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第6章 接入网应用 6.1 IP分组多媒体通信 6.2 行业应用 2017/5/8 Dr. Zhanqi XU, access to him at : web.xidian.edu.cn/zqxu, Xidian University 1 MultiMedia Communication Based on Packet Network Architecture, Protocols, Progress Overview Protocols (H.323 & SIP) IP Telephone Architecture 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 2 Overview Features Multimedia Communication (MMC) means more 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,…) 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 3 –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,… 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 4 MMC network architecture PSTN Computer Net V5/ No.7, No.1 Integrated Access PSTN Telephone CATV Fiber/ Cable Modem Cable xDSL CO. Copper/Optical PSTN Tel Cable Modem IP Tel 2017/5/8 LAN IP Tel LAN Cable Tel LAN Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 5 Applications Areas Education Examples Distance teaching/learning interactively, examination on-network,… VoD (video on demand), Live Entertainment picture, on-line game/Chat, … 2017/5/8 Electronic Commerce Trading, shopping, stock exchange, banking, … Public Info. News, magazine, forum, E-mail,… Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 6 Protocols Generally speaking,MMC includes almost all techniques in info. processing, transmission, and switching, the limited-space makes our discussion to packet-based network. 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 (Quality of Services). 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 7 H.323 Architecture Control and management Application Video Coding Terminal H.245 H.225.0 (Sig. Ch.) H.225.0 (RAS) RTCP TCP Audio Coding RTP UDP IP NIC ( Network Interface Controller) PBX Gateway IP Backbone Client Gatekeeper 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 8 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. 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 9 H.323 Protocols Stack Items Protocols or Function 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,… RTCP Additional info. to session participants: QoS feedback, identification, session control,… RAS (H.225.0) RAS: Registration, Admission, Status Conveying the registration, admissions, bandwidth, status, … Sign. Ch. (H.225.0) setup or release of call connection based on Q.931 Ch. CTRL (H.245) Capability Negotiation, coding, conference req.,… UDP Efficient but unreliable transport of packets TCP Conn.-oriented , reliable transport of packets 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 10 H.323 Protocols Stack-video coding/decoding H.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 HDTV MPEG-4 video coding method for low bit rates 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 11 H.323 Protocols Stack-RTP/RTCP comments RTP 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 12 to2017/5/8 play Dr. Zhanqi XU, National Key Lab on ISN, Xidian University SIP# Developed by IETF MMUSIC (Multi-Party Multimedia Session Control) work group, evolved from HTTP –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 UDP (reliability for both) –SIP Architecture (next page) 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 13 SIP Architecture Control and management Application Terminal SIP Video/Audio coding RTCP TCP RTP Request UDP Response IP NIC 2 Redirect Server 5 3 4 6 7 Location Service 11 1 Agent Server SIP Proxy 12 SIP Client 1 2017/5/8 10 8 SIP Client 2 9 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University SIP Proxy 14 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 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 2017/5/8translations? their 15 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 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 2017/5/8 16 H.323 vs. SIP Items H.323 SIP Messages Binary-based Text-based Develop & Update Complicated Easy Elements & Interactions Hundreds, Complicated 37 headers, Simple Setup of a task V.1(call,ctrl,media) 3 Single round-trip round-trip, V.2 faststart Extensibility ITU developed only Any registered State State or stateless Mobility support Limited Easier Market Becoming less Growing extensively ( Codecs) Scalability (large number of call processing) 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 17 IP Telephone General – 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 Time Events Players March,1995 First commercial IP phone for PC’s Vocaltec 1996 PC-to-phone,Phone-to-phone Free world Dialup,MIT,… 1997~1998 Part commercial application Vocaltec, Net2phone,… 1999~ High density (4~8 T1/E1), large capacity (>100T1) Audiocodes, analogic, NMS,… 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 18 IP Phone Network Gatekeeper Gateway IP backbone network Gatekeeper Gateway PSTN FAX PSTN Telephone Fax Gateway Hong Kong Fax Telephone Gatekeeper New York PSTN Shanghai Telephone 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 19 – 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 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 20 – Voice Processing •PCM(64Kb/s)compression 8Kb/s(G.729a),… •Encapsulation ( packetized ): IP Header 20 Bytes UDP header RTP Header 8 Bytes Payload 12 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 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 21 – Coding Comparison Coding G.711 G.728 G.729a G.723.1 NetCoder 2017/5/8 Rate(Kbps) Complexity (MIPS) 64 N/A Very good N/A 16 Very high (40) Good 8 or 16 ms 8 Moderate (10) Fair 10ms(2X5) ModerateHigh (14/20) Good/Fair 30ms (4X7.5) Low (7.5) Very good (-) 20ms 6.4/5.3 9.6/8.0/7.2 Quality Frame Size Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 22 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/min, IP 0.3 Yuan/min – Provide integrated voice, data, image by one terminal – Web-based multimedia services,… 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 23 Advantages & Disadvantages – 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 Quality vs. Latency Excellent 0 2017/5/8 >450 Good 150 Poor 300 unacceptable 450 One-way in ms Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 24 Latest Advanced Products (around 2000) Company Model Analogic TP-400 AG4000 Max. nu. 4 of T1/E1 4 1,2,4 Bus Interface cPCI cPCI Extended Interface H.110 H.110 DSP TMS320C549 AudioCode TMS320AC48105 C549 2017/5/8 TAP-810 Audiocode Natural MicroSystem Dialogic D/300PCI-E1 D/300SC-2E1 2 cPCI or PCI PCI or SC H.110 H.100 Motorla 5630X Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 25 Company On-Board Ethernet Analogic 10/100M Channels of 120/96 compression Solaris, UNIX,Win NT OS SDK TAP-8XX Advantages DSP (advanced) Disadvantages 2017/5/8 Hard in R&D Audiocode Natural MicroSystem Dialogic 100Base-T no no 120/96 (plus 60/48 (plus 120/96 daughter board)daughter board) Win NT Win NT, Solaris - Fusion Win NT Solaris,UNIX - DSP,RTP/ Easy to R&D Wide RTCP onLocal service service board Hard in Daughter Low density R&D board Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 26 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 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 27 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 ? 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 28 Products 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. 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 29 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,… 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 30 The future 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 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 31 Appendix 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 past H.100/H.110 is the CT ( Computer Telephony) Bus implementation on the PCI/cPCI form. H.100: 4096 bi-directional time slots H.110: 32 data streams at 8.192Mb/s. OS: Operation System 2017/5/8 SDK#: Software Development Kit Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 32 6.1 IP分组多媒体通信 6.2 行业应用 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 33 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。 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 34 通信类 互连 互通 消费电 子类 IT类 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 35 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 36 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。 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 37 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 38 二、 家居网的主要网络技术 HomePlug MoCA HomePNA 无线网络 2017/5/8 Dr. Zhanqi XU, National Key Lab on ISN, Xidian University 39 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技术指标 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 Upper Layers (Core Networks ) 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 Convergence Layers 802.3 MPEG2 TS MAC Layer Physical Layer DSS TS 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) 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 Ethern et 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 HFC EoC(多达10种变形) 三、 新一代家居网技术 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。 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)