Tim hieu cong_nghe_3_g

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    TNG QUAN V H THNG THNG TIN DI NG TH H BA 1. M u S pht trin nhanh chng ca dch v s liu m IP t ra cc yu mi i vi cng ngh vin thng di ng. Thng tin di ng th h 2 mc d s dng cng ngh s nhng l h thng bng hp v c xy dng trn c ch chuyn mch knh nn khng th p ng c dch v mi ny. 3G (third-generation) cng ngh truyn thng th h th ba l giai on mi nht trong s tin ha ca ngnh vin thng di ng. Nu 1G (the first gerneration) ca in thoi di ng l nhng thit b analog, ch c kh nng truyn thoi. 2G (the second generation) ca TD gm c hai cng nng truyn thoi v d liu gii hn da trn k thut s. Trong bi cnh ITU a ra n tiu chun ha h thng thng tin di ng th h th 3 vi tn gi IMT 2000. IMT 2000 m rng ng k kh nng cung cp dch v v cho php s dng nhiu phng tin thng tin. Mc ch ca IMT 2000 l a ra nhiu kh nng mi nhng cng ng thi m bo s pht trin lin tc ca h thng thng tin di ng th h th hai (2G) vo nhng nm 2000. 3G mang li cho ngi dng cc dch v gi tr gia tng cao cp, gip chng ta thc hin truyn thng thoi v d liu (nh e-mail v tin nhn dng vn bn), download m thanh v hnh nh vi bng tn cao. Cc ng dng 3G thng dng gm hi ngh video di ng; chp v gi nh k thut s nh in thoi my nh; gi v nhn e-mail v file nh km dung lng ln; ti tp tin video v MP3; thay cho modem kt ni n my tnh xch tay hay PDA v nhn tin dng ch vi cht lng cao

    2. Th no l cng ngh 3G 3G l thut ng dng ch cc h thng thng tin di ng th h th 3 (Third

    Generation). c rt nhiu ngi nhm ln mt cch v hoc hu gia hai khi nim 3G v UMTS (Universal Mobile Telecommunications Systems). hiu th no l cng ngh 3G, chng ta hy xt qua i nt v lch s pht trin ca cc h thng in thoi di ng. Mc d cc h thng thng tin di ng th nghim u tin c s dng vo nhng nm 1930-1940 trong trong cc s cnh st Hoa K nhng cc h thng in thoi di ng thng mi thc s ch ra i vo khong cui nhng nm 1970 u nhng nm 1980. Cc h thng in thoi th h u s dng cng ngh tng t v ngi ta gi cc h thng in thoi k trn l cc h thng 1G.

    Khi s lng cc thu bao trong mng tng ln, ngi ta thy cn phi c bin php nng cao dung lng ca mng, cht lng cc cuc m thoi cng nh cung cp thm mt s dch v b sung cho mng. gii quyt vn ny ngi ta ngh n vic s ho cc h thng in thoi di ng, v iu ny dn ti s ra i ca cc h thng in thoi di ng th h 2.

    chu u, vo nm 1982 t chc cc nh cung cp dch v vin thng chu u (CEPT Confrence Europene de Postes et Telcommunications) thng nht thnh lp mt nhm nghin cu c bit gi l Groupe Spciale Mobile (GSM) c nhim v xy dng b cc ch tiu k thut cho mng in thoi di ng ton chu u hot ng

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    di tn 900 MHz. Nhm nghin cu xem xt nhiu gii php khc nhau v cui cng i n thng nht s dng k thut a truy nhp phn chia theo m bng hp (Narrow Band TDMA). Nm 1988 phin bn d tho u tin ca GSM c hon thnh v h thng GSM u tin c trin khai vo khong nm 1991. K t khi ra i, cc h thng thng tin di ng GSM pht trin vi mt tc ht sc nhanh chng, c mt 140 quc gia v c s thu bao ln ti gn 1 t. Lc ny thut ng GSM c mt ngha mi l h thng thng tin di ng ton cu (Global System Mobile). Cng trong thi gian k trn, M cc h thng in thoi tng t th h th nht AMPS c pht trin thnh cc h thng in thoi di ng s th h 2 tun th tiu chun ca hip hi vin thng M IS-136. Khi cng ngh CDMA (Code Division Multiple Access IS-95) ra i, cc nh cung cp dch v in thoi di ng M cung cp dch v mode song song, cho php thu bao c th truy cp vo c hai mng IS-136 v IS-95.

    Do nhn thc r v tm quan trng ca cc h thng thng tin di ng m Chu u, ngay khi qu trnh tiu chun ho GSM cha kt thc ngi ta tin hnh d n nghin cu RACE 1043 vi mc ch chnh l xc nh cc dch v v cng ngh cho h thng thng tin di ng th h th 3 cho nm 2000. H thng 3G ca chu u c gi l UMTS. Nhng ngi thc hin d n mong mun rng h thng UMTS trong tng lai s c pht trin t cc h thng GSM hin ti. Ngoi ra ngi ta cn c mt mong mun rt ln l h thng UMTS s c kh nng kt hp nhiu mng khc nhau nh PMR, MSS, WLAN thnh mt mng thng nht c kh nng h tr cc dch v s liu tc cao v quan trng hn y s l mt mng hng dch v.

    Song song vi chu u, Lin minh Vin thng Quc t (ITU International Telecommunications Union) cng thnh lp mt nhm nghin cu nghin cu v cc h thng thng tin di ng th h 3, nhm nghin cu TG8/1. Nhm nghin cu t tn cho h thng thng tin di ng th h th 3 ca mnh l H thng Thng tin Di ng Mt t Tng lai (FPLMTS Future Public Land Mobile Telecommunications System). Sau ny, nhm nghin cu i tn h thng thng tin di ng ca mnh thnh H thng Thng tin Di ng Ton cu cho nm 2000 (IMT-2000 International Mobile Telecommunications for the year 2000). ng nhin l cc nh pht trin UMTS (chu u) mong mun ITU chp nhn h thng chp nhn ton b nhng xut ca mnh v s dng h thng UMTS lm c s cho h thng IMT-2000. Tuy nhin vn khng phi n gin nh vy, c ti 16 xut cho h thng thng tin di ng IMT-2000 (bao gm 10 xut cho cc h thng mt t v 6 xut cho cc h thng v tinh). 3. Cc tiu ch chung xy dng IMT 2000 nh sau:

    IMT-2000 cung cp h tng k thut cho cc dch v gia tng v cc ng dng trn mt chun duy nht cho mng thng tin di ng.

    - S dng di tn quy nh quc t 2GHz nh sau: ung ln: 1885 2025 MHz; ng xung: 2110 -2200 MHz. IMT-2000 h tr tc ng truyn cao hn: tc

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    ti thiu l 2Mbps cho ngi dng vn phng hoc i b; 348Kbps khi di chuyn trn xe. Trong khi , h thng vin thng 2G ch c tc t 9,6Kbps ti 28,8Kbps.

    - L h thng thng tin di ng ton cu cho cc loi hnh thng tin v tuyn: + Tch hp cc mng thng tin hu tuyn v v tuyn + Tng tc cho mi loi dch v vin thng t c nh, di ng, thoi, d liu,

    Internet n cc dch v a phng tin - C th h tr cc dch v nh: + Cc phng tin ti nh o trn c s mng thng minh, di ng cc nhn v

    chuyn mng ton cu + m bo chuyn mng quc t cho php ngi dng c th di chuyn n bt k

    quc gia no cng c th s dng mt s in thoi duy nht. + m bo cc dch v a phng tin ng thi cho ting, s liu chuyn mch

    knh v s liu chuyn mch gi. - D dng h tr cc dch v mi xut hin. Mi trng hot ng ca IMT 2000 c chia thnh 4 vng vi tc bit R

    nh sau: + Vng 1: Trong nh, pico, Rb 2 Mbit/s + Vng 2: thnh ph, macr, R b 384 kbit/s + Vng 2: ngoi , macr, Rb 144 kbit/s + Vng 4: ton cu, Rb = 9,6 kbit/s. IMT-2000 c nhng c im chnh: 3.1 Tnh linh hot: Vi s lng ln cc v sp nhp v hp nht trong ngnh cng nghip in thoi

    di ng v kh nng a dch v ra th trng ngoi nc, nh khai thc khng mun phi h tr giao din v cng ngh khc. iu ny chc chn s cn tr s pht trin ca 3G trn ton th gii. IMT-2000 h tr vn ny, bng cch cung cp h thng c tnh linh hot cao, c kh nng h tr hng lot cc dch v v ng dng cao cp. IMT-2000 hp nht 5 k thut (IMT-DS, IMT-MC, TMT-TC, IMT-SC, IMT-FT) v giao tip sng da trn ba cng ngh truy cp khc nhau (FDMA - a truy cp phn chia theo tn s,

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    TDMA - a truy cp phn chia theo thi gian v CDMA - a truy cp phn chia theo m). Dch v gia tng trn ton th gii v pht trin ng dng trn tiu chun duy nht vi 5 k thut v 3 cng ngh.

    3.2. Tnh kinh t: S hp nht gia cc ngnh cng nghip 3G l bc quan trng quyt nh gia

    tng s lng ngi dng v cc nh khai thc. . 3.3. Tnh tng thch: Cc dch v trn IMT-2000 c kh nng tng thch vi cc h thng hin c.

    Chng hn, mng 2G chun GSM s tip tc tn ti mt thi gian na v kh nng tng thch vi cc h thng ny phi c m bo hiu qu v lin mch qua cc bc chuyn.

    3.4. Thit k theo modul: Chin lc ca IMT-2000 l phi c kh nng m rng d dng pht trin s

    lng ngi dng, vng ph sng, dch v mi vi khon u t ban u thp nht. Phn loi cc dch v ca IMT-2000

    Kiu Phn loi Dch v chi tit

    Dch v di ng

    Dch v di ng - Di ng u cui/di ng c nhn/di ng dch v Dch v thng tin nh v - Theo di di ng/theo di di ng thng minh

    Dch v vin thng

    Dch v m thanh - Dch v m thanh cht lng cao(16 64 kbit/s) - Dch v m thanh AM (32 64 kbit/s) - Dch v truyn thanh FM (64 384kbit/s)

    Dch v s liu - Dch v s liu tc trung bnh (64 144 kbit/s) - Dch v s liu tc tng i cao (144 2 Mbit/s) - Dch v s liu tc cao ( 2Mbit/s)

    Dch v a phng tin

    - Dch v Video (384kbit/s) - Dch v hnh chuyn ng (384kbit/s - 2Mbit/s) - Dch v hnh chuyn ng thi gian thc ( 2Mbit/s)

    Dch v Internet

    Dch v Internet n gin - Dch v truy nhp Web (384kbit/s - 2Mbit/s)

    Dch v Internet thi gian thc - Dch v Internet (384kbit/s - 2Mbit/s)

    Dch v internet a phng tin

    - Dch v Website a phng tin thi gian thc ( 2Mbit/s)

    4. L trnh pht trin t cc h thng th h hai n th h 3 4.1. Lch trnh nghin cu pht trin h thng thng tin di ng th h ba.

    Cng trnh nghin cu ca cc nc Chu u cho W-CDMA bt u t cc n CDMT (Code Division Multiple Testbed): Phng th nghim a truy nhp theo m) v FRAMES (Future Radio Multiple Access Scheme: S a truy nhp v tuyn tng lai) t u thp nin 90. Cc d n ny cng tin hnh thc nghim cc h thng W-

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    CDMA nh gi cht lng ng truyn. Cng tc tiu chun ho chi tit c thc hin 3GPP. Lch trnh trin khai W-CDMA c cho hnh v.

    Lch trnh nghin cu v a mng W-CDMA vo khai thc

    Chu u v Chu , h thng W-CDMA c a ra khai thc vo u nm 2002

    Lch trnh nghin cu pht trin ca cdma2000/3GPP2 chia thnh 2 pha: - Pha 1: (1997 1999) + Nghin cu pht trin mu u tin ca h thng; + Nm 1997: Xy dng tiu chun , xy dng cu trc mu u tin h thng v

    thit k cc phng tin th nghim chung. +Nm 1998: Tip tc xy dng mu th u tin ca h thng v cc phng tin

    th nghim chung; + Nm 1999: Kim tra kt ni cho m hnh u tin ca h thng. - Pha 2: (2000 -2002) + Pht trin h thng vi mc tiu thng mi cc nh sn xut hng u ; + Nm 2002: Bt u dch v thng mi

    4.2. L trnh pht trin t h thng IS-95 th h hai n cdma 2000 th h ba Mc d mng cdma One (IS-95) khng phi l cc mng u tin cung cp truy nhp s liu, nhng y l cc mng c thit k duy nht truyn s liu . Trc ht chng x l truyn dn s liu v ting theo cch rt ging nhau. kh nng truyn dn tc thay i c sn trong cdmaOne cho php quyt nh lng thng tin cn pht, v th cho php ch s dng tim nng mng theo nhu cu. V cc h thng cdmaOne s dng truyn ting ng gi trn ng trc (cc ng truyn dn t BTS n MSC), nn kh nng truyn s liu gi c sn trong thit b. Cng ngh truyn dn s liu gi ca cdmaOne s dng ngn xp giao thc s liu gi s t ong (CDPD: Cellular Digital Packet Data) ph hp vi TCP/IP. B sung