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Multimedia Communication Based on Packet Network

Explore the architecture, protocols, and progress of multimedia communication (MMC) based on packet networks, including IP telephony, switching, media processing, and network architecture.

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Multimedia Communication Based on Packet Network

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

  2. MultiMedia Communication Based on Packet Network • Overview Architecture, Protocols, Progress • Protocols (H.323 & SIP) • IP Telephone Architecture Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  3. 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,…) Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  4. Switching • Circuit-switched ( traditional CS, fast CS,…) • Packet-switched (ATM,MPLS , Ethernet, FR , Token ring, Tokenbus), 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,… Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  5. PSTN CATV • MMC network architecture Computer Net V5/ No.7, No.1 Integrated Access PSTN Telephone Modem Fiber/ Cable Cable xDSL CO. Copper/Optical PSTN Tel Cable Modem Cable Tel IP Tel IP Tel LAN LAN LAN Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  6. Education Entertainment Electronic Commerce Public Info. Applications Areas Examples 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,… Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  7. 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). Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  8. Video Coding Audio Coding Terminal RTP TCP UDP IP Gateway PBX Client Gatekeeper H.323 Architecture Control and management Application H.245 H.225.0 (Sig. Ch.) H.225.0 (RAS) RTCP NIC ( Network Interface Controller) IP Backbone Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  9. 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. Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  10. H.323 Protocols Stack Items Protocols or Function Audio Coding G.711, G.722, G.723.1, G.726, G.728, G.729 H.261, H.263 Video Coding Processing related to sequencing, sync., payload type, source identification,… RTP(Real-Time Trans. Prot.) Additional info. to session participants: QoS feedback, identification, session control,… RTCP RAS: Registration, Admission, Status Conveying the registration, admissions, bandwidth, status, … RAS (H.225.0) Sign. Ch. (H.225.0) setup or release of call connection based on Q.931 Capability Negotiation, coding, conference req.,… Ch. CTRL (H.245) Efficient but unreliable transport of packets UDP Conn.-oriented , reliable transport of packets TCP Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  11. 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 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  12. 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 to play Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  13. 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) Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  14. Control and management Video/Audio coding Terminal Request RTCP RTP Response TCP IP NIC 2 5 Redirect Server Location Service 4 11 1 Agent Server SIP Proxy 12 3 SIP Proxy SIP Client 2 SIP Client 1 8 7 10 9 6 SIP Architecture Application SIP UDP Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  15. 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) SIP Components • 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? Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  16. (the below message is from RFC2543) INVITE sip:watson@boston.bell-telephone.com SIP/2.0 Via: SIP/2.0/UDP 169.130.12.5 From: <sip:a.g.bell@bell-telephone.com> To: T. A. Watson <sip:watson@bell-telephone.com> Call-ID: 187602141351@worcester.bell-telephone.com 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 SIP message example Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  17. 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 round-trip, V.2 faststart Single round-trip Extensibility ( Codecs) ITU developed only Any registered Scalability (large number of call processing) State State or stateless Mobility support Limited Easier Market Becoming less Growing extensively Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  18. 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,… Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  19. IP Phone Network PSTN PSTN PSTN Gateway Gatekeeper Gatekeeper Gateway FAX Telephone Fax Telephone Gatekeeper Gateway Hong Kong New York Fax Shanghai Telephone IP backbone network Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  20. 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 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  21. IP Header UDP header RTP Header 8 Bytes 12 Bytes 20 Bytes Voice Processing • PCM(64Kb/s)compression 8Kb/s(G.729a),… • Encapsulation ( packetized ): Payload • 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 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  22. Coding Comparison Coding Rate(Kbps) Complexity (MIPS) Quality Frame Size G.711 64 N/A Very good N/A G.728 16 Very high (40) Good 8 or 16 ms G.729a 8 Moderate (10) Fair 10ms(2X5) G.723.1 6.4/5.3 Moderate- High (14/20) Good/Fair 30ms (4X7.5) NetCoder 9.6/8.0/7.2 Low (7.5) Very good (-) 20ms Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  23. 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,… Advantages & Disadvantages Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  24. >450 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 Good Poor unacceptable One-way in ms 0 150 300 450 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  25. Latest Advanced Products (around 2000) Company Analogic Audiocode Natural Micro- System Dialogic Model TAP-810 TP-400 AG4000 D/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 DSP TMS320- C549 AudioCode AC48105 TMS320- C549 Motorla 5630X Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  26. Company Analogic Audiocode Natural Micro- System Dialogic On-Board Ethernet 10/100M 100Base-T no no Channels of compression 120/96 120/96 120/96 (plus daughter board) 60/48 (plus daughter board) OS Solaris, UNIX,Win NT Win 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 board Low density Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  27. 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 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  28. 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 ? Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  29. 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. Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  30. 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,… Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  31. 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 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  32. 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 SDK#: Software Development Kit Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  33. 6.1 IP分组多媒体通信 • 6.2 行业应用 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University

  34. 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。 34 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University 2019/12/19

  35. 通信类 消费电子类 互连 互通 IT类 35 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University 2019/12/19

  36. 36 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University 2019/12/19

  37. 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。 37 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University 2019/12/19

  38. 38 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University 2019/12/19

  39. 二、家居网的主要网络技术 • HomePlug • MoCA • HomePNA • 无线网络 39 Dr. Zhanqi XU,National Key Lab on ISN, Xidian University 2019/12/19

  40. 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

  41. HomePlug网络结构

  42. 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

  43. HomePlug协议栈 两个面：control，data

  44. 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

  45. MoCA网络结构

  46. 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

  47. 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）

  48. 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

  49. HomePNA网络结构

  50. HomePNA协议栈

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