Hệ thống viễn thông di động toàn cầu_UMTS

8/2/2019 H thng vin thng di ng ton cu_UMTS

1/6

H thng vin thng di ng ton cu (UMTS)H thng vin thng di ng ton cu (UMTS) l 1 trong cc cng ngh di ng 3G. UMTSda trn nn tng CDMA bng rng (WCDMA), c chun ha bi T chc cc i tc phttrin 3G (3GPP), v l li p ca Chuu cho yu cu pht trin 3G i vi h thng di ngt ong ca t chc ITU IMT2000. UMTS i khi cn c gi l 3GSM, ch s kt hp v

bn cht cng ngh 3G ca UMTS v chun GSM truyn thng.Lch sNgay t u nhng nm 90 ca th k 20, Hip hi Tiu chun Vin thng chu u (ETSI) bt u trng cu phng n k thut ca tiu chun3G v vi vng gi chung k thut 3G lUMTS (Universal Mobile Telecommunications Systems) c ngha l cc h thng thng tin ding a nng. CDMA bng rng (WCDMA) ch l mt trong cc phng n c khuyn ngh(bng rng ln ti 5 MHz).Sau s tham gia tch cc ca Nht Bn vo vic xy dng cc tiu chun ny thc ynhanh chng s pht trin ca cng ngh3G trn phm vi ton cu. Nm 1998, chu u v Nhtt c s nht tr v nhng tham s ch cht ca Khuyn ngh CDMA bng rng v a n trthnh phng n k thut dng giao din khng gian FDD (ghp tn s song cng - Frequency

Division Duplex) trong h thng UMTS. V t phng n k thut nyc gi l WCDMA nu r s khc bit vi tiu chun CDMA bng hp ca M (bng rng ch c 1,25 MHz). Tip tc pht trin mt cch logic, UMTS tr thnh mt trong nhng tiu chun 3G ca t chctiu chun ho th gii 3GPP (T chc nhng ngi bn hp tc v 3G) v khng ch nh nghagiao din khng gian; ch th ca n bao gm cc khuyn ngh v cc giao din v mt lot ccquy phm k thut v cc mch kt ni v mch phn nhm nng ct caCDMA. UMTS l vit tt ca Universal Mobile Telecommunication System. UMTS l mng di ng thh th 3 (3G) s dng k thut tri ph W(wideband)-CDMA. UMTS c chun ha bi tchc 3GPP. UMTS i khi cn c gi l 3GSM ch kh nng "interoperability" gia GSMv UMTS. UMTS c pht trin ln t cc nc s dng GSM. UMTS s dng bng tng khcvi GSM.

c trngUMTS, dng cng ngh CDMA bng rng WCDMA, h tr tc truyn d liu ln n 21Mbps (v l thuyt, vi chun HSPDA). Thc t, hin nay, ti ng xung, tc ny ch cth t 384 kbps (vi my di ng h tr chun R99), hay 7.2 Mbps (vi my di ng h trHSPDA). D sao, tc ny cng ln hn kh nhiu so vi tc 9.6 kbps ca 1 n knhGSM hay 9.6 kbps ca a knh trong HSCSD (14.4 kbit/s ca CDMAOne) v mt s cng nghmng khc.Nu nh th h 2G ca mng t ong l GSM, th GPRS c xem l th h 2.5G. GPRS, dngchuyn mch gi, khc so vi chuyn mch knh (dnh knh ring) ca GSM, h tr tc dliu cao hn (l thuyt t: 140.8 kbit/s, thc t, khong 56 kbit/s). E-GPRS hay EGDE, c

xem l th h 2.75G, l s ci tin v thut ton m ha. GPRS dng 4 mc m ha (codingschemes; CS-1 to 4), trong khi EDGE dng 9 mc m ha v iu ch (Modulation and CodingSchemes; MCS-1 to 9). Tc truyn d liu thc ca EDGE t ti 180 kbit/s.T nm 2006, mng UMTS c nhiu quc gia nng cp ln, vi chun HSPDA, c xemnh mng 3.5G. Hin gi, HSPDA cho php tc truyn ng xung t 21 Mbps. Di hihn, mt nhnh ca t chc 3GPP ln k hoch pht trin mng 4G, vi tc 100 Mbit/s ngxung v 50 Mbit/s ng ln, dng cng ngh giao din v tuyn da trn Ghp knh tn strc giao.


2/6

Mng UMTS u tin trin khai nm 2002 nhn mnh ti cc ng dng di ng nh: TV di nghay thoi Video. Tuy nhin, kinh nghim trin khai Nht v mt s nc khc cho thy rng,nhu cu ngi dng vi thoi Video l khng cao. Hin ti, tc truyn d liu cao ca UMTSthng dnh truy cp Internet.

Cng ngh

Mt b pht ca UMTS t trn nc ta nhUMTS kt hp giao din v tuyn WCDMA, TD-CDMA, hay TD-SCDMA, li Pha ng dngdi ng ca GSM (MAP), v cc chun m ha thoi ca GSM. UMTS (W-CDMA) dng cc cp knh 5 MHz trong k thut truyn dn UTRA/FDD. Ban u,bng tn n nh cho UMTS l 18852025 MHz vi ng ln (uplink) v 21102200 MHz chong xung (downlink). M, bng tn thay th l 17101755 MHz (uplink) v 21102155MHz (downlink), do bng tn 1900 MHz dng.UMTS l mt mng RAN (mng truy nhp v tuyn) thay v GERAN nh ca GSM/EGDE.UMTS v GERAN c th dng chung mng li CN, v cho php chuyn mch thng sut giacc RAN nu cn. Mng li CN c th kt ni n nhiu mng ng trc khc nhau nh ca

Internet v ISDN. UMTS (cng nh GERAN) gm 3 lp thp nht ca m hnh truyn thngOSI. Lp mng (OSI 3) gm giao thc Qun l ti nguyn v tuyn RRM, qun l cc knh sngmang (bearer channels) gia my di ng v mng.
http://upload.wikimedia.org/wikipedia/commons/1/1e/UMTS-fridge.jpg


3/6

Kin trc mng UMTS

Kin trc mng UMTS

Nh hnh v th hin, Mng UMTS bao gm 2 phn, phn truy nhp v tuyn (UMTS TerrestrialRadio Access NetworkUTRAN) v phn mng li (core). Phn truy nhp v tuyn bao gmNode B v RNC. Cn phn core th c core cho data bao gm SGSN, GGSN; Phn core chovoice th c MCS v GMSC.

H thng vin thng di ng ton cu l 1 trong s cc chun di ng 3G, pht trin ln tEGDE 2.75G; GPRS 2.5G v mng t ong GSM 2G


4/6

Kin trc UMTS

Kin trc m

ng UMTS

Nh hnh v th hin, Mng UMTS bao gm 2 phn, phn truy nhp v tuyn (UMTSTerrestrial Radio Access Network- UTRAN) v phn mng li (core). Phn truy nhp vtuyn bao gm Node B v RNC. Cn phn core th c core cho data bao gm SGSN,GGSN; Phn core cho voice th c MCS v GMSC.Node B: Chc nng chnh ca Node B l x l lp vt l (L1) giao din v tuyn nh mha knh, an xen, tri ph, iu ch... N cng thc hin mt chc nng ti nguyn vtuyn nh iu khin cng sut vng trong,...RNC: Trong trng hp Node B ch c mt kt ni vi mng th RNC chu trch nhimiu khin Node B c gi l CRNC. Ngc li, khi Node B c hn mt kt ni mng thcc RNC c chia thnh hai loi khc nhau theo vai tr logic ca chng.

- RNC phc v(Serving RNC): y l RNC kt ni cng lu lng v bo hiuRANAP vi mng li.SRNC cng kt cui bo hiu iu khin ti nguyn v tuyn gia UEv UTRAN, x l s liu lp 2 (L2) t/ti giao din v tuyn. SRNC ca Node B ny cngc th l CRNC ca mt Node B khc.- RNC tri(Drift RNC): y l RNC bt k khc vi SRNC, iu khin cc c MS sdng. Khi cn, DRNC c th thc hin kt hp v phn chia phn tp v m. DRNCkhng thc hin x l lp 2 i s liu t/ti giao din v tuyn m chnh tuyn s liumt cch trong sut gia cc giao din Iub v Iur. MtUE c th khng c hoc c mt hay
http://vi.wikipedia.org/wiki/T%E1%BA%ADp_tin:UMTS_Network_Architecture.svg


5/6

nhiu DRNC.

Cc Giao din trong mng: Giao din Iub

Giao din Iub l mt giao din quan trng nht trong s cc giao din ca h thng mngUMTS. Sd nh vy l do tt ccc lu lng thoi v s liu u c truyn ti quagiao din ny, cho nn giao din ny tr thnh nhn t rng buc bc nht i vi nhcung cp thit bng thi vic nh c giao din ny mang ngha rt quan trng. cim ca giao din vt l i vi BTS dn n dung lng Iub vi BTS c mt gi tr quynh. Thng thng kt ni vi BTS ta c th s dng lung E1, E3 hoc STM1 nukhng c th s dng lung T1, DS-3 hoc OC-3. Nh vy, dung lng ca cc ngtruyn dn ni n RNC c thcao hn tng ti ca giao din Iub ti RNC.Chng hn nuta cn u ni 100BTS vi dung lng Iub ca miBTS l 2,5 Mbps, bit rng cu hnh chomi BTS hai lung 2 Mbps v tng dung lng kh dng ca giao din Iub s l 100 x 2 x 2

= 400 Mbps. Tuy nhin tng ti ca giao din Iub ti RNC vn l 250 Mbps ch khng phil 400 Mbps.

Giao din Iur

Ta c th thy r v tr ca giao din Iur trong cu hnh ca phn t ca mng UMTS. Giaodin Iur mang thng tin ca cc thu bao thc hin chuyn giao mm gia hai Node B cc RNC khc nhau. Tng tnh giao din Iub, rng bng ca giao din Iur gn bnghai ln lu lng do vic chuyn giao mm gia hai RNC gy ra.

Giao din Iu

Giao din Iu l giao din kt ni gia mng li CN v mng truy nhp v tuyn UTRAN.Giao din ny gm hai thnh phn chnh l: Giao din Iu-CS: Giao din ny ch yu l truyn ti lu lng thoi gia RNC vMSC/VLR. Vic nh c giao din Iu-CS ph thuc vo lu lng d liu chuyn mchknh m ch yu l lng ting. Giao din Iu-PS: L giao din gia RNC v SGSN. nh c giao din ny ph thuc volu lng d liu chuyn mch gi. Vic nh c giao din ny phc tp hn nhiu so vigiao din Iub v c nhiu dch v d liu gi vi tc khc nhau truyn trn giao din ny.

Giao din Uu

y l giao din khng dy (duy nht) ca mng UMTS. Tt c giao din khc u c dydn ht. Lin lc trn giao din ny da vo k thut FDD/TDD WCDMA. Tht ra, nu nhntrn tng th kin trc mng UMTS ta s thy l "nt c chai" ca mng UMTS chnh l capacity ca giao din Uu ny. N s gii hn tc truyn thng tin ca mng UMTS.Nu ta c thtng tc data rate ca giao din ny th ta c thtng tc ca mngUMTS. Th h tip theo ca UMTS s dng OFDMA kt hp MIMO thay v WCDMA tng tc ....

Li mng Core Network


6/6

Trong phn mng li (core) c 2 phn, mng li data (gm 2 thc th chnh l SGSN vGGSN) v mng li cho voice (gm GMSC v MSC). Ngoi 4 thc th va nu, chng tacn c cc thnh phn khc nh l HLR (HSS), VLR, AuC, EiR, BG. Vi tr, v cc chcnng chnh ca tng thnh phn sc miu t ngn gn trong bi vit ny.

SGSN = Serving GPRS Support Node. Trong mng li GPRS ca 1 operator cnhiu SGSN ch khng phi ch c 1. Mi SGSN kt ni trc tip vi 1 s RNC. Mi RNCli qun l 1 s Node B, v mi node-B s c mt sUE ang ni kt. SGSN qun l tt ccc UE ang s dng dch v data trong vng ca n. Vi tr ca SGSN l

-Authenticate (xc minh) cc UE ang dng dch v data ni kt vi n- Qun l vic ng k ca 1 UE vo mng GPRS (data)- Qun l qu trnh di ng ca UE. C th l SGSN phi bit l UE hin ang ni kt vithng Node-B no ti mt thi im. Ty theo UE ang mode active (ang lin lc) hayidle (khng lin lc) m chnh xc ca thng tin lin quan n v tr UE s khc nhau.SGSN s phi qun l v theo di sthay i v tr (location area identity/ routing area

identity) ca UE theo thi gian.- To dng, duy tr v gii phng cc "PDP context" (cc thng tin lin quan n connectionca UE m n cho php/qui nh vic gi v nhn thng tin ca UE)- Nhn v chuyn thng tin t ngoi mng data (Internet chng hn) n UE v ngc li.- Qun l vic tnh tin (billing) i vi cc UE- Tm v nh thc idle UE khi c cuc gi tm n UE (paging)- etc...

GGSN= Gateway GPRS Support Node . Nh ng tn gi ca n, n l mt cigateway gia mng GPRS/UMTS v cc mng ngoi (external network, nh Internetchng hn, cc mng GPRS khc). Vi tr ca n

- Nhn v chuyn thng tin t UE gi ra ngoi mng external v ngc li tngoi nUE. Packet thng tin t SGSN gi n GGSN sc "decapsulate" trc khi gi ra ngoiv thng tin truyn gia SGSN v GGSN l truyn trn 'GTP tunnel'.- Nu thng tin tngoi n GGSN gi n mt UE trong khi cha tn ti PDP context,th GGSN s yu cu SGSN thc hin paging v sau s thc hin qu trnh PDPcontext chuyn cuc gi n UE.- Trong sut qu trnh lin lc thng qua ni kt mng UMTS, UE s ch connect vi 1GGSN (m GGSN ni kt vi dch vm UE ang dng). D c di chuyn i u i na,GGSN vn khng i. D nhin l SGSN, RNC v Node-B sthay i. GGSN cng thamgia vo qun l qu trnh di ng ca UE.

SGSN v GGSN u c 1 a ch IP cnh (c th l private IP).

Documents

Hệ thống viễn thông di động toàn cầu_UMTS