Ngân hàng câu hỏi &đáp án GSM ( Nguyễn Phạm Anh Dũng) Font VN time

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<p>Ngn hng cu hi thi v p n cho i hcHc phntHng tin di ng Bin son TS. Nguyn Phm Anh Dng1Ngn hng Cu hi thi mn TTD(3VHT)Cc cu hi thi cho mn TTD c chia thnh 4 loi cu hi:V1.3a bao gm cc kin thc v: mng TTD, cc dch v TTD, c im truyn dn TTD (3 im)V1.3bbaogmcckinthcv: cutrcgiaodinv tuyn, kin trc giao thc v th tcni mng ca GSM,(3 im)V1.3cbaogmcckinthcv: giaodinvtuyncu CDMA IS-95 (3 im) V1.1 bao gm mt s bitp tnh ton cho mng GSM v CDMA IS-95 (1 im)Khng c cc cu hi V1.4 v V1.2.Rt thm bn lai cu hi trn s c mt thi 10 im bao qut ton b mncho thi gian thi 120 phtI. Cc cu hi loi V1.3 a(3 im) 1. Trnh by m hnh tham kho h thng thng tin di ng 2. Trnh by cu trc a l h thng thng tin di ng.3. Trnh by khi nim t ong v mu ca h thng thng tin di ng4. Trnh by cc thng s khung ting ca b m ha ting: CDMA, GSMv EFR GSM5. Trnh by cu hnh tham kho MS v truyn ti dch v phi thoi6. Trnh by nguyn l truyn dn s liu di b trong sut vi modem GSM7. Trnh bytruyn Fax GSM8. Trnh by m hnh suy hao ng truyn Hata Okumura9. Trnh by cc dng phainh trn ng truyn v tuyn TTD10. Trnh by cc nh hng ca phainh ln truyn dn v tuyn trong TTD v cc bin php chng phainh.11. Trnh by hin tng xa gn trong thng tin di ngII. Cc cu hi loi V1.3 b(3 im) 1. Trnh by cu trc s lp vt l ca GSM MS 2. Trnh by cu trc cc knh vt l ca GSM3. Trnh by cu trc cc knh logic ca GSM24. Trnh by sp t cc knh logic ln cc knh vt l GSM5. Trnh by o, nhy tn v chuyn giao GSM6. Trnh by truyn dn ting trong GSM7. Trnh by SMS im n im trong GSM8. Trnh by Kin trc ngn xp giao thc ca GSM9. Trnh by nh tuyn cuc gi n MS t mng c nh10. Trnh by th tc MOC GSM 11. Trnh by th tc MTP GSM12. Trnh by chuyn mng quc t GSM II i. Cc cu hi loi V1.3 c(3 im) 1. Trnh by cu trc cc knh vt lv quy hoch m CDMA IS 95.2. Trnh by cu trc knh logic CDMA IS-953. Trnh by chc nng cc knh logic CDMA IS-954. Trnh by cu trc lp vt lknh lu lng ng xung CDMA IS-955. Trnh by cu trc lp vt l knh lu lng ng ln CDMA IS-956. Trnh by iu khin cng sut vng h CDMA IS-957. Trnh by iu khin cng sut vng kn CDMA IS-958. Trnh by cc kiu chuyn giao CDMA IS-95IIi. Cc cu hi loi V1.1 (1 im) 1. Cho 24 tn s nh s t 1 n 24, hy phn b tn s cho mu ti s dng tn s 3/9 h thng GSM2. Ti gi cao im mi ngi s dng trung bnh gi 90 giy, hi mi ngi s dng chim bao nhiu Erlang trong gi cao im v nu mt GSM BTS cung cp22knh lu lng th n c th phc v c bao nhiu thu bao. Cho GOS=2% v bng tra cu lu lng cho m hnh B .Cp bc phc v (GOS)S trung k0,005 0,01 0,015 0,02 0,03 0,05 0,07 0,120 11,092 12,041 12,680 13,188 14,002 15,25216,273 17,61421 11,860 12,848 13,514 14,042 14,890 16,19117,255 18,65222 12,635 13,660 14,352 14,902 15,782 17,13418,240 19,69323 13,429 14,479 15,196 15,766 16,679 18,08219,229 20,73733. Mt vng dn cc din tch 10 km2cn dung lng 70 Erlang, hi nu mi GSM BTS c th ph sng 2km2, th cn bao nhiu knh cho GSM BTS khi cho GOS=2% v bng tra cu Erlang m hnh B. Cn lm g khi nhu cu lu lng tivng dn c ny tng gp i .Cp bc phc v (GOS)S trung k0,005 0,01 0,015 0,02 0,03 0,05 0,07 0,120 11,092 12,041 12,680 13,188 14,002 15,25216,273 17,61421 11,860 12,848 13,514 14,042 14,890 16,19117,255 18,65222 12,635 13,660 14,352 14,902 15,782 17,13418,240 19,69323 13,429 14,479 15,196 15,766 16,679 18,08219,229 20,7374. Mt GSM BTS c ba knh tn s, trong hai khe thi gian c dnh cho iu khin v bo hiu, hi BTS ny c dung lng l bao nhiu. Nu mc s dng ca mi ngi s dng l 30mErlang, hi BTS c th phc v bao nhiu ngi. Cho GOS=2% v bng tra cu Erlang m hnh B.Cp bc phc v (GOS)S trung k0,005 0,01 0,015 0,02 0,03 0,05 0,07 0,120 11,092 12,041 12,680 13,188 14,002 15,25216,273 17,61421 11,860 12,848 13,514 14,042 14,890 16,19117,255 18,65222 12,635 13,660 14,352 14,902 15,782 17,13418,240 19,69323 13,429 14,479 15,196 15,766 16,679 18,08219,229 20,7375. Tnh cng sut u ra my pht ca knh lu lng cho mt ngi s dng trn ng xung CDMA IS-95 khi bit:+ Tng EIRP ca cc knh lu lng,P = 57 dBm+ S knh lu lng c cung cp trn on N = 20+ H s khuych i anten BTS, Gb = 14 dBi+ Tn hao ng ni u ra my pht n u vo an ten, Lph= 2,5 dB+ H s tch cc ting, =0,56. Tnh mt ph cng sut nhiu t cc ngi s dng khc trong cng v t khc knh lu lng trn ng xung CDMA IS-95 khi bit:+ Tng cng sut thu my thu MS, Prx = -97 dBm+ Cng sut thu knh lu lng, PrxTCH = -110 dBm 4+ Bng thng knh v tuyn, B = 1,25 MHz+ H s nhiu t cc khc, = 0,67. Tnh t s tn hiu trn tp m cng nhiu cho knh lu lng ng xung CDMA IS-95 khi cho:+Mt ph cng sut nhiu t cc knh lu lng ng xung trong cng I0=-158 dBm/Hz+ H s nhiu tcc khc, = 0,6+ Tc bit knh lu lng, Rb = 9600 bit+ Cng sut thu knh lu lng, PuTCH = -109 dBm+ Mt ph cng sut tp m, N0 = -166 dBm/Hz p n cc cu hi TTDI. Cc cu hi loi V1.3a(3 im)Thang im1. th nht 1 im2. th hai 1 im3. th 1 ba imCu 15Trnh by m hnh tham kho h thng thng tin di ng (2G)p n( th nht) M hnh tham kho h thng thng tin di ng (TTD) c cho hnh 1.TE1TE2TE2SmRmRmMT0MT1TApMT2UmBTS BSC A-bisOS IWFPDNPSTNISDNPLMNAEFMSCEIRHLR VLRAUCHDCBGOLTrm gcCc b qun l di ngCc VLRkhcMSMSCMng ngoiHnh 1. M hnh tham khao h thng thng tin di ng (2G)Cc phn t chnh ca m hnh tham kho nh sau:( th hai)* MSMS (Mobile Station: trm di ng) 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 hoc thit b cm tay. Loi thit b nh cm tay s l thit b trm di ng ph bin nht. Ngai vic cha cc chc nng v tuyn chung v x 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 vimt s thit b khc (nh: giao din vi my tnh c nhn, FAX ...). Hin nay ngi ta ang c gng sn sut 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 sut. Vy ta c th lit k ba chc nng chnh :1. Thit b u cui (TE) thc hin cc chc nng khng lin quan n mng di ng : FAX, my tnh).2. Kt cui trm di ng (MT) thc hin cc chc nng lin quan n truyn dn giao din v tuyn.63. B thch ng u cui (TAF) lm vic nh mt ca ni thng thit b u cui vi kt cui di ng. Cn s dngb thch ng u cui khi giao din ngoi trm di ng tun theo tiu chun ISDN u ni u cui cn thit b u cui li c giao din u cui - modem. * BTSMt BTS(Base Station TransceiverStation: trmthupht gc) bao gm cc thit b pht thu, anten v x l tn hiu c th cho giao din v tun. C th coi BTS l cc MODEM v tuyn phc tp c thm mt s cc chc nng khc. Mt b phn quan trng ca ca BTS l TRAU (Transcoder/Adapter Rate Unit: khi chuyn i m v tc ). 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 ch trong nhiu trng hp n c t gia BSC v MSC. * BSCBSC (Base Station Controller: b iu khin trm gc) c nhim v qun l tt c giao din v tuyn 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.( th ba)* MSCh thng thng tin di ngchc nng chuyn mchchnh cthchinbi MSC(MobileServicesSwitchingCenter: trung tm chuyn mch cc dch v di ng), 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 BSC, mt khc n giao din vi mng ngoi. MSC lm nhim v giao dinvi mng ngoi c gi l MSC cng (GMSC: Gate MSC). Mng thng tin di ng cng cn giao din vi mng ngoi s dng cc kh nng truyn ti ca cc mng ny cho vic truyn ti s liu ca ngi s dng hoc bo hiu gia cc phn t ca mng. Chng hn mng TTD c th s dng mng bo hiu knh chung s 7 (CCS No7), mng ny m bo hot ng tng tc gia cc phn t trong mt hay nhiu mng TTD. MSC thng l mt tng i ln iu khin v qun l mt s cc b 7iu khin trm gc (BSC). Mt tng iMSC thch hp cho mt vng th v ngoi c dn cvo khong mt triu (vi mt thu bao trung bnh). kt niMSC vimt s mng khc cn phithch ng cc c im truyn dn ca mng TTD vi cc mng ny. Cc thch ng ny c gi l IWF (Interworking Function: chc nng tng tc). IWF bao gm mt thit b thch ng giao thc v truyn dn. N cho php kt ni vi cc mng: PDN (Packet Data Network: mng s liu cng cng chuyn mch gi) , n cng tn ti khi cc mng khc ch n thun l PSTN (Public Switched Telephone Network: mng in thoi chuyn mch cng cng) hay ISDN (Intergrated Services Digital Network: mng a dch v kin kt). 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.* HLRCcthngtinlinquan nviccungcpccdchvvin thng c lu gi HLR (Home location Register: b ghi nh v th-ng tr) khng ph thuc v v tr hin thi ca thu bao. HLR cng cha cc thng tin lin quan n v tr hin thi ca thu bao. Thng HLR l mt my tnh ng ring khng c kh nng chuyn mch v c kh nng qun l hng trm ngn thu bao. * VLRVLR (Visitor Location Register: b ghi nh v tm tr) l c s d liu th hai trong mng TTD. N c ni vi mt hay nhiu MSC v c nhim v lu gi tm thi s liu thu bao ca cc thu bao hin ang nm trong vng phc v ca MSC tng ng v ng thi lu gi s liuv v tr ca cc thu bao ni trn mc chnh xc hn HLR. Cc chc nng VLR thng c lin kt vi cc chc nng MSC.*GMSCMng TTD c th cha nhiu MSC, VLR, HLR. thit lp mt cuc gin ngi s dng TTD, trc ht cuc gi phic 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 iang qun l thu bao thiim hin thi(MSC tm tr). vy trc ht cc tng i cng phi da trn s 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 bn ngoi, thng qua giao tip ny n lm nhim v cng kt ni cc mng bn ngoi vi mng TTD. Ngoi ra tng i ny cng c giao din bo hiu s 7 (CCS No7) c th tng tc vi cc phn t khc ca mng TTD. Vphngdinkinhtkhngphi baogitngi cngcng ng ring m n thng c kt hp vi MSC.8* OSOS (Operation System: h thng khai thc) thc hin khai thc v bo dng tp trung cho mng TTD.Hthngkhai thcvbodngcthcxydngtrn nguyn l TMN (Telecomunications Management Network: mng qun l vin thng). Khi ny mt mt h thng khai thc v bo dng c ni n cc phn t ca mng vin thng (cc MSC, BSC, HLR v cc phn t mng khc tr BTS, v truy nhp n BTS c thc hin qua BSC). Mt khc h thng khai v bo dng li c ni n mt my tnh ch ng vai tr giao tip ngi my. H thng ny thng c gi l OMC (Operation and Mainternance Center: trung tm khai thc v bo dng). * AUCAUC(Authentication Center: trung tm nhn thc) qun l cc thng tin nhn thc v mt 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 MS. GSM b nh ny c dng SIM-CARD c th rt ra v cm li c.* EIRQunlthit bdi ngcthchinbi EIR(Equipment Identity Register: b ng k nhn dng thit b). EIR lu d 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 (thit b b nh cp hoc hot ng khng tt). Mt thit b khng c php s b cm. (Lu khc vi thit b s c php ca thu bao c xc nhn bi AUC). Cu 2Trnh by cu trc a l ca h thng thng tin di ngThang im1. th nht 1 im2. th hai 1 im3. th 1 ba imp n9Do tnh cht di ng ca thu bao di ng nn mng di ng phi c t chc theo mt cu trc a l nht nh mng c th theo di c v tr ca thu bao.( th nht) Phn chia theo vng mngTrong mt quc gia c th c nhiu vng mng vin thng, vic gi vo mt vng mng no phi c thc hin thng qua tng i cng. Ccvngmngdi ngci dinbngtngi cng GMSC. Tt c cc cuc gi n mt mng di ng t mt mng khc u c nh tuyn n GMSC. Tng i ny lm vic nhmt tng i trung k vo cho mng GSM/PLMN. y l ni thc hin chcnnghi nhtuyncucgi ktcui trmdi ng. GMSCchophphthngnhtuyncccucgi votmng ngoi n ni nhn cui cng: cc tram di ng b gi. ( th hai)Phn chia theo vng phc v MSC/VLRMt mng thng tin di ng c phn chia thnh nhiu vng nh hn, mi vng nh ny c phc v bi mt MSC/VLR (hnh 1). Ta gi y l vng phc v ca MSC/VLR. MSCMSCMSCMSCGMSCVLRVLRVLRVLRI IIIIIIVHnh 1. Cc vng phc v MSC/VLR nh tuyn mt cuc gi n mt thu bao di ng, ng truynquamngs cni nMSCangphcvthubaodi ng cn gi. mi vng phc v MSC/VLR thng tin v thu bao c ghi li tm thi VLR. Thng tin ny bao gm hai loi:101. Thng tin v ng k v cc dch v ca thu bao.2. Thng tin v v tr ca thu bao (thu bao ang vng nh v no).( th ba) Phn chia theo vng nh v Mi vng phc v MSC/VLR c chia thnh mt s vng nh v: LA (Location Area) (hnh 2). MSC VLRLA1 LA2 LA3LA4LA5 LA5Hnh 2. Phn chia vng MSC/VLR thnh LAVng nh v l mt phn ca vng phc v MSC/VLR m mt trmdi ngcthchuynngtdovkhngcncpnht thng tin v v tr cho MSC/VLR qun l v tr ny. C th ni vng nh v l v tr c th nht ca trm di ng m mng cn bit nh tuyn cho mt cuc gi n n. vng nh v ny thng bo tm s c pht qung b tm thu bao di ng b gi.H thng c th nhn dng vng nh v bng cch s dng nhn dng vng nh v (LAI: Location Area Identity). Vng nh v c th bao gm mt s v thucmt haynhiu BSC,nhngchthucmt MSC.Phn chia theo Vng nh v c chia thnh mt s (hnh 3). l mt vng ph v tuyn c mng nhn dng bng nhn dng ton cu (CGI: Cell Global Identity). Trm di ng nhn dng bng m nhn dng trm gc (BSIC: Base Station Identity Code). Vng ph ca cc thng c m phng bng hnh lc gic tin cho vic tnh ton thit k.11MSC VLRLA5LA1LA2 LA3LA412345LA6Hnh 3. Phn chia vng nh v thnh cc Cu 3Trnh by khi nim t ongv mu cah thng thngtin dingThang im1. th nht 1 im2. th hai 1 im3. th 1 ba imp n( th nht)Khi nim ph sng t ong ph ton b mng thng tin v tuyn ngi ta thc hin ph sng thnh nhiu vng chng ln vi nhau. Khi nim ph sng ny c gi l t ong. Ngoi ra phng php ph sng t ong cn l mt bin php quan trng gii quyt vn v nghn tn s v dung lng mng. N cho php t c dung lng rt cao trong mt phn b ph tn hu hn m khng cn cc thay i c bn v cng ngh. Phng php t ong c xy dng trn tng thay th mt my pht cng sut ln ph mt vng rng ln bng nhiu my pht ph cc vng nh hn c gi l cc . Mi BTS c n nh mt phn ca tng s knh c c trong ton b h thng v cc BTS gn nhau c c n nh cc nhm knh khc nhau sao cho ton b cc knh kh dng c n nh cho mt s lng tng i nh cc BTS gn nhau. Cc BTS gn nhau c n nh cc nhm knh khc 12nhau sao cho nhiu gia cc BTS (v cc my di ng chu s gim st ca chng) c gim thiu.Bng cch sp t cc BTS trong khng gian v cc nhm knh dnh cho chng mt cch c h thng trn ton b mng,cc knh kh dng c phn btrn ton b vng a lvcti sdngnhiulntheoscnthit chngno nhiu gia cc trm ng knh vn c duy tr di mc quy nh.( th hai) Khi nhu cu dch v tng (cn nhiuknh hn trong mt vng phc v cho trc), ta c th tng s BTS (cng vi gim cng sut pht trnh tng nhiu), nh vy cung cp thm dung lng v tuyn m khng cn tng ph tn v tuyn.y l nguyn tc cn bn xy dng tt c cc h thng thng tin v tuyn hin i, v n cho php s dng mt s knh c nh phc v mt s l-ng ln thu bao bng cch ti s dng cc knh trn ton b vng phc v. Ngoi ra phng php t ong cho php mi thit b trong mt n-c hoc trong cng mt chu lc c sn sut vi cng mt tp knh v c th s dng c mi ni trong vng ny. Mc d phng php t ong m bo vic b sung dung lng bng cch b sung thm cc trm , trong thc tcc nh cung cp dchv di ng rt kh c c cc trm mi trong cc vng thnh ph. Chnh v vy cc nh cung cp dchv ny thin v lp t thm cc knh v cc trm gc trn cng mt trm hin c hn l tm im t trm mi.Bng cch s dng cc chiu cao anten khc nhau (thng trn cng mt to nh hoc mt thp) v cc mc cng sut khc nhau ngi ta c th to ra cc ''ln'' hoc ''nh''cng t ti mt v tr.K thut ny c gi l phng php dng d v n c s dng m bo cng ph ln cho cc ngi s dng tc cao trong khi vn m bo ccvng ph din tch nh cho cc ngi s dng tc thp. Hnh 1 cho thy mt dng dc t cng vi cc mi...</p>