tng gp i dung lng thu bao thoi v to ra cc knh d liu ln ti 144 Kbps. Tc ny cho php mt s nh cung cp dch v cho rng mnh ang thc hin 3G. trong thc t, tc ngi s dng trong khong 50 60 Kbps. Kt lun R rng l s c khng ch mt con ng i ti cc h thng v tuyn di ng 3G, v cng r rng l IMT2000 c ng o chp nhn. Tuy nhin tnh khng tng thch ca cc cng ngh 3G, vic thiu ph tn, thiu cc ng dng v thit b 3G t ra mt s vn cn gii quyt. T quan im cng ngh, c CDMA2000 v WCDMA u s dng cc k thut tri ph rng. Tuy nhin, chng c cu trc knh, m chip, tc chip th tc ng b ho khc nhau. Cn c thi gian hi ho cc tr ngi v cng ngh ny. gii quyt c vn ph trn ton cu s tn km v mt nhiu thi gian. Cui

cng cn c nhiu dch v hn na thu ht khch hng. Chng ta thy s ph bin ca email v tin nhn i vi PDA v in thoi di ng. Gi y chng ta cn c mt lot cc ng dng a phng tin i hi phi c tc d liu ca 3G.

KT LUN CHUNG H thng CDMA s dng cng ngh tri ph truyn cc tn hiu gia cc trm gc v cc my u cui thu bao. Cc tn hiu ny xut hin nh tp m Gaussan theo mi mu gn nh mt bin ngu nhin Gaussan, nh vy vic s dng dng sng nh phn ngu nhin gn nh dng dng sng tp m Gaussan nh c th linh ng v r rng iu ch dng sng ny vi mt tn hiu s cha thng tin nn hiu qu thc t c gi tr vi k thut tri ph trc tip (DS) c kh nng truyn thng tin tc cao. Trong h thng CDMA c rng bng thng ln h s ti s dng tn s bng 1 do rt thun li cho vic m rng dung lng h thng mt cch c iu khin v mt knh bng tn trong CDMA c s dng chung cho tt c cc BS. Vi vic phn tp a ng ci tin cht lng thoi, s dng k thut m ho khc nhau tng tin cy v tnh bo mt tt. i vi h thng thng tin di ng th h 3 hot ng trn di ph rng v cung cp c cc dch v thoi, a phng tin. Mt s u im ca h thng thng tin di ng th h 3: 1. Tc truy nhp cao m bo cc dch v bng thng rng nh Internet nhanh hoc cc dch v a phng tin. 2. Linh hot, m bo cc dch v mi nh nh s c nhn ton cu v in thoi v tinh. Cc tnh nng ny cho php m rng ng k tm ph ca cc h thng thng tin di ng. 3. Tnh tng thch vi cc h thng thng tin di ng hin c, m bo s pht trin lin tc ca h thng thng tin di ng. Nhiu tiu chun ca h thng thng tin di ng th h 3 IMT 2000 c xut. Trong s dng hai h thng WDMA v CDMA2000 c ITU chp nhn. Cc h thng ny u s dng cng ngh CDMA, iu ny cho php thc hin tiu chun ho ton Th gii cho giao din v tuyn ca h thng thng tin di ng th h III