2015-6-8 1 第 6 章接入网应用第 6 章接入网应用 6.2 行业应用 6.1 IP 分组多媒体通信 access to him at : Dr. Zhanqi XU, access to him at : web.xidian.edu.cn/zqxu

23/4/18 1

第第 66章接入网应用章接入网应用

6.2 行业应用

6.1 IP分组多媒体通信

Dr. Zhanqi XU, access to him at : access to him at : web.xidian.edu.cn/zqxuweb.xidian.edu.cn/zqxu, Xidian University

23/4/18 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 2

Overview

Protocols (H.323 & SIP)

IP Telephone Architecture

MultiMedia Communication MultiMedia Communication Based on Packet NetworkBased on Packet Network

MultiMedia Communication MultiMedia Communication Based on Packet NetworkBased on Packet Network

Architecture, Protocols, ProgressArchitecture, Protocols, ProgressArchitecture, Protocols, ProgressArchitecture, Protocols, Progress


Features

Multimedia Communication (MMC) meansmore than one set of forms comprising still/moving images, graphic, text, and sound are reproduced on an intelligent terminal

Implementation of MMC–Transmission media• Wireless ( Radio, Microwave, Satellite, optical, …)• Wired ( Twisted Pair, Cable, Optic Fiber,…)

OverviewOverview


–Switching• Circuit-switched ( traditional CS, fast CS,…) • Packet-switched (ATM,MPLS , Ethernet, FR , Token ring, Token bus), X.25,…)

–Media processing

• Sampling ( 8Khz, 16Khz, …)

• Coding( G.711 A/-law for voice, …)

• Compressing / Decompressing ( G723.1, G729A, for voice; H.261/H.263, JPEG (Joint Photographic Experts Group) , MPEG-4 (Motion Picture Experts Group) for Video

• Storing , editing,…


MMC network architecture

Integrated Access

Computer Net

CATV

Modem

V5/ No.7, No.1

PSTN

xDSL CO.

LAN LAN

Copper/Optical

LAN

PSTN Telephone

Fiber/ CableCable

IP Tel

Cable TelCable Modem

IP Tel

PSTN Tel


Applications

Distance teaching/learning interac-

tively, examination on-network,…

VoD (video on demand), Live

picture, on-line game/Chat, …

Trading, shopping, stock exchange,

banking, …

News, magazine, forum, E-mail,…

ExamplesAreas

Education

Entertainment

ElectronicCommerce

Public Info.


Protocols

H.323 • Specified by ITU in 1996 ( V2, 1998)

• Describes the protocols stacks of terminal equipments,

and services for multimedia communication over LAN

and IP networks

• These networks don’t provide guaranteed QoS QoS (Quality (Quality

of Services).of Services).

Generally speaking,MMC includes almost all techniques in info. processingprocessing, , transmissiontransmission, , and switchingswitching, the limited-space makes our discussion to packet-based network.


IPBackbone

IPBackbone

RTCPRTCPH.225.0(Sig. Ch.)Sig. Ch.)H.225.0

(Sig. Ch.)Sig. Ch.)H.245 H.245

Control and management

IPIP

Video CodingVideo Coding Audio CodingAudio Coding

GatekeeperGatekeeper

GatewayGateway

Client Client

Term

in

al

Term

in

al

H.323 Architecture

NIC ( Network Interface Controller)NIC ( Network Interface Controller)

TCPTCP

PBXPBX

ApplicationApplication

UDPUDP

RTPRTPH.225.0(RASRAS)

H.225.0(RASRAS)


Main Components in H.323

– Terminal: media processing and call control•PC, Video/TV, Telephone, Fax, …. •H.323-compliant ( multimedia-PC,Telephone,…)

•Other terminals:– H.320 terminal on N_ISDN– H.310/H.321 terminal on B_ISDN using ATM– H.324 terminal on PSTN

– Gateway: translation of call signaling, media format, multiplexing , etc.

– Gatekeeper 网闸 : providing administration of access, bandwidth, address translation, etc.


H.323 Protocols Stack

Audio Coding G.711, G.722, G.723.1, G.726, G.728, G.729

Video Coding H.261, H.263

RTP(Real-Time Trans. Prot.)Processing related to sequencing, sync., payload

type, source identification,…

RTCPAdditional info. to session participants: QoS

feedback, identification, session control,…

RAS (H.225.0)

RAS: Registration, Admission, Status

Conveying the registration, admissions, bandwidth,

status, …

UDP Efficient but unreliable transport of packets

Ch. CTRL (H.245) Capability Negotiation, coding, conference req.,…

Sign. Ch. (H.225.0) setup or release of call connection based on Q.931

TCP Conn.-oriented , reliable transport of packets

Items Protocols or Function


H.323 Protocols Stack － video coding/decodingH.261: compression/decompression of digital video, specified by ITU

in 1990 , P*64kbps, mainly in ISDN, (from M777 p52)H.263, defined by ITU, compression of the moving picture component of audio-visual service at low bit rates.

JPEG treats its picture independently( intraframe coding) while H.261 tries to predict the current picture from the previous one (interframe coding)MPEG-Motion Picture Experts Group, belongs a family of ISO/IEC (International Electrical Committee )MPEG-1 uses the same format as H.261, but allows a greater choice of image size MPEG-2 developed by ISO/IEC, ITU , up to 100Mbps for Video, supports HDTVMPEG-4 video coding method for low bit rates


H.323 Protocols Stack-RTP/RTCP commentsRTP comments: Sequencing: sequence nu. for detecting lost packets Sync. : timestamps to compensate the different delay jitter, needed by player-out buffers. Payload: identified the encoding of media, to change the encoding of media dynamically due to the bandwidth availability. Source identification: identifier for the originator of the frame in multicast session. RTCP comments:In RTP session, the participants periodically send RTCP packets to obtain QoS info, etc. QoS feedback: no. of lost packets, round-trip time, jitter, etc. Session CTRL: leaving a session by sending BYE packet Identification: info. such as e-mail, name, phone Intermedia Sync.: synchronizing the video and audio for receiver to play


–SIP features• Open, simple, and lightweight protocol•Text –based protocol (text: 文本、明文 )• Internet heritage – easier to integrate with

telephony/Video and Internet functions• Already implemented on most soft-switches and

gateways• Advanced extensibility• Transport independent-TCP or UDPTCP or UDP (reliability for

both)–SIP Architecture (next pagenext page)

SIP#

Developed by IETF MMUSIC (Multi-Party Multimedia Session Control) work group, evolved from HTTP


NIC NIC

IPIP

7

SIP ProxySIP Proxy

Control and management

SIP Architecture

Redirect Server

Redirect Server

2

3 4 6

8

9

1011

SIP Client 1SIP Client 1

Request

Response

121 Agent ServerAgent Server

Location Service

Location Service

5

SIP Client 2SIP Client 2

SIP ProxySIP Proxy

SIPSIP

Term

in

al

Term

in

al

TCPTCP UDPUDP

Video/Audio codingVideo/Audio coding

RTPRTPRTCPRTCP

ApplicationApplication


SIP Components

Clients

– End systems

– Send SIP requests

– Usually contain SIP user agent server

Redirect Server

– “Network” server; redirects users to try other server (user agent may act as a redirect server)

User Agent Server– Listens for call

requests– Prompts user or

executes program to determine response

Proxy Server– “Network Server” Proxies

request to another server (user agent also may do this)

– Can “fork” request to multiple servers, creating a search tree

注解： agent接近用户， proxy一般远离用户；（仅对 SIP）前者翻译为“用户代理”，后者译为“网络代理”；what is your better idea about their translations?


SIP message example

(the below message is from RFC2543)

INVITE sip:[email protected] SIP/2.0

Via: SIP/2.0/UDP 169.130.12.5

From: <sip:[email protected]>

To: T. A. Watson <sip:[email protected]>

Call-ID: [email protected]

Content-Length: 885

Encryption: PGP version=2.6.2, encoding=ascii

NOTE: "MIME security with pretty good privacy (PGP)", RFC 2015, October 1996.

SIP has only a limited number of methods:

1) Invite, 2) ACK, 3)Options, 4) Bye, 5)Cancel, 6)Register

Cancel: unusually cancel a connection which is going on


H.323 vs. SIP

Messages

Develop & Update Complicated

Elements & Interactions

Hundreds,

Complicated

Setup of a task V.1(call,ctrl,media) 3 round-trip, V.2 faststart

Extensibility ( Codecs)

ITU developed only

Market Becoming less

Mobility support Limited

Scalability (large

number of call processing)State

Binary-based

Easy

37 headers, Simple

Single round-trip

Any registered

Growing extensively

Easier

State or stateless

Text-based

Items H.323 SIP


IP TelephoneGeneral

– Definition In contrast to traditional telephone in CS network, it

means real-time services, such as voice, video, etc, transferred in best-effort PS network.

– Brief history

TimeTime EventsEvents

March,1995First commercial IP

phone for PC’s

1999~High density (4~8 T1/E1),

large capacity (>100T1)

1997~1998 Part commercial application

1996 PC-to-phone,Phone-to-phone

PlayersPlayers

Vocaltec

Audiocodes, analogic, NMS,…

Vocaltec, Net2phone,…

Free world Dialup,MIT,…


IP Phone Network

IP backbone network

IP backbone network

New YorkNew York

TelephoneFax

Gatekeeper

PSTN PSTN

Gateway

Telephone

Fax

Gatekeeper

PSTNPSTN

Gateway

ShanghaiShanghai

TelephoneFAX

Gatekeeper

PSTN PSTN

Gateway

Hong KongHong Kong


– Call Procedure

• Pick the hook up (Off-hooks), dial special service number,

ex 17900 for China Telecom• Voice response: Please input account & password • When it is OK, voice response: input the called

number,ex 86-21-56781234# for Shanghai• Voice response: the time allowed XXX, please wait• Local Gateway performs PSTN-IP translation , send

necessary info. to remote gateway by using H.323 or SIP

• Remote gateway is ringing to the called user, performs the negotiation of parameters, such as coding, RTP/RTCP sessions,etc.

• If user answered, the info. is sent to original gateway• Voice transmission begins


PayloadPayloadRTP HeaderRTP Header

12 Bytes12 Bytes

UDP headerUDP header

8 Bytes8 Bytes

IP HeaderIP Header

20 Bytes20 Bytes

•Transmission and switching in packet network, ex. Ethernet, FR, ATM,…• Disassemble : extracted voice payload from the IP Packet• Voice payload decompression (echo canceling, gain control,..)reproduced Voice

•PCM(64Kb/s)compression 8Kb/s(G.729a),…•Encapsulation ( packetized ):

– Voice Processing


– Coding Comparison

Coding

G.711

G.728

NetCoder

G.723.1

G.729a

Rate(Kbps)

64

16

8

N/A Very good N/A

Very high

(40)Good 8 or 16 ms

Moderate

(10)Fair 10ms(2X5)

6.4/5.3Moderate-

High (14/20)Good/Fair

30ms

(4X7.5)

9.6/8.0/7.2 Low (7.5)Very good

(-)20ms

Complexity(MIPS)

QualityFrame

Size


Advantages & Disadvantages

– Death of distance, distance becomes less significant

– Very low price,even free (More calls with less bandwidth)

In china, domestic toll 1 Yuan/min1 Yuan/min, IP 0.3 Yuan/min0.3 Yuan/min – Provide integrated voice, data, image by one

terminal

– Web-based multimedia services,…


Advantages & Disadvantages

unacceptableunacceptablePoorPoorGoodGoodExcellentExcellent

0 450300150 One-way in ms

Quality vs. Latency

Quality vs. Latency

– Limited and finite in capacity, area

– Significant drawbacks (gap, influent, click noise,..) in network congestion, or in large-delayed route,…

Comments: These were really true when this presentation was written in 2000

>450


Latest Advanced Products (around 2000)

CompanyAnalogicAudiocodeNatural Micro-

SystemDialogic

Model TAP-810 TP-400 AG4000D/300PCI-E1

D/300SC-2E1

Max. nu. of T1/E1

4 4 1,2,4 2

Bus Interface

cPCI cPCI cPCI or PCI PCI or SC

Extended Interface

H.110 H.110 H.110 H.100

DSPTMS320-C549

AudioCode AC48105

TMS320-

C549

Motorla

5630X


On-BoardEthernet

10/100M 100Base-T no no

Channels of compression

120/96 120/96120/96 (plus

daughter board)

60/48 (plus

daughter board)

OSSolaris,

UNIX,Win NTWin NT

Win NT,

Solaris

Win NT

Solaris,UNIX

SDK TAP-8XX - Fusion -

Advantages(advanced)

DSP

DSP,RTP/

RTCP on-

board

Easy to R&D

Local service

Wide

service

Dis-advantages

Hard in

R&D

Hard in

R&D

Daughter

boardLow density

AnalogicAudiocodeNatural Micro-

SystemDialogicCompany


Research & Development

– Hardware: Higher density, integrated more functions into one board or chassis , e.g., a DSP daughter board is inserted to main board, now it is not used any more.

– In software

•Support more OS, extend to Solaris , Unix,…

•Support more signaling , for example, SS7,…

•Support new protocols being developed, ex. Vovida.com provides open MGCP

•Some software is embedded into board, NMS put its RTP/RTCP on board


Research & Development

– In China, the gateway with capacity up to 160 E1

has been developed

– Application-oriented, web-based( 800,…), call

transfer,…

– New application, IP-based-PBX, call centre,

telephone banking,…

Question:

Could you describe the similarities and

dissimilarities/differences of call-free services in

the modes between the traditional telephone and

Internet web-based ?


In China China had chosen H.323 as the standard used

domestically (comments: this was true around 2000)

There are a lot of players to announce to provide SIP solution, e.g., capital telecom company.

It is reasonable to say that the largest telecom companies provide the SIP solutions in two years, such as Zhongxing, Huawei . (this was really true when the PPT was written in 1999)

Today, there are more and more manufacturers involved in SIP products, which represents the future of IP-based multimedia communication.

Products Products


Products Products

International (when time was in 2000) There are a lots of H.323-based products used

widely, including telephone (hardware/ software), Gateways, Gatekeepers, MCUs (Multi-points Control Unit), etc. The players include Audiocodes, Cisco, Clarent( 冠远 ), Dialogic, Nortel networks, Lucent, …

There are a few hundreds players to provide solutions of SIP, e.g., Audiocodes, Nortel networks, Lucent,…


The SIP will become more and more important, but it takes a long way to coexist with H.323 and to replace (?) absolutely

The researching topics include: H.323 interworking with SIP H.323 and SIP applications in wired and wireless networks

(3G - 3rd generation, WLAN,…) H.323/SIP interworking with Softswitch system (H.248, we

discuss it in next section) IP Multimedia Subsystem (IMS #)- a new networking

architecture, widely used and dominates the session control protocol in mobile networks (3G,4G) and mixed Fixed/mobile networks

The futureThe future


Quality of Voice is measured via Mean Opinion Score(MOS ， 5~1) #, 5 Is the best and 1 is the worst

G.726 ADPCM 8K~32K (Adaptive Differential PCM) G.728 LD-CELP (Low Delay of Code Excited Linear Predictive) G.729# CS-ACELP (Constant-Structure, Algebraic CELP) G.723.1 6.4K MP-MLQ ( Multi Pulse, Maximum –Likelihood

Quantization) 5.3K ACELP We must note that ITU compression algorithms are not the best.

According to Audiocodes.com, its NetCoder quality at 9.6 Kbps is indistinguishable from G.711 PCM.

PCI#– Peripheral Component Interconnection cPCI#— compact PCI , SC-widely used computer bus in the pastH.100/H.110 is the CT ( Computer Telephony) Bus implementation on

the PCI/cPCI form.H.100: 4096 bi-directional time slotsH.110: 32 data streams at 8.192Mb/s.

OS: Operation System SDK#: Software Development Kit

AppendixAppendix


6.2 行业应用

6.1 IP分组多媒体通信


接入网广泛地应用于生活、工作和国民经济的众多部门，本节简述在家居网、行业的应用。

一、家居网定义与组成家庭网络，是指在家庭范围内（可扩展至邻居或小区）将个人计算机（ PC）、家电、安全和照明系统等相互连接，组成一个家庭内部的网络，并与广域网相连接，在家庭内部以及家庭与公网之间提供多种服务的一种新的组网和应用技术。

家庭网络，是指在家庭范围内（可扩展至邻居或小区）将个人计算机（ PC）、家电、安全和照明系统等相互连接，组成一个家庭内部的网络，并与广域网相连接，在家庭内部以及家庭与公网之间提供多种服务的一种新的组网和应用技术。


IT 类

通信类

消费电子类互连

互通



家庭网络由以下部分组成：（ 1）外部网络：运营商提供的物理网络接口和服务，如广电网、 PSTN、因特网、其它网络等；

（ 2）家庭主网关：实现家庭内部网络与外部网络连接的“桥接器”，实现与所附接设备、内部多个子网关的数据传送与控制；

（ 3）子网关：实现各子网内部与家庭主网关连接的“桥接器”，实现与所附接设备的数据传送与控制；

（ 4）终端：实现不同功能的信息传送、控制等功能。

家庭网络由以下部分组成：（ 1）外部网络：运营商提供的物理网络接口和服务，如广电网、 PSTN、因特网、其它网络等；

（ 2）家庭主网关：实现家庭内部网络与外部网络连接的“桥接器”，实现与所附接设备、内部多个子网关的数据传送与控制；

（ 3）子网关：实现各子网内部与家庭主网关连接的“桥接器”，实现与所附接设备的数据传送与控制；

（ 4）终端：实现不同功能的信息传送、控制等功能。



二、家居网的主要网络技术

HomePlug

MoCA

HomePNA

无线网络

HomePlug 概述

HomePlug PowerLine Alliance 家庭插座电力线联盟

HomePlug 技术使用家庭中的电源线作为家庭网络基础设施，通过覆盖于整个家庭的电源线，进行家庭内部音频、视频、数据业务的传输

用户只需简单地将 HomePlug 适配器插入一个标准的电源插座，然后将通信终端与该适配器相连，即可通过电源线建立网络

HomePlug 网络结构

HomePlug 技术指标

物理拓扑结构为共享总线型，逻辑拓扑结构为全互联结构

单信道带宽为 28.2MHz, 占用频带 1.8-30MHz

物理层最大速率 200Mbps ， MAC 层最大速率100Mbps

双工方式为 TDD ，多址方式为 TDMA 和 CSMA/

CA

支持组播 , 支持 VLAN

提供基于优先级和基于流的 QoS 保证单个局端支持最大终端数为 253 个

HomePlug 协议栈

两个面： control ， data

MoCA

Multimedia over Coax Alliance ，同轴电缆多媒体联盟，成立于 2004.1

MoCA 技术采用目前有线电视 CATV 使用的同轴电缆，因此无需另行布线、施工，就可在家庭内部构建高速的家庭网络

2006.3.28 ， MoCA MAC/PHY v1.0 发布 2007 年底， MoCA 1.1 标准通过

MoCA 网络结构

MoCA 网络的频率范围在 850MHz-1525MHz ，每个信道带宽为 50MHz ，每个 MoCA 网络最多可支持 16 个 MoCA 节点之间的通信

MoCA 标准的物理层使用 TDD 方式， MoCA

MAC 层协议是建立在全协调的 TDMA 信道上MoCA 网络中最大的 PHY 层速率为 270Mbps ，，

最大的 MAC 层速率为 175Mbps ，最大的数据包长度为 1518 字节，最大的网路时延为 5ms ，平均网络时延为 3.5ms

MoCA 技术指标

MoCA 协议栈PHY 层进行物理层组帧，信道预均衡，

调制技术，功率控制等MAC 层进行控制帧和数据帧的传输，

控制帧包括节点接纳，链路维护，带宽请求， MAP 帧等相关帧；数据帧主要指上层数据流

汇聚层主要功能是将上层数据进行封装 ,

使得上层数据与 MAC 层进行适配 , 同时还包括优先级映射等（ TS ：transport System ：定义若干多媒体流的“封装 encapsulation” 协议）

Up p er L ay er s ( C o r e N etw o r k s )

C o n v er g en c e L ay er s

8 0 2 .3 M P E G 2 T S D S S T S

M AC L ay er

P h y s ic a l L ay er

HomePNA 概述HomePNA （ Home Phone Line Networking Alliance ，家庭电

话线网络联盟）HomePNA 技术利用现有电话线和家庭内部同轴电缆传输宽带

数据信号，无需重新布线，满足用户宽带上网的要求HomePNA 1.0, HomePNA 2.0

2005 年 5 月， ITU 推出了数据传输率达 128Mbps 的HomePNA 3.0 规范 , 该标准数据率可以扩展到 240Mbps ，最大连接设备数目增至 50 个

2007 年 3 月 ,ITU 宣布 HomePNA 3.1 规范 ,HomePNA 3.1 标准允许服务提供商通过家庭内部电话线和电缆以最高 320Mbps

的速度提供高速的三重业务整合（ triple-play ）等互联网服务

HomePNA 网络结构

HomePNA 协议栈

HomePNA 协议栈

HomePNA 帧格式

Ethernet type

无线网络 IEEE 802.11b/g/n外网（家庭网

关） 3G/4G 上网卡，以太网， EPON ， ADSL等

专用无线网络：无线电话子母机，对讲机

Zigbee 网络： Zigbee协议包括高层应用规范 (profile) 、汇聚层、网络层、数据链路层和物理层，其中数据链路层和物理层标准由 IEEE802.15.4负责制定，网络层和传送层由 Zigbee 联盟制定。

已学过的相关技术

HFCEoC （多达 10种变形）

由于目前家庭内部组网的技术很多，为了能够更好的进行信息的互联互通和兼容性的考虑， HomeGrid论坛成员希望制定统一的互联方案，以此来替代诸如MoCA ， HomePNA ， HomePlug 等所作的工作，使用该标准的芯片能以超过 1Gbps 的速率在同轴电缆，电话线和电力线上传输数据。

三、新一代家居网技术

国际电联 G.hn 标准

由 ITU 提出的 G.hn （ home networking ）是关于家庭电话线，电源线和同轴电缆的一套协议规范；

G.hn 支持数据传输，高清电视，语音服务，共享服务等所有家庭多媒体业务；

G.hn 标准基于 OFDM 技术，提供严格的 QoS 支持以进行可靠的视频传输，并避免与线路中已有服务造成干扰。

G.hn 标准特征

多介质：电力线，电话线，同轴电缆；性能：高达 1G 的信息速率；突发性：视频，音频以及数据服务的 QoS 保证安全： AES128加密；共存：对非 G.hn 的兼容；管理：遵从 TR-69 的管理协议；网状网：支持区域扩展和自动中继；低功耗：满足 smart grid 和 European CoC 要求

G.hn 网络拓扑

G.hn 协议栈

G.hn 协议栈包括物理层和数据链路层

G.hn 的数据链路层分为 3 个子层– APC( 应用协议汇聚子层 )

– LLC( 逻辑链路控制子层 )

– MAC( 媒质接入控制子层 )

G.hn 的物理层分为 3 个子层– PCS( 物理编码子层 )

– PMA( 物理媒质连接子层 )

– PMD( 物理媒质相关子层 )

Documents

2015-6-8 1 第 6 章 接入网应用 第 6 章 接入网应用 6.2 行业应用 6.1 IP 分组多媒体通信 access to him at : Dr. Zhanqi XU, access to him at : web.xidian.edu.cn/zqxu

2015-6-8 1 第 6 章接入网应用第 6 章接入网应用 6.2 行业应用 6.1 IP 分组多媒体通信 access to him at : Dr. Zhanqi XU, access to him at : web.xidian.edu.cn/zqxu