Nghiên cứu kiến trúc và dịch vụ IMS trong các mạng thế hệ mới

bộ giáo dục đào tạo trờng đại học bách khoa hà nội - LUậN VĂN THạC Sỹ KHOA HọC Nghiên cứu kiến trúc dịch vụ Ims mạng hệ Ngành: kỹ thuật điện tử M số: đoàn thị quế Ngời hớng dẫn khoa học: TS NGUYễN NAM QUÂN Hà Nội Năm 2009 i LI CAM OAN Tụi xin cam oan lun thc s khoa hc ny chớnh tụi nghiờn cu v thc hin di s hng dn ca TS Nguyn Nam Quõn Nu cú gỡ sai phm, tụi xin hon ton chu trỏch nhim Ngi lm cam oan on Th Qu ii MC LC MC LC .ii DANH MC CC Kí HIU V T VIT TT v DANH MC CC HèNH V ix LI NểI U CHNG 1: TNG QUAN V NGN V PHN H IMS 1.1 Gii thiu 1.2 Mng vin thụng th h mi (NGN) 1.2.1 Khỏi nim NGN 1.2.2 Cu trỳc chc nng NGN 1.2.3 V trớ, vai trũ ca phõn h IMS kin trỳc NGN 10 1.3 Kt chng 13 CHNG 2: KIN TRC IMS 14 2.1 Cỏc yờu cu v kin trỳc 14 2.1.1 Thit lp cỏc phiờn IP Multimedia 14 2.1.2 H tr kt ni IP 14 2.1.3 C ch m bo QoS cho cỏc dch v IP Multimedia 16 2.1.4 Bo mt trao i 17 2.1.5 Tớnh cc 17 2.1.6 H tr chuyn vựng 19 2.1.7 Liờn lm vic vi cỏc mng khỏc 20 2.1.8 H tr iu khin dch v 21 2.1.9 Phỏt trin dch v 21 2.1.10 Thit k phõn lp 22 2.1.11 Truy nhp c lp 23 2.2 Cỏc giao thc chớnh c s dng IMS 24 iii 2.2.1 Giao thc iu khin phiờn SIP 24 2.2.2 Giao thc Diameter 36 2.2.3 2.3 Cỏc giao thc khỏc 39 Cỏc thc th chc nng kin trỳc IMS 39 2.3.1 Cỏc thc th iu khin phiờn, cuc gi (CSCFs) 40 2.3.2 Cỏc thc th c s d liu (HSS, SLF) 45 2.3.3 Mỏy ch ng dng (AS) 47 2.3.4 Thc th qun lý ti nguyờn a phng tin (MRF) 48 2.3.5 Cỏc thc th thc hin chc nng tng tỏc vi cỏc mng (BGCF, MGCF, IMS-MGW, SGW) 49 2.3.6 Thc th IMS-ALG v TrGW 51 2.4 Mt s giao din kin trỳc IMS 52 2.4.1 Giao din Gm 52 2.4.2 Giao din Mw 53 2.4.3 Giao din ISC 54 2.4.4 Giao din Cx 55 2.4.5 Giao din Mr 57 2.4.6 Giao din Mp 57 2.5 nh danh IMS 59 2.6 2.5.1 nh danh chung 60 2.5.2 nh danh riờng 61 2.5.3 Mi quan h gia nh danh chung v nh danh riờng 61 Tiờu chun lc, h s ngi dựng v h s dch v 62 2.7 Kt chng 67 CHNG 3: XY DNG DCH V GI TR GIA TNG TRấN NN KIN TRC IMS 69 3.1 Kin trỳc phõn phi dch v IMS 69 iv 3.2 Mt s dch v giỏ tr gia tng xõy dng trờn nn kin trỳc IMS 70 3.2.1 Presence 70 3.2.2 Conferencing 78 3.2.3 Messaging 82 3.3 Kt chng 87 CHNG 4: THC HIN Mễ PHNG DCH V INSTANT MESSAGING TRấN NN IMS 88 4.1 Gii thiu chung v phn mm OpenIMS ca FOKUS 88 4.2 Thc hin mụ phng dch v instant messaging trờn nn IMS 91 4.2.1 Mụ hỡnh trin khai dch v 91 4.2.2 Kt qu thc hin 91 KT LUN 95 TI LIU THAM KHO 96 TểM TT LUN VN 97 SUMMARY 98 v DANH MC CC Kí HIU V T VIT TT T vit tt 3GPP AAA API T gc Ngha ting Vit The 3rd Generation T chc (d ỏn) chun hoỏ mng Partnership Project di ng 3G Authentication/Authorizati Nhn thc, Cp quyn, Thanh on/Accounting toỏn Application Program Giao din chng trỡnh ng dng Interface AS Application Server Mỏy ch ng dng ATM Asynchronous Transfer Phng thc truyn khụng ng Mode b AuC Authentication Center Trung tõm nhn thc BGCF Breakout Gateway Control Chc nng iu khin cng Function chuyn tip Customized Applications Logic m rng dch v cho mng for Mobile network di ng CAMEL Enhanced Logic CDMA Code Division Multiple a truy nhp phõn chia theo mó Access COPS Comon Open Policy Giao thc trao i thụng tin chớnh Service sỏch dch v CS Circuit Switched Chuyn mch kờnh CSCF Call Session Control Chc nng iu khin phiờn Function DNS Domain Name System H thng tờn ETSI European Vin chun hoỏ vin thụng chõu vi Telecommunication u Standards Institute GGSN Gateway GPRS Support Nỳt h tr cng GPRS Node GPRS General Packet Radio Dch v vụ tuyn gúi chung Service HLR Home Location Register Thanh ghi nh v thng trỳ HSS Home Subcriber Server Mỏy ch cha d liu ca thuờ bao mng nh HTTP Hyper Text Transfer Giao thc truyn siờu bn Protocol I - CSCF Interrogating CSCF CSCF thc hin chc nng nh tuyn IETF Internet Engineering Task Nhúm c trỏch k thut Internet Force iFC Initial filter criteria Tiờu chun lc to IM CN IP Multimedia Core Mng lừi a phng tin IP Network IMS IMS-ALG IMSI Internet Protocol (IP) Phõn h a phng tin trờn nn Multimedia Subsystem giao thc IP IMS Application Level Cng chuyn tip mc ng Gateway dng ca mng lừi IMS International Mobile Ch s thuờ bao di ng quc t Subscriber Identifier IP Internet Protocol Giao thc Internet IPv4 Internet Protocol version Giao thc IP phiờn bn IPv6 Internet Protocol version Giao thc IP phiờn bn vii ISDN Integrated Services Digital Mng s tớch hp a dch v Network ITU-T Telecommunication B phn chun hoỏ v vin thụng Standardization Sector of - T chc Vin thụng quc t the International Telecommunication Union MGCF Media Gateway Control Chc nng iu khin cng Function phng tin MGW Media Gateway Function Chc nng cng phng tin MRFC Multimedia Resource B iu khin chc nng ti Function Controller nguyờn a phng tin Multimedia Resource B x lý chc nng ti nguyờn a Function Processor phng tin MSC Mobile Switching Centre Trung tõm chuyn mch di ng NGN Next Generation Network Mng th h mi LAN Local Area Network Mng cc b OSA Open Service Architecture Kin trỳc dch v m P - CSCF Proxy CSCF CSCF chc nng lm Proxy PDF Policy Decision Function Chc nng quyt nh chớnh sỏch PS Packet Switched Chuyn mch gúi QoS Quality of Service Cht lng dch v RTCP Real-time Transport Giao thc iu khin truyn d Control Protocol liu thi gian thc Real-time Transport Giao thc truyn d liu theo thi Protocol gian thc S - CSCF Serving CSCF CSCF phc v SCE Service Creation Mụi trng kin to dch v MRFP RTP viii Environment SCS Service Capability Server Server tớnh nng phc v SDH Synchronous Digital Phõn cp s ng b Hierachy SDP Session Description Giao thc mụ t phiờn Protocol SDS Service Developing Thc th h tr phỏt trin dch v Support SIP Session Initiation Protocol Giao thc to phiờn SLF Subscriber Locator Chc nng nh v thuờ bao Function SGSN Serving GPRS Support Nỳt h tr dch v GPRS Node SGW Signalling Gateway Chc nng cng bỏo hiu Function TCP Transmission Control Giao thc iu khin truyn dn Protocol TISPAN THIG Telecoms & Internet T chc chun hoỏ cho mng tiờn converged Services and tin s dng cỏc giao thc v Protocols for Advanced dch v hi t cho mng Vin Networking thụng v mng Internet Topology Hiding Inter- Cng liờn mng n cu hỡnh network Gateway TLS Transmission Layer Bo mt lp truyn dn Security TrGW Transition Gateway Thnh phn chuyn i phiờn bn IP ix UDP User Datagram Protocol Giao thc d liu ngi dựng UE User Equipment u cui thuờ bao URI Uniform Resource nh danh ti nguyờn Identifier WDM Wavelength Division Ghộp kờnh phõn chia theo bc Multiplexing súng DANH MC CC BNG BIU Bng 2.1: Cỏc bn tin yờu cu ca SIP 31 Bng 2.2: Cỏc bn tin ỏp ng ca SIP 33 Bng 2.3: Cỏc thc th IMS v giao din tng ng 57 DANH MC CC HèNH V Hỡnh 1.1: Phõn h IMS hi t mng Hỡnh 1.2: Cỏc lp chc nng ca NGN Hỡnh 1.3: Cu trỳc chc nng mng NGN theo 3GPP/TISPAN 10 Hỡnh 1.4: Kin trỳc IMS NGN 13 Hỡnh 2.1: Cỏc kh nng la chn kt ni IMS mt ngi s dng ang chuyn vựng 15 Hỡnh 2.2: Tng quan v bo mt ca IMS 17 Hỡnh 2.3: Tng quan tớnh cc IMS 18 Hỡnh 2.4: S la chn chuyn vựng IMS/CS 19 Hỡnh 2.5: Kin trỳc phõn lp ca IMS 22 Hỡnh 2.6: H tr cỏc truy nhp c lp IMS 23 Hỡnh 2.7: SIP Proxy Server 28 84 ny s lu li bn tin v ngi dựng ng ký thỡ server s gi bant in nhn ti ngi dựng Thụng thng mt tin nhn thng c gi n mt a ch l mt nhn dng cụng cng ca ngi dựng Tuy nhiờn, ngi dựng cng cú th gi mt tin nhn riờng l ti mt vi ngi nhn s dng server danh sỏch Mt ngi dựng IMS v c bn cú th to mt danh, s dng a ch SIP cú dng l nhn dng dch v cụng cng (PSI) v to danh ny vi mt hp cỏc SIP URI Bt c no mt MESSAGE request c gi ti PSI tng ng vi danh sỏch ny, request c nh tuyn ti server danh sỏch Server danh sỏch s nhn tin nhn ny v to ln lt mt request mi cho mi mt thnh viờn danh sỏch Hỡnh 3.13: Vớ d v dch v c cung cp tin nhn tc thi 85 Hỡnh 3.13 ch mt vớ d v mt dch v cung cp cho khỏch hng s dng tin nhn tc thi Trong vớ d ny, AS úng vai trũ l b iu khin ca h thng voicemail AS quan tõm no thỡ ngi dựng ng nhp vo mng IMS, AS cú th thụng bỏo ti ngi dựng v nhng voicemail m ngi dựng cha nhn Dch v ny c thc hin nh sau: - Ngi dựng ng ký vi mng IMS nh thụng thng - Khi ng ký thnh cụng thỡ S CSCF ỏnh giỏ b lc tiờu chun Mt nhng b lc tiờu chun ch th rng S-CSCF cn phi thc hin ng ký thnh viờn th ba vi mt AS khỏc - S-CSCF gi ng ký ti AS ny Mc ớch ca ng ký ny nhm bỏo cho AS bit rng ngi dựng ó ng nhp thnh cụng vo mng IMS - Sau nhn ng ký (21), AS to bn tin MESSAGE request cha ng mt vi thụng tin hu ớch, cú th l a ch ca mt website ngi dựng cú th vo website ny ly cỏc voicemail 3.2.3.4 Messaging da trờn phiờn Trong ch ny ngi dựng tham gia mt phiờn m phiờn ú ni dung media ch yu l cỏc tin nhn bn ngn Cng nh cỏc phiờn thụng thng khỏc, mt phiờn tin nhn tn ti t cỏc thnh phn tham gia bt u phiờn Sau phiờn c thit lp thỡ lung bn tin i trc tip t ngi dựng ny n ngi dựng khỏc Messaging da trờn phiờn cú th l ngang hng ging vi mt cuc gi thoi thụng thng, vi s khỏc nht l ni dung media ch yu l tin nhn Phiờn ny cng cú th kt hp vi cỏc phiờn media khỏc Giao thc c s dng truyn ti nhng tin nhn phiờn l Message Session Relay Protocol (MSRP) MSRP l mt giao thc da trờn text Cỏc bn tin MSRP cú th l request hoc response, nhng khụng ging giao thc SIP, khụng phi MSRP 86 request no cng c tr li bi mt MSRP respone Hin ti cú ba method c nh ngha MSRP, ú l: + Send: Gi mt tin nhn vi mt kớch thc tu ý t mt im cui ti mt im cui + Report: Mt im cui hoc im chuyn tip cung cp thụng bỏo truyn ti tin nhn + AUTH: c s dng bi mt im cui nhn thc MSRP s dng TCP (Transmission Control Protocol) nh l giao thc cho tng transport v cú th mang cỏc d liu c úng gúi theo kiu MIME (Multipurpose Internet Mail Extension) Tin nhn cú kớch thc tu ý vỡ c im ca giao thc MSRP l cú kh nng truyn mt bn tin kớch thc ln v chia thnh nhng gúi nh truyn i, sau ú cỏc gúi nh c t ng ghộp li phớa ngi nhn Hỡnh 3.14 th hin lung bn tin in hỡnh ca mt phiờn tin nhn Hỡnh 3.14: Lung bn tin in hỡnh ca messaging da trờn phiờn 87 3.3 Kt chng Trờn õy l c s lý thuyt cho vic xõy dng mt s dch v giỏ tr gia tng c bn trờn nn kin trỳc IMS õy khụng phi l nhng dch v cui cựng, cỏc nh cung cp dch v cú th phỏt trin cỏc dch v mi mt cỏch d dng da trờn cỏc nn tng dch v ca IMS Trong mụ hỡnh kin trỳc dch v ca IMS, kin trỳc linh hot v cú tớnh m nht l kin trỳc OSA, nú giỳp cho cỏc nh cung cp th cú th ch ng vic xõy dng, phỏt trin v trin khai cỏc dch v Vic phỏt trin cỏc gateway cho NGN l mt nhng bc i ban u l trỡnh phỏt trin kin trỳc OSA cho NGN/IMS 88 CHNG 4: THC HIN Mễ PHNG DCH V INSTANT MESSAGING TRấN NN IMS 4.1 Gii thiu chung v phn mm OpenIMS ca FOKUS OpenIMS l mt d ỏn trin khai IMS trờn mó ngun m ca FOKUS (Fraunhofer Institute for Open Communication Systems) D ỏn mó ngun m OPENIMS nhm mc ớch ỏp ng s thiu ht ca cỏc phn mm mó ngun m cho IMS vi nhng gii phỏp linh ng v cú th m rng c Mc ớch ca nú l to mt cng ng cỏc nh phỏt trin cho phn core ca mng NGN Phn mm mó ngun m ny cho phộp s phỏt trin ca cỏc dch v IMS v th nghim cỏc khỏi nim xung quanh phn IMS core Hỡnh 4.1 mụ t cỏc thnh phn chớnh ca OpenIMS Hỡnh 4.1: Cỏc thnh phn ca OpenIMS * Open Source IMS Core: õy l phn lừi ca OpenIMS, nú gm cú thnh phn chớnh : + HSS (Home Subcriber Server): Trong OpenIMS gi l FHoSS 89 + Call Session Control Functions ( CSCFs ): L trung tõm ca mó ngun m Open Source IMS Core, ny iu khin bt k bỏo hiu IMS no OpenIMSCore c a ti website http://openimscore.org/ c phỏt trin ti website http://developer.berlios.de/projects/openimscore/ *u cui IMS (IMS Client): Trong tt c cỏc thnh phn ca OpenIMS, IMS client l thnh phn quyt nh ỏnh giỏ s thnh cụng ca IMS Nú hot ng nh mt mụi trng a ng dng chng minh kh nng phỏt trin dch v trờn mng IMS Cú nhiu phn mm IMS Client, b khung OpenIMS Client ca FOKUS cung cp giao din lp trỡnh c cho cỏc nh phỏt trin dch v ca IMS c im ca OpenIMS Client: + Xõy dng cỏc IMS API chun + Cú kh nng thay i mt cỏch mm theo yờu cu + Tng thớch a nn (Windows XP, Windows CE, Linux) + c trin khai trờn Java hoc NET + D dng kt ni vi cỏc thit b khỏc + Tuõn theo cỏc chun IEFT, 3GPP, TISPAN Hỡnh 4.2: OpenIMS Client chy ln u tiờn 90 Khi OpenIMS Client ng ln u tiờn, nú s hin ca s cho phộp cu hỡnh Phn User Profile ta cú th cu hỡnh cỏc thụng s sau: + Display name: Tờn ngi s dng s c dựng ng dng + Public Identity: Nhn dng cụng cng, vớ d sip:ha@open-ims.test + Private Identity: Nhn dng cỏ nhõn, vớ d ha@open-ims.test + Secret Key: Chỡa khúa bo mt, s c s dng cỏc quỏ trỡnh chng thc trờn mng Phn Server profile cho phộp ta cu hỡnh: + Proxy IP: a ch IP ca mỏy ch P-CSCF mng, vớ d 192.168.7.97 + Port Nr: S cng ca P-CSCF mng, vớ d 4060 + Realm : Tờn ca mng IMS, vớ d open-ims.test * Open IMS SIP AS ( SIPSEE Sip Servlet Execution Environment ) õy l SIP Application Server cung cp s hi t ca mụi trng dch v l SIP v HTTP cho vic xõy dng cỏc dch v * Parlay X Gateway (OCS-X) Cho phộp cỏc nh phỏt trin dch v to cỏc ng dng qua web * IMS Management Kin trỳc IMS Management qun lý v iu khin mi thnh phn cn cho mng lừi IMS * XML Document Management Server ( XDMS) Mỏy ch cung cp hng dn ngi dung v thụng tin dch v v cỏch truy cp * Media Server: H tr cỏc dch v nh : + Voicemail, lu li bn tin ri gi vo mail 91 + Hi tho ( Conferencing ) + Nhc ch 4.2 Thc hin mụ phng dch v instant messaging trờn nn IMS Phn ny s thc hin vic mụ phng liờn quan n ti, da trờn phn mm OPENIMS thc hin dch v Instant Messaging gia cỏc ngi dựng 4.2.1 Mụ hỡnh trin khai dch v Hỡnh 4.3: Mụ hỡnh thc hin dch v instant messaging IMS 4.2.2 Kt qu thc hin chy dch v instant messaging, u tiờn phi chy core bao gm P-CSCF, I-CSCF, S-CSCF v FhoSS, t cu hỡnh cho cỏc IMS client Hai IMS client c s dng thc hin dch v Messaging l alice@ims.hut.vn v bob@ims.hut.vn Tip n tin hnh ng ký ng nhp vo h thng cho cỏc IMS Client Sau c client thc hin ng ký ti h thng, trng thỏi ca hai client ny l available 92 Hỡnh 4.4: Trng thỏi ngi dựng trờn mỏy Alice client Hỡnh 4.5: Trng thỏi ngi dựng trờn mỏy Bob client Trờn mỏy Alice client, tab Instant Messaging, gừ vo a ch URI ca Bob V bm Start Chat 93 Hỡnh 4.6: Gừ a ch URI ca Bob trờn mỏy Alice client Xut hin ca s instant messaging ca Alice, gừ ni dung tin nhn v n nỳt Start chat, ú tin nhn s c gi ti Bob Hỡnh 4.7: ca s instant messaging ca Alice Ni dung tin nhn c hin ca s ca instant messaging nh hỡnh 4.8 94 Hỡnh 4.8: Ni dung tin nhn 95 KT LUN Nhng kt qu t c ca lun vn: - Phõn tớch c vai trũ hi t mng v tớch hp dch v ca IMS mng NGN - Phõn tớch c chc nng ca cỏc thc th kin trỳc mng lừi IMS ng thi trỡnh by khỏ chi tit v giao thc SIP, l giao thc bỏo hiu chớnh c s dng IMS - Phõn tớch cu trỳc phõn phi dch v, cỏc nn tng dch v, c ch kớch hot dch v IMS - a c s lý thuyt xõy dng cỏc dch v giỏ tr gia tng trờn nn IMS nh dch v: presence, conferencing, messaging ú l nhng dch v tng lai s tr nờn ht sc ph bin cho ngi dựng di ng ca mng 3G - Thc hin mụ phng dch v Instant messaging s dng phn mm mó ngun m OPEN IMS Nhng hng nghiờn cu tip theo: Do thi gian cú hn, lun mi ch dng li vic nghiờn cu lý thuyt v kin trỳc IMS, c s lý thuyt xõy dng mt s dch v giỏ tr gia tng trờn IMS da theo cỏc ti liu chun gn nht ca 3GPP, IETF, ESTI/TISPAN Trong thi gian ti, lun tip tc cp nht nhng chun mi v IMS, tỡm hiu thờm c s lý thuyt xõy dng dch v IPTV trờn nn IMS, õy l dch v tng lai s mang li ngun doanh thu ln cho cỏc nh khai thỏc vin thụng ng thi, trờn c s lý thuyt xõy dng cỏc dch v ó nghiờn cu c, lun s tin hnh phỏt trin mt s dch v media ng dng NGN 96 TI LIU THAM KHO Ting Vit [1] Ngụ M Hnh (2006), Mng th h sau v tin trỡnh chuyn i, NXB Bu in, H Ni Ting Anh [2] 3GPP, http:// www.3gpp org/ftp/Specs [3] 3GPP TS 23.002: Network Architecture [4] 3GPP TS 23.221: Architectural requirements [5] 3GPP TS 22.228: Service requirements for the IP multimedia core network subsystem [6] ESTI/T ISPAN, http:// www etsi.org/tispan [7] IETF, http:// www ietf org/rfc [8] IETF RFC 3261: Session Initiation Protocol [9] IETF RFC 3588: Diameter command Protocol [10] ITU-T, http://www.itu.int [11] http://www.openimscore.org [12] Gonzalo Camarillo and Miguel A.Garcia-Martin, The 3G IP Multimedia Subsystem (IMS): Merging the Internet and the Cellular Worlds, Second Edition, John Wiley & Sons, 2006 [13] Miika Poikselka, Georg Mayer, Hisham Khartabil and Aki Niemi, The IMS: IP Multimedia Concepts and Services, Second Edition, John Wiley & Sons, 2006 97 TểM TT LUN VN Ni dung ca lun c trỡnh by chng: Chng 1: Gii thiu xu hng phỏt trin mng vin thụng, vai trũ ca IMS s hp nht cỏc mng Chng ny cng gii thiu tng quan v cu trỳc NGN thy c v trớ, vai trũ ca IMS 3GPP kin trỳc ny Chng 2: Nghiờn cu v kin trỳc IMS theo tiờu chun ca 3GPP bao gm: cỏc yờu cu v kin trỳc, cỏc giao thc chớnh c s dng, cỏc thc th mng, chc nng ca cỏc thc th v mt s giao din quan trng kin trỳc IMS Chng 3: Trỡnh by cu trỳc phõn phi dch v, cỏc nn tng dch v, c s lý thuyt xõy dng cỏc dch v giỏ tr gia tng (presence, conferencing, messaging) trờn nn IMS Chng 4: Gii thiu v phn mm mó ngun m OPEN IMS ca FOKUS Thc hin mụ phng dch v Instant messaging gia IMS client s dng phn mm OPEN IMS 98 SUMMARY Content of the thesis is presented in four chapters: Chapter 1: Introduction on development trend of telecommunication networks, role of IMS in converged networks This chapter also presented an overview of NGN architecture in order to indicate the position and the role of IMS - 3GPP in this architecture Chapter 2: Research on the architecture of the 3GPP IMS standard, including: architectural requirements on the protocols to be used, the network entities, the functions of the entities and reference points (interfaces) between the network entities Chapter 3: Understanding on the structure of service distribution, the service platform, basis of theory building value added services (presence, conferencing, messaging services) based on the IMS Chapter 4: Introduction on open source software (Open IMS) of the FOKUS Sumulation of Instant messaging service between two IMS clients using OPEN IMS ... Mj Gi BGCF MRF Mm MGW Dữliệuvàbáohiệu Báohiệu MRFC Mp Mi SGSN Iu Mr T-SGW Mk MạngIMSngoài MạngPSTNkếthừa Hỡnh 1.4: Kin trỳc IMS NGN 1.3 Kt chng Kin trỳc NGN s dng IMS lm phõn h iu khin chung... vai trũ ca phõn h IMS kin trỳc NGN IMS u nh mt chun cho mng vụ tuyn c cu thnh v phỏt trin bi 3GPP Sau ú cỏc t chc 3GPP2, ESTI/TISPAN, ITU-T ó sm nhn thy th mnh ca IMS v la chn IMS nh mt phn ca... tin IP Network IMS IMS-ALG IMSI Internet Protocol (IP) Phõn h a phng tin trờn nn Multimedia Subsystem giao thc IP IMS Application Level Cng chuyn tip mc ng Gateway dng ca mng lừi IMS International