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Danh mc cc t kha v t vit tt...................................................... 5

Danh mc cc hnh v ........................................................................... 6

Danh mccc bng ............................................................................... 7

M U ......................................................................................... 8

Chng 1 . GII THIU IPTV ....................................................... 11

1.1 Khi nim ................................................................................................... 11

1.2 Phn loi dch v IPTV .............................................................................. 12

1.2.1 Dch v truyn hnh qung b ............................................................. 12

1.2.2 Dch v theo nhu cu (On-Demand) ................................................... 14

1.2.3 Dch v tng tc (Interactive) ........................................................... 16

1.2.4 Dch v thng tin v truyn thng ...................................................... 17

1.2.5 Cc dch v gia tng khc ................................................................... 19

Chng 2 . TNG QUAN V H THNG TRUYN HNH

TRN MNG xDSL .............................................................................. 21

2.1 Kin trc h thng cung cp dch v IPTV ................................................ 212.1.1 M hnh tng qut ............................................................................... 21

2.1.2 Cc thnh phn cung cp dch v Broadcast Video............................ 21

2.1.3 Cc thnh phn cung cp dch v VoD ............................................... 22

2.1.4 Cc thnh phn chung ......................................................................... 24

2.1.5 Kin trc sn phm ............................................................................. 25

2.2Nhng yu cu t ra cho dch v video .................................................... 26

2.2.1 Bng thng rng.................................................................................. 26

2.2.2 Bng thng khng i xng................................................................ 27

2.2.3 Cht lng dch v .............................................................................. 27

2.2.4 S sn sng ca dch v ...................................................................... 27

2.2.5 Thi gian chuyn knh i vi dch v Broadcast ............................. 28

2.3 Kin trc mng cung cp dch v IPTV ..................................................... 28

2.4 Video site .................................................................................................... 292.5 Mng truyn dn......................................................................................... 30

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Chng 3 . CC GII PHP K THUT PHT TRIN H

THNG TRUYN HNH TRN MNG xDSL ................................... 36

3.1 Gii php la chn chun nn hnh nh ..................................................... 36

3.1.1 Chun nn MJPEG v Wavelet........................................................... 36

3.1.2 Chun nn MPEG-x v H.26x ............................................................ 38

3.1.3 Chun nn MPEG-2 ............................................................................ 39

3.1.4 Chun nn MPEG-4 ............................................................................ 40

3.1.5 Chun nn H.264/MPEG-4 Part 10/AVC ........................................... 42

3.1.6 Yu cu v bng thng ca cc chun nn ......................................... 453.2 La chn giao thc mng ........................................................................... 45

3.2.1 Giao thc cho dch v multicast ......................................................... 45

3.2.2 Giao thc IGMP.................................................................................. 45

3.2.3 Giao thc PIM..................................................................................... 47

3.3 Giao thc cho dch v unicast .................................................................... 50

3.3.1 Giao thc RTSP .................................................................................. 50

3.3.2 M rng giao thc RTSP .................................................................... 51

3.3.3 Bn tin RTSP ...................................................................................... 52

3.3.4 ng dng ca giao thc RTSP ........................................................... 52

3.4 Giao thc cho dch v VoIP ....................................................................... 53

3.4.1 SIP ....................................................................................................... 53

3.4.2 ng dng ca SIP ............................................................................... 56

3.4.3 ng dng ca SIP trong mng NGN .................................................. 57

3.5 La chn cng ngh mng truy nhp ......................................................... 57

3.5.1 Cng ngh mng truy nhp xDSL ...................................................... 58

3.5.2 Cng ngh mng truy nhp F .............................................................. 59

3.5.3 Kh nng ca PON.............................................................................. 60

3.5.4 Cng ngh mng truy nhp Wimax .................................................... 60

3.6 Phng thc phc v IPTV........................................................................ 62

Chng 4 . GII PHP CUNG CP DCH V IPTV CHO MNGxDSL ....................................................................................... 65

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4.1 Yu cu v h tng truyn ti ..................................................................... 65

4.1.1 Mng li .............................................................................................. 65

4.1.2 Mng gomv mng truy nhp ............................................................ 66

4.1.3 Mng khch hng ................................................................................ 67

4.2 Trin khai bc 1 ....................................................................................... 67

4.2.1 M hnh u ni .................................................................................. 67

4.2.2 M hnh hot ng .............................................................................. 69

4.2.3 Lu lng multicast (xem Hnh 4-6 ) ................................................. 72

4.3 Yu cu v bng thng ............................................................................... 72

4.3.1 Cc k hiu v tham s thng k u vo ........................................... 72

4.3.2 Dung lng mng dnh cho dch v BTV .......................................... 72

4.3.3 Dung lng mng dnh cho dch v VoD .......................................... 73

4.3.4 Dung lng mng phc v ng b ni dung gia cc VoD server.. 73

4.4 Yu cu tnh nng thit b, cc giao thc cn h tr.................................. 73

4.5 Trin khai bc 2 ....................................................................................... 74

4.5.1 M hnh u ni .................................................................................. 744.5.2 M hnh hot ng .............................................................................. 75

4.5.3 Mng khch hng (home network) ..................................................... 75

4.5.4 Mng truy nhp (access network) ....................................................... 76

4.5.5 Mng gom hay vng core mng MAN (distribution network) ........... 76

4.5.6 Truy nhp u cui v a ch IP ........................................................ 77

4.5.7 Lu lng multicast ............................................................................ 78

4.6 Yu cu bng thng .................................................................................... 78

4.6.1 Cc k hiu v tham s thng k u vo ........................................... 78

4.6.2 Dung lng mng dnh cho dch v BTV .......................................... 78

4.6.3 Dung lng mng dnh cho dch v VoD .......................................... 78

4.7 Dung lng mng phc v ng b ni dung gia cc VoD server (theo

bc 2):.................................................................................................................. 79

4.7.1 Phng n gim ti mng core v mng gom. .................................... 79

4.7.2 Yu cu tnh nng thit b, cc giao thc cn h tr........................... 81

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4.8 Tnh ton bng thng c th theo m hnh thc nghim trn . ............... 82

4.8.1 Theo bc 1 ........................................................................................ 82

4.8.2 Theo bc 2 ........................................................................................ 84

Kt lun ....................................................................................... 91

Ti Liu Tham Kho ........................................................................... 92

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Danh mc cc t kha v t vit tt

IPTV Internet Protocol Television

VoD Video-on-Demand

Broadcast Qung b tn hiu

PPV Pay-per-View l dch v tr tin xem nhng

knh truyn hnh mong mun.

STB Set-top-box l thit b thu tn hiu IPTV ti cc

end-user

EPG Giao din la chn ca IPTV th hin trn mn

hnh TV

Middleware Thit b trung gian h tr trong qu trnh truyn tn

hiu IPTV

DSLAM Thit b vin thng qun l ng truyn t nh

cung cpn khch hng

BRAS Thit b vin thng qun lng truyn gia cc

DSLAM.

DSCP (Differentiated Service Code Point)

STP (Spaning Tree Protocol).

DRM Thit b h tr gim s nghn mng .

PKI (Public Key Infrastructure)

PIM-SM/SSM ( Protocol Independent Multicast Sparse

Mode/Source Specific Mode)

PPPoE Giao thc kt ni Internet trn modem ADSL

SHE (Super HeadEnd)

VHO (Video Headend Office)

VSO (Video Switching Office).

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Danh mc cc hnh v

Hnh 1-1 Cng ngh ca tng lai ............................................................................ 11

Hnh 1-2 Cc dch v IPTV c cung cp .............................................................. 12

Hnh 2-1 M hnh tng qut h thng cung cp dch v IPTV................................. 21

Hnh 2-2 Kin trc sn phm h thng cung cp dch v IPTV ............................... 25

Hnh 2-3 Kin trc mng cung cp dch v IPTV .................................................... 29

Hnh 2-4 Kin trc truy nhp a knh o .................................................................. 32

Hnh 2-5 Kin trc truy nhp EtherType .................................................................. 32Hnh 2-6 Kin trc truy nhp a VLAN ................................................................... 33

Hnh 3-1 Qu trnh nhn, thng bo ti cc thu bao join vo group G v sourse

S ................................................................................................................................. 49

Hnh 3-2 S trin khai .......................................................................................... 59

Hnh 3-3 Cng ngh truy cp FTTx .......................................................................... 60

Hnh 3-4 Cng ngh mng truy cp Wimax ............................................................. 61

Hnh 4-1 Cc LSP c thit lp qua mng li IP/MPLS dnh cho cc lu lng

unicast........................................................................................................................ 65

Hnh 4-2 Multicast VPN c thit lp qua mng IP/MPLS dnh cho cc lu lng

multicast .................................................................................................................... 66

Hnh 4-3M hnh u ni h thng cung cp dch v IPTV.................................... 68

Hnh 4-4 M hnh S-VLAN trong mng truy nhp giai on 1................................ 70

Hnh 4-5 Truy nhp u cui v a ch IP ............................................................... 70

Hnh 4-6 Lu lng multicast bc 1....................................................................... 71

Hnh 4-7 M hnh u ni ......................................................................................... 75

Hnh 4-8 Lu lng multicast bc 2....................................................................... 77

Hnh 4-9 B tr VoD server gim ti mng gom....................................................... 81

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Danh mc cc bng

Bng 3-1 Yu cu v bng thng i vi cc chun nn .......................................... 45

Bng 3-2 . Cc bn tin yu cu ca SIP .................................................................... 56

Bng 3-3 Cc loi bn tin p ng ca SIP .............................................................. 56

Bng 3-4 Cc dng chun ca ADSL ....................................................................... 58

Bng 3-5 Bng thng cc kiu dch v IPTV ........................................................... 61

Bng 3-6 Cc yu cu QoS cho dch v IPTV .......................................................... 62

Bng 4-1 Mng Core ................................................................................................. 83

Bng 4-2 Lu lng khu vc A, B ........................................................................... 83

Bng 4-3 Lu lng khu vc D ................................................................................ 83

Bng 4-4 Lu lng khu vc E, F ............................................................................ 84

Bng 4-5 Lu lng khu vc C ................................................................................ 84

Bng 4-6 Mng core bc 2...................................................................................... 85

Bng 4-7 Lu lng khu vc A, B bc 2 ( trng hp 200.000 thu bao) ............ 85

Bng 4-8 Lu lng cc khu vc cn li bc 2 (trng hp MAN c 4 core

switch, 200.000 thu bao) ......................................................................................... 85

Bng 4-9 Lu lng cc khu vc cn li bc 2 (trng hp MAN c 3 core

switch, 200.000 thu bao) ......................................................................................... 86

Bng 4-10 Lu lng khu vc A, B bc 2 ( trng hp 500.000 thu bao) .......... 86

Bng 4-11 Lu lng cc khu vc cn li bc 2 (trng hp MAN c 4 core

switch, 500.000 thu bao) ......................................................................................... 87

Bng 4-12 Lu lng cc khu vc cn li bc 2 (trng hp MAN c 3 core

switch, 500.000 thu bao) ......................................................................................... 87

Bng 4-13 Lu lng khu vc A, B bc 2 ( trng hp 1 triu thu bao)............. 88

Bng 4-14 Lu lng cc khu vc cn li bc 2 ( trng hp MAN c 4 core

switch, 1 triu thu bao) ............................................................................................ 88

Bng 4-15 Lu lng cc khu vc cn li bc 2 ( trng hp MAN c 3 core

switch, 1 triu thu bao) ............................................................................................ 89

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M U

1. Gii thiuS pht trin ca mng Internet ton cu ni ring v cng ngh thng tin ni

chung em li tin b v pht trin vt bc ca khoa hc k thut. Internet

khng nhng rt ngn khong cch v khng gian, thi gian m cn mng li

cho mi ngi, mi quc gia v c th gii nhng li ch to ln. Tc pht trin

nhanh chng ca cng ngh thng tin l mt trong nhng li ch to ln, c vai tr

quan trng v tm nh hng rng khp.

Vi s pht trin nhanh chng ca mng Internet bng rng cn lm thay i c

v ni dung v k thut truyn hnh. Hin nay truyn hnh c nhiu dng khc nhau:

truyn hnh s, truyn hnh v tinh, truyn hnh cp, truyn hnh Internet v IPTV.

IPTV ang l cp cao nht v l cng ngh truyn hnh ca tng lai. S vt

tri trong k thut truyn hnh ca IPTV l tnh nng tng tc gia h thng vi

ngi xem, cho php ngi xem ch ng v thi gian v kh nng trin khai

nhiu dch v gi tr gia tng tin ch khc trn h thngnhm p ng nhu cu ca

ngi s dng.

Hin nay trn th gii c mt s quc gia trin khai thnh cng IPTV. Theo

cc chuyn gia d bo th tc pht trin thu bao IPTV s tng theo cp s nhn

theo tng nm. Vit Nam hin nay, mt s nh cungcp ang th nghim dch v

IPTV trn mng bng rng ADSL.Nm 1994, World News Now ca ABC c

bui trnh chiu truyn hnh qung b qua mng Internet u tin, s dng phnmm CU-SeeMe videoconferencing. T chc lin quan n IPTV u tin xut hin

l vo nm 1995, vi s thnh lp Precept Software bi Judith Estrin v Bill

Carrico. H thit k v xy dng mt sn phm internet video gi l "IP/TV".

IP/TV l mt MBONE tng thch vi cc ng dng trn Windows v Unix, thc

hin truyn m thanh, hnh nh thng qua c giao thc unicast v IP multicast

RTP/RTCP. Phn mm ny c vit bi Steve Casner, Karl Auerbach, v Cha

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Chee Kuan. H thng ny c Cisco Systems mua vo nm 1998 v Cisco

d li tn "IP/TV".

AudioNet bt u tin hnh nghin cu live webcasts vi WFAA-TV trong thng

nm 1998, v KCTU-LP vo mng 10 thng 1 nm 1998. Kingston

Communications, mt nh cung cp dch v vin thng UK, trin khai KIT

(Kingston Interactive Television), v IPTV qua mng bng rng DSL vo thng 9

nm1999 sau khi th nghim dch v TV v VoD. Nh cung cp ny thm dch

v VoD vo h thng trong thng 10 nm 2001 vi h thng Yes TV. Kingston l

mt trong nhng cng ty u tin trn th gii trin khai IPTV v IP VoD qua mng

ADSL. Hin nay, IPTV ang pht trin mnh ti chu v ang bt u pht trin

ti Vit Nam.

2. Mc tiu ca tiMc ch chnh ca ti l gii thiu v dch v truyn hnh IPTV v nhng

cng ngh, ng dng c s dng n trong dch v ny. ti c chia lm 4

chng nhm gip ngi c d dng hn trong vic tm hiu v cng ngh IPTV.

3. Hng gii quytvn Tham kho nhng ti liu, bi bo t nhiu ngun khc nhau, t rt ra nhng

nhn xt, nh gi v u, nhc im ca tng m hnh v ra gii php cho mt

m hnh c th. T m hnh ra rt ra nhng kt qu v kt lun v nhng yu

cu tng th cho mt m hnh cung cp dch v IPTV.

4. B cc ca tiChng I gii thiu v IPTV v cc dch v ng dng nhm mc ch gii thiu

v dch v IPTV l g, nhng u im ca n so vi truyn hnh cp hin nay.

Ngoi ra n cn tm tt nhng loi dch v IPTV s cung cp v nhng chc nng

chnh ca cc loi dch v ny.

Chng II tng quan v h thng truyn hnh trn mng xDSL, mc ch chnh

ca phn ny gip ngi c hiu r hn v kin trc h thng ca mt dch v

IPTV, cc thnh phn chnh cung cp dch v Broadcast video, cc thnh phn cung

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cp dch v VoD (video on demand),nhng yu cu t ra cho dch v video v m

hnh tng qut ca kin trc mng cung cp dch v IPTV.

Chng III ra cc gii php k thut cng ngh pht trin h thng truyn hnh

trn mng xDSL. Mc ch ca phn ny gip chng ta hiu c cch thc trin

khai mt h thng IPTV trn mng xDSL. Phn ny gii thch v cc chun nn

hnh nh s dng trong dch v truyn hnh v gii php chn chun nn hnh nh

ti u, mt s yu cu v bng thng i vi chun nn hnh nh v cc giao thc

mng cho dch v IPTV.

ChngIV ra gii php cung cp dch v IPTV cho mt m hnh mng xDSL

cth Vit Nam, phn ny ra gii php cung cp IPTV cho mt m hnh mng

c th. Trong xut ra cc bc nhm gii quyt v yu cu ng truyn cng

nh n nh v bng thng cho mt m hnh cung cp dch v IPTV vi s

lng thu bao ngy cng tng. Gii quyt cc yu cu ra trong qu trnh cung

cp dch v IPTV t nh cung cp n khch hng nhm t n nh trong qu

trnh cung cp dch v.

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Chng 1 .GII THIU IPTV

1.1 Khi nimIPTV (Internet Protocol Television) l dch v truyn ti hnh nh k thut s ti

ngi s dng qua giao thc IP trn mng Internet vi kt ni bng thng rng. N

thng c cung cp kt hp vi VoIP, video theo yu cu... nn cn c gi l

cng ngh TriplePlay (d liu, m thanh v hnh nh). Nhng trong mt mitrng

m thch thc nhn ln theo cp s m v cng ngh phi lin tc c cp nht, b

ba dch v ni trn chuyn thnh b t khi c thm xem truyn hnh Internet qua

in thoi di ng (MobileTV).

Hnh 1-1 Cng ngh ca tng lai

Kh nng ca IPTV gn nh l v hn v n ha hn mang n nhng ni dung

k thut s cht lng cao nh video theo yu cu (Video-on-Demand- VoD), hi

tho, truyn hnh tng tc/trc tip, game, gio dc t xa, video blogging (vBlog),

tin nhn nhanh qua TV...

Trc y, cng ngh ny gn nh khng th hot ng c do tc kt ni

quay s qu chm, nhng trong vi nm ti, IPTV s tr nn thnh hnh bi hn

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100 triu h gia nh trn ton th gii ng k thu bao bng thng rng. Cc

nh cung cp dch v vin thng coi IPTV nh mt c hi tng doanh thu trn th

trng v l v kh li hi chng li s bnh trng ca truyn hnh cp.

1.2 Phn loi dch v IPTVH thng IPTV pht trin da trn h thng mng bng thng rng ang trin

khai c kh nng cung cp c cc dch v nh m t phn di y.

Hnh 1-2 Cc dch v IPTV c cung cp

1.2.1 Dch v truyn hnh qung b 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 t h thng truyn hnh

mt t, truyn hnh cp, truyn hnh v tinh 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 t v tinh

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- Cc knh truyn hnh m ho t v tinh - Cc knh truyn hnh ring ca nh cung cp TV.

Vi gii php IPTV, nh cung cp dch v c th ng nhiu loi knh truyn

hnh thnh cc gi nhm cung cp cho khch hng vi cc gi cc linh hot khc

nhau. Cc knh truyn hnh c h tr tnh nng tr tin theo tng knh hoc theo

tng thi im ngi xem mun xem (Pay-per-ViewPPV). Set-top-box (STB) c

giao din hng dn xem chng trnh v k hoch pht sng chng trnh TV cp

nht d dng. Ngi xem c th chuyn knh thun tin trn STB ti u cui ca

khch hng.

Time-shifted TVTm dng TV l tnh nng gip ngi xem c th tm dng knh truyn hnh

ang pht v c th xem tip sau . V d ngi xem tm dng khi cn nghe in

thoi, sau khi cuc gi kt thc ngi xem c th xem chng trnh TV tip tc t

thi im trc hoc xem tip nh bnh thng. Giao din v chc nng ca

dch v c th hin r rng, trc quan thng qua EPG v STB, thun tin cho

ngi s dng. Ngi dng c th xem tip t thi im tm dng v h thng p

ng knh LiveTV nh bnh thng. Hnh thc ny c th tnh ph linh hot, thu

cc theo gi dch v hoc theo PPV.

Virtual Channel from VoDsChc nng ny cho php h thng ghp mt s ni dung VoD ty chn thnh

mt knh ring v pht trn mng. Sau khi kch hot, knh o ny hot ng v

c y cc tnh nng nh mt knh TV bnh thng. Dch v cho php bin tpcc ni dung VoD cng th loi (m nhc, thi trang, th thao, ..) thnh mt knh

chuyn theo th hiu ca khch hng. Ngi qun tr c kh nng qun l v theo

di cc knh o to ra.

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

ty chn lp li nhiu ln trn cc knh multicast khc nhau. Vi cng mt ni dung

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pht cch nhau mt khong thi gian, do vy khch hng c th tr tin PPV (Pay-

per-view) v xem ti cc thi im ty .H thng c kh kh nng thit lp dch

v NVoD vi cc chng trnh truyn hnh hoc VoD. H tr kh nng tnh cc

theo PPV hoc theo gi dch v.

Mobile TVDch v ny l hng pht trin tng lai m bo cung cp knh truyn hnh,

VoD v cc dch v ca h thng IPTV n cc khch hng ca mng di ng. Gii

php hon chnh h thng IPTV c th kt ni, trin khai cung cp dch v

Mobile-TV. Vic tnh cc c th tch hp vi h thng Billing c lp c ccphng thc tnh cc linh ng v hiu qu.

1.2.2 Dch v theo nhu cu (On-Demand) VoD (Video on Demand)i vi dch v VoD, ngi xem la chn cc video (phim, video clip) trc tip

t th vin ca nh cung cp xem qua trn TV ca khch hng. Th vin h tr

tnh nng tm kim, hin th danh sch v miu t cc video cng vi vic gii thiu

hp dn ca video. Nhm khuyn khch khn gi mua phim, ngi xem s c

xem qua cc bn tm tt phim, xem trc cc on phim demo ri mi quyt nh

c mua hay khng. Dch v VoD c nhng tnh nng c bn ca thit b ghi hnh

VCR nh l tm dng, chy tip, chuyn nhanh v pha trc, chuyn nhanh v

pha sau. Tnh nng chuyn nhanh v pha trc, chuyn nhanh v pha sau cn t

c tc 2X, 4X, 8X, 16X, 32X v 64X. H thng cho php gii thiu thng tin

tm tt v cc b phim v video trn giao din ca EPG. Ty vo mc ch kinh

doanh ca nh cung cp dch v, ngi xem c th xem nhiu ln bt c lc no

nh ch pht sng. Nh cung cp c th gn km trailer qung co v ni dung

demo, h tr lu cc thng tin VoD a thch vo Favourite, sau c th chn li.

Chc nng kho chng trnh, phim hoc ni dung khng dnh cho tr em. VoD c

th phn loi thnh VoD min ph (Free on Demand - FoD) v VoD tr tin.

TVoD (TV on Demand)

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Tnh nng ny cho php cc chng trnh LiveTV c lu li trn server trong

mt khong thi gian no . Khch hng sau c th la chn xem li (nh

i vi VoD) cc chng trnh m mnh b l.Thi gian lu tr cc chng trnh

c th t thay i linh ng theo nhu cu thc t. H thng s h tr c 2 cch thc

l lu tr theo thi gian v lu tr theo chng trnh c chn no . Thng tin

v cc (nu c) i vi dch v c hin th ng n khch hng a ra quyt

nh la chn. H tr cc tnh nng c bn ca thit b ghi hnh VCR, l tm

dng, chy tip, chuyn nhanh v pha trc, chuyn nhanh v pha sau. Tnh nng

chuyn nhanh v pha trc, chuyn nhanh v pha sau cn t c tc 2X, 4X,

8X, 16X, 32X v 64X.

Games on Demand (Chi game theo yu cu)Dch v ny cung cp nhng tr chi gii tr n gin cho khch hng. Cc tr

chi ny c th chi trc tuyn bng cch truyn (streaming) t h thng IPTV

server n STB. STB thng phi h tr Java (JVM) chi c cc game. H

thng c ch tnh im v ghi thng tin ngi chi.

Music on DemandCc thu bao c th xem nhng clip ca nhc theo yu cu ging nh dch v

VoD.

Karaoke on DemandCc thu bao c th chn v xem cc bi karaoke qua STB trn TV. T list cc

bi karaoke c gii thiu, thu bao c th mua mt hoc nhiu bi ht cng

lc. Bng cch ghp ni thm h thng m thanh chuyn dng, khch hng c th

thoi mi ht karaoke theo yu cu. H thng c kh nng qun l, tm kim ni

dung karaoke theo yu cu. Tm kim theo tn bi ht hoc tn ca s, cho php cp

nht v b sung cc ni dung karaoke d dng. H tr playlist lu danh sch cc bi

ht c chn. H thng c ch tnh im v ghi thng tin ngi ht. H tr ghi

thng tin bi ht vo th mc Favorite.

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1.2.3 Dch vtng tc (Interactive) Personal Video Recorder (PVR), Client Personal Video Recording (cPVR)Trong trng hp ny, thu bao c th thu 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, kho gii m s c download t trn h thng ti thi im xem ni dung.

Chc nng ny thu bao c th chia s nhng hnh nh ca h cho bn b v

nhng ngi thn ca h.

Networked Personal Video Recorder (nPVR)nPVR l mt thnh phn mng ghi v pht li ni dung ca cc knh truyn

hnh. C th khng nht thit ghi li tt c cc knh truyn hnh, nPVR s gii hn

trc ch nhng chng trnh c chn, nhng chng trnh ny c th c ghi

li vi mc ch iu khin lu tr d liu.EPG s c nhim v xc nh xem knh

no m nPVR c th cung cp. Da trn list ny, cc thu bao c th lu li cc

chng trnh m h chn trong th vin nPVR 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 th tu thch s dng nhng cc chc nng iu khin nh Play,

Pause, FF, RW. Nh cung cp dch v s thit lp cc quy tc ghi cho mi knh TV

ring, chng hn thi gian lu tr cho knh c ghi.

Guess v VotingCung cp tnh nng bnh chn trc tip v dch v tr chi d on cho ngi

xem qua TV. Vic d on, bnh chn c kt hp th hin trc tip trn cc

chng trnh truyn hnh. Cho php to cc kch bn bnh chn hoc d on d

dng v linh ngtheo nhiu tiu ch khc nhau. Chc nng bnh chn c th thc

hin ng thi trong khi vn ang xem chng trnh TV. H tr m thanh, hnh nh

minh ha cho cc mc a ra. Thao tc bnh chn, d on cn c h tr

thun tin thng qua Remote Control.

TVEducation

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Cung cp tt c cc dch v hc tp, o to theo cc ni dung v theo tng la

tui. H thng h tr kh nng qun l ni dung cc chng trnh hc tp, o to.

Giao din h thng m bo thn thin, EPG hin th d dng thun tin cho khch

hng. H thng cho php pht trin, tch hp thm cc dch v learning mi vo h

thng IPTV hin ti theo yu cu. C gii php hon chnh cho cc nh cung cp

third-party tch hp vo h thng cung cp dch v.

TVCommerceThng mi qua TV l cc dch v tng tc cho php khch hng trao i, mua

bn v u gi nhng sn phm c gii thiu trn TV hoc nhng chng trnhqung co. thu bao c th ng 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. H

thng c s ng b, nht qun t server, middleware, EPG n STB cung cp

dch v n khch hng. H tr gii thiu, qung b cc thng tin sn phm trn cc

knh Live TV, VoD .. mt cch linh ng v hiu qu. C gii php tch hp vi h

thng thanh ton qua ngn hng, gii php m bo an ton cho Online-Payment.

Chc nng tng tc qua mobileDch v ny cho php thu bao c th xem v tng tc hnh nh thng qua cc

thit b cm tay nh trn mn hnh TV. Ngoi ra cn c th cho php thu bao t

thit b cm tay ca mnh iu khin mi qu trnh tng tc ca STB i vi h

thng qua thit b cm tay ca mnh. V d, khi thu bao ang bn i cng tc

nhng mun thu mt chng trnh m h thch xem ti mt thi im no vo b

nh trn STB ca mnh ti nh. H c th iu khin t thit b cm tay ca h trnthit b cm tay.

1.2.4 Dch v thng tin v truyn thng Internet on TV (Web Browser)

Dch v ny cho php ngi dng truy cp vo nhng trang web trn Internet. H

chc nng s c 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

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ch duyt cc trang web v hin th thng tin chnh xc ln mn hnh. Ni dung

hin th c th thay i font ch theo yu cu. H tr font ch Unicode.

TVInformationDch v ny cung cp cc thng tin n khch hng thng qua h thng IPTV.

Cc thng tin c th cung cp rt a dng v phong ph, bao gm tin tc, thng tin

th trng, 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 v thng tin mi vo H

thng IPTV hin ti. Cc nh cung cp ni dung thng tin third-party c th tch

hp vo h thng cung cp dch v. TV Messaging

Chc nng ny cho php ngi xem TV c th chat trc vi nhau thng qua h

thng IPTV. Ngoi chat trc tip vi nhau, khch hng c th chat vi cc ngi

dng ca h thng khc nh Yahoo, MSN, cc tin nhn SMS .. H thng c th

qun l thng tin c nhn ca cc thnh vin (Profile). Qun l danh sch bn b

nh thm, xa, sa thng tin, c ch thng bo ti ngi dng khi c 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 h tr bn phm khng dy,

font ch Unicode v tch hp b g ting Vit.

Video ConferenceHi tho truyn hnh cho php nhiu thu bao tham gia i thoi trc tuyn thng

qua truyn hnh. Gii php ny cho php tchc cc cuc hp, cc bui hi tho,

o to trc tuyn t xa, ngi dng c th tham gia t bt c v tr a l no min

l c kt ni h thng IPTV.H thng h tr vic thay i cc thng s v cht

lng hnh nh, chun nn, cho ph hp vi bng thng ca mng li.

Video Phone (SIP Phone)in thoi truyn hnh thng qua giao thc VoIP thng dng nh SIP, H323.

Dch v cho php 2 thu bao c th lin lc bng hnh nh v m thanh vi nhau

da trn chun SIP/IP. Cc d liu m thanh v hnh nh s c STB m ho v

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c gi thng qua IP ti tng thu bao ring bit. H thng cung cp dch v

VoIP-Phone cho php thu bao IPTV c th gi in cho nhau hoc gi ra cc mng

in thoi khc.H thng cung cp gii php hon chnh cho vic tch hp h thng

VoIP-Phone. Cung cp cc thit b tch hp i km (handset) h tr cho vic gi

in thoi. H tr kh nng m rng, tch hp n cc mng in thoi khc nh

fixed-phone, mobile phone,..

1.2.5 Cc dch vgia tng khc Tin nhn SMS/MMS

Chc nng ny cho php ngi dng TV c th gi nhn tin nhn SMS, MMS

n cc mng di ng. Cho php gi nhn tin nhn trc tip gia khch hng ca h

thng IPTV v khch hng ca mng mobile.H thng c giao din nhp tin nhn

d dng, STB s h tr bn phm khng dy trong tng lai. C ch cnh bo

ngi dng khi c SMS mi n.

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 cc STB cu hnh thp c hn ch l khng th gi c file nh km, cn pht

trin kh nng tch hp thit b u vo (USB chng hn..) upload ni dung.

Chc nng ny h tr y chun SMTP, POP3 thng dng. H tr cc tnh nng

email-client c bn nh CC, BCC, HTMLmail, chn ch k (signature), sp xp

message theo cc tiu ch khc nhau... Cho php cu hnh, to nhiu ti khon email

kt ni gi nhn email n cc mail-server khc nhau. Qun l thng tin Address

Book.

Media Sharing (Photo Album)Chc nng ny chophp khch hng thng qua h thng IPTV c th to, lu tr

v qun l cc album nh ca mnh. H thng album cho php qun l theo cc

category khc nhau. H tr giao din thn thin, EPG hin th d dng thun tin.

Chc nng tm kim thng tin nh, to cc th mc c nhn (Private).

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Video BlogDch v ny cho php khch hng IPTV c th to ring cho mnh mt blog c

kh nng lu tr cc clip video. Ngi dng c th son tho, thm mi cc mc,

bi vit d dng. H thng h tr qun l thng tin c nhn ca cc thnh vin

(Profile), cho php phn quyn cc thnh vin khc nhau. Khch hng c th qun

l danh sch bn b nh thm, xa, sa thng tin.

Global Monitoringng dng cho theo di giao thng, gim st an ninh v gim st h gia nh t

xa. Vi loi hnh dch v ny, h thng IPTV c th ng dng cho tp khch hngnhm ln nh cc cng ty, doanh nghip. H thng h tr gii php hon chnh cho

php tch hp cung cp dch v trn h thng IPTV trin khai. Cung cp cc thit

b tch hp ikm (camera, remote,..) pha khch hng h tr cho vic monitoring.

Game Online (Multiplayer game)Dch v cung cp nhng tr chi quy m ln, chi trc tuyn v c nhiu ngi

chi tham gia ng thi.H thng c gii php hon chnh cho cc nh cung cpgame third-party tch hp vo h thng IPTV trin khai cung cp dch v. H tr

tnh tin mt cch linh ng v hiu qu (tnh tin theo thi gian chi game, cc ch

khuyn mi theo yu cu ...).

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Chng 2 .TNG QUAN V H THNG TRUYN HNHTRN MNG xDSL

2.1 Kin trc h thng cung cp dch v IPTV2.1.1 M hnh tng qut

Hnh 2-1 M hnh tng qut h thng cung cp dch v IPTV

Dch v IPTV c chia lm 02 loi chnh: Dch v video qung b (Broadcast

Video) v dch v video theo yu cu (Video on Demand VoD).

2.1.2 Cc thnh phn cung cp dch v Broadcast Video B nn video thi gian thc

B nn video thi gian thc tip nhn tn hiu audio, video t cc ngun pht

broadcast video (tn hiu c th dng tng t hoc s), sau chuyn i tn

hiu ny thnh lung cc gi IP mang d liu audio/video dng c nn s.

EPG

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EPG cung cp thng tin v cc knh truyn hnh n broadcast client chy trn

cc STB. EPG thng c xy dng di dng mt HTTP server v cc knh

truyn hnh c hin th di dng cc trang web. ng dng EPG s m nhn

vic xc thc v chng thc mt thu bao i vi cc dch v broadcast. EPG cn

cung cp a ch IP multicast c s dng pht knh truyn hnh vo mng IP.

Broadcast client dng a ch ny thc hin giao thc IGMP trong qu trnh chn

v chuyn knh.

Broadcast ClientBroadcast Client l mt tin trnh ng dng chy trn STB m nhim vic cung

cp giao din ngi dng v iu khin cho cc dch v Broadcast video . Broadcast

client cng vi EPG to ra giao din xc thc thu bao cho cc dch v. Vic xc

thc thng c thc hin bng cc giao thc xc thc ca tng ng dng

(Application layer). Broadcast client hin th thng tin v cc knh truyn hnh s

dng d liu ly c t EPG v to ra giao din iu khin phc v thay i knh

bng IGMP.

2.1.3 Cc thnh phn cung cp dch v VoD H thng phn phi ni dung

H thng phn phi ni dung (Asset Distribution System ADS) ly ni dung

video t cc nh cung cp nidung v s dng cc qui tc kinh doanh phn phi

ni dung ny n nhng khu vc khc nhau trong h thng mng ca nh cung cp

dch v.ADS c th c s dng thay i cc thng tin m t (metadata) ca

ni dung video nhm b sung cc thng tin lin quan n cc quy tc kinh doanh

nh gi ca ni dung video, gi dch v ca ni dung video, ni dung video c cn

c m ha khng, Da trn cc quy tc kinh doanh, ADS s phn phi ni

dung n phn h qun l ti nguyn ti cc video server cc khuvc khc nhau.

Navigation serverNavigation server cung cp cc thng tin v ni dung VoD cho on-demand client

chy trn STB. Navigation server thng c thc hin bi mt HTTP server v

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hin th thng tin v cc ni dung video di dng cc trang web. Navigation server

s dng thng tin t h thng qun l ti nguyn xc nh nhng ni dung video

no c hin th n thu bao. i vi cc ni dung c cung cp di dng gi

thu bao th navigation server c th s dng thng tin trong c s d liu khch

hng iu chnh nhng thng tin c hin th.

Phn h qun l phinPhn h qun l phin l im lin lc trung tm cho cc yu cu phin VoD t

on-demand client chy trn STB. Thnh phn ny qun l vng i ca mt phin

video v m nhim vic iu phi cc ti nguyn khc nhau nhm gi cc lungvideo tng ng vi cc yu cu t on-demand client. Khi nhn c mt yu cu

phin video t on-demand client, phn h qun l phin s dng dch v ca phn

h bn quyn xc nh xem thu thu bao c c php xem ni dung video m

thu bao ang yu cu hay khng. Nu yu cu c chp nhn, phn h bn quyn

s tr li cc thng tin c lin quan (chng hn nh nh dng m ha c s dng

cho ni dung video). Sau , phn h qun l phin xc nh VoD server ti u

phc v thu bao. Tip theo, phn h qun l ti nguyn s gi 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 Access System CAS) ly

thng tin v thut ton m ha cng nh l gi kha m ha n STB. Cui

cng, cc thng tin lin quan n ni dung video (a ch IP/UDP/RTP) c gi

n STB.

Phn h bn quynPhn h bn quyn c chc nng xc nh mt ni dung video ch c xem bi

nhng thu bao c cp php. Phn h bn quyn s dng cc thng tin t ADS

xy dng c s d liu cho bit cc ni dung video trong cc gi thu bao khc

nhau.

Video pump

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Video pump l thnh phn lu tr v streaming ca h thng VoD. Vid eo pump

cha cc thit b lu tr, ni dung video c t chc sao cho c th gi bt k mt

ni dung video no vi mt tc xc nh trc. Thnh phn streaming thc hin

ly file t h thng lu tr v y vo mng. Video pump phi c kh nng iu

khin cc lung video mc ti thiu, v d nh fast -forward, rewind phc v

cho qu trnh xem ni dung ca thu bao.

Phn h qun l ti nguynPhn h qun l ti nguyn qun l cc lung video, cc thit b lu tr ca mt

nhm cc video pump. Phn h ny nh v, sao chp ni dung cng nh cp phtcc video pump cho cc yu cu video nhn c t phn h qun l phin.

u vo, phn h qun l ti nguyn tip nhn ni dung t h thng phn phi

ni dung v sao chp ni dung ny n cc video pump m n qun l. Phn h ny

s a ra quyt nh khi no v u cn c sao chp ni dung da trn cc

thng tin nh cc thng tin qun l t h thng phn phi ni dung, cc yu cu

video t thu bao. u ra, n c nhim v p ng cc yu cu video t phn h

qun l phin bng cch ch ra video pump s phc v cho yu cu .

On-demand clienty l mt tin trnh ng dng chy trn STB, c nhim v cung cp giao din

ngi dng v iu khin cho cc dch v video theo yu cu. On-demand client

cung cpgiao din ngi dng duyt cc ni dung theo yu cu bng cch s

dng cc dch v ca navigation server. On-demand client cng tng tc vi phn

h qun l phin yu cu mt lung video theo yu cu.

2.1.4 Cc thnh phn chungH thng truy nhp c iu kin (Conditional Access System CAS) ng vai

tr l h tng qun l v phn phi cc kha m ha c s dng m ha cc

ni dung video. M ha ni dung c s dng nh l lp bo v th hai chng li

nn n cp ni dung. Lp bo v u tin cho c dch v broadcast ln dch v theo

yu cu c tch hp trong ng dng chy trn STB.Cc ng dng chy trn STB

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s dng c ch xc thc ngi dng kim tra mt thu bao c c php xem

ni dung mong mun khng. Tuy nhin, cc ng dng ny li khng bo v bn

thn lung video. CAS s dng cc gii thut m ha ni dung ngn chn nhng

thu bao xem ni dung tri php.Bi v truy nhp c iu kin to ra thm s phc

tp cng nh chi ph cho h thng truyn ti nn thng m ha ni dung bng CAS

ch p dng vi nhng knh truyn hnh hoc ni dung cao cp. i vi dch v

broadcast, m ha c thc hin trong b nn video thi gian thc. i vi cc

dch v theo yu cu, m ha c th c thc hin trong b nn video thi gian

thc hoc trong qu trnh x l sao chp ni dung n cc video pump.

2.1.5 Kin trc sn phm

Hnh 2-2 Kin trc sn phm h thng cung cp dch v IPTV

MiddlewareMiddleware c vai tr gn kt cc thnh phn logic vi nhau to thnh mt h

thng phn mm phc v IPTV/video hon chnh. Middleware to ra giao din

ngi dng cho c dch v broadcast ln dch v theo yu cu. N cng c s

dng lm nhim v ca mt phn mm gn kt tch hp cc sn phm ca cc

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nh cung cp gii php ng dng khc. Cc sn phm middleware thng c s

dng tch hp cc VoD server, cc h thng truy nhp c iu kin, v cc STB

ca cc nh sn xut khc nhau trong cng mt gii php khai thc. Middleware

cung cp chc nng client v servercho c dch v broadcast ln dch v theo yu

cu. Cc thnh phn cung cp chc nng client l cc ng dng client chy trn

STB, trong khi cc thnh phn cung cp chc nng server l EPG v navigation

server.

VoD serverVoD server c chc nng lu tr vy cc lung ni dung (di dng thi gian

thc) vo mng cho cc dch v theo yu cu. VoD server bao gm mt tp hp

nhiu video pump c qun l bi phn h qun l ti nguyn. VoD server phi

hp cng vi middleware v c th c tch hp vi CAS khi yu cu tin m ha

(pre-encryption) c s dng .

H thng truy nhp c iu kinH thng truy nhp c iu kin (CAS) cung cp cc dch v m ha v gii m

ha, cc chc nng to v phn phi kha m ha, cho cc dch v broadcast cng

nh cc dchv theo yu cu. CAS bao gm phn h qun l ti nguyn m ha, h

thng m ha (encryption engine), v tin trnh gii m ha video ti STB. CAS

tng tc vi middleware khi s m ha theo phin c yu cu cho cc dch v

theo yu cu. CAS cng c th tng tc vi middleware khi cn phn phi kha

m ha gia phn h qun l ti nguyn m ha v tin trnh gii m ha trn STB.

Cui cng, CAS tng tc vi VoD server khi tin m ha c s dng cho mtni dung no .

2.2 Nhng yu cu t ra cho dch v video2.2.1 Bng thng rng

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So vi cc dch v thoi, Internet th bng thng dnh cho cc dch v video cao

hn nhiu. Mt lung video vi phn gii chun (standard-definition) vi chun

nn MPGE-4/H.264 yu cu bng thng 2Mbps. i vi h tng mng truy nhp

DSL th c th thy rng ng truyn DSL thng ch c kh nng truyn ng

thi t 1 n 2 lung video cng mt lc. iu ny c ngha l thu bao ch c th

xem ng thi 2 knh truyn hnh hay 2 ni dung video.Bn cnh , bi v cc

dch v theo yu cu hot ng theo phng thc unicast, trong khi dch v

broadcast video hot ng theo phng thc multicast nn c th ni bng thng

dnh cho cc dch v theo yu cu trong mng phn phi cng nh mng gom ln

hn rt nhiu so vi dch v Broadcast video.

2.2.2 Bng thng khng i xngLu lng video (bao gm c theo yu cu ln broadcast) u c truyn i

trong mng theo mt hng (hng xung). Ch c cc thng tin iu khin l c

truyn di theo hng ngc li (hng ln). Do , chi ph v h tng c th gim

bt khi xy dng cc lin kt n hng.

2.2.3 Cht lng dch vCht lng video khi truyn trn mng IP phi m bo khng b gim st so vi

cc loi hnh truyn hnh thng thng (truyn hnh cp, s, v tinh). m bo

s suy gim cht lng video khi truyn qua mng IP kh nhn bit c t pha

khch hng cn c gng hn ch s xut hin ca cc li suy gim cht lng m

khch hng c th nhn bit d dng.Khc vi cc dch v Internet, thoi, i vi

cc dch v video th vic mt gi nh hng rt ln n cht lng hnh nh. Do

, yu cu t ra cho cc dch v video ngt ngho hn so vi cc dch v khc. T

l mt gi phi m bo mc nh nht c th.

2.2.4 Ssn sng ca dch vMi loi dch v c mt mc sn sng khc nhau. Cc dch v broadcast c

tnh cht quan trng l tnh thi gian thc, thu bao khng th quay tr li xem

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on chng trnh pht. Do s sn sng t ra i vi dch v broadcast l rt

cao. Trong khi , i vi cc dch vvideo theo yu cu th thu bao hon ton c

th xem li cng nh b qua mt on ni dung no . Hn na t l thu bao s

dng dch v ny ti a cng ch nm trong khong t 10% n 20%. Do , yu

cu v tnh sn sng i vi dch v ny thp hn ng k so vi dch v broadcast.

2.2.5 Thi gian chuyn knh i vi dch v BroadcastMt ch tiu quan trng i vi cc dch v broadcast video l thi gian m thu

bao phi ch i khi chuyn t mt knh ny sang mt knh khc. i vi cc dch

v truyn hnh tng t, khong thi gian ny gn nh l tc thi. i vi cc dch

truyn hnh s, khong thi gian ny nm trong khong t 1 n 1.5 giy. L do ca

hin tng ny l do trong truyn hnh s, tn hiu video c m ha theo cc

chun nn nn 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 cc khung 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 s dng gm c: khung I, khung B, v

khung P. Trong s ny khung I l khung mang y thng tin, c tnh cht quyt

nh n s hin th chnh xc ca hnh nh. Trn thc t, cc khung I khng c

gi i lin tc m c gi i xen k cng cc khung B v khung P. Khong thi

gian gia 2 khung I lin tip s quyt nh thi gian chuyn knh.Trong mng IP,

bn cnh gii thut nn, cc yu t sau cng nh hng n khong thi gian gia

cc khung I (i vi thit b u cui STB):

c im ca STB Tr do giao thc multicast Cc yu cu v bo mt, bn quyn.

2.3 Kin trc mng cung cp dch v IPTV

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Hnh 2-3 Kin trc mng cung cp dch v IPTV

Theo kin trc ny, h thng cung cp dch v IPTV gm cc video site v mng

truyn dn.

2.4 Video siteTrong h thng mng, h thng cung cp dch v IPTV c chia thnh 3 khu

vc chnh nh sau:

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

Ti SHE, cc knh truyn hnh qun b c thu sng v chuyn i thnh cc

lung multicast thng qua cc b nn video thi gian thc (real -time encoder). Bn

cnh , ti SHE cn c h thng qun l phn phi ni dung phc v cho cc dch

v video theo yu cu. Ngoi ra cc h thng h tr qun tr, vn hnh, bo dng,

v tnh cc cng c b tr ti SHE. Hu ht cc phng n trin khai IPTV trn

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mng c nh u xy dng mt SHE. Thng thng, SHE c b tr trong mng

li ca mng truyn dn.

Video Headend OfficeVHO l ni t h thng video server. y l ni m phn ln cc video pump

phc v cho cc dch v video theo yu cu c trang b. Ti y cng c th c

cc b nn video thi gian thc dnh cho dch v broadcast video cc b. Mt VHO

thng phc v trong phm vi mt th. C th coi VHO tng ng vi mt

im POP trong dch v truy nhp Internet. Kt ni gia VHO v mng li

IP/MPLS l mt router bin (Distribution Edge Router DER). DER kt ni mngli v cc lung video ti ch vi mng phn phi bng thng rng mang cc

lung video ca c dch v broadcast video ln dch v video theo yu cu n

VSO.

Video Switching OfficeCc VSO cha cc router ca mng gom (Aggregation Router- AR) l cc router

lm nhim v thu gom lu lng t cc DSLAM ca mng gom. VSO thng c

t ti i chuyn mch trung tm (central switching office), l im kt cui vt l

cho cc ng dy thu bao. Cc thit b ca VSO s kt ni mng phn phi vi

mng gom. Lu lng n v i khi cc DSLAM c thu gom ti cc AR, AR c

th nm trong VSO trung gian hoc VSO bin (terminal).

2.5 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

h thng mng cung cp c nhiu dch v mt cch tch bit nhau. Trong phn

ny s trnh by v cc vn sau:

nh x dch v Kin trc cht lng dch v

Kin trc bin lp 3

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Kin trc multicast. nh x dch v

nh x dch v ngha l nh x cc dch v khc nhau (c cung cp n khch

hng) vi cc topo mng logic khc nhau ca h tng mng truy nhp v mng gom.

Khi cc dch v khc nhau c nh x vo cc topo logic khc nhau th cc dch v

ny s c kt cui ti cc thit b bin lp 3 khc nhau. Khi cc dch v khc

nhau c nh x vo cc topo logic khc nhau th nh x logic ny thng xut

pht t thit b CPE ti thu bao. Nh vy, cn c nhng phng n khc nhau

mang nh x ny i bng cch s dng cc phng thc ng gi trong mng truynhp cng nh mng gom.

nh x dch v trong mng truy nhp: C 3 phng n nh x dch v trong

mng truy nhp, l:

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

ATM VC) ring r c s dng phn bit cc khng gian a ch khc nhau cho

tng loi dch v. Cc VC ny cng c s dng p cc tham s cht lng

dch v cho tng loi dch v. Trong hnh 4, DSLAM nh x cc ATM VC trn

ng day ADSL vo cc VLAN dch v trn ng uplink.( hnh 24 )

Kin trc truy nhp EtherType. Vi kin trc ny, trng EtherType trongkhung Ethernet c s dng phn bit hai khng gian a ch khc nhau. y,

gi s rng dch v Internet s dng phng thc ng gi PPPoE, cn dch v

video s dng phng thc ng gi IP. Khi cc gi IP v PPP c mang trong

khung Ethernet, trng EtherType c s dng phn bit hai loi gi ny. Mt

im ng ch l dch v thoi phi c mang trong 1 trong 2 topo logic c

m t bi trng EtherType trong khung Ethernet. Ngha l hoc dch v thoi c

mang trong khung Ethernet vi trng EtherType l IP hoc dch thoi c mang

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trong khung Ethernet vi trng EtherType l PPPoE.Do mt VC c s dng

cho tt c cc dch v nn cht lng dch v c quyt nh bi cc tham s cht

lng dch v lp Ethernet hoc lp IP. Trong hnh 5, DSLAM nh x cc gi tr

EtherType khc nhau vo cc VLAN dch v khc nhau.(hinh 25 )

Hnh 2-4 Kin trc truy nhp a knh o

Hnh 2-5 Kin trc truy nhp EtherType

Kin trc truy nhp a VLAN. Trong kin trc truy nhp da VLAN, phng

thc ng gi 802.1q c s dng trn cc ng truyn ADSL, cc VLAN ID

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khc nhau c s dng phn bit cc khng gian a ch ca cc dch v khc

nhau. Sau , DSLAM thc hin cc VLAN ID ny trn ng uplink vo mt tp

VLAN ID khc dng nhn dng khng gian a ch trn link .(Hnh 2-5)

Hnh 2-6 Kin trc truy nhp a VLAN

Trong m hnh ny, mt VC c s dng cho tt c cc dch v. Do , cng

ging nh kin trc truy nhp EtherType, cht lng dch v c quyt nh bi

cc tham s cht lng dch v lp Ethernet hoc lp IP. Trong hnh 7, DSLAM

nh x VLAN ID trn ng truyn ADSL vo cc VLAN dch v trn ng

uplink (Hnh 2-6 )

nh x dch v trong mng truy nhp. C hai kin trc khc nhau nh cc dch

v t thu bao vo cc VLAN trong mng gom Ethernet: l kin trc N:1 VLAN v

kin trc 1:1 VLAN. im khc bit gia hai kin trc ny l cch thc nh x cc

ng dy thu bao v cc dch v vo cc VLAN:

Kin trc N:1 VLAN nh xnhiu ng dy thu bao v dch v vo cng mt

VLAN .

Kin trc 1:1 VLAN: nh x mi 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 dch

v c nh x vo mt VLAN trong mng gom Ethernet. C nhiu cch nh x

cc nhm thu bao v dch v vo cc VLAN.

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V d, mi VLAN trong m hnh ny c th c s dng gom tt c cc thu

bao ca cng mt dch v. Khi s dng m hnh ny, tt c cc thu bao ng vi

mt dch v v mt DSLAM c nh x vo mt VLAN duy nht. DSLAM thc

hin chc nng chuyn tip (Ethernet bridge) gia cc ng dy DSL m DSLAM

gom vo mt VLAN vi VLAN trn Ethernet uplink. Mt trong nhng vn v

bo mt lin quan n chuyn tip Ethernet l mt thu bao c thxem c thng

tin ca mt thu bao khc. V vy, cc DSLAM phi c kh nng ngn chn hin

tng chuyn tip gia cc ng dy DSL v ng Ethernet uplink.

M hnh 1:1 VLAN. Trong m hnh 1:1 VLAN, mi ng dy thu bao c

nhn din trong mng gom thng qua mt VLAN ID. Kin trc ny tng t nh

kin 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 s lng

bit VLAN tag theo 802.1q l 12 nn trong trng hp s lng thu bao ln hn

4096 th mng gom lp 2 phi s dng ng gi 802.1ad (hay cn gi l Q-in-Q).

Trong m hnh ny, DSLAM phi nh x ng dy thu bao vo mt VLAN tag

ng Ethernet uplink. Khi s dng ng gi 802.1q th DSLAM nh x ng dyDSL vo mt 802.1a VLAN ID. Trong trng hp ng gi 802.1ad th DSLAM

phi nh x ng dy DSL vo mt cp 802.1ad tag trong (inner) v ngoi (outer).

Kin trc cht lng dch vCht lng dch v ti mng truy nhp v mng gom c th thc hin theo 2 kin

trc khc nhau: kin trc tp trung v kin trc phn tn.

Trong kin trc cht lng dch v tp trung, tt c cc chc nng cht lng

dch v c thc hin ti BRAS nu cc thit b mng gom lp 2 v DSLAM

khng c kh nng thc hin cht lng dch v. Trong kin trc ny, tt c cc

dch v u i qua mt nut BRAS duy nht. Nh vy, vi phng n thc hin nh

th ny th vic sao chp cc lung multicast s c thc hin ti BRAS.

Trong kin trc cht lng dch v phn tn, cht lng dch v c thc hin

bng cch lp lch cho cc link vt l. Vi phng n ny, mi link vt l phi c

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kh nng phn loi lu lng v da theo mt th t cu hnh sn p dng

cht lng dch v.

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 c cc dch v u c kt cui ti mt nt

BRAS duy nht. V vy, kin trc ny phi s dng kin trc cht lng dch v tp

trung.

Multi-edge: Trong kin trc multi-edge, cc dchv khc nhau c kt cui ti

cc thit b lp 3 khc nhau. iu ny c th thc hin bng cch nh x cc dch vkhc nhau vo cc VLAN ID khc nhau ti DSLAM, hoc s dng phn gii ARP

vi cc ntlp 3 khc nhau vi cc a ch subnet khc nhau.

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

tn.

Trong kin trc tp trung, sao chp cc lung multicast c thc hin tp trung

ti mt nt BRAS. iu ny nh hng kh nhiu n bng thng c s dn g

cho dch v broadcast video v tt c cc lung multicast u c gi unicast t

BRAS.

Trong kin trc phn tn, tt c cc nt lp 3, mng gom v mng truy nhp u

c kh nng thc sao chp cc lung multicast. Cc nt lp 3 s dng IP multicast

sao chp cc lung multicast, trong khi cc thit b lp 2 s dng IGMP

snooping.Khi s dng kin trc phn tn th cng c ngha l s dng m hnh N:1 VLAN

cho dch v multicast video. Mt VLAN duy nht c s dng cho lung video

multicast, iu ny cho php ch to ra mt bn sao duy nht ca lung multicast

cho nhiu thu bao. Vi kin trc ny th cht lng dch v cng c thc hin

theo kin trc phn tn.

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Chng 3 .CC GII PHP K THUT PHT TRIN HTHNG TRUYN HNH TRN MNG xDSL

Nguyn tc la chn gii php k thut, cng ngh da trn cc gii php k

thut ph hp vi thc trng mng li ca ni trin khai, cung cp dch v

IPTV vi cht lng tt nht ti khch hng.

3.1 Gii php la chn chun nn hnh nhCng vi s pht trin mnh m ca my tnh v s ra i ca Internet th vic

tm ra mt phng php nn nh nhm gim bt khng gian lu tr thng tin v

truyn thng trn mng l yu cu cp thit. Cc k thut nn video u c gng

gim lng thng tin cn thit cho mt chui cc bc nh m khng lm gim cht

lng nh.

Mc ch ca nn video l gim bt s bt khi lu tr v truyn bng cch loi b

lng 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 thng

thng, nh sau khi c s ho s c nn li. Qu trnh nn s x l cc d liu

trong nh a hnh nh vo mt khng gian hp hn nh trong thit b nh k

thut s hoc qua ng dy in thoi ...

Vi th trng lu hnhk thut s hin nay, cc chun nn ph bin l Motion

JPEG (MJPEG), Wavelet, H.261/ H.263/ H.263+/ H.263++ v MPEG-1/ MPEG-2/

MPEG-4. Nhn chung, c 02 nhm tiu chun ch yu l nhm 1 gm nh dng

nn MJPEG v Wavelet v nhm 2 gm cc nh dng chun cn li.

3.1.1 Chun nn MJPEG v WaveletTnh cht chung ca cc nh s l tng quan gia cc pixel cnh nhau ln,

iu ny dn ti d tha thng tin biu din nh. Vic d tha thng tin dn ti

vic m ho khng ti u. Do vy cn tm phng n biu din nh vi tng quan

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nh nht gim thiu d tha thng tin ca nh. C 2 kiu d tha thng tin

sau:

D tha trong min khng gian: l tng quan gia khng gian pixel canh (cc pixel ln cn ca nh c gi tr gn ging nhau, tr nhng pixel

gip ng bin nh).

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

Trng tm ca cc nghin cu v nn nh l gim bt mt s bit biu din nh

bng vic loi b d tha trong min khng gian v min tn s cng nhiu cngtt. Cc chun nn MJPEG v Wavelet u tun theo nguyn tc tm ra cc phn t

d tha min khng gian (mi Frame nn t ng). Trong khi , c trng ca cc

chun nn thuc nhm 2 l loi b d tha c min khng gian v min tn s ca

nh.

MPEG l nh dng nn nh lu i nht v c dng ph bin. Khi dng

chun nn MJPEG, nh c phn chia thnh cc khi vung nh, mi khi vung

c kch thc 8 x 8 pixel v biu din mc xm ca 64 im nh. M ho bin i

cosin ri rc DCT (Discrete Cosin Tranform) trong chun nn ny khai thc s

tng ng gia 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 rt ngn 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 trnton b b mt nh, mt lot cc b phn lc khu chuyn i s phn tch cc d

kin v tng imnh v cho ra mt tp cc h s. Do chun Wavelet c tc dng

vi ton b b mt nh nn cc sai lch nh gii nn s khc vi MJPEG. Hiu

ng ghp mnh khng xy n vi nh c quan st nhng phn gii hnh nh

gim cng nh mt vi vt m s xut hin. Cc nh dng Wavelet v MJPEG u

gy ra hin tng mt thng tin nh gii nn. S d tha kh nng lu nh mt

ngi cm th khi dng chun nn Wavelet t hn MJPEG 30%.

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3.1.2 Chun nn MPEG-x v H.26xMPEG khng phi l mt cng c nn n l m u im ca nh nn dng

MPEG l ch MPEG c mt tp hp cc cng c m ho chun, chng c th kt

hp vi nhau mt cch linh ng phc v cho mt lot cc ng dng khc nhau.

Nguyn l chung ca nn tn hiu video l loi b s d tha v khng gian (spatial

redundancy) v s d tha v thi gian (temporal redundancy). Trong MPEG, vic

loi b s d tha v thi gian (nn lin nh) c thc hin trc ht nh s dng

tnh cht gia cc nh lin tip. Dng tnh cht ny to ra cc bc nh mi nh

vo thng tin t nhng bc nh gi trc . Do vy pha b m ho ch cn gi

li nhng nh c s thay i so vi nh trc, sau dng phng php nn v

khng gian trong nhng bc nh sai khc ny. Ni mt cch c th, nguyn l

chung ca cc chun nn l phng on trc chuyn ng ca cc frame b m

ho. Mi frame ti mt thi im nht nh s c nhiu kh nng 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 t frame ny ti frame khc. Pha bn thu, tc b gii m lu tr snnhng thng tin khng thay i t frame ny ti frame khc, chng c dng

in thm vo v tr trng trong nh c khi phc.

Tuy nhin, do s tng ng gia cc frame rt ln nn s pht hin ra cc sai

lch l rt kh. Do vy nh khi phc kh t c nh nh gc. iu ny ng

ngha vi vic cht lng nh cng tng t nh khi dng chun Wavelet v

MJPEG, nhng dung lng knh truyn v khng gian lu tr ca cc chun nn

H.26x v MPEG-x l nh hn (v d nh khng gian lu tr ca chun H.263 nh

hn Motion JPEG t 3 ti 5 ln). S khc bit gia cc chun nn ny (nh H.26x

v MPEG-x) ch yu nm khu tin on cc frame mi v cch thc tnh ton

sai lch gia cc frame hin ti v frame 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 phn gii hnh 352 x 288) do dng ch yu trong

vin thng. Trong khi , chun MPEG-2 dng cho th trng gii tr c phn

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gii hnh cao hn, v mang li cht lng hnh nh tt (cao hn 1,5 Mbps vi

phn gii 352x288 hoc 6 Mbps cho phn gii hon chnh).

3.1.3 Chun nn MPEG-2MPEG-2, ra i nm 1994, l tn ca mt nhm cc tiu chun m ha cho tn

hiu m thanh v hnh nh s, c chp thun bi MPEG (Moving Picture Expert

Group) v c cng b trong tiu chun quc t ISO/IEC 13818. MPEG -2 thng

c s dng m ha m thanh v hnh nh cho cc tn hiu broadcast bao gm

truyn hnh v tinh qung b trc tip v truyn hnh cp. MPEG-2 vi mt s sa

i cng l khun dng c s dng bi cc phim DVD thng mi tiu chun.

MPEG-2 bao gm cc phn chnh sau:

MPEG-2 Video part (Part 2): tng t MPEG-1, nhng ch h tr video xen k

(interlaced video, l khun dng c s dng cho cc h thng truyn hnh qung

b). MPEG-2 video khng c ti u ha cho cc tc bit thp (nh hn 1

Mbps), nhng li thc hin tt hn MPEG-1 tc 3 Mbps v cao hn. Tt c cc

b gii m tn hiu video tun theo chun MPEG-2 hon ton c kh nng pht li

cc lung video MPEG-1. Do c nhiu ci tin, MPEG-2 video v cc h thng

MPEG-2 c s dng trong hu ht cc h thng truyn dn HDTV.

MPEG-2 Audio part (Part 3): ci tin chc nng amm thanh ca MPEG-1 bng

cch 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 thanh MPEG-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 s liu (intra frame, forward predictive frame v bidirectional pridicted

frame) c th c sp xp theo mt trt t c th gi l cu trc nhm cc hnh nh

(group of pictures, GOP).

Mt lung video MPEG-2 c to nn bi mt chui cc khung s liu m ha

hnh 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 lung

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video c phn ra thnh mt knh cha thng tin v sng (luminance, cn gi

l knh Y) v hai knh thnh phn mu (chrominance, cn gi l cc tn hiu mu

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

M ha tc bit thp vi tn s ly mu gim i mt na (MPEG -1 Layer1/2/3 LSF).

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

3.1.4

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 v k thut cng nh ph hp vi nhiu loi

th trng.Vi n lc khng ngng a ra th trng sn phm u vit nht ca

ngnh cng nghip . My ghi hnh k thut s chun MPEG-4 vi bn cht l mt

thit b thu hnh k thut s c hiu sut cao, c chn p ng nhu cu cp

thit ca th trng v mt nh dng nn nh hon ho vi tnh nng ni tri l, c

th thu c h thng ln cc ngun hnh nh.

MPEG-4 thc s l mt dng nn nh mang tnh t ph ca cng ngh nn hnh

ng i, th hin r nt nhng tiu chun sau:

p dng nhng tiu chun c tnh m cao vi s h tr c lc t ngnhcng nghip an ninh v cng nghip my tnh.

Hiu sut ln Kh nng 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 m

tng dng bit ring r. Mt profile (cht lng ca video) l mt phn b xc nh

trn ton bit stream (iu chnh bit stream v b phn gii mu), mt level ( phn

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gii ca video) s xc nh mt s tiu ch bt buc cho tham s ca bc nh (kch

thc nh, s lng bit, ...).

Nhng chun nn MPEG-4 c profile dng n gin chim lnh a phn th

trng. MPEG-4 c pht trin v hon thin tr thnh nh dng nn hnh tin

tin, hon ho, vi tiu ch tp trung pht trin nhng nhn t gip tng cng cht

lng hnh nh, cng nh phc v c lc cho cc thit b gim st c cc frame

dng ch nht. Mi bit stream hinth trong nh dng nn MPEG-4 cung cp mt

m t mang tnh phn tng v hnh nh hin th. Tng lp d liu c a vo

lung bit bi nhng mt m c bit gi l mt m khi ngun.

Mi vt th nh 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 nh

c m ho di dng a lp khng gian hoc a lp thi gian, i t phn gii th

ti phn gii tinh. B phn gii m c th t c phn gii hnh mong mun,

tu theo nhng thng s nh di thng tn hin c, hiu sut my v theo mong

mun ca ngi dng.C 02 loi VOL, loi th nht 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). Loi VOL 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 s

tham kho cc nh khc qua khu b chuyn ng b gii m. Mi frame nh

thng thng c biu din bi mt VOP dng ch nht.

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 lIntra VOP (I-VOP).

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

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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 cao

cht lng hnh nh khi dng, mt u im khc ca B-VOP l dng k thut a

lp thi gian. Vi k thut ny, Frame d liu hin th c tng cng. Nhng lp

tng cng a thng tin vo gia cc lp frame.

nh dng nn nh MPEG-4 h tr qu trnh lng t ho, do vy cng gip p

ng nhng i hi khc nhau v tc bt. Lng t ho c cc chun nn nh

H.263 v MPEG-1, MPEG-2. B phn m ho nh dng nn ca MPEG -4 cngtng thch vi nhng b m ha trong cc chun nn trc y.

3.1.5 Chun nn H.264/MPEG-4 Part 10/AVCH.264, hay MPEG-4 Part 10, cn gi l AVC (Advanced Video Coding), l

chun m ha tn hiu video s c dng nn cc tn hiu s liu mc cao.

H.264 c vit bi ITU-T Video Coding Exterts Group (VCEG) cng vi

ISO/IEC MPEG nh mt n lc hp tc c chn lc mang tn Joint Video Team(JVT). Chun ITU-T H.264 v chun ISO/IEC MPEG-4 Part 10 (trc y l

ISO/IEC 14496-10) l hon ton ging nhau v mt k thut.

H.264 c t tn theo dng tiu chun H.26x ca ITU -T, trong khi AVC theo

pha ISO/IEC MPEG. Mc ch ca H.264 l to ra mt chun c kh nng cung

cp cht lng video cao tc bit thp hn hn (bng mt na hoc thp hn

na) so vi yu cu ca cc chun trc (MPEG -2, H.263 hay MPEG-2 Part 2)

m khng lm tng nhiu s phc tp trong thit trin khai. Mt mc tiu khc l

cho php tiu chun c p dng cho nhiu kiu ng dng (cho c tc bit thp

v cao, v c phn gii video thp v cao) v c th lm vic tt trn nhiu kiu

mng v h thng (qung b, lu tr DVD, mng gi RTP/IP, cc h thng in

thoi a phng tin ca ITU-T).

JVT gn y hon thin vic pht trin mt s m rng so vi chun ban u,

c bit n vi tn gi M rng phm vi trung thc (Fidelity Range

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Extensions, FRExt). Cc m rng ny h tr m ha video trung thc cao bng cch

tng chnh xc 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 cng c thm vo trong cc m rng FRExt nh chuyn i thch

ng gia cc khi 4x4 v 8x8, cc ma trn trng s lng t ha da trn cm bin

ca cc b m ha c th, h tr thm nhiu khng gian mu sc, ...

Mt s tnh nng mi ca H.264/MPEG-4 Part 10 cho php chun ny nn cc

tn hiu video hiu qu hn so vi cc chun c v v linh hot hn cho cc ng

dng trong cc mi trng mng.

Mt s cc tnh nng quan trng l:

B chuyn ng a hnh s dng cc hnh nh c m ha trc lmtham chiu theo cch linh hot hn cc chun c, cho php ln ti 32 hnh

nh tham chiu 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 trong hu ht cc trng hp.

B chuyn ng block c kch thc bin i vi kchthc block rng n16x16 v nh n 4x4, cho php phn mnh chnh xc cc vng chuyn

ng.

Cu trc cp macroblock, cho php cc macroblock kch thc 16x16 (sovi 16x8 MPEG-2).

chnh xc b chuyn ng ln n 1/4 pixel, cho php th hin chnh xccc dch chuyn ca vng chuyn ng.

nh s khung, cho php to ra cc chui con (iu chnh v thi gian bngcch gp mt nh gia cc nh khc), pht hin v giu cc hnh b mt (xy

ra do mt gi trn mng hoc li knh).

m th t hnh, cho php gi cc hnh v cc gi tr mu theo trt t trongcc hnh c gii m tch bit vi thng tin nh thi (cho php thng tin

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nh thi c chuyn i v iu khin c lp bi h thng m khng nh

hng n ni dung hnh nh c gii m).

Cc k thut ny, cng vi nhiu k thut khc, lm cho H.264 hot ng tt hn

so vi cc tiu chun trc, trong nhiu trng hp v mi trng ng dng khc

nhau. H.264 thng lm vic tt hn rt nhiu so vi MPEG-2, cho cht lng tt

hn tc bt ch bng mt na hoc thp hn so vi yu cu ca MPEG-2.

H.264 cung cp cc profile sau:

Baseline profile (BP): Dng cho cc ng dng chi ph thp i hi t tinguyn hn, ch yu dng cho cc ng dung hi ngh truyn hnh v ding.

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

d liu.

High Profile (HiP): Dng cho cc ng dng qung b v lu tr a, cbit 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, h tr 10 bittrn 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 dngvideo qut xen k, c xy dng bn trn ca Hi10P, h tr khun dng

ly mu sc 4:2:2 trong khi s dng 10 bit trn mt mu ca chnh xcca hnh nh c gii m.

High 4:4:4 Profile (Hi444P): c xy dng bn trn ca Hi422P, h tr lymu sc 4:4:4, ln n 12 bit trn mt mu.

MPEG tch hp y cc h tr ca H.264/AVC vo cc h thng tiu

chun ca mnh (MPEG-2 v MPEG-4) v cc tp tin a phng tin theo tiu

chun ISO.

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ITU-T a H.264/AVC vo b tiu chun H.32x cho h thng in thoi a

phng tin. Da trn cc tiu chun ITU-T, H.264/AVC c s dng rng ri cho

ng dng hi ngh truyn hnh, v c ng dng trong cc sn phm ca cc

cng ty chim u th trn th trng (nh Polycom v Tendberg). iu quan trng

hn c l tt c cc sn phm hi ngh truyn hnh mi u h tr H.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

my thu hnh v c kh nng s thay th chun m ha H.262/MPEG-2 hin ti

ang s dng trong cc h thng truyn hnh s qung b mt t v v tinh.

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

Bng 3-1 Yu cu v bng thng i vi cc chun nn

nt tiu chun nt cao ng dng

MPEG-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

C th thy c t th so snh trn, k thut m ha H.264 rt hiu qu

di bng thng thp. Cht lng video ca chun H.264 ti bng thng 1,5 Mbps tt

hn so vi chun MPEG-2 bng thng 3 Mbps. S dng chun nn H.264 c th

tit kim c hn mt na bng thng.

3.2 La chn giao thc mng3.2.1 Giao thc cho dch v multicast3.2.2 Giao thc IGMP

Giao thc IGMP pht trin t giao thc Host Membership Protocol, c m t

trong ti liu ca Deering. Giao thc IGMP c ba phin bn verion 1, verion 2,v

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verion 3. IGMP pht trin t IGMPv1 (RFC1112) n IGMPv2 (RFC2236) v n

phin bn cui cng IGMPv3 (RFC3376). Cc thng ip IGMP c gi bn

trong gi tin IP vi trng protocol number bng 2, trong trng TTL c gi tr

bng 1. Cc gi IGMP ch c truyn trong LAN v khng c tip tc chuyn

sang LAN khc do gi tr TTL ca n.

Hai mc ch quan trng nht ca IGMP l:

Thng bo cho router multicast rng c mt my mun nhn multicasttraffic ca mt nhm c th.

Thng bo cho router rng mt c mt my mun ri mt nhm multicast(ni cch 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

nhnghost no mun nhn.

Trc khi mt host c th nhn bt k mt multicast traffic no, mt ng dng

multicast phi c ci t v chy trn host . Sau khi mt host tham gia vo mt

nhm, phn mm s tnh ton a ch multicast v sau card mng s bt u lng

nghe a ch multicast MAC. Trc khi mt host hoc mt ngi dng mun tham

gia vo mt nhm, ngi dng cn phi bit nhm no ang tn ti v lm th no

tham gia vo nhm . i vi cc ng dng mc doanh nghip, ngi dng ch

cn n gin nhp vo mt link trn mt trang web hoc a ch multicast c th cu

hnh trc trn client. V d, mt ngi dng c th c yu cu log vo mt

my ch v xc thc bng tn v ngi dng. Nu tn ngi dng c xc thc,ng dng multicast s tng ci trn PC ca ngi dng, ngha l ngi dng

tham gia vo nhm multicast. Khi ngi dng khng cn mun dng ng dng

multicast na, ngi dng phi ri khi nhm. V d, ngi dng n gin ch cn

ng ng dng multicast ri khi nhm. i vi c ch multicast, mt ngi

dng cn phi tm ra ng dng no h mun chy, a ch multicast c dng bi

ng dng.

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Lm th no mt router bit c cc my cn nghe multicast traffic? nhn

multicast traffic t mt ngun, c ngun v cc my nhn u tin phi gia nhp

(join) vo mt nhm multicast. Nhm ny c xc nh thng qua a ch

multicast. Mt host c th tham gia vo mt nhm multicast bng cch gi cc yu

cu n router gn nht. Tc v ny c thc hin thng qua giao thc IGMP.

IGMPv1 c nh ngha trong RFC1112 v bn ci tin ca n, IGMPv2 c

nh ngha trong RFC2236. Khi c vi host mun tham gia vo nhm, giao thc

PIM s thng bo cho nhau gia cc router v hnh thnh nn cy multicast gia cc

routers. IGMP v ICMP c nhiu im tng ng, cng chia s mt vi chc nng

tng t. IGMP cng ng gi trong gi tin IP (protocol number 2), nhng IGMP

gii hn ch trong mt kt ni lp 2. m bo router khng bao gi tip tc

chuyn gi tin i, trng TTL ca IGMP lun c gi tr bng 1.

3.2.3 Giao thc PIMGiao thc PIM l giao thc s l gi tin multicast c lp nhau. Hin nay c ba

loi PIM ang c s dng l : PIM-SM , PIM-DM , PIM-SSM

Giao thc PIM-SM( Protocol independent multicastsparse mode)

Giao thc nh tuyn ch sparse c s dng khi c t s lng cc ng

dng multicast. Cc giao thc PIM ch sparse khng truyn lu lng ca nhm

ti bt k router no tr phi n nhn c mt thng ip yu cu cc bn sao ca

cc gi tin c gi ti mt nhm multicast c bit.

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

Router nhn c mt yu cu nhn gi tin t mt 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 ch ca

giao thc khng hon ton i lp. PIM-SM gi s rng khng c my no mun

nhn lu lng multicast cho n khi no cc my ch ng hi. Kt qu l, cho

n khi no trong mt subnet c mt my yu cu nhn multicast th multicast mi

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c phn phi vo subnet . Vi PIM-SM, cc router downstream phi yu cu

nhn multicast dng thng ip PIM Join. Khi cc router nhn c cc thng ip

ny, cc router bn di phi nh k gi thng ip Join ln router upstream. Nu

khc i, router upstream s khng a lu lng xung, t kt ni vo trong trng

thi prune. Tin trnh ny th ngc li vi tin trnh c dng trong PIM-DM,

trong mc nh l pht tn lu lng multicast vi cc router downstream cn

phi lin tc gi thng ip Prune hay thng ip lm mi trng thi State refresh

gi cho mt kt ni l trong trng thi prune. PIM-SM ph hp khi ch c nhng

t l nh cc phn on mng nhn lu lng multicast.

Giao thc PIM-DM ( dense mode).Thng c s dng khi m lu lng lung

multicast l rt ln. PIM-DM lun c mt cng trong trng thi prune trong khong

ba pht. Cc thng ip prune lit k mt ngun v nhm. i vi giao thc PIM-

DM ny th bt c khino mt router nhn c thng ip prune n s tm mt

hang (S, G) SPT trong bng 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 l khong 3 pht, sao cho trong khong 3 phtcng ny c t trong trng thi forwarding . c th khc phc c nhng

tnh trng nh l cc kt ni b loi b, lin kt b loi b v 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 c s yu km ca PIM-DM trong

tin trnh pruning.

Trong giao thc PIM-DM cc router cn gi thng ip Graft router nhn

c a mt cng vo trng thi forwarding cho mt nhm multicast no .

Giao thc PIM-DM nhn bit cc thit b lng ging bng cch trao i cc gi

hello. Thng tin lng ging ny c dng trc xy dng cy n tt c cc

lng ging. Sau , cc nhnh ca cy s ln lt c loi b. Nu mt dng

multicast bt u, cy s c xy dng, cy s ch tn ti khi cc t hnh vin tch

cc cn tn ti. Nu mt host mi ng k tham gia nhm, nhnh ca phn on

mng s c nh thm vo cy.

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Giao thc PIM-SSM l giao thc m rng ca PIM. Khi s dng SSM th mt

client c th nhn lung multicast trc tip t a ch ngun. PIM-SSM s dng

chc nng ca PIM-SM to ra mt cy SPT gia ngun v ch nhn, tuy nhin

n xy dng SPT m khng cn s gip ca router RP.

Mc nh l nhm a ch multicast c gii hn trong di a ch 232.0.0.0 ti

232.255.255.255. Tuy nhin, chng ta c th m rng tm hot ng ca SSM sang

lp di lp D bao gm a ch mc cao.

Vic cu hnh PIM-SSM c s khc bit so vi cu hnh PIM-SM truyn thng.

yta khng cn phi chia s tree hay l RP mapping, hoc l RP toRP ngun

ly li thng qua Multicast source discovery Protocol ( MSDP).

Trin khai SSM l rt d dng. Chng ta ch cn cu hnh PIM-SM trn tt c

interface ca router v ch nh ci no cn SSM, bao gm mt cch r rng

IGMPv3 trn Lan. Nu PIM-SM khng c cu hnh r rng trn c ngun v

nhm thnh vin interface th gi tin multicast s khng c forwarded. Trn danh

sch h tr IGMPv3 c s dng PIM-SSM. Nh ti ngun, trc khi active v bt

u gi gi tin multicast th quan tm n ni nhn gi tin multicast l SSM .Trong vic cu hnh mng theo PIM-SSM , mt thu bao ti mt knh SSM ( s

dng 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

t RPF lng ging.

Hnh 3-1 Qu trnh nhn, thng bo ti cc thu bao join vo group G v sourse S

Giao thc PIM l gii php h tr truyn tn hiu multicast. Khi m s lng cc

nhm multicast cn phi truyn tng ln th PIM l mt gii php quan trng

qun l v gim st lu lng multicast.

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3.3 Giao thc cho dch v unicast3.3.1 Giao thc RTSP

Giao thc RTSP c pht trin bi IETF v thnh lp vo nm 1998 vi chun

RFC 2326. y l giao thc c ng dng iu khin d liu vi thi gian

thc. RTSP cung 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 th bao gm c d liu sng

v clip lu tr. y l giao thc dnh cho pht trin d liu a phng tin , cung

cp cch phn pht cc knh nh UDP, TCP v vic m bo theo thi gian

thc. iu khin lung bi RTSP c ths dng RTP , nhng s hot ng ca

RTSP l khng ph thuc vo k thut vn chuyn truyn data. Giao thc c

c tnh gi lp trong c php v hot ng ti HTTP/1.1, v m rng k thut ti

HTTP c th l hu ht cc trng hp a ch ti RTSP. Tuy nhin RTSP c s

khc bit quan trng v l thuyt so vi HTTP:

RTSP gii thiu mt s phng php mi v c s khc giao thc xc nhn

Mt RTSP server cn xc nh trng thi bng cch mc nh hu ht tt c cc

trng hp, tng phn vi trng thi t nhin ca HTTP.

C RSTP server v client c th a ra yu cu

D liu mang i out-of-band bng giao thc khc.

Giao thc RTSP c mt s nhng c im sau y:

Kh nng m rng. Phng php mi v cc thng s c th d dng thmvo RTSP.

D dng phn tch. Giao thc RTSP c th d dng phn tch bng tiuchun HTTP hoc MIME.

Bo mt. RTSP s dng k thut bo mt web. Tt c k thut nhn thcu c bn v chng thc u trc tip c p dng. Mt s c th dng li

hoc bo mt lp mng.

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Vn chuyn c lp. RTSP c th s dng mt trong hai phng phptruyn gi tin khng tin cy UDP v ng tin cy RDP, hoc l giao thc

lung tin cy TCP c thc hin lp ng dng ng tin cy.

Kh nng chy nhiu server. Mi mt lung media gia ccphn trnh dinc th t ti cc server khc nhau. Cc client s t ng thit lp mt vi

phin iu khin hin ti vi cc server media khc nhau. Gia chng c

ng b vi nhau lp giao vn.

iu khin thit b ghi. Giao thc ny c th iu khin c 2 qu trnh ghiv chy li thit b, hoc cng c th nm xen k gia hai mode.

iu khin lung v hi ngh ban u. iu khin lung a ra t limi ca server ti hi ngh. Ch c nhng yu cu hi ngh l mt trong hai

cung cp hoc l c th s dng to ra hi ngh ring. Trong thc t SIP v

h323 c th s dng mi mt server ti hi ngh.

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

Proxy v firewall tin li. Giao thc nn sn sang s l bi c hai ng dngv lp giao vn. Mt firewall c th khng hiu cch setup v m tin ch

cho UDP media.

3.3.2 Mrng giao thc RTSPKhng phi tt c cc server u c mt chc nng ging nhau, cc server media

cn thit s c h tr cc yucu khc nhau. V d:

Mt server c th ch c kh nng Playback theo cch th khng cn h tr

yu cu record.

Mt server c th khng c kh nng tm kim nu n ch h tr cc s kin

sng.

Mt s server c th khng h tr cc thng s lung v theo cch n khng

h tr get-parameter v set-parameter.

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Giao thc RTSP c th m rng ra theo ba cch, danh sch y a ra hp l

theo vic thay i ln c h tr:

Hin nay phng php c th m rng vi cc thng s mi, cc thng s di c

th an ton khi b qua bng cch nhn v. Nu my client cn ph nh tha li

ACK khi m phng php m rng khng c h tr, mt tag tng ng vi phn

m rng c th thm vo theo yu cu.

Mt phng php mi c th a vo .Nu nhn mt bn tin m khng hiu bn

tin yu cu g, n s tr li vi li 501 (khng th thc hin) v bn gi khng nn

c th li. Mt client c th s dng la chn phng php i hi v cch h

tr bi server. Cc server nn a ra mt danh sch cc phng php m n h tr

s dng.Mt phin bn mi ca giao thc c th c nh ngha cho php hu

ht tt c giao din thay i.

3.3.3 Bn tin RTSPGiao thc RTSP l giao thc c bn s dng ISO 10646 k t t trong UTE 8

encoding. ng gii hn bi CRLF nhng m ngi nhns nn chun b hiu

c CR v LF bng chnh bn thn gihn.Vi 10646 k t c sp xp trnh

s chng cho, nhng m n khng xut hin cc ng dng nh l US -ASCII

c s dng. N c m ha c th s dng cho giao thc RTCP. ISO 8859 -1

bin dch trc tip vo Unicode vi octer cao nht l khng. Bn tin RTSP c th

truyn qua cc giao thc thp hn lp giao vn.

3.3.4 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 tr

trong vic truyn tn hiu multicast c th truyn cc knh truyn hnh. c th

xem c cc knh truyn hnh th tn hiu nhn c phi theo thi gian thc.

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3.4 Giao thc cho dch v VoIP3.4.1 SIP

Giao thc khi to phin (SIP) l mt giao thc bo hiu mi xut hin thc hin

iu khin phin cho cc kt ni a dch v. V c bn, hot ng iu khin bao

gm khi to, thay i v kt thc mt phin c lin quan n cc phn t a

phng tin nh video, thoi, tin nhn, game trc tuyn, ...

SIP em li ba nng lc chnh cho mng vin thng. Th nht, n kch thch s

pht trin ca cc m hnh ng dng v dch v da trn web. y l mt iu ht

sc thut li cho nh cung cp dch v do c th s dng mt ngun ti nguyn di

do cc cng c sn c, ng thi cng thun li i vi ngi s dng khi ngi

s dng quen thuc vi k thut web v n cng c trin khai trn phn

ln cc thit b thng minh ngy nay. iu ny tng cng kh nng cung cp cc

dch v mi mt cch nhanh chng.

Nng lc th hai l kh nng m rng, do SIP l giao thc bo hiu ng cp v

c tnh phn b cao. Khc vi cc giao thc bo hiu truyn thng thng c tnh

x l tp trung cao, in hnh l SS7, trong hot ng ca n tp trung ti mt s

im bo hiu trong mt cu trc mng bo hiu phc tp; cc phn t ca SIP phn

tn n tn bin ca mng v c nhng ti tn cc im u cui.

Cui cng l kh nng ph cp ca SIP. c pht trin bi IETF, SIP k tha

cc c im ca hai giao thc Internet c pht trin rt ph bin: l Hyper

Text Transport Protocol (HTTP) s dng cho Web v Simple Mail Transport

Protocol (SMTP) s dng cho e-mail. Da vo cc nguyn tc c c t mitrng IP, SIP c thit k l giao thc c lp vi ng dng, rt mm do v c

kh nng p dng trong nhiu mi trng khc nhau v cung cp cc dch v a

dng.

Tm li, c im ca SIP l n gin, m, d dng trin khai, v tng thch vi

cc giao thc IP c.

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SIP c pht trin bi SIP Working Group trong IETF. Phin bn u tin c

ban hnh 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

3261 hon ton tng thch ngc vi RFC 2543, do cc h thng thc thi theo

RFC 2543 hon ton c th s dng vi cc h thng theo RFC 3261.

Mt bn tin SIP c hai phn, phn mo u v phn thn. Phn thn cho php

phc v cc ng dng khc nhau mt cch linh hot. Ban u phn thn ch dng

chuyn ti cc tham s miu t phin SDP nh codec, a ch IP u cui, ... Phn

thn c s dng m rng cc ng dng ca khc nhau ca SIP v d nh SIP -

T cho lin vn PSTN-SIP-PSTN hoc MSCML (Media Server Control Markup

Language) cho dch v hi ngh.

S ph cp ca SIP dn ti vic mt lot nhm lm vic lin quan n SIP

c thnh lp. Nhm SIPPING (Session Initiation Protocol investigation working

group) c thnh lp vi mc ch nghin cu cc ng dng v pht trin cc yu

cu m rng cho SIP. Nhm SIMPLE (SIP for Instant Messaging and Presence

Leveraging Extensions) c nhim v chun ho cc giao thc cho cc ng dngnhn 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 h tr 5

chc nng sau:

User locationXc nh v tr thit b u cui khch hng. User availabilityXc nh trng thi v tnh sn sng ca thu bao b gi

bt u thit lp ng truyn.

User capabilitiesXc nh phng tin v cc thng s c s dng. Session setupThit lp cc thng s ca phin cho c thu bao ch gi v

thu bao b gi.

Session managementTo, kt thc v sa i phin.

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SIP khng phi l mt h thng truyn thng c trin khai theo chiu dc m

n l mt thnh phn c s dng cng vi cc giao thc khc ca IETF to

nn mt cu trc a phng tin hon chnh. Mc d SIP c s dng kt hp vi

cc giao thc khc, nhng cc hot ng v tnh nng c bn ca n khng ph

thuc vo cc giao thc ny.

C 4 loi thc th chnh c nh ngha trong SIP:

User Agent (UA) ng vai tr ca thit b u cui trong bo hiu SIP. UAbao gm hai loi UserAgent Client (UAC) v User Agent Server (UAS).

UAC khi to cuc gi v UAS tr li cuc gi. iu ny cho php thc

hin cuc gi ngang hng thng qua m hnh client-server.

Redirect Server tip nhn yu cu nhng khng chuyn sang server k bnm gi tr li n ch gi ch ra a ch ca b gi.

Proxy Server tip nhn cc yu cu, quyt nh ni gi n v chuyn chngsang server k tip (s dng nguyn tc nh tuyn next hop).

Registrar tip nhn ng k t cc UA cp nht thng tin v v tr cachng.

SIP khng phi l mt giao thc bo hiu hot ng c lp. Hot ng ca SIP

c s phi hp vi mt s giao thc bo hiu khc. Cc giao thc l SDP (giao

thc miu t phin) (RFC 2327) s dng SIP nh mt phng tin chuyn ti v

RTP (giao thc truyn ti thi gian thc) c s dng lm phng tin chuyn

ti SIP. SDP c s dng m t c tnh ca phin. SDP c chuyn ti trong

phn thn ca bn tin SIP.

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

yu cuc phn bit theo tn (Bng 3-2) trong khi cc bn tin p ng c nh

s .

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Bng 3-2 . Ccbn tin yu cu ca SIP

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 Hu yu cu ang nm trong hng i

REGISTER u cui SIP ng k vi registrar server

OPTIONS S dng xc nh nng lc ca server

INFO S dng ti cc thng tin

Bng 3-3 Cc loi bn tin p ng ca SIP

Bn tin ngha

1xx Cc bn