de tai iptv

8/13/2019 De tai IPTV

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Bng 1. Hthng truyn hnh trn mng xDSL

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Phn 1GII THIU IPTV V

CC DCH VNG DNG

1.1.Khi nimIPTV (Internet Protocol Television) l dch vtruyn ti hnh nh kthut sti ngisdng qua giao thc IP trn mng Internet vi kt ni bng thng rng. N thngc cung cp kt hp vi VoIP, video theo yu cu... nn cn c gi l cng nghTriplePlay (d liu, m thanh v hnh nh). Nhng trong mt mi trng m thchthc nhn ln theo cp smv cng nghphi lin tc c cp nht, bba dch vni trn chuyn thnh btkhi c thm xem truyn hnh Internet qua in thoi ding (MobileTV).

Hnh 1. IPTV Cng nghca tng lai

Khnng ca IPTV gn nh l v hn v n ha hn mang n nhng ni dungkthut scht lng cao nh video theo yu cu (Video-on-Demand- VoD), hi tho,truyn hnh tng tc/trc tip, game, gio dc txa, video blogging (vBlog), tin nhnnhanh qua TV...

Trc y, cng nghny gn nh khng thhot ng c do tc kt niquay squ chm., nhng trong vi nm ti, IPTV strnn thnh hnh bi hn 100


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triu hgia nh trn ton thgii ng k thu bao bng thng rng. Cc nh cungcp dch vvin thng coi IPTV nh mt c hi tng doanh thu trn thtrng v lvkh li hi chng li sbnh trng ca truyn hnh cp.

1.2.Phn loi dch vIPTVHthng IPTV pht trin da trn hthng mng bng thng rng ang trin khai, ckhnng cung cp c cc dch vnh m tphn di y.

Hnh 2. Cc dch vIPTV c cung cp

1.2.1.Dch vtruyn hnh qung b1.2.1.1.Live TVy c hiu l dch v truyn hnh s trn nn mng IP cung cp dng pht(Broadcast) nhng chng trnh truyn hnh c thu li ththng truyn hnh mtt, truyn hnh cp, truyn hnh vtinh hoc knh truyn hnh ring ti khch hng.

Cc knh truyn hnh c thu tnhng ngun thu khc nhau, bao gm: Cc knh truyn hnh analog ca quc gia. Cc knh truyn hnh c thu min ph tvtinh. Cc knh truyn hnh m ho tvtinh. Cc knh truyn hnh ring ca nh cung cp TV.

Vi gii php IPTV, nh cung cp dch v c thng nhiu loi knh truynhnh thnh cc gi nhm cung cp cho khch hng vi cc gi cc linh hot khc


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nhau. Cc knh truyn hnh c h tr tnh nng tr tin theo tng knh hoc theotng thi im ngi xem mun xem (Pay-per-View PPV). Set-top-box (STB) cgiao din hng dn xem chng trnh v k hoch pht sng chng trnh TV cpnht d dng. Ngi xem c th chuyn knh thun tin trn STB ti u cui cakhch hng.

1.2.1.2.Time-shifted TVTnh nng tm dng TV l tnh nng gip ngi xem c thtm dng knh truyn hnhang pht v c thxem tip sau . V d ngi xem tm dng khi cn nghe inthoi, sau khi cuc gi kt thc ngi xem c thxem chng trnh TV tip tc tthiim trc hoc xem tip nh bnh thng.

Giao din v chc nng ca dch vc thhin r rng, trc quan thng quaEPG v STB, thun tin cho ngi sdng. Ngi dng c thxem tip tthi imtm dng v hthng p ng knh LiveTV nh bnh thng.

Hnh thc ny c thtnh ph linh hot, thu cc theo gi dch vhoc theo PPV.1.2.1.3.Virtual Channel from VoDsChc nng ny cho php hthng ghp mt sni dung VoD ty chn thnh mt knhring v pht trn mng. Sau khi kch hot, knh o ny hot ng v c y cctnh nng nh mt knh TV bnh thng.

Dch vny cho php bin tp cc ni dung VoD cng th loi (m nhc, thitrang, th thao, ..) thnh mt knh chuyn theo th hiu ca khch hng. Ngiqun trc khnng qun l v theo di cc knh o to ra.

1.2.1.4.NVoD (Near Video on Demand)Chc nng ny cho php hthng pht mt chng trnh truyn hnh hoc VoD

ty chn lp li nhiu ln trn cc knh multicast khc nhau. Vi cng mt ni dungpht cch nhau mt khong thi gian (Interval), do vy khch hng c thtrtin PPV(Pay-per-view) v xem ti cc thi im ty .

H thng c kh khnng thit lp dch vNVoD vi cc chng trnh truynhnh hoc VoD. Htrkhnng tnh cc theo PPV hoc theo gi dch v.

1.2.1.5.Mobile TVDch vny l hng pht trin tng lai m bo cung cp knh truyn hnh, VoD vcc dch vca hthng IPTV n cc khch hng ca mng di ng.

Gii php hon chnh hthng IPTV c thkt ni, trin khai cung cp dchvMobile-TV. Vic tnh cc c thtch hp vi hthng Billing c lp c cc

phng thc tnh cc linh ng v hiu qu.


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1.2.2.Dch vtheo nhu cu (On-Demand)1.2.2.1.VoD (Video on Demand)i vi dch vvideo theo yu cu (VoD), ngi xem la chn cc video (phim, videoclip) trc tip tth vin ca nh cung cp xem qua trn TV ca khch hng. Th

vin htrtnh nng tm kim, hin thdanh sch v miu tcc video cng vi vicgii thiu hp dn ca video. Nhm khuyn khch khn gimua phim, ngi xem sc xem qua cc bn tm tt phim, xem trc cc on phim demo ri mi quytnh c mua hay khng.

Dch vVoD c nhng tnh c bn ca thit bghi hnh VCR nh l tm dng,chy tip, chuyn nhanh vpha trc, chuyn nhanh vpha sau. Tnh nng chuynnhanh vpha trc, chuyn nhanh vpha sau cn t c tc 2X, 4X, 8X, 16X,32X v 64X.

Hthng cho php gii thiu thng tin tm tt vcc bphim v video trn giao

din ca EPG. Ty vo mc ch kinh doanh ca nh cung cp dch v, ngi xem cthxem nhiu ln bt clc no nh chpht sng. Nh cung cp c thgn kmtrailer qung co v ni dung demo, h tr lu cc thng tin VoD a thch voFavourite, sau c thchn li. Chc nng kho chng trnh, phim hoc ni dungkhng dnh cho trem.

VoD c thphn loi thnh VoD min ph (Free on Demand - FoD) v VoD trtin.

1.2.2.2.TVoD (TV on Demand)Tnh nng ny cho php cc chng trnh LiveTV c lu li trn server trong mt

khong thi gian no . Khch hng sau c thla chn xem li (nh i viVoD) cc chng trnh m mnh bl.

Thi gian lu tr cc chng trnh c tht thay i linh ng theo nhu cuthc t. H thng s h tr c 2 cch thc l lu tr theo thi gian v lu tr theochng trnh c chn no .

Thng tin vcc (nu c) i vi dch vc hin thng n khch hnga ra quyt nh la chn.

Htrcc tnh nng c bn ca thit bghi hnh VCR, l tm dng, chy tip,chuyn nhanh vpha trc, chuyn nhanh vpha sau. Tnh nng chuyn nhanh v

pha trc, chuyn nhanh vpha sau cn t c tc 2X, 4X, 8X, 16X, 32X v64X.

1.2.2.3.Games on Demand (Chi game theo yu cu)Dch vny cung cp nhng tr chi gii tr n gin cho khch hng. Cc tr chiny c thchi trc tuyn bng cch truyn (streaming) ththng IPTV server n


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STB. STB thng phi htrJava (JVM) chi c cc game. Hthng c chtnh im v ghi thng tin ngi chi.

1.2.2.4.Music on DemandCc thu bao c thxem nhng clip ca nhc theo yu cu ging nh dch vVoD.

1.2.2.5.Karaoke on DemandCc thu bao c th chn v xem cc bi karaoke qua STB trn TV. T list cc bikaraoke c gii thiu, thu bao c thmua mt hoc nhiu bi ht cng lc. Bngcch ghp ni thm hthng m thanh chuyn dng, khch hng c ththoi mi htkaraoke theo yu cu.

H thng c kh nng qun l, tm kim ni dung karaoke theo yu cu. Tmkim theo tn bi ht hoc tn ca s, cho php cp nht v b sung cc ni dungkaraoke ddng. Htrplaylist lu danh sch cc bi ht c chn. Hthng c ch

tnh im v ghi thng tin ngi ht. H tr ghi thng tin bi ht vo th mcFavorite.

1.2.3.Dch vtng tc (Interactive)1.2.3.1.Personal Video Recorder (PVR), Client Personal Video Recording (cPVR)Trong trng hp ny, thu bao c ththu li cc chng trnh vo th mc ca mnh,cc thu bao s tr tin thng qua ti khon. i vi ni dung c m ho, khogii m sc download ttrn hthng ti thi im xem ni dung. Chc nng nythu bao c thchia snhng hnh nh ca hcho bn b v nhng ngi thn ca

h.1.2.3.2.Networked Personal Video Recorder (nPVR)nPVR l mt thnh phn mng ghi v pht li ni dung ca cc knh truyn hnh.C thkhng nht thit ghi li tt ccc knh truyn hnh, nPVR sgii hn trc chnhng chng trnh c chn, nhng chng trnh ny c thc ghi li vi mcch iu khin lu trdliu.

EPG sc nhim vxc nh xem knh no m nPVR c thcung cp. Da trnlist ny, cc thu bao c th lu li cc chng trnh m h chn trong th vinnPVR hoc thng qua EPG chng hn nh mt biu tng hay mt icon. Trong lc

xem nhng chng trnh do nPVR cung cp, thu bao c thtuthch sdng nhngcc chc nng iu khin nh Play, Pause, FF, RW. Nh cung cp dch vsthit lpcc quy tc ghi cho mi knh TV ring, chng hn thi gian lu trcho knh c ghi.


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1.2.3.3.Guess v VotingCung cp tnh nng bnh chn trc tip v dch vtr chi don cho ngi xem quaTV. Vic d on, bnh chn c kt hp th hin trc tip trn cc chng trnhtruyn hnh.

Cho php to cc kch bn bnh chn hoc d on d dng v linh ng theonhiu tiu ch khc nhau. Chc nng bnh chn c th thc hin ng thi trong khivn ang xem chng trnh TV.

Htrm thanh, hnh nh minh ha cho cc mc a ra. Thao tc bnh chn,don cn c htrthun tin thng qua Remote Control.

1.2.3.4.TV EducationCung cp tt ccc dch vhc tp, o to theo cc ni dung v theo tng la tui.H thng h tr khnng qun l ni dung cc chng trnh hc tp, o to. Giaodin hthng m bo thn thin, EPG hin thddng thun tin cho khch hng.

H thng cho php pht trin, tch hp thm cc dch v learning mi vo hthng IPTV hin ti theo yu cu. C gii php hon chnh cho cc nh cung cp third-

party tch hp vo hthng cung cp dch v.

1.2.3.5.TV CommerceThng mi qua TV l cc dch vtng tc cho php khch hng trao i, mua bnv u gi nhng sn phm c gii thiu trn TV hoc nhng chng trnh qungco. thu bao c thng k, thc hin cc dch v ny h thng cn h tr cc

phng thc t hng, thanh ton, giao hng n tn tay ngi dng.

Hthng c sng b, nht qun tserver, middleware, EPG n STB cungcp dch vn khch hng. H trgii thiu, qung b cc thng tin sn phm trncc knh Live TV, VoD .. mt cch linh ng v hiu qu. C gii php tch hp vihthng thanh ton qua ngn hng, gii php m bo an ton cho Online-Payment.

1.2.3.6.Chc nng tng tc qua mobileDch vny cho php thu bao c thxem v tng tc hnh nh thng qua cc thit bcm tay nh trn mn hnh TV. Ngoi ra cn c thcho php thu bao tthit bcmtay ca mnh iu khin mi qu trnh tng tc ca STB i vi hthng qua thit bcm tay ca mnh.

V d, khi thu bao ang bn i cng tc nhng mun thu mt chng trnh mhthch xem ti mt thi im no vo bnhtrn STB ca mnh ti nh. Hcthiu khin tthit bcm tay ca htrn thit bcm tay.


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1.2.4.Dch vthng tin v truyn thng1.2.4.1.Internet on TV (Web Browser)Dch vny cho php ngi dng truy cp vo nhng trang web trn Internet. Hchcnng sc cc tnh nng c bn ca trnh duyt web nh Back, Refresh, Stop, History

v Boookmark, ..Cc thnh phn h thng middleware, EPG, STB c c ch duyt cc trang

web v hin th thng tin chnh xc ln mn hnh. Ni dung hin th c th thay ifont chtheo yu cu. Htrfont chUnicode.

1.2.4.2.TV InformationDch vny cung cp cc thng tin n khch hng thng qua h thng IPTV. Ccthng tin c th cung cp rt a dng v phong ph, bao gm tin tc, thng tin thtrng, mua sm, thng tin chng khon, u gi, d bo thi tit, thng tin giao

thng, Cho php pht trin, tch hp thm cc dch vthng tin mi vo Hthng IPTV

hin ti. Cc nh cung cp ni dung thng tin third-party c thtch hp vo hthngcung cp dch v.

1.2.4.3.TV MessagingChc nng ny cho php ngi xem TV c thchat trc vi nhau thng qua hthngIPTV. Ngoi chat trc tip vi nhau, khch hng c thchat vi cc ngi dng ca hthng khc nh Yahoo, MSN, cc tin nhn SMS ..

Hthng c thqun l thng tin c nhn ca cc thnh vin (Profile). Qun ldanh sch bn b nh thm, xa, sa thng tin, c chthng bo ti ngi dng khic message mi n. Qun l thng tin Offline Message.

Ngoi ra cc tnh nng khc s pht trin nh h tr voice chat v video(webcam), STB htrbn phm khng dy, font chUnicode v tch hp bg tingVit.

1.2.4.4.Video ConferenceHi tho truyn hnh cho php nhiu thu bao tham gia i thoi trc tuyn thng quatruyn hnh. Gii php ny cho php tchc cc cuc hp, cc bui hi tho, o to

trc tuyn txa, ngi dng c ththam gia tbt cvtr a l no min l c ktni hthng IPTV.

Hthng htrvic thay i cc thng svcht lng hnh nh, chun nn, cho ph hp vi bng thng ca mng li.


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1.2.4.5.Video Phone (SIP Phone)in thoi truyn hnh thng qua giao thc VoIP thng dng nh SIP, H323. Dch vcho php 2 thu bao c thlin lc bng hnh nh v m thanh vi nhau da trn chunSIP/IP. Cc dliu m thanh v hnh nh sc STB m ho v c gi thng quaIP ti tng thu bao ring bit.

Hthng cung cp dch vVoIP-Phone cho php thu bao IPTV c thgi incho nhau hoc gi ra cc mng in thoi khc.

Hthng cung cp gii php hon chnh cho vic tch hp hthng VoIP-Phone.Cung cp cc thit btch hp i km (handset) htrcho vic gi in thoi. Htrkh nng m rng, tch hp n cc mng in thoi khc nh fixed-phone, mobile

phone,..

1.2.5.Cc dch vgia tng khc1.2.5.1.Tin nhn SMS/MMSChc nng ny cho php ngi dng TV c thgi nhn tin nhn SMS, MMS n ccmng di ng. Cho php gi nhn tin nhn trc tip gia khch hng ca h thngIPTV v khch hng ca mng mobile.

Hthng c giao din nhp tin nhn ddng, STB shtrbn phm khng dytrong tng lai. C chcnh bo ngi dng khi c SMS mi n.

1.2.5.2.TV MailChc nng ny ging nh mt trnh email-client. Ngi dng c th gi, nhn, c

trc tip email thng qua mn hnh giao din trn mn hnh TV. Tuy nhin hin ti ccSTB cu hnh thp c hn chl khng thgi c file nh km, cn pht trin khnng tch hp thit bu vo (USB chng hn..) upload ni dung.

Chc nng ny h tr y chun SMTP, POP3 thng dng. H tr cc tnhnng email-client c bn nh: CC, BCC, HTML mail, chn chk (signature), sp xpmessage theo cc tiu ch khc nhau... Cho php cu hnh, to nhiu ti khon emailkt ni gi nhn email n cc mail-server khc nhau. Qun l thng tin AddressBook.

1.2.5.3.Media Sharing (Photo Album)Chc nng ny cho php khch hng thng qua h thng IPTV c thto, lu trvqun l cc album nh ca mnh.

Hthng album cho php qun l theo cc category khc nhau. Htrgiao dinthn thin, EPG hin thddng thun tin. Chc nng tm kim thng tin nh, to ccth mc c nhn (Private).


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1.2.5.4.Video BlogDch vny cho php khch hng IPTV c th to ring cho mnh mt blog c khnng lu trcc clip video. Ngi dng c thson tho, thm mi cc mc, bivit ddng.

Hthng htrqun l thng tin c nhn ca cc thnh vin (Profile), cho phpphn quyn cc thnh vin khc nhau. Khch hng c th qun l danh sch bn bnh thm, xa, sa thng tin.

1.2.5.5.Global MonitoringDch vny ng dng cho theo di giao thng, gim st an ninh v gim st h gianh txa. Vi loi hnh dch vny, hthng IPTV c thng dng cho tp khchhng nhm ln nh cc cng ty, doanh nghip.

Hthng htrgii php hon chnh cho php tch hp cung cp dch vtrn hthng IPTV trin khai. Cung cp cc thit b tch hp i km (camera, remote,..)

pha khch hng htrcho vic monitoring.

1.2.5.6.Game Online (Multiplayer game)Dch vny cung cp nhng tr chi quy m ln, chi trc tuyn v c nhiu ngichi tham gia ng thi.

Hthng c gii php hon chnh cho cc nh cung cp game third-party tch hpvo h thng IPTV trin khai cung cp dch v. H tr tnh tin mt cch linhng v hiu qu(tnh tin theo thi gian chi game, cc chkhuyn mi theo yucu ...).


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Phn 2TNG QUAN VHTHNG

TRUYN HNH TRN MNG xDSL

2.1.Kin trc hthng cung cp dch vIPTV

2.1.1.M hnh tng qut

Hnh 3. M hnh tng qut hthng cung cp dch vIPTV

Dch vIPTV c chia lm 02 loi chnh: Dch vvideo qung b (BroadcastVideo) v dch vvideo theo yu cu (Video on Demand VoD).

2.1.2.Cc thnh phn cung cp dch vBroadcast Video2.1.2.1.. Bnn video thi gian thcBnn video thi gian thc tip nhn tn hiu audio, video tcc ngun pht broadcastvideo (tn hiu c thdng tng thoc s), sau chuyn i tn hiu ny thnhlung cc gi IP mang dliu audio/video dng c nn s.


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2.1.2.2.EPGEPG cung cp thng tin v cc knh truyn hnh n broadcast client chy trn ccSTB. EPG thng c xy dng di dng mt HTTP server v cc knh truyn hnhc hin thdi dng cc trang web. ng dng EPG sm nhn vic xc thc vchng thc mt thu bao i vi cc dch vbroadcast.

EPG cn cung cp a ch IP multicast c sdng pht knh truyn hnhvo mng IP. Broadcast client dng a chny thc hin giao thc IGMP trong qutrnh chn v chuyn knh.

2.1.2.3.Broadcast ClientBroadcast Client l mt tin trnh ng dng chy trn STB m nhim vic cung cpgiao din ngi dng v iu khin cho cc dch vBroadcast video. Broadcast clientcng vi EPG to ra giao din xc thc thu bao cho cc dch v. Vic xc thc thngc thc hin bng cc giao thc xc thc ca tng ng dng (Application layer).

Broadcast client hin ththng tin vcc knh truyn hnh sdng dliu ly c tEPG v to ra giao din iu khin phc vthay i knh bng IGMP.

2.1.3.Cc thnh phn cung cp dch vVideo theo yu cu (VoD)2.1.3.1.Hthng phn phi ni dungHthng phn phi ni dung (Asset Distribution System ADS) ly ni dung video tcc nh cung cp ni dung v sdng cc qui tc kinh doanh phn phi ni dungny n nhng khu vc khc nhau trong hthng mng ca nh cung cp dch v.

ADS c th c s dng thay i cc thng tin m t (metadata) ca nidung video nhm bsung cc thng tin lin quan n cc quy tc kinh doanh nh gica ni dung video, gi dch vca ni dung video, ni dung video c cn c mha khng, Da trn cc quy tc kinh doanh, ADS sphn phi ni dung n phnhqun l ti nguyn ti cc video server cc khu vc khc nhau.

2.1.3.2.Navigation serverNavigation server cung cp cc thng tin vni dung VoD cho on-demand client chytrn STB. Navigation server thng c thc hin bi mt HTTP server v hin ththng tin vcc ni dung video di dng cc trang web. Navigation server sdngthng tin ththng qun l ti nguyn xc nh nhng ni dung video no chin thn thu bao. i vi cc ni dung c cung cp di dng gi thu bao thnavigation server c th s dng thng tin trong c s d liu khch hng iuchnh nhng thng tin c hin th.

2.1.3.3.Phn hqun l phinPhn hqun l phin l im lin lc trung tm cho cc yu cu phin VoD ton-demand client chy trn STB. Thnh phn ny qun l vng i ca mt phin video


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v m nhim vic iu phi cc ti nguyn khc nhau nhm gi cc lung videotng ng vi cc yu cu ton-demand client.

Khi nhn c mt yu cu phin video ton-demand client, phn h qun lphin sdng dch vca phn hbn quyn xc nh xem thu thu bao c cphp xem ni dung video m thu bao ang yu cu hay khng. Nu yu cu cchp nhn, phn hbn quyn strli cc thng tin c lin quan (chng hn nh nhdng m ha c sdng cho ni dung video). Sau , phn hqun l phin xcnh VoD server ti u phc vthu bao. Tip theo, phn hqun l ti nguyn sgi i lung video. Trong trng hp ni dung cn c m ha, phn h qun l

phin trao i thng tin vi h thng truy nhp c iu kin (Conditional AccessSystem CAS) ly thng tin vthut ton m ha cng nh l gi kha m han STB. Cui cng, cc thng tin lin quan n ni dung video (a chIP/UDP/RTP)c gi n STB.

2.1.3.4.Phn hbn quynPhn hbn quyn c chc nng xc nh mt ni dung video chc xem bi nhngthu bao c cp php. Phn hbn quyn sdng cc thng tin tADS xy dngc sdliu cho bit cc ni dung video trong cc gi thu bao khc nhau.

2.1.3.5.Video pumpVideo pump l thnh phn lu trv streaming ca hthng VoD. Video pump chacc thit b lu tr, ni dung video c t chc sao cho c th gi bt k mt nidung video no vi mt tc xc nh trc. Thnh phn streaming thc hin ly filet h thng lu tr v y vo mng. Video pump phi c khnng iu khin cclung video mc ti thiu, v dnh: fast-forward, rewind phc vcho qu trnhxem ni dung ca thu bao.

2.1.3.6.Phn hqun l ti nguynPhn hqun l ti nguyn qun l cc lung video, cc thit blu trca mt nhmcc video pump. Phn hny nh v, sao chp ni dung cng nh cp pht cc video

pump cho cc yu cu video nhn c tphn hqun l phin.

u vo, phn hqun l ti nguyn tip nhn ni dung ththng phn phini dung v sao chp ni dung ny n cc video pump m n qun l. Phn hny sa ra quyt nh khi no v u cn c sao chp ni dung da trn cc thng tin

nh: cc thng tin qun l ththng phn phi ni dung, cc yu cu video tthubao.

u ra, n c nhim vp ng cc yu cu video tphn hqun l phinbng cch chra video pump sphc vcho yu cu .


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2.1.3.7.On-demand clienty l mt tin trnh ng dng chy trn STB, c nhim vcung cp giao din ngidng v iu khin cho cc dch vvideo theo yu cu. On-demand client cung cpgiao din ngi dng duyt cc ni dung theo yu cu bng cch sdng cc dchvca navigation server. On-demand client cng tng tc vi phn hqun l phinyu cu mt lung video theo yu cu.

2.1.4.Cc thnh phn chungHthng truy nhp c iu kin (Conditional Access System CAS) ng vai tr l htng qun l v phn phi cc kha m ha c s dng m ha cc ni dungvideo. M ha ni dung c sdng nh l lp bo vthhai chng li nn n cpni dung. Lp bo vu tin cho cdch vbroadcast ln dch vtheo yu cu ctch hp trong ng dng chy trn STB.

Cc ng dng chy trn STB sdng c chxc thc ngi dng kim tra

mt thu bao c c php xem ni dung mong mun khng. Tuy nhin, cc ng dngny li khng bo v bn thn lung video. CAS s dng cc gii thut m ha nidung ngn chn nhng thu bao xem ni dung tri php.

Bi v truy nhp c iu kin to ra thm sphc tp cng nh chi ph cho hthng truyn ti nn thng m ha ni dung bng CAS chp dng vi nhng knhtruyn hnh hoc ni dung cao cp. i vi dch vbroadcast, m ha c thc hintrong bnn video thi gian thc. i vi cc dch v theo yu cu, m ha c thc thc hin trong bnn video thi gian thc hoc trong qu trnh xl sao chpni dung n cc video pump.

2.1.5.Kin trc sn phm


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2.1.5.3.Hthng truy nhp ciu kinHthng truy nhp c iu kin (CAS) cung cp cc dch vm ha v gii m ha,cc chc nng to v phn phi kha m ha, cho cc dch vbroadcast cng nh ccdch vtheo yu cu. CAS bao gm phn hqun l ti nguyn m ha, hthng mha (encryption engine), v tin trnh gii m ha video ti STB.

CAS tng tc vi middleware khi sm ha theo phin c yu cu cho ccdch v theo yu cu. CAS cng c th tng tc vi middleware khi cn phn phikha m ha gia phn hqun l ti nguyn m ha v tin trnh gii m ha trnSTB. Cui cng, CAS tng tc vi VoD server khi tin m ha c sdng cho mtni dung no .

2.2.Nhng yu cu t ra cho dch vvideo

2.2.1.Bng thng rngSo vi cc dch vthoi, Internet th bng thng dnh cho cc dch vvideo cao hnnhiu. Mt lung video vi phn gii chun (standard-definition) vi chun nnMPGE-4/H.264 yu cu bng thng 2Mbps.

i vi h tng mng truy nhp DSL th c th thy rng ng truyn DSLthng ch c khnng truyn ng thi t1 n 2 lung video cng mt lc. iuny c ngha l thu bao chc thxem ng thi 2 knh truyn hnh hay 2 ni dungvideo.

Bn cnh , bi v cc dch vtheo yu cu hot ng theo phng thc unicast,

trong khi dch vbroadcast video hot ng theo phng thc multicast nn c thnibng thng dnh cho cc dch vtheo yu cu trong mng phn phi cng nh mnggom ln hn rt nhiu so vi dch vBroadcast video.

2.2.2.Bng thng khng i xngLu lng video (bao gm c theo yu cu ln broadcast) u c truyn i trongmng theo mt hng (hng xung). Chc cc thng tin iu khin l c truyndi theo hng ngc li (hng ln). Do , chi ph vhtng c thgim bt khi xydng cc lin kt n hng.

2.2.3. Cht lng dch vCht lng video khi truyn trn mng IP phi m bo khng bgim st so vi ccloi hnh truyn hnh thng thng (truyn hnh cp, s, vtinh). m bo ssuygim cht lng video khi truyn qua mng IP kh nhn bit c tpha khch hngcn cgng hn chsxut hin ca cc li suy gim cht lng m khch hng cthnhn bit ddng.


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Khc vi cc dch vInternet, thoi, i vi cc dch vvideo th vic mt ginh hng rt ln n cht lng hnh nh. Do , yu cu t ra cho cc dch vvideongt ngho hn so vi cc dch vkhc. Tlmt gi phi m bo mc nhnht cth.

2.2.4.Ssn sng ca dch vMi loi dch v c mt mc sn sng khc nhau. Cc dch vbroadcast c tnhcht quan trng l tnh thi gian thc, thu bao khng th quay tr li xem onchng trnh pht. Do ssn sng t ra i vi dch vbroadcast l rt cao.

Trong khi , i vi cc dch vvideo theo yu cu th thu bao hon ton cthxem li cng nh bqua mt on ni dung no . Hn na tlthu bao sdngdch vny ti a cng chnm trong khong t10% n 20%. Do , yu cu vtnhsn sng i vi dch vny thp hn ng kso vi dch vbroadcast.

2.2.5.Thi gian chuyn knh i vi dch vBroadcastMt chtiu quan trng i vi cc dch vbroadcast video l thi gian m thu bao

phi ch i khi chuyn t mt knh ny sang mt knh khc. i vi cc dch vtruyn hnh tng t, khong thi gian ny gn nh l tc thi. i vi cc dch truynhnh s, khong thi gian ny nm trong khong t 1 n 1.5 giy. L do ca hintng ny l do trong truyn hnh s, tn hiu video c m ha theo cc chun nnnn cn mt khong thi gian nht nh gii nn tn hiu.

c im ca cc chun nn l chia tn hiu hnh tng t thnh mt chui cckhung nh tnh v thc hin cc gii thut nh gi loi b s d tha thng tin

cng nh xc nh chuyn ng. Cc loi khung hnh c sdng gm c: khung I,khung B, v khung P. Trong sny khung I l khung mang y thng tin, c tnhcht quyt nh n shin thchnh xc ca hnh nh. Trn thc t, cc khung I khngc gi i lin tc m c gi i xen kcng cc khung B v khung P. Khong thigian gia 2 khung I lin tip squyt nh thi gian chuyn knh.

Trong mng IP, bn cnh gii thut nn, cc yu t sau cng nh hng nkhong thi gian gia cc khung I (i vi thit bu cui STB):

c im ca STB Trdo giao thc multicast. Cc yu cu vbo mt, bn quyn.


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2.3.Kin trc mng cung cp dch vIPTV

Hnh 5. Kin trc mng cung cp dch vIPTV

Theo kin trc ny, hthng cung cp dch vIPTV gm cc video site v mngtruyn dn.

2.3.1.Video siteTrong h thng mng, h thng cung cp dch v IPTV c chia thnh 3 khu vcchnh nh sau:

SHE (Super HeadEnd). VHO (Video Headend Office) VSO (Video Switching Office).

2.3.1.1.Super HeadendTi SHE, cc knh truyn hnh qung b c thu sng v chuyn i thnh cc lungmulticast thng qua cc bnn video thi gian thc (real-time encoder). Bn cnh ,

ti SHE cn c h thng qun l phn phi ni dung phc vcho cc dch vvideotheo yu cu. Ngoi ra cc hthng htrqun tr, vn hnh, bo dng, v tnh cccng c btr ti SHE. Hu ht cc phng n trin khai IPTV trn mng cnhu xy dng mt SHE. Thng thng, SHE c b tr trong mng li ca mngtruyn dn.


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2.3.1.2.Video Headend OfficeVHO l ni t hthng video server. y l ni m phn ln cc video pump phc vcho cc dch vvideo theo yu cu c trang b. Ti y cng c thc cc bnnvideo thi gian thc dnh cho dch vbroadcast video cc b.

Mt VHO thng phc v trong phm vi mt th. C th coi VHO tngng vi mt im POP trong dch vtruy nhp Internet. Kt ni gia VHO v mngli IP/MPLS l mt router bin (Distribution Edge Router DER). DER kt ni mngli v cc lung video ti chvi mng phn phi bng thng rng mang cc lungvideo ca cdch vbroadcast video ln dch vvideo theo yu cu n VSO.

2.3.1.3.Video Switching OfficeCc VSO cha cc router ca mng gom (Aggregation Router - AR) l cc router lmnhim vthu gom lu lng tcc DSLAM ca mng gom. VSO thng c t tii chuyn mch trung tm (central switching office), l im kt cui vt l cho cc

ng dy thu bao. Cc thit bca VSO skt ni mng phn phi vi mng gom.Lu lng n v i khi cc DSLAM c thu gom ti cc AR, AR c thnm trongVSO trung gian hoc VSO bin (terminal).

2.3.2.Mng truyn dnIPTV l mt dch v trong m hnh mng cung cp dch v triple-play. Mt vn quan trng i vi mng truyn dn trong kin trc triple-play l lm thno mt hthng mng cung cp c nhiu dch vmt cch tch bit nhau. Trong phn ny strnh by vcc vn sau:

nh xdch v. Kin trc cht lng dch v. Kin trc bin lp 3. Kin trc multicast.

2.3.2.1.nh xdch vnh xdch vngha l nh xcc dch vkhc nhau (c cung cp n khch hng)vi cc topo mng logic khc nhau ca htng mng truy nhp v mng gom. Khi ccdch vkhc nhau c nh xvo cc topo logic khc nhau th cc dch vny sc kt cui ti cc thit bbin lp 3 khc nhau. Khi cc dch vkhc nhau c nh

xvo cc topo logic khc nhau th nh xlogic ny thng xut pht tthit bCPEti thu bao. Nh vy, cn c nhng phng n khc nhau mang nh xny i bngcch sdng cc phng thc ng gi trong mng truy nhp cng nh mng gom.

nh xdch vtrong mng truy nhp

C 3 phng n nh xdch vtrong mng truy nhp, l:

Kin trc truy nhp a knh o (Multi-VC)


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Kin trc truy nhp EtherType Kin trc truy nhp a VLAN (Multi-VLAN).

Kin trc truy nhp a knh o.Trong kin trc ny, cc knh o ATM (hayATM VC) ring rc sdng phn bit cc khng gian a chkhc nhau chotng loi dch v. Cc VC ny cng c sdng p cc tham scht lng dchvcho tng loi dch v. Trong hnh 4, DSLAM nh xcc ATM VC trn ng dayADSL vo cc VLAN dch vtrn ng uplink.

Hnh 6. Kin trc truy nhp a knh o

Kin trc truy nhp EtherType. Vi kin trc ny, trng EtherType trong

khung Ethernet c sdng phn bit hai khng gian a chkhc nhau. y, gisrng dch vInternet sdng phng thc ng gi PPPoE, cn dch vvideo sdng phng thc ng gi IP. Khi cc gi IP v PPP c mang trong khungEthernet, trng EtherType c sdng phn bit hai loi gi ny. Mt im ngch l dch v thoi phi c mang trong 1 trong 2 topo logic c m t bitrng EtherType trong khung Ethernet. Ngha l hoc dch vthoi c mang trongkhung Ethernet vi trng EtherType l IP hoc dch thoi c mang trong khungEthernet vi trng EtherType l PPPoE.

Do mt VC c s dng cho tt c cc dch vnn cht lng dch v cquyt nh bi cc tham scht lng dch vlp Ethernet hoc lp IP. Trong hnh 5,

DSLAM nh xcc gi trEtherType khc nhau vo cc VLAN dch vkhc nhau.


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Hnh 7. Kin trc truy nhp EtherType

Kin trc truy nhp a VLAN.Trong kin trc truy nhp da VLAN, phngthc ng gi 802.1q c sdng trn cc ng truyn ADSL, cc VLAN ID khcnhau c sdng phn bit cc khng gian a chca cc dch vkhc nhau. Sau, DSLAM thc hin cc VLAN ID ny trn ng uplink vo mt tp VLAN IDkhc dng nhn dng khng gian a chtrn link .

Trong m hnh ny, mt VC c sdng cho tt ccc dch v. Do , cngging nh kin trc truy nhp EtherType, cht lng dch vc quyt nh bi cctham s cht lng dch v lp Ethernet hoc lp IP. Trong hnh 7, DSLAM nh xVLAN ID trn ng truyn ADSL vo cc VLAN dch vtrn ng uplink.

Hnh 8. Kin trc truy nhp a VLAN


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nh xdch vtrong mng truy nhp

C hai kin trc khc nhau nh cc dch vtthu bao vo cc VLAN trong mnggom Ethernet: l kin trc N:1 VLAN v kin trc 1:1 VLAN. im khc bit gia haikin trc ny l cch thc nh x cc ng dy thu bao v cc dch v vo ccVLAN:

Kin trc N:1 VLAN nh xnhiu ng dy thu bao v dch vvo cng mtVLAN.

Kin trc 1:1 VLAN: nh xmi dng dy thu bao vo mt VLAN ring r.

M hnh N:1 VLAN. Trong m hnh N:1 VLAN, nhiu thu bao v nhiu dchvc nh xvo mt VLAN trong mng gom Ethernet. C nhiu cch nh xccnhm thu bao v dch vvo cc VLAN.

V d, mi VLAN trong m hnh ny c thc sdng gom tt ccc thubao ca cng mt dch v. Khi sdng m hnh ny, tt ccc thu bao ng vi

mt dch vv mt DSLAM c nh xvo mt VLAN duy nht. DSLAM thchin chc nng chuyn tip (Ethernet bridge) gia cc ng dy DSL mDSLAM gom vo mt VLAN vi VLAN trn Ethernet uplink. Mt trongnhng vn vbo mt lin quan n chuyn tip Ethernet l mt thu bao cthxem c thng tin ca mt thu bao khc. V vy, cc DSLAM phi c khnng ngn chn hin tng chuyn tip gia cc ng dy DSL v ngEthernet uplink.

M hnh 1:1 VL AN. Trong m hnh 1:1 VLAN, mi ng dy thu bao cnhn din trong mng gom thng qua mt VLAN ID. Kin trc ny tng tnhwkin trc gom cc ng truyn DSL theo ATM trc y, bi v mi thu bao

trong kin trc ATM c nhn din ti BRAS bi mt knh o ATM. V slng bit VLAN tag theo 802.1q l 12 nn trong trng hp slng thu bao lnhn 4096 th mng gom lp 2 phi sdngng gi 802.1ad (hay cn gi l Q-in-Q). Trong m hnh ny, DSLAM phi nh xng dy thu bao vo mt VLANtag ng Ethernet uplink. Khi sdng ng gi 802.1q th DSLAM nh xng dy DSL vo mt 802.1a VLAN ID. Trong trng hp ng gi 802.1ad thDSLAM phi nh xng dy DSL vo mt cp 802.1ad tag trong (inner) vngoi (outer).

2.3.2.2.Kin trc cht lng dch vCht lng dch vti mng truy nhp v mng gom c ththc hin theo 2 kin trckhc nhau: kin trc tp trung v kin trc phn tn.

Kin trc tp trung

Trong kin trc cht lng dch vtp trung, tt ccc chc nng cht lng dch vc thc hin ti BRAS nu cc thit bmng gom lp 2 v DSLAM khng c khnng thc hin cht lng dch v. Trong kin trc ny, tt ccc dch vu i qua


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mt nut BRAS duy nht. Nh vy, vi phng n thc hin nh thny th vic saochp cc lung multicast sc thc hin ti BRAS.

Kin trc phn tn

Trong kin trc cht lng dch vphn tn, cht lng dch vc thc hin bng

cch lp lch cho cc link vt l. Vi phng n ny, mi link vt l phi c khnngphn loi lu lng v da theo mt tht cu hnh sn p dng cht lng dchv.

2.3.2.3.Kin trc bin lp 3Kin trc bin lp 3 c phn lm kin trc: Single-edge v multi-edge

Single- edge

Vi kin trc ny, tt ccc dch vu c kt cui ti mt nt BRAS duy nht. Vvy, kin trc ny phi sdng kin trc cht lng dch vtp trung.

Multi-edge

Trong kin trc multi-edge, cc dch vkhc nhau c kt cui ti cc thit blp 3khc nhau. iu ny c ththc hin bng cch nh xcc dch vkhc nhau vo ccVLAN ID khc nhau ti DSLAM, hoc sdng phn gii ARP vi cc nut lp 3 khcnhau vi cc a chsubnet khc nhau.

2.3.2.4.Kin trc multicastKin trc multicast cng c chia thnh kin trc tp trung v kin trc phn tn.

Kin trc tp trungTrong kin trc tp trung, sao chp cc lung multicast c thc hin tp trung timt nut BRAS. iu ny nh hng kh nhiu n bng thng c sdng cho dchvbroadcast video v tt ccc lung multicast u c gi unicast tBRAS.

Kin trc phn tn

Trong kin trc phn tn, tt ccc nt lp 3, mng gom v mng truy nhp u c khnng thc sao chp cc lung multicast. Cc nut lp 3 sdng IP multicast sao chpcc lung multicast, trong khi cc thit blp 2 sdng IGMP snooping.

Khi sdng kin trc phn tn th cng c ngha l sdng m hnh N:1 VLAN

cho dch v multicast video. Mt VLAN duy nht c s dng cho lung videomulticast, iu ny cho php chto ra mt bn sao duy nht ca lung multicast chonhiu thu bao. Vi kin trc ny th cht lng dch vcng c thc hin theo kintrc phn tn.


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Phn 3HIN TRNG C SHTNGMNG VIN THNG CA VNPT

3.1.Mng ng trc

Hnh 9. Mng ng trc ca VNPT

Mng ng trc ca VNPT c nhim vtruyn dn cc lu lng thng tin lintnh cng nh thng tin i quc t. Hthng mng ng trc gm cc core router, ccPE v BRAS.

Hin nay, mng li VNPT gm 3 core router Juniper M160 t ti H Ni, Nng, v Thnh phHCh Minh. Vi cc core router ny, nng lc chuyn mch camng li c thln n 160 Mbps. Dng router M-series ca Juniper htrnhiu m

hnh dch vmi: ng thi chy cc dch v khc nhau: Layer 2 Virtual Circuit, Layer 2 VPN,

Layer 2.5 interworking VPN, Layer 3 1547 VPN, VPLS, IPSec, IP over IP, vGRE.

Khnng mrng ln, c thhtrhng nghn VPN. iu khin cht lng dch vvi cc chstrv jitter thp cng vi hiu qu

cao trong htrcc dch vthoi, video v cc ng dng thi gian thc khc.


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C thp dng cc m hnh dch vtheo DLCI, VP (Virtual Path), VC (VirtualCircuit), VLAN, knh thu ring, v theo cht lng dch v.

Phn loi, gii hn tc , iu khin, lp lch xoay vng, lp lch theo mc utin, p dng trong vn hnh hthng.

nh xcht lng dch vlp 2 (802.1p, CLP, DE) vi cht lng dch vlp 3

(IP DSCP, MPLS EXP). H trIPv6 (thc hin bng phn cng, IPv6 over MPLS, IPv6 over IPv4 GRE

tunnel, IPv6/IPv4 dual stack). H trmulticast: IGMP v1/v2/v3, PIM-SM, PIM-DM, MLD, SSM, RP, MSDP,

BSR, multicast trong cc VPN MPLS/BGP.

Cc core router c kt ni vng vi nhau bng cc giao din POS (Packet OverSDH). Mng ng trc hin nay sdng cng nghtruyn dn SDH. Giao din ktni gia cc core router sdng khung STM-16 vi dung lng 2.5 Gbps.

Tcc core router, mng li kt ni n hthng mng gom v mng truy nhp

ca VNPT thng qua cc PE v cc BRAS. Cc BRAS hin nay chyu l cc routerJuniper E-series m cthl ERX-1410 (nng lc chuyn mch ln n 10Gbps). as cc tnh hin nay ang s dng cng mt thit bng vai tr lm BRAS v PE.Ring ti H Ni, Nng, v Thnh phHCh Minh th sdng PE l cc routerJuniper M20.

Cc PE, BRAS kt ni n cc core router theo cu trc dng sao. Kt ni gia PE/BRAS v core router thc hin qua cc giao din POS, ng gi

trong cc khung truyn dn STM-1 (dung lng 155 Mbps) hoc STM-4 (dunglng 622 Mbps). Ring ti H Ni, Nng, Thnh phHCh Minh, kt nitPE/BRAS n cc core router l cc giao din GE (dung lng 1Gbps).

Hin nay, VNPT ang tin hnh chuyn i ton bh thng mng sang mngthhmi (Next Generation Network NGN). Trong , mng li s sdng cngngh chuyn mch nhn MPLS trn nn tng IP (IP/MPLS). Ton b mng li hinnay vn hnh theo giao thc IP/MPLS.

Vi hin trng ny, cc lu lng unicast v multicast qua mng li theo phngn sau:

i vi cc lu lng unicast: thit lp cc ng chuyn mch nhn LSP tngun n ch, cthl tmt PE/BRAS ny n mt PE/BRAS khc.

i vi cc lu lng multicast sdng multicast VPN gia cc PE/BRAS khc

nhau trong cng mt nhm multicast.D kin, khi trin khai NGN hon tt, m hnh kt ni mng li v mng

gom/mng truy nhp ca cc tnh thnh nh sau:


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PE/BRAS

DSLAMs

Access switch

Layer 2

swtich

IP/MPLS core network

Hnh 11. Mng truy nhp v mng gom ti cc tnh thnh cha trin khai MEN

3.2.2.M hnh mi ( vang trin khai MEN)i vi cc tnh thnh trin khai mng MEN, hthng mng c chia lm 2 thnh

phn: phn li v phn truy nhp.

Phn li ca mng MEN bao gm t3 n 4 thit bCarrier Ethernet cln (cngi l cc core switch) kt ni vng vi nhau (sdng cng nghRPR). Dung lngti thiu ca vng core l 10Gbps.


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Hnh 12. M hnh mng gom v mng truy nhp ti cc tnh thnh tin hnh trin khai MEN

Cc core switch kt ni vo mng li ca VNPT thng qua cc PE/BRAS. Dkin, khi xy dng hon tt, mi mng MEN skt ni vo mng li ca VNPT qua 2PE kt ni full-mesh vi 2 core switch ca MEN. Kt ni t core switch n PEthng l kt ni GE.

Phn truy nhp bao gm cc DSLAM, cc thit bMSAN, v cc thit bCarrierEthernet khc (cn gi l cc access switch).

Cc DSLAM kt ni dng sao n cc access switch bng cc giao din GE. D

kin sdn thay thtt ccc ATM-DSLAM bng cc IP-DSLAM. Kt ni gia cc access switch v cc core switch c ththeo cu trc dng vng,

dng mesh hoc dng sao sdng cc giao din GE.


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Phn 4CC GII PHP K THUT - CNG NGH

PHT TRIN HTHNG TRUYN HNHTRN MNG xDSL

Nguyn tc la chn gii php kthut, cng nghda trn cc gii php kthut phhp vi thc trng mng li ca VNPT, cung cp dch vIPTV vi cht lng ttnht ti khch hng.

4.1.Gii php la chn chun nn hnhnhCng vi spht trin mnh mca my tnh v sra i ca Internet th vic tm ramt phng php nn nh nhm gim bt khng gian lu trthng tin v truyn thngtrn mng l yu cu cp thit. Cc kthut nn video u cgng gim lng thngtin cn thit cho mt chui cc bc nh m khng lm gim cht lng nh.

Mc ch ca nn video l gim bt sbt khi lu trv truyn bng cch loi blng thng tin d tha trong tng frame v dng k thut m ho ti thiu holng thng tin quan trng cn lu gi. Vi mt thit b lu hnh k thut s thngthng, nh sau khi c sho sc nn li. Qu trnh nn sx l cc d liu

trong nh a hnh nh vo mt khng gian hp hn nh trong thit bnhkthutshoc qua ng dy in thoi ...

Vi th trng lu hnh k thut shin nay, cc chun nn phbin l MotionJPEG (MJPEG), Wavelet, H.261/ H.263/ H.263+/ H.263++ v MPEG-1/ MPEG-2/MPEG-4. Nhn chung, c 02 nhm tiu chun chyu l nhm 1 gm nh dng nnMJPEG v Wavelet v nhm 2 gm cc nh dng chun cn li.

4.1.1.Chun nn MJ PEG v WaveletTnh cht chung ca cc nh sl tng quan gia cc pixel cnh nhau ln, iu nydn ti d tha thng tin biu din nh. Vic d tha thng tin dn ti vic m hokhng ti u. Do vy, ta cn tm phng n biu din nh vi tng quan nhnht, gim thiu d tha thng tin ca nh.

C 2 kiu d tha thng tin nh sau:

D tha trong min khng gian: l tng quan gia khng gian pixel ca nh (ccpixel ln cn ca nh c gi tr gn ging nhau, trnhng pixel gip ngbin nh).


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D tha trong min tn s: l tng quan gia nhng di mu hoc cc di phkhc nhau.

Trng tm ca cc nghin cu vnn nh l gim bt mt sbit biu din nhbng vic loi bd tha trong min khng gian v min tn scng nhiu cng tt.Cc chun nn MJPEG v Wavelet u tun theo nguyn tc tm ra cc phn t dtha min khng gian (mi Frame nn tng). Trong khi , c trng ca cc chunnn thuc nhm 2 l loi bd tha cmin khng gian v min tn sca nh.

MPEG l nh dng nn nh lu i nht v c dng ph bin. Khi dngchun nn MJPEG, nh c phn chia thnh cc khi vung nh, mi khi vung ckch thc 8 x 8 pixel v biu din mc xm ca 64 im nh. M ho bin i cosinri rc DCT (Discrete Cosin Tranform) trong chun nn ny khai thc stng nggia cc pixel trong mi khi, ly ra cc biu din nh vi tng quan nh. Chui

biu din s b rt ngn, tu theo mc nn ca h thng hin hnh vi qui trnh rtngn chui biu din. V vy, hnh nh sau khi gii nn thng c nhiu sai lch so vi

nh gc.chun nn Wavelet, thay v m ho theo tng khi 8 x 8, vic thc hin trn

ton bbmt nh, mt lot cc bphn lc khu chuyn i sphn tch cc dkin vtng im nh v cho ra mt tp cc hs. Do chun Wavelet c tc dng viton bbmt nh, nn cc sai lch nh gii nn skhc vi MJPEG. Hiu ng ghpmnh khng xy n vi nh c quan st, nhng phn gii hnh nh gim cngnh mt vi vt msxut hin.

Cc nh dng Wavelet v MJPEG u gy ra hin tng mt thng tin nh giinn. Sd tha khnng lu nh mt ngi cm thkhi dng chun nn Wavelet thn MJPEG 30%.

4.1.2.Chun nn MPEG-x v H.26xMPEG khng phi l mt cng cnn n l, m u im ca nh nn dng MPEG lchMPEG c mt tp hp cc cng cm ho chun, chng c thkt hp vi nhaumt cch linh ng phc vcho mt lot cc ng dng khc nhau. Nguyn l chungca nn tn hiu video l loi bsd tha vkhng gian (spatial redundancy) v sd tha vthi gian (temporal redundancy). Trong MPEG, vic loi bsd tha vthi gian (nn lin nh), c thc hin trc ht nhsdng tnh cht gia cc nhlin tip. Chng ta dng tnh cht ny to ra cc bc nh mi nhvo thng tin t

nhng bc nh gi trc . Do vy pha bm ho ta chcn gili nhng nh cs thay i so vi nh trc, sau ta dng phng php nn v khng gian trongnhng bc nh sai khc ny. Ni mt cch cth, nguyn l chung ca cc chun nnl phng on trc chuyn ng ca cc frame bm ho. Mi frame ti mt thiim nht nh sc nhiu khnng ging vi cc frame ng ngay trc v sau .Cc b m ho s tin hnh qut ln lt nhng phn nh trong mi frame (marco

blocks) v pht hin ra marco block no khng thay i tframe ny ti frame khc.Pha bn thu, tc bgii m lu trsn nhng thng tin khng thay i t frame


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ny ti frame khc, chng c dng in thm vo vtr trng trong nh c khiphc.

Tuy nhin, do stng ng gia cc frame l rt ln, nn spht hin ra cc sailch l rt kh. Do vy nh khi phc kh t c nh nh gc. iu ny ng nghavi vic cht lng nh cng tng tnh khi dng chun Wavelet v MJPEG, nhngdung lng knh truyn v khng gian lu trca cc chun nn H.26x v MPEG-x lnhhn (v dnh khng gian lu trca chun H.263 nhhn Motion JPEG t3 ti5 ln). Skhc bit gia cc chun nn ny (nh H.26x v MPEG-x) chyu nm khu tin on cc frame mi v cch thc tnh ton sai lch gia cc frame hin ti vframe phng on. Chun nn H.26x (gm cc th h H.261, H.262 v H.263, ...),thng c tc m ho tn hiu thp hn MPEG-x (khong 1,5 Mbps vi phngii hnh 352 x 288) do dng chyu trong vin thng. Trong khi , chun MPEG-2dng cho thtrng gii tr c phn gii hnh cao hn, v mang li cht lng hnhnh tt (cao hn 1,5 Mbps vi phn gii 352x288 hoc 6 Mbps cho phn gii honchnh).

4.1.3.Chun nn MPEG-2MPEG-2, ra i nm 1994, l tn ca mt nhm cc tiu chun m ha cho tn hiu mthanh v hnh nh s, c chp thun bi MPEG (Moving Picture Expert Group) vc cng btrong tiu chun quc tISO/IEC 13818. MPEG-2 thng c sdngm ha m thanh v hnh nh cho cc tn hiu broadcast bao gm truyn hnh vtinh qung b trc tip v truyn hnh cp. MPEG-2 vi mt ssa i cng l khundng c sdng bi cc phim DVD thng mi tiu chun.

MPEG-2 bao gm cc phn chnh sau:

MPEG-2 Video part (Part 2): tng tMPEG-1, nhng chh trvideo xen k(interlaced video, l khun dng c s dng cho cc h thng truyn hnhqung b). MPEG-2 video khng c ti u ha cho cc tc bit thp (nhhn 1 Mbps), nhng li thc hin tt hn MPEG-1 tc 3 Mbps v cao hn.Tt ccc bgii m tn hiu video tun theo chun MPEG-2 hon ton c khnng pht li cc lung video MPEG-1. Do c nhiu ci tin, MPEG-2 video vcc h thng MPEG-2 c s dng trong hu ht cc h thng truyn dnHDTV.

MPEG-2 Audio part (Part 3): ci tin chc nng amm thanh ca MPEG-1 bngcch cho php m ha cc chng trnh m thanh vi nhiu hn hai knh. Part 3

cng cng tng thch vi chun trc, cho php cc b gii m m thanhMPEG-1 gii m cc thnh phn m thanh ni (stereo).

MPEG-2 c dng m ha hnh nh ng v m thanh v to ra ba kiukhung sliu (intra frame, forward predictive frame v bidirectional pridicted frame)c thc sp xp theo mt trt tcthgi l cu trc nhm cc hnh nh (group of

pictures, GOP).


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Mt lung video MPEG-2 c to nn bi mt chui cc khung sliu m hahnh nh. C ba cch m ha mt hnh nh l: intra-coded (I picture), forward

predictive (P picture) v bidirectional predictive (B picture). Cc hnh nh ca lungvideo c phn ra thnh mt knh cha thng tin vsng (luminance, cn gi lknh Y) v hai knh thnh phn mu (chrominance, cn gi l cc tn hiu mu phn

bit Cb v Cr).MPEG-2 sdng cc chun m ha m thanh mi, l:

M ha tc bit thp vi tn sly mu gim i mt na (MPEG-1 Layer 1/2/3LSF).

M ha a knh, ln n 5.1 knh. MPEG-2 AAC.

4.1.4.Chun nn MPEG-4So vi cc chun nn nu trn, chun MPEG-4 l nh dng nn hnh nh tin tin

nht, p ng nhng i hi vkthut cng nh ph hp vi nhiu loi thtrng.Vi n lc khng ngng a ra th trng sn phm u vit nht ca ngnh

cng nghip . My ghi hnh kthut schun MPEG-4 vi bn cht l mt thit bthuhnh k thut s c hiu sut cao, c chn p ng nhu cu cp thit ca thtrng vmt nh dng nn nh hon ho vi tnh nng ni tri l, c ththu c hthng ln cc ngun hnh nh.

MPEG-4 thc sl mt dng nn nh mang tnh t ph ca cng nghnn hnhng i, thhin r nt nhng tiu chun sau:

p dng nhng tiu chun c tnh mcao vi sh trc lc tngnh cng

nghip an ninh v cng nghip my tnh. Hiu sut ln Khnng truyn theo dng v mng li Ti thiu ho dung lng knh truyn v khng gian lu tr trong khi vn gi

c tnh trung thc ca nh.

Chun MPEG-4 cung cp cc phn btrong kt cu logic v nng lc gii mtng dng bit ring r. Mt profile (cht lng ca video) l mt phn bxc nh trnton bit stream (iu chnh bit stream v bphn gii mu), mt level (phn gii cavideo) sxc nh mt stiu ch bt buc cho tham sca bc nh (kch thc nh,slng bit, ...).

Nhng chun nn MPEG-4 c profile dng n gin chim lnh a phn thtrng. MPEG-4 c pht trin v hon thin tr thnh nh dng nn hnh tintin, hon ho, vi tiu ch tp trung pht trin nhng nhn t gip tng cng chtlng hnh nh, cng nh phc vc lc cho cc thit bgim st c cc frame dngchnht. Mi bit stream hin th trong nh dng nn MPEG-4 cung cp mt m tmang tnh phn tng vhnh nh hin th. Tng lp dliu c a vo lung bit binhng mt m c bit gi l mt m khi ngun.


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Mi vt thnh c th c m ho di dng a lp (scalable) hoc n lp(non scalable).

VOL (video object layer) s h tr qu trnh m ho a lp. Mt vt th nhc m ho di dng a lp khng gian hoc a lp thi gian, i tphn gii th ti

phn gii tinh. Bphn gii m c tht c phn gii hnh mong mun, tutheonhng thng s nh dii thng tn hin c, hiu sut my v theo mong mun cangi dng.

C 02 loi VOL, loi thnht mang y chc nng ca nh dng nn MPEG-4, loi cn li vi nhng chc nng c gim bt (VOL vi header dng ngn). LoiVOL ny gip lung bit tng thch vi ng bin H.263.

VOP (video object plane)- nh c m ho c lp hoc m ho trn c sthamkho cc nh khc qua khu b chuyn ng b gii m. Mi frame nh thngthng c biu din bi mt VOP dng chnht.

Vi chun nn MPEG-4, c 3 kiu khc nhau m ho cho khi nh:

VOP c m ho c lp. Trong trng hp ny VOP c m ho gi l IntraVOP (I-VOP).

VOP c tin on qua k thut b chuyn ng nhmt VOP khc ctin on trc . l loi P-VOP (Predicted VOP).

VOP c tin on da trn cc VOP trc v sau n thuc dng B-VOP(Bidirectiional Interpolated VOP).

B-VOP c thm vo da trn I-VOP v P-VOP. Ngoi vic c th nng caocht lng hnh nh khi dng, mt u im khc ca B-VOP l dng kthut a lpthi gian. Vi kthut ny, Frame dliu hin thc tng cng. Nhng lp tng

cng a thng tin vo gia cc lp frame.nh dng nn nh MPEG-4 htrqu trnh lng tho, do vy cng gip p

ng nhng i hi khc nhau vtc bt. Lng tho c cc chun nn nhH.263 v MPEG-1, MPEG-2. B phn m ho nh dng nn ca MPEG-4 cngtng thch vi nhng bm ha trong cc chun nn trc y.

4.1.5.Chun nn H.264/MPEG-4 Part 10/AVCH.264, hay MPEG-4 Part 10, cn gi l AVC (Advanced Video Coding), l chun mha tn hiu video sc dng nn cc tn hiu sliu mc cao. H.264 c vit

bi ITU-T Video Coding Exterts Group (VCEG) cng vi ISO/IEC MPEG nh mt nlc hp tc c chn lc mang tn Joint Video Team (JVT). Chun ITU-T H.264 vchun ISO/IEC MPEG-4 Part 10 (trc y l ISO/IEC 14496-10) l hon ton gingnhau vmt kthut.

H.264 c t tn theo dng tiu chun H.26x ca ITU-T, trong khi AVC theopha ISO/IEC MPEG. Mc ch ca H.264 l to ra mt chun c khnng cung cpcht lng video cao tc bit thp hn hn (bng mt na hoc thp hn na) so


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vi yu cu ca cc chun trc (MPEG-2, H.263 hay MPEG-2 Part 2) m khnglm tng nhiu sphc tp trong thit trin khai. Mt mc tiu khc l cho phptiu chun c p dng cho nhiu kiu ng dng (cho ctc bit thp v cao, v cphn gii video thp v cao) v c thlm vic tt trn nhiu kiu mng v hthng(qung b, lu trDVD, mng gi RTP/IP, cc hthng in thoi a phng tin ca

ITU-T).JVT gn y hon thin vic pht trin mt smrng so vi chun ban u,

c bit n vi tn gi Mrng phm vi trung thc (Fidelity Range Extensions,FRExt). Cc mrng ny htrm ha video trung thc cao bng cch tng chnhxc ly mu (bao gm m ha 10 bit v 12 bit) v thng tin mu sc phn gii cao(bao gm cc cu trc ly mu YUV 4:2:2 v YUV 4:4:4). Nhiu c im khc cngc thm vo trong cc mrng FRExt nh chuyn i thch ng gia cc khi 4x4v 8x8, cc ma trn trng slng tha da trn cm bin ca cc bm ha cth,htrthm nhiu khng gian mu sc, ...

Mt stnh nng mi ca H.264/MPEG-4 Part 10 cho php chun ny nn cc tnhiu video hiu qu hn so vi cc chun c v v linh hot hn cho cc ng dngtrong cc mi trng mng.

Mt scc tnh nng quan trng l:

B chuyn ng a hnh sdng cc hnh nh c m ha trc lm thamchiu theo cch linh hot hn cc chun c, cho php ln ti 32 hnh nh thamchiu c s dng (cc chun c ch s dng 1, hoc 2 vi trng hp B

picture). Tnh nng c bit ny cho php ci thin tc bit v cht lng tronghu ht cc trng hp.

B chuyn ng block c kch thc bin i vi kch thc block rng n

16x16 v nhn 4x4, cho php phn mnh chnh xc cc vng chuyn ng. Cu trc cp macroblock, cho php cc macroblock kch thc 16x16 (so vi

16x8 MPEG-2). chnh xc b chuyn ng ln n 1/4 pixel, cho php thhin chnh xc cc

dch chuyn ca vng chuyn ng. nh skhung, cho php to ra cc chui con (iu chnh vthi gian bng cch

gp mt nh gia cc nh khc), pht hin v giu cc hnh bmt (xy ra do mtgi trn mng hoc li knh).

m ththnh, cho php gicc hnh v cc gi trmu theo trt ttrong cchnh c gii m tch bit vi thng tin nh thi (cho php thng tin nh thi

c chuyn i v iu khin c lp bi hthng m khng nh hng n nidung hnh nh c gii m).

Cc kthut ny, cng vi nhiu kthut khc, lm cho H.264 hot ng tt hnso vi cc tiu chun trc, trong nhiu trng hp v mi trng ng dng khcnhau.


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H.264 thng lm vic tt hn rt nhiu so vi MPEG-2, cho cht lng tt hntc bt chbng mt na hoc thp hn so vi yu cu ca MPEG-2. H.264 cungcp cc profile sau:

Baseline profile (BP): Dng cho cc ng dng chi ph thp i hi t ti nguynhn, chyu dng cho cc ng dung hi nghtruyn hnh v di ng.

Main Profile (MP): Dng cho cc ng dng qung b v lu tr. Extended profile (XP): C khnng nn kh cao, gim thiu khnng mt d

liu. High Profile (HiP): Dng cho cc ng dng qung b v lu tra, c bit cho

cc ng dng truyn hnh yu cu nt cao (HD-DVD, Bluray disc). High 10 Profile (Hi10P): c xy dng bn trn ca HiP, htr10 bit trn

mt mu ca chnh xc ca hnh nh c gii m. High 4:2:2 Profile (Hi422P): dng cho cc ng dng chuyn nghip s dng

video qut xen k, c xy dng bn trn ca Hi10P, htrkhun dng ly musc 4:2:2 trong khi sdng 10 bit trn mt mu ca chnh xc ca hnh nh

c gii m. High 4:4:4 Profile (Hi444P): c xy dng bn trn ca Hi422P, htrly mu

sc 4:4:4, ln n 12 bit trn mt mu.

MPEG tch hp y cc htrca H.264/AVC vo cc hthng tiu chunca mnh (MPEG-2 v MPEG-4) v cc tp tin a phng tin theo tiu chun ISO.

ITU-T a H.264/AVC vo b tiu chun H.32x cho h thng in thoi aphng tin. Da trn cc tiu chun ITU-T, H.264/AVC c sdng rng ri chong dng hi nghtruyn hnh, v c ng dng trong cc sn phm ca cc cngty chim u thtrn thtrng (nh Polycom v Tendberg). iu quan trng hn cl

tt ccc sn phm hi nghtruyn hnh mi u htrH.264/AVC.H.264 cng c s dng trong nhiu loi dch v Video-on-Demand trn

Internet cung cp phim v cc show din truyn hnh trc tip n my tnh v mythu hnh v c kh nng s thay th chun m ha H.262/MPEG-2 hin ti ang sdng trong cc hthng truyn hnh squng b mt t v vtinh.

4.1.6.Yu cu vbng thng ca cc chun nnSo snh hot ng ca chun nn khc nhau nh trong bng di y:

nt tiu chun nt cao ng dngMPEG-1 Ln n 1,5 Mbps - Video on Internet, MP3

MPEG-2 4 - 5 Mbps 18 - 20 Mbps Digital TV, DVD

MPEG-4 Part 10

H.2642 - 4 Mbps 8 - 10 Mbps Multi video

Yu cu vbng thng i vi cc chun nn


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C ththy c tthso snh trn, k thut m ha H.264 rt hiu qudi bng thng thp. Cht lng video ca chun H.264 ti bng thng 1,5 Mbps tthn so vi chun MPEG-2 bng thng 3 Mbps. Sdng chun nn H.264 c thtitkim c hn mt na bng thng.

4.2.La chn giao thc mng

4.2.1.Giao thc cho dch vmulticast4.2.1.1.Giao thc IGMPGiao thc IGMP pht trin tgiao thc Host Membership Protocol, c m ttrongti liu ca Deering. Giao thc IGMP c ba phin bn verion 1, verion 2,v verion 3.IGMP pht trin t IGMPv1 (RFC1112) n IGMPv2 (RFC2236) v n phin bncui cng IGMPv3 (RFC3376). Cc thng ip IGMP c gi bn trong gi tin IPvi trng protocol number bng 2, trong trng TTL c gi tr bng 1. Cc giIGMP chc truyn trong LAN v khng c tip tc chuyn sang LAN khc dogi trTTL ca n.

Hai mc ch quan trng nht ca IGMP l:

Thng bo cho router multicast rng c mt my mun nhn multicast traffic camt nhm cth.

Thng bo cho router rng mt c mt my mun ri mt nhm multicast (nicch khc, c mt my khng cn quan tm n vic nhn multicast traffic na).Cc router thng dng IGMP duy tr thng tin cho tng cng ca router l

nhng nhm multicast no router cn phi chuyn v nhng host no mun nhn.Trc khi mt host c thnhn bt kmt multicast traffic no, mt ng dng

multicast phi c ci t v chy trn host . Sau khi mt host tham gia vo mtnhm, phn mm s tnh ton a chmulticast v sau card mng sbt u lngnghe a chmulticast MAC. Trc khi mt host hoc mt ngi dng mun tham giavo mt nhm, ngi dng cn phi bit nhm no ang tn ti v lm thno thamgia vo nhm . i vi cc ng dng mc doanh nghip, ngi dng chcn ngin nhp vo mt link trn mt trang web hoc a chmulticast c thcu hnh trctrn client. V d, mt ngi dng c thc yu cu log vo mt my chv xcthc bng tn v ngi dng. Nu tn ngi dng c xc thc, ng dng multicast

s t ng ci trn PC ca ngi dng, ngha l ngi dng tham gia vo nhmmulticast. Khi ngi dng khng cn mun dng ng dng multicast na, ngi dng

phi ri khi nhm. V d, ngi dng n gin chcn ng ng dng multicast ri khi nhm. i vi c chmulticast, mt ngi dng cn phi tm ra ng dng nohmun chy, a chmulticast c dng bi ng dng.

Lm thno mt router bit c cc my cn nghe multicast traffic? nhnmulticast traffic tmt ngun, cngun v cc my nhn u tin phi gia nhp (join)


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vo mt nhm multicast. Nhm ny c xc nh thng qua a ch multicast. Mthost c ththam gia vo mt nhm multicast bng cch gi cc yu cu n router gnnht. Tc vny c thc hin thng qua giao thc IGMP. IGMPv1 c nh nghatrong RFC1112 v bn ci tin ca n, IGMPv2 c nh ngha trong RFC2236. Khic vi host mun tham gia vo nhm, giao thc PIM sthng bo cho nhau gia cc

router v hnh thnh nn cy multicast gia cc routers. IGMP v ICMP c nhiu imtng ng, cng chia smt vi chc nng tng t. IGMP cng ng gi trong gitin IP (protocol number 2), nhng IGMP gii hn chtrong mt kt ni lp 2. m

bo router khng bao gitip tc chuyn gi tin i, trng TTL ca IGMP lun c gitrbng 1.

4.2.1.2.Giao thc PIMGiao thc PIM l giao thc sl gi tin multicast c lp nhau. Hin nay c ba loiPIM ang c sdng l : PIM-SM , PIM-DM , PIM-SSM

Giao thc PIM-SM( Protocol independent multicast sparse mode)Giao thc nh tuyn ch sparse c s dng khi c t s lng cc ng dngmulticast. Cc giao thc PIM chsparse khng truyn lu lngca nhm ti bt krouter no trphi n nhn c mt thng ip yu cu cc bn sao ca cc gi tinc gi ti mt nhm multicast c bit.

Mt router lng ging yu cu cc gi chnhm mt trong hai mc ch :

Router nhn c mt yu cu nhn gi tin tmt vi router lng ging Mt host trn mt phn on mng gi thng ip IGMP join cho nhm .

PIM-SM hot ng vi mt chin lc khc hn vi PIM-DM mc d c chca

giao thc khng hon ton i lp. PIM-SM gisrng khng c my no mun nhnlu lng multicast cho n khi no cc my chng hi. Kt qul, cho n khi notrong mt subnet c mt my yu cu nhn multicast th multicast mi c phn phivo subnet . Vi PIM-SM, cc router downstream phi yu cu nhn multicast dngthng ip PIM Join. Khi cc router nhn c cc thng ip ny, cc router bn di

phi nh kgi thng ip Join ln router upstream. Nu khc i, router upstream skhng a lu lng xung, t kt ni vo trong trng thi prune. Tin trnh ny thngc li vi tin trnh c dng trong PIM-DM, trong mc nh l pht tn lulng multicast vi cc router downstream cn phi lin tc gi thng ip Prune haythng ip lm mi trng thi State refresh gicho mt kt ni l trong trng thi

prune. PIM-SM ph hp khi ch c nhng t l nh cc phn on mng nhn lulng multicast.

Giao thc PIM-DM ( dense mode)

Giao thc PIM-DM thng c sdng khi m lu lng lung multicast l rt ln.PIM-DM lun c mt cng trong trng thi prune trong khong ba pht. Cc thngip prune lit k mt ngun v nhm. i vi giao thc PIM-DM ny th bt ckhino mt router nhn c thng ip prune n stm mt hang (S, G) SPT trong bng


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nh tuyn multicast v nh du cc cng trong thng ip prune l nhn c.Tuy nhin , cc router cng thit lp gi tr prune timer, v thng th mc nh lkhong 3 pht, sao cho trong khong 3 pht cng ny c t trong trng thiforwarding . c thkhc phc c nhng tnh trng nh l cc kt ni bloi b,lin kt bloi bv sau 3 pht th cc link tip tc hot ng th PIM-DM c c ch

lm mi trng thi stase refresh. Cc thng ip lm mi trng thi khc phc csyu km ca PIM-DM trong tin trnh pruning.

Trong giao thc PIM-DM cc router cn gi thng ip Graft router nhnc a mt cng vo trng thi forwarding cho mt nhm multicast no .

Giao thc PIM-DM nhn bit cc thit blng ging bng cch trao i cc gihello. Thng tin lng ging ny c dng trc xy dng cy n tt ccc lngging. Sau , cc nhnh ca cy sln lt c loi b. Nu mt dng multicast btu, cy sc xy dng, cy sch tn ti khi cc thnh vin tch cc cn tn ti.

Nu mt host mi ng k tham gia nhm, nhnh ca phn on mng sc nh

thm vo cy.Giao thc PIM-SSM

Giao thc PIM-SSM l giao thc mrng ca PIM. Khi sdng SSM th mt client cthnhn lung multicast trc tip ta chngun. PIM-SSM sdng chc nng caPIM-SM to ra mt cy SPT gia ngun v ch nhn, tuy nhin n xy dng SPTm khng cn sgip ca router RP.

Mc nh l nhm a chmulticast c gii hn trong di a ch232.0.0.0 ti232.255.255.255. Tuy nhin, chng ta c thmrng tm hot ng ca SSM sang lpdi lp D bao gm a chmc cao.

Vic cu hnh PIM-SSM c skhc bit so vi cu hnh PIM-SM truyn thng.y ta khng cn phi chia stree hay l RP mapping, hoc l RP to RP ngun lyli thng qua Multicast source discovery Protocol ( MSDP).

Trin khai SSM l rt ddng. Chng ta ch cn cu hnh PIM-SM trn tt cinterface ca router v chnh ci no cn SSM, bao gm mt cch r rng IGMPv3trn Lan. Nu PIM-SM khng c cu hnh r rng trn cngun v nhm thnh vininterface th gi tin multicast skhng c forwarded. Trn danh sch htrIGMPv3c s dng PIM-SSM. Nh ti ngun, trc khi active v bt u gi gi tinmulticast th quan tm n ni nhn gi tin multicast l SSM . Trong vic cu hnhmng theo PIM-SSM , mt thu bao ti mt knh SSM ( sdng IGMPv3) s thng

bo vi cc thu bao join vo nhm G v ngun S. Kt ni trc tip vi router PIM-SM , router c phn cng nhn lm DR, nhn bn tin tRPF lng ging.


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Hnh 13. Qu trnh nhn v thng bo ti cc thu bao join vo group G v sourse S

Giao thc PIM l gii php htrtruyn tn hiu multicast. Khi m slng ccnhm multicast cn phi truyn tng ln th PIM l mt gii php quan trng qun lv gim st lu lng multicast.

4.2.2.Giao thc cho dch vunicast4.2.2.1.Giao thc RTSPGii thiu

Giao thc RTSP c pht trin bi IETF v thnh lp vo nm 1998 vi chun RFC2326. y l giao thc c ng dng iu khin dliu vi thi gian thc. RTSPcung cp mt khung lm vic cho php iu khin theo yu cu v thi gian thc,ging nh audio v video. Ngun d liu c thbao gm cd liu sng v clip lutr. y l giao thc dnh cho pht trin dliu a phng tin , cung cp cch phn

pht cc knh nh UDP, TCP v vic m bo theo thi gian thc. iu khinlung bi RTSP c th s dng RTP , nhng s hot ng ca RTSP l khng phthuc vo kthut vn chuyn truyn data. Giao thc c ctnh gilp trong c

php v hot ng ti HTTP/1.1, v mrng kthut ti HTTP c thl hu ht cctrng hp a ch ti RTSP. Tuy nhin RTSP c s khc bit quan trng v lthuyt so vi HTTP:

RTSP gii thiu mt sphng php mi v c skhc giao thc xc nhn. Mt RTSP server cn xc nh trng thi bng cch mc nh hu ht tt ccc

trng hp, tng phn vi trng thi tnhin ca HTTP.

CRSTP server v client c tha ra yu cu. Dliu mang i out-of-band bng giao thc khc.

c im ca giao thc

Giao thc RTSP c mt snhng c im sau y:

Khnng mrng.Phng php mi v cc thng sc thddng thm voRTSP.


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Ddng phn tch.Giao thc RTSP c thddng phn tch bng tiu chunHTTP hoc MIME.

Bo mt.RTSP sdng kthut bo mt web. Tt ckthut nhn thc u cbn v chng thc u trc tip c p dng. Mt sc thdng li hoc bo mt lp mng.

Vn chuyn c lp.RTSP c thsdng mt trong hai phng php truyngi tin khng tin cy UDP v ng tin cy RDP, hoc l giao thc lung tin cy TCPc thc hin lp ng dng ng tin cy.

Khnng chy nhiu server. Mi mt lung media gia cc phn trnh din cth t ti cc server khc nhau. Cc client s t ng thit lp mt vi phin iukhin hin ti vi cc server media khc nhau. Gia chng c ng bvi nhau lp giao vn.

iu khin thit bghi.Giao thc ny c thiu khin c2 qu trnh ghi vchy li thit b, hoc cng c thnm xen kgia hai mode.

iu khin lung v hi nghban u. iu khin lung a ra tli mica server ti hi ngh. Chc nhng yu cu hi nghl mt trong hai cung cp hocl c thsdng to ra hi nghring. Trong thc tSIP v h323 c thsdng mimt server ti hi ngh.

Ph hp vi nhng ng dng c nhn. RTSP h tr frame level thng quaSMPTE cho php chnh sa txa.

Proxy v firewall tin li.Giao thc nn sn sang sl bi chai ng dng vlp giao vn. Mt firewall c th khng hiu cch setup v m tin ch cho UDPmedia.

4.2.2.2.Mrng giao thc RTSPKhng phi tt ccc server u c mt chc nng ging nhau, cc server media cnthit sc htrcc yu cu khc nhau. V d:

Mt server c thchc khnng Playback theo cch th khng cn htryucu record.

Mt server c thkhng c khnng tm kim nu n chhtrcc skin sng. Mt sserver c thkhng htrcc thng slung v theo cch n khng

htrget-parameter v set-parameter.

Giao thc RTSP c thmrng ra theo ba cch, danh sch y a ra hp ltheo vic thay i ln c htr:

Hin nay phng php c thmrng vi cc thng smi, cc thng sdi cthan ton khi bqua bng cch nhn v. Nu my client cn phnh tha liACK khi m phng php m rng khng c h tr, mt tag tng ng vi

phn mrng c ththm vo theo yu cu.


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Mt phng php mi c tha vo .Nu nhn mt bn tin m khng hiu bntin yu cu g, n strli vi li 501 (khng ththc hin) v bn gi khngnn c th li. Mt client c th sdng la chn phng php i hi vcch htrbi server. Cc server nn a ra mt danh sch cc phng php mn htrsdng.

Mt phin bn mi ca giao thc c thc nh ngha cho php hu ht ttcgiao din thay i.

4.2.2.3.Bn tin RTSPGiao thc RTSP l giao thc c bn s dng ISO 10646 k t t trong UTE 8encoding. ng gii hn bi CRLF nhng m ngi nhn snn chun bhiuc CR v LF bng chnh bn thn gi hn.

Vi 10646 k tc sp xp trnh schng cho, nhng m n khng xuthin cc ng dng nh l US-ASCII c sdng. N c m ha c thsdngcho giao thc RTCP. ISO 8859-1 bin dch trc tip vo Unicode vi octer cao nht lkhng. Bn tin RTSP c thtruyn qua cc giao thc thp hn lp giao vn.

4.2.2.4.ng dng ca giao thc RTSPCng ngh IPTV l cng ngh i hi tn hiu c truyn i theo thi gian thc.Chnh v vy m giao thc RTSP c ngha rt quan trng. Giao thc RTSP h trtrong vic truyn tn hiu multicast c thtruyn cc knh truyn hnh. c thxem c cc knh truyn hnh th tn hiu nhn c phi theo thi gian thc.

4.2.3.Giao thc cho dch vVoIP4.2.3.1.SIPGiao thc khi to phin (SIP) l mt giao thc bo hiu mi xut hin thc hin iukhin phin cho cc kt ni a dch v. Vc bn, hot ng iu khin bao gm khito, thay i v kt thc mt phin c lin quan n cc phn ta phng tin nhvideo, thoi, tin nhn, game trc tuyn, ...

SIP em li ba nng lc chnh cho mng vin thng. Thnht, n kch thch spht trin ca cc m hnh ng dng v dch vda trn web. y l mt iu ht scthut li cho nh cung cp dch vdo c thsdng mt ngun ti nguyn di do cccng csn c, ng thi cng thun li i vi ngi sdng khi ngi sdng

quen thuc vi kthut web v n cng c trin khai trn phn ln cc thit bthng minh ngy nay. iu ny tng cng khnng cung cp cc dch v mi mtcch nhanh chng.

Nng lc thhai l khnng mrng, do SIP l giao thc bo hiu ng cp vc tnh phn bcao. Khc vi cc giao thc bo hiu truyn thng thng c tnh xltp trung cao, in hnh l SS7, trong hot ng ca n tp trung ti mt sim


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bo hiu trong mt cu trc mng bo hiu phc tp; cc phn tca SIP phn tn ntn bin ca mng v c nhng ti tn cc im u cui.

Cui cng l khnng phcp ca SIP. c pht trin bi IETF, SIP k thacc c im ca hai giao thc Internet c pht trin rt phbin: l HyperText Transport Protocol (HTTP) sdng cho Web v Simple Mail Transport Protocol(SMTP) sdng cho e-mail. Da vo cc nguyn tc c c tmi trng IP, SIPc thit kl giao thc c lp vi ng dng, rt mm do v c khnng p dngtrong nhiu mi trng khc nhau v cung cp cc dch va dng.

Tm li, c im ca SIP l n gin, m, ddng trin khai, v tng thch vicc giao thc IP c.

Spht trin ca SIP

SIP c pht trin bi SIP Working Group trong IETF. Phin bn u tin c banhnh vo nm 1999 trong ti liu RFC 2543. Sau , SIP tri qua nhiu thay i v ci

tin. Phin bn mi nht hin nay c ban hnh trong IETF RFC 3261. RFC 3261hon ton tng thch ngc vi RFC 2543, do cc h thng thc thi theo RFC2543 hon ton c thsdng vi cc hthng theo RFC 3261.

Mt bn tin SIP c hai phn, phn mo u v phn thn. Phn thn cho phpphc vcc ng dng khc nhau mt cch linh hot. Ban u phn thn chdng chuyn ti cc tham smiu tphin SDP nh codec, a chIP u cui, ... Phn thnc sdng mrng cc ng dng ca khc nhau ca SIP v dnh SIP-T cholin vn PSTN-SIP-PSTN hoc MSCML (Media Server Control Markup Language)cho dch vhi ngh.

Sphcp ca SIP dn ti vic mt lot nhm lm vic lin quan n SIP

c thnh lp. Nhm SIPPING (Session Initiation Protocol investigation workinggroup) c thnh lp vi mc ch nghin cu cc ng dng v pht trin cc yu cumrng cho SIP. Nhm SIMPLE (SIP for Instant Messaging and Presence LeveragingExtensions) c nhim vchun ho cc giao thc cho cc ng dng nhn tin tc thi.Cc nhm lm vic khc l PINT (PSTN and Internet Internetworking), SPIRITS(PSTN/IN requesting Internet Services).

Cc c im ca SIP

thc hin chc nng iu khin phin, SIP htr5 chc nng sau:

User location Xc nh vtr thit bu cui khch hng. User availability Xc nh trng thi v tnh sn sng ca thu bao bgi bt

u thit lp ng truyn. User capabilities Xc nh phng tin v cc thng sc sdng. Session setup Thit lp cc thng sca phin cho cthu bao chgi v thu

bao bgi. Session management To, kt thc v sa i phin.


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SIP khng phi l mt hthng truyn thng c trin khai theo chiu dc mn l mt thnh phn c sdng cng vi cc giao thc khc ca IETF to nnmt cu trc a phng tin hon chnh. Mc d SIP c sdng kt hp vi ccgiao thc khc, nhng cc hot ng v tnh nng c bn ca n khng phthuc vocc giao thc ny.

C 4 loi thc thchnh c nh ngha trong SIP:

User Agent (UA) ng vai tr ca thit bu cui trong bo hiu SIP. UA baogm hai loi User Agent Client (UAC) v User Agent Server (UAS). UAC khito cuc gi v UAS tr li cuc gi. iu ny cho php thc hin cuc gingang hng thng qua m hnh client-server.

Redirect Server tip nhn yu cu nhng khng chuyn sang server k bn mgi trli n chgi chra a chca bgi.

Proxy Server tip nhn cc yu cu, quyt nh ni gi n v chuyn chng sangserver ktip (sdng nguyn tc nh tuyn next hop).

Registrar tip nhn ng k tcc UA cp nht thng tin vvtr ca chng.SIP khng phi l mt giao thc bo hiu hot ng c lp. Hot ng ca SIP

c sphi hp vi mt sgiao thc bo hiu khc. Cc giao thc l SDP (giao thcmiu tphin) (RFC 2327) sdng SIP nh mt phng tin chuyn ti v RTP (giaothc truyn ti thi gian thc) c sdng lm phng tin chuyn ti SIP. SDPc sdng m tc tnh ca phin. SDP c chuyn ti trong phn thn ca

bn tin SIP.

Cc bn tin SIP

Cc bn tin ca SIP c chia lm hai loi: yu cu v p ng. Cc loi bn tin yu

cu c phn bit theo tn (Bng 1) trong khi cc bn tin p ng c nh s(Bng2).

Bn tin ngha

INVITE Khi to mt phin

ACK Khng nh rng client nhn c bn tin p ng cho bn tinINVITE

BYE Yu cu kt thc phin

CANCEL Huyu cu ang nm trong hng iREGISTER u cui SIP ng k vi registrar server

OPTIONS Sdng xc nh nng lc ca server

INFO Sdng ti cc thng tin

Cc bn tin yu cu ca SIP


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Bn tin ngha

1xx Cc bn tin chung

xx Thnh cng

3xx Chuyn a ch4xx Yu cu khng c p ng

5xx Scca server

6xx Scton mng

Cc loi bn tin p ng ca SIP

4.2.3.2.ng dng ca SIPDo c pht trin tcc giao thc Internet nh HTTP v SMTP, cc nh pht trintrn mi trng Internet c thnhanh chng to ra v a vo sdng cc dch vmi

da trn SIP. V d in hnh nht l Windows Messenger ca Microsoft. WindowsMessenger c tch hp trong hiu hnh Windows XP v c cc tnh nng chnhnh sau:

Qun l danh bcho tng ngi sdng, v c chc nng hin thtnh trng hinti (Presence) ca tng c nhn trong danh sch.

Tin nhn tc thi Thoi v video Truyn file Thoi tPC ti my in thoi ca mng cng cng.

Bng vic tch hp Windows Messenger vo h iu hnh, Microsoft to raSIP client tim tng trong mi my tnh c nhn, nh cho php cc nh pht trintrin rng ri dch vSIP trn ton mng.

Ngoi ra c th lit k y mt sng dng SIP clients khc nh: eCONF,Wave3 Session (www.wave3software.com), Network Convergence Laboratory atClaremont Graduate University (ncl.cgu.edu).

Mt sng dng SIP server bao gm: Microsoft Live Communications Server,HCL Technologies (www.hcltech.com), Indigo, Ubiquity, SNOM, VOCAL, Iptel,DynamicSoft, Siemens, Nortel, eCONF.

4.2.3.3.ng dng ca SIP trong mng NGNSIP rt c ch v ngy cng c sdng rng ri trong cc kin trc ca mng

NGN. Thng 11 nm 2000, SIP c chp nhn nh mt giao thc bo hiu ca 3GPPv trthnh mt thnh phn chnh thc ca cu trc IMS. Cn phi ch rng, khi sdng trong mt mi trng c th(v dnh IMS), SIP khng cn c ginguynnh nh ngha ban u ca IETF. Thay vo , n c mrng cho nhng ng dngcth. 3GPP cng pht trin nhng mrng khi sdng SIP trong cu trc IMS.


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Mc ra i v xut hin cc sn phm thng mi sau H.323, nhng SIP trthnh giao thc bo hiu c sdng rng ri nht cho cc dch vVoIP. MSF

pht trin m rng ca SIP cho dch vny trn nn mng NGN theo cu trc iukhin Call Server.

4.3.La chn cng nghmng truy nhpi vi nhiu ngi IPTV gi ln slin tng ca hng trm cc dch vgii tr theoyu cu, cc knh truyn hnh c pht ti bt cni u, bt ckhi no. IPTV hahn khnng kim sot ton bca thu bao thay i cch thc sdng phng tintruyn thng i vi cc knh tng tc unicast. i vi cc nh qun l mng, IPTVnm gicnh ca ti cc ngun thu nhp tcc dch vtruyn thng trn nn mng

bng thng rng.

IPTV thc hin bng cch thay i thnh nh tng tthnh hnh nh s. Cc

u im trong cng nghnn gip cho IPTV c thcung cp m thanh v hnh nh tiuchun hoc cht lng cao.

Cu hi cch no trin khai dch vIPTV mt cch tt nht? khng thc cu trli. Ngy nay, mng cung cp dch v bao gm: mng DSL, mng quang th ng,cp, hoc tng hp ca cc mng trn. Tng mng u c u im v thch thc. Sauy l mt sm hnh mng cung cp dch vIPTV:

4.3.1.Cng nghmng truy nhp xDSLVi cng nghnn hin nay, cDSL hoc ADSL u c thcung cp dch v

IPTV. VDSL c khnng cung cp bng thng ln hn cho thu bao (ln ti 50 Mbpsng down), nhng n li t lnghch vi khong cch. Thu bao phi gn cc COhoc cc thit bRemote terminal do tc ng truyn ca mng gim theo khongcch. i vi cc nh qun l mng vic trin khai dch v IPTV thng qua mngxDSL vn duy tr c ngun ti chnh. Mt ng download xDSL cung cp High definition TV. HDTV hin ti yu cu 19.2 Mbps cho mt knh so vi 2.5 Mbps yucu cho standard-definition TV i hi phi sdng cng nghmng truy nhp ADSL2+ hoc VDSL. Thay i knh yu cu STB phi gi mt tn hiu ti DSLAM, iuny c thto ra mt svn tim tng i vi cc chng trnh HD tc ti aca VDSL. Cc dng chun ca ADSL

Common name Downstream rate Upstream rateADSL 8 Mbps 1.0 Mbps

ADSL (G.DMT) 12 Mbps 1.3 Mbps

ADSL over 12 Mbps 1.3 Mbps

ADSL over 12 Mbps 1.8 Mbps


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ADSL.Lite 4 Mbps 0.5 Mbps

ADSL2 12 Mbps 1.0 Mbps

ADSL2 12 Mbps 3.5 Mbps

RE-ADSL2 5 Mbps 0.8 Mbps

ADSL2+ 24 Mbps 1.0 Mbps

RE-ADSL2+ 24 Mbps 1.0 Mbps

ADSL2+M 24 Mbps 3.5 Mbps

Hin ti cc thu bao ti cc tnh sdng cng nghmng truy nhp xDSL, ticc tnh thnh phln (H Ni, Hi Phng, Thnh PhHCh Minh) cc thu bao sdng chyu cng nghmng truy nhp ADSL 2+ tc download ln ti 24 Mbps.

Hnh 14. S trin khai

4.3.2.Cng nghmng truy nhp FTTxTrong trin khai thc t, s khc nhau gia FTTN v FTTC khng c nhiu vthng th cc thit bFTTC thng gn thu bao hn.

nh ngha ca FTTP (fiber to the premises FTTP thnh thong c sdng din tFTTH v FTTB.

C 2 cng nghchnh c sdng cho cu trc ny l VDSL2 (c sdngtrong FTTN, FTTC v i lc sdng trong FFTB) v PON.

4.3.2.1.Khnng ca PONi tng khi nghin cu khnng ca PON l xc nh liu ng dng PON c thm bo c cc yu cu vbng thng hay khng. N khng chquan trng trong


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cc cng download m cn quan trng i vi cc cng upload khi cng nghmulticast c sdng.

Khnng ca PON phi m bo s lng ngi sdng ti a m khng nhhng ti cht lng hnh nh vi bt k tlnn no.

Vic trin khai FTTx cho dch vIPTV l kh khquan ti cc tnh v thnh phln.

Hnh 15. Cng nghmng truy nhp FTTx

4.3.2.2.Cng nghmng truy nhp WimaxWimax ngy cng c sdng rng ri cung cp cc kt ni Internet bng thngrng m khng thsdng cc cng nghnh DSL hoc cp. Chng ta cng sc thcung cp dch v IPTV thng qua cc kt ni ti thu bao bng cng nghWimax.

Cng nghWimax theo chun IEEE 802.16d vi tc bitrate cho tng sector ln ti10 Mbps trn bng thng 3.5 MHz cung cp mt sknh IPTV nhng khng phhp khi trin khai rng ri. Tuy nhin Wimax cho mobile chun IEEE 802.16e cthc sdng cung cp dch vIPTV ti cc thit bcm tay bng cch sdngtc bitrate thp hn.


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Hnh 16. Cng nghmng truy nhp Wimax

Vic truyn ti dch vIPTV vi cc bng thng khc nhau:

Bit rate SIMO 1x2 SIMO 2x2

Max. DL Throughput per BS(Mbps) 18.4 37.410 MHz BandwidthTDD 2:1 Max. UL Throughput per BS(Mbps) 4 8

Max. DL Throughput per BS(Mbps) 12.96 25.910 MHz BandwidthTDD 1:1 Max. UL Throughput per BS(Mbps) 7 14.1

Max. DL Throughput per BS(Mbps) 9.36 18.75 MHz BandwidthTDD 2:1 Max. UL Throughput per BS(Mbps) 2 4

Cc yu cu QoS cho dch vIPTV

Service Delay J itter Packet loss rate

BTV 1s 1s 1/1000

VoD 1s 1s 1/1000

Video Conference 90ms 20ms 1/1000


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4.4.Phng thc phc vIPTVKhi c ngun in, STB snhn mt a chIP private bng cch nhn thc thng quamy chDHCP (iu ny chyu c trin khai trong giai on u tin v trongtng lai strin khai nhiu my chDHCP nu thy cn thit), sau sgi yu cu

ca trang chcng thng tin ti phn mm Middleware. C thsdng cc la chnDHCP, chng hn 82 hay 60.

Bdliu ca STB stng c ng k trong hthng qun l Middlewaremi khi c mt khch hng STB kt ni thnh cng vi Middleware. Cc a chIP sc phn btc thi thng qua DHCP sao cho ph hp vi a chMAC ca STB.

Vn cn thit i vi ngi sdng l cn nhp ng m sPIN xc nhchnh xc tn STB. Tnh nng nh cu hnh tng c ci sn nhm loi bviccu hnh thcng cho set-top box. Chkhi no ti khon c nhn dng chnh xctrong hthng Middleware th thu bao mi nhn c dch vtrn set-top box.

Hthng Middleware skim tra tnh hp php ca thu bao (tnh trng cc vquyn khai thc ni dung) da trn danh sch thu bao trn my ch/c sdliu ccha ID v a chMAC ca thu bao. Thng tin ny sc nhp liu ngay vo hthng cng thi gian cung cp ni dung chng trnh cho STB.

Nu xc nh ng quyn c cp php xem ni dung ca thu bao v sPINng, hthng Middleware scung cp mt trang chcng thng tin cho STB (thngtin EPG dnh cho knh qung b v danh sch ni dung cho yu cu). Chng hn trangchcng thng tin scho bit thu bao c xem ni dung chng trnh dnh cho bm, chng trnh phi trph hay tt ccc chng trnh. Cn nu khng ng quync cp php v sPIN ca thu bao khng ng th thng bo li shin ra. Ngoi

ra Middleware phi cung cp EPG/danh mc ni dung bng multicast.Khi ngi dng chn mt knh truyn pht t EPG, a ch multicast router/

DSLAM/ BRAS gn nht sc phn mm Middleware gi li bng a chmulticastca knh truyn pht ny. STB ca ngi dng s thc hin giao thc qun l nhmInternet v2 (IGMP v2) gi yu cu ti multicast router/ DSLAM/ BRAS gn nhtnhm thu c knh truyn pht ny. V chkhi , ngi dng mi c thgia nhpvo dng chng trnh multicast.

Hthng Middleware slu gimt dy cc a chIP kca chIP ca ccSTB, cc my chVoD, my chDRM

Trng hp ngi dng chn xem ni dung c thu ph, hthng Middleware cthxc thc ngi dng ny v lin kt vi cc my chDRM gi kho gii mchnh xc ti STB ca ngi .

Hthng Middleware c khnng xc nhn ni dung sc xem trc khi mychVoD bt u phn phi cc dng RTSP ti STB. Cng nh th, cMW v mychni dung scung cp mt sphng thc nh m ttrong ti liu ny. Thmna, Middleware cn c thbt u truyn pht ni dung tphn cui chng trnh


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quay ngc tr li trong trng hp tm ngng ti chng trnh gia chng v l dono .

H thng DRM cha kho cho phn ni dung ca mt c sdliu kho ngthi b mt phn phi c sdliu ny ti STB. Hthng DRM cng shtrthmvo phn ni dung cc chc nng ththut trong khi xem (tua nhanh, tua li,...).

M hnh thu ph dch vkh linh hot v c thhot ng trn c strph chocc chng trnh xem, thu bao trn gi xem phim chng hn cho mt bphim, victnh tin sda vo cc chng trnh xem.

H thng DRM s da trn cc khi nim ca h thng PKI (Public KeyInfrastructure C shtng kho cng cng). PKI dng cc thkthut sX.509 xc nhn mi thnh t trong h thng DRM ng thi m ho an ton d liu cdng cc kho chung/ring.

H thng Middleware s cung cp mt giao din "Subcriber_API" ("Thubao_API").

cung cp mt dch vlin tc bao gm chthng ktha ca nh cung cp,Middleware sa ra cc giao din API, giao din ny smrng khnng thc hinnhng chc nng mi v gip chuyn giao dliu gia cc hthng. Tvic thit lpmt thu bao trong hthng qun l thu bao ca nh cung cp n vic trnh by mtmu ho n thng nht trong hthng thanh ton ca nh cung cp, tt cu cMiddleware thc hin tri chy tu n cui".

Ngi dng sc bit vvic sdng hin thi v ho n thanh ton ca htrn Middleware gn km vi ni dung chng trnh phc v. Qua , hnm cthi im v ngy thng bt u hay ngng sdng dch v, s lng pht sinh, m

lng/thi gian (dnh cho nhng ni dung c thu ph). Hthng Middleware c nghstch hp vi hthng tnh cc trong hot ng ny.

Ngi xem c th chn cc knh pht sng min ph hoc bt kni dung nokhc tSTB-Remote bng cch nhn sknh v bng thao tc cun (chng hn qua

phm strn iu khin txa hoc qua la chn ca EPG trong giao din ngi dngTV).


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Phn 5GII PHP CUNG CP DCH VIPTV CHO

MNG xDSL CA VNPT

5.1.Htng truyn tiHtng truyn ti c thchia lm 3 phn nh sau:

Mng li. Mng gom v mng truy nhp. Mng khch hng.

5.1.1.Mng liMng li c nhim v truyn ti cc lu lng thng tin gia h thng IPTV v ccPE/BRAS ti cc tnh thnh. Lu lng truyn ti bao gm 2 loi chnh l unicast (ccthng tin iu khin, cc lung video trong dch vvideo theo yu cu) v multicast(dch vbroadcast video).

Cc lu lng unicast c truyn qua mng li IP/MPLS bng cch thit lp ccng chuyn mch nhn (Label Switching path LSP) gia cc PE/BRAS.

Hnh 17. Cc LSP c thit lp qua mng li IP/MPLS dnh cho cc lu lng unicast

Cc lu lng multicast c truyn qua mng li IP/MPLS bng cch thit lpcc multicast VPN. xy dng bng nh tuyn multicast, cc thit bmng li sdng giao thc PIM-SM/SSM ( Protocol Independent Multicast Sparse Mode/SourceSpecific Mode).


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Hnh 18. Multicast VPN c thit lp qua mng IP/MPLS dnh cho cc lu lng multicast

5.1.2.Mng gom v mng truy nhpMng gom v mng truy nhp c nhim v truyn ti thng tin tmng li n thu

bao.

Ta bit rng, cc dch vc nh xvo mng truy nhp theo cc m hnhkhc nhau: m hnh N:1 VLAN v m hnh 1:1 VLAN. Vi s tng trng s lngthu bao ngy cng ln, cng nh s lng dch vngy cng nhiu th m hnh 1:1

VLAN c hn ch. Slng VLAN l gii hn, do slng thu bao c thphc vcng bgii

hn theo. Cng do slng VLAN hn chnn khnng nng cp, mrng cng nh a

thm cc dch vmi gp kh khn.

Do , m bo khnng mrng hthng, phng n nh xdch vtrongmng gom v mng truy nhp c sdng l N:1 VLAN.

5.1.3.Mng khch hngTi pha khch hng, sdng cc thit bu cui khc nhau cho cc loi dch vkhcnhau:

PC cho dch vInternet. Set top- box cho dch vIPTV.

Sdng thit b truy nhp DSL (modem, home gateway) tch cc PCV chocc dch vkhc nhau v chuyn tip n cc thit bu cui tng ng.


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5.2.Trin khai dch vIPTV trn mng ca VNPTH thng IPTV c xy dng hon ton trn nn tng IP. Sau khi hon thnh, tithiu hthng phi cung cp c cc dch vsau:

Dch vtruyn hnh qung b (BTV) vi 100 knh. Dch vvideo theo yu cu (VoD). Cc dch vvideo tng tc (Interactive Video).

Hthng c khnng cung cp dch vvi slng thu bao trn ton quc vokhong 1 triu thu bao, trong tp trung ti cc thnh phln, cc khu vc ng dnc, c nhu cu cao.

Ltrnh trin khai hthng IPTV c chia lm 02 giai on. Giai on 1 trinkhai trn h thng mng hin ti ca VNPT. Dkin lng thu bao trong giai onny vo khong 60.000 thu bao, tp trung chyu ti 6 tnh thnh l H Ni, Thnh

phHCh Minh, Nng, Hi Phng, Bnh Dng, v ng Nai.

Phn bthu bao dkin nh sau: H Ni, TP HCh Minh: 20.000 thu bao Hi Phng, Nng, Bnh Dng, ng Nai: 5.000 thu bao.

Giai on 2 c trin khai trn h thng mng NGN ca VNPT. y l giaion m hthng mng ng trc quc gia c chuyn i hon ton sang NGNtrn nn cng nghIP/MPLS. Hthng mng gom (mng MAN) v mng truy nhp ticc bu in tnh c bn hon tt.

Dkin hthng c chuyn i v mrng tng bc ph hp vi tc phttrin thu bao nh sau:

Bc 1:Lng thu bao l 200.000. Phn bthu bao c mrng ra 10 tnhthnh, trong :

H Ni, Thnh phHCh Minh: 60.000 thu bao. Cc tnh thnh cn li: 10.000 thu bao.

Bc 2: Lng thu bao l 500.000. Phn bthu bao c mrng ra 20 tnhthnh, trong :

H Ni, Thnh phHCh Minh: 150.000 thu bao. Cc tnh thnh cn li: khong t5.000 n 15.000 thu bao.

Bc 3:Lng thu bao t 1.000.000. Phn b thu bao c m rng ra 40tnh thnh, trong :

H Ni, Thnh phHCh Minh: 250.000 thu bao. Cc tnh thnh cn li: khong t5.000 n 25.000 thu bao.


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5.3.Trin khai giai on 1

5.3.1.M hnh u niTt ccc lu lng ttrung tm IPTV u c nh tuyn n thit bPE M20 ca

Cng ty Vin Thng Lin Tnh (VTN). Cc lu lng dch vsau i qua mng coren BRAS ti cc cc tnh thnh. TBRAS, cc lu lng c y xung cc accessswitch, switch lp 2, DSLAM, v cui cng ti thu bao.

1GE

Hnh 19. M hnh u ni hthng cung cp dch vIPTV

Ch :

Hin nay cc ATM-DSLAM ang dn c thay thbi cc IP-DSLAM. V vy,cc thu bao ca dch vIPTV sc trin khai trn cc IP-DSLAM.

Do nhu cu sdng cng nh bng thng chim dng ca dch vVoD rt lnnn gim ti cho hthng mng, c bit l mng ng trc, cc VoD server thcp sc trin khai ti cc a im gn vi thu bao hn. C hai vtr c thbtrcc VoD server thcp:


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Btr VoD server ti BRAS. Btr VoD server ti access switch.

Gii php btr VoD server thcp ti cc BRAS khthi hn v:

Btr VoD server ti cc access switch i hi chi ph rt ln cho mt slng

ln VoD server. BRAS l im tp trung lu lng vi slng thu bao hp l. BRAS hot ng lp 3 nn vic cu hnh, m bo QoS, v qun l cng d

dng hn.

5.3.2.M hnh hotng5.3.2.1.Mng khch hng (home network)Mng khch hng sdng m hnh nh xdch vmulti-VC.

Dch vIPTV c cung cp trn cc kt ni ADSL2+. Mi kt ni ADSL2+ nthu bao gm c 2 PVC khc nhau nhm cung cp 2 loi dch v:

PVC 1: cung cp dch vtruy nhp Internet tc cao (HSI). PVC 2: cung cp dch vvideo (bao gm cVoD, BTV,...).

Khch hng sdng cc thit bu cui khc nhau cho tng loi dch v:

Video: STB (Set-Top Box). Internet: PC.

Kt ni ADSL2+ c kt cui bi modem hoc home gateway. Cc thit bnychuyn cc lu lng trn cc PVC n cc giao din u ra tng ng kt ni vi cc

thit bu cui dch v.5.3.2.2.Mng truy nhp (access network)Mng truy nhp ti cc tnh thnh c trin khai theo m hnh S-VLAN (Service-VLAN hay VLAN per service). M hnh tng ng vi m hnh N:1 VLAN.

Nguyn tc thc hin m hnh ny nh sau:

Mng truy nhp ti cc tnh thnh bao gm cc thit bmng, cc kt ni mng tcc DSLAM n BRAS.

Trong mng truy nhp cu hnh cc VLAN khc nhau cho tng loi dch v s

c cung cp. Ti bin ca mng truy nhp, cc lu lng trc khi i vo mng c phn loinh xvo cc VLAN dch v.

Cthi vi hthng mng hin ti, m hnh S-VLAN hot ng nh sau:

Ti cc IP-DSLAM, mi cng ADSL2+ gm 3 PVC, mi PVC dnh cho mtdch v(Internet, VoIP, video).


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Ti cc giao din uplink, cc PVC c nh xvo cc S-VLAN tng ng vitng loi dch vsdng phng thc ng gi 802.1q. Cc S-VLAN ny baogm:

HSI VLAN: VLAN dnh cho dch vtruy nhp Internet. VoIP VLAN: VLAN dnh cho dch vVoIP. VoD VLAN: VLAN dnh cho dch vVoD. BTV VLAN: VLAN dnh cho dch vtruyn hnh (multicast).

Hnh 20. M hnh S-VLAN trong mng truy nhp giai on 1

Ti cc switch lp 2, access switch, cu hnh cc giao din trunk mang lu lngca cc S-VLAN ny.

BRAS c nhim vkt cui cc S-VLAN v thc hin nh tuyn cc gi tin n

ch mong mun.Cc bin php m bo QoS c p dng trn tng S-VLAN thng qua cu hnh

802.1p i vi cc S-VLAN tng ng. Ti BRAS, ni kt cui cc S-VLAN, thchin QoS lp 3 bng DSCP (Diffrentiated Service Code Point). Nh vy ti BRAS cncu hnh chuyn i QoS t802.1p ca lp 2 sang DSCP ca lp 3.

5.3.2.3.Truy nhp u cui v a chIPi vi dch vtruy nhp Internet tc cao (HSI), thu bao thc hin quay sPPPoEn BRAS. BRAS cp a chIP cho tng kt ni PPPoE, thc hin NAT (nu cn) vchuyn tip cc lu lng ra Internet.

i vi cc dch vvideo, a chIP c cp pht ng bng DHCP. Ti BRAScu hnh DHCP relay chuyn tip cc gi tin DHCP n DHCP server v thc hinnh tuyn cc gi tin ca cc dch vny n ch mong mun.


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Hnh 21. Truy nhp u cui v a chIP giai on 1

5.3.2.4.Lu lng multicastcc lu lng multicast c thtruyn ti trong hthng mng mt cch hiu qu,cc tnh nng multicast cn c htrti cc thit bmng. Cc giao thc thc hinti cc thit bmng nh trn hnh 5.

Ch :

Vi h thng mng hin ti chy MPLS, nu BRAS khng h trmulticastVPN th cn chy song song native IP v IP/MPLS trn mng ng trc, trong native IP dng truyn cc lu lng multicast.

Nu BRAS h tr multicast VPN th c th chy multicast VPN truyn cc lulng multicast qua mng ng trc.


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1GE

Hnh 22. Lu lng multicast giai on 1

5.3.3.Yu cu vbng thng5.3.3.1.Cc k hiu v tham sthng k u vo Slng thu bao ti mt tnh thnh: Si. Tlthu bao sdng dch vVoD ti mt thi im: R1= 30%. Tlp ng thu bao ca VoD server thcp: R2=80%. Bng thng cho mt lung video: B = 2 Mbps. Slng access switch kt ni n mt BRAS: SW. Gisslng thu bao phn btrn cc access switch l tng i ng u,

khi lng thu bao trong cng phc vca mi access switch liS

SW .

5.3.3.2.Dung lng mng dnh cho dch vBTVHthng scung cp 100 knh truyn hnh, mi knh truyn hnh yu cu bng thng2 Mbps.

BTVC =1002Mbps=200Mbps


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5.3.3.3.Dung lng mng dnh cho dch vVoD Dung lng mng core: c 20% yu cu VoD khng c p ng bi cc VoD

server thcp, cc yu cu ny sc phc vbi VoD server t ti trung tmIPTV. Nh vy dung lng bchim dng trong mng core l:

( )1VoD 1 2iiC = S R 1-R B

Dung lng kt ni tBRAS n core router

( )i 1 22VoD

C =SR 1-R B

Dung lng kt ni tBRAS n access switch

i1

3VoDSC = R B

SW

5.3.3.4.Dung lng mng phc vng bni dung gia cc VoD serverQu trnh ng bni dung gia cc VoD server c thc hin vo thi gian rnh rica mng. Bng thng dnh cho tc vny c lp khoch ttrc v hon ton cthkim sot c. Ty thuc khi lng cn ng bm bng thng dnh ra c ththay i t100 Mbps n 500 Mbps.

5.3.4.Yu cu tnh nng thit b, cc giao thc cn htr5.3.4.1.IP-DSLAM IGMP snooping, proxy. Phn loi lu lng v nh xPVC S-VLAN. 802.1q. 802.1p.

5.3.4.2.Switch lp 2 IGMP snooping. 802.1q. 802.1p.

5.3.4.3.Access switch IGMP snooping. 802.1q. 802.1p.

5.3.4.4.BRAS IGMP v2, v3. PIM-SM.


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DHCP relay. 802.1q. 802.1p. DSCP (Differentiated Service Code Point). Phn loi lu lng v nh x802.1p DSCP.

OSPF.

5.4.Trin khai dn giai on 2

5.4.1.M hnh u niTrung tm IPTV c kt ni trc tip vo mng core IP/MPLS qua PE ca VTN.Ring hthng VoD server c trin khai vi mt VoD server cha y ni dungt ti trung tm IPTV, v nhiu VoD server thcp c btr gn vi thu bao.

Cc VoD server th cp ch lu mt phn ni dung ca VoD server trung tmnhm mc ch p ng nhng ni dung VoD c nhu cu cao ti mt thi im nhtnh. Vtr t VoD server thcp c thl:

PE: gim ti mng core, nhng khi slng thu bao ln th kt ni gia cc coreMAN switch v cc PE sc yu cu bng thng rt ln.

Core MAN switch: so vi phng n t ti PE th phng n ny chgim ticho kt ni tmng MAN ln PE, cc phn khc ca mng khng c li ghn.

Access switch: vn chnh ca phng n ny l slng VoD server cn ut rt ln v vic qun l gp nhiu kh khn.


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Hnh 23. M hnh u ni giai on 2

5.4.2.M hnh hotng5.4.2.1.Mng khch hng (home network)Mng khch hng hon ton khn

de tai iptv

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