bai tong ket LTE-4G moi

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Phn 1 TIN TRNH PHT TRIN CA CC H THNG THNG TIN DI NG T 1G -> 4GI. H thng 1G ( h thng tng t ) :1. Lch s pht trin : Cng ngh di ng u tin l cng ngh tng t, l h thng truyn tn hiu tng t (analog), l mng in thoi di ng u tin ca nhn loi, c khi mo Nht vo nm 1979. Nhng cng ngh chnh thuc th h th nht ny c th k n l : NMT (Nordic Mobile Telephone) c s dng cc nc Bc u, Ty u v Nga. Cng c mt s cng ngh khc nh AMPS (Advanced Mobile Phone Sytem h thng in thoi di ng tin tin) c s dng M v c; TACS (Total Access Communication Sytem h thng giao tip truy cp tng hp) c s dng Anh, C45 Ty c, B o Nha v Nam Phi, Radiocom 2000 Php; v RTMI Italia. 2. c im ca h thng ny l : Hu ht cc h thng u l h thng analog v yu cu chuyn d liu ch yu l m thanh. Vi h thng ny, cuc gi c th b nghe trm bi bn th ba. Mt s chun trong h thng ny l: NTM, AMPS, Hicap, CDPD, Mobitex, DataTac. Nhng im yu ca th h 1G l dung lng thp, xc sut rt cuc gi cao, kh nng chuyn cuc gi khng tin cy, cht lng m thanh km, khng c ch bo mtdo vy h thng 1G khng th p ng c nhu cu s dng .

II. H thng 2G ( Digital ) :Nm 1982, hi ngh qun l bu in v vin thng Chu u (CEPT European Conference of Postal and Telecommunications ad minstrations) thnh lp 1 nhm nghin cu, GSM Group Speciale Mobile, mc ch pht trin chun mi v thng tin di ng Chu u. Nm 1987, 13 quc gia k vo bn ghi nh v ng gii thiu mng GSM vo nm 1991. Nm 1988, Tr s chun vin thng Chu u (ETSI European Telecommunication Standards Institute) c thnh lp, c trch nhim bin i nhiu tin c k thut GSM thnh chun European. S pht trin k thut t FDMA -1G, 2G - l kt hp FDMA v TDMA. Tt c cc chun ca th h ny u l chun k thut s v c nh hng thng mi, bao gm: GSM, iDEN, D-AMPS, IS-95, PDC, CSD, PHS, GPRS, HSCSD, WiDEN v CDMA2000 (1xRTT/IS-2000). Trong khong 60% s mng hin ti l theo chun ca chu u. 1. c im ca h thng : H thng GSM lm vic trong mt bng tn hp, di tn c bn t (890- 960MHz). Bng tn c chia lm 2 phn: - Uplink band t (890 915) MHz - Downlink ban t (935 960)MHz Bng tn gm 124 sng mang c chia lm 2 bng, mi bng rng 25MHz,

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khong cch gia 2 sng mang k nhau l 200KHz. Mi knh s dng 2 tn s ring bit cho 2 ng ln v xung gi l knh song cng. Khong cch gia 2 tn s l khng i bng 45MHz. Mi knh v tuyn mang 8 khe thi gian TDMA v mi khe thi gian l mt knh vt l trao i thng tin gia MS v mng GSM. Tc m t (6.513)Kbps. 125 knh tn s c nh s t 0 n 124 c gi l knh tn s tuyt i ARFCN (Absolute Radio Frequency Channel Number). Ful(n) = 890 MHz + (0,2MHz) * n Fdl(n) = Ful(n) + 45MHz Vi 1