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1、Chapter 3 Multimedia Subnetwork Technology,Prof. Guohui Li School of Information System & Management National University of Defense Technology Spring 2010,COURSE 600-081205602,2019/5/24,MMCN-Chapter3,2,Chapter 3,3.1 Review of relevant requirements 3.2 Multimedia transmission over WAN 3.3 Multimedia
2、transmission over LAN 3.4 Multimedia transmission with ATM 3.5 Summary,2019/5/24,MMCN-Chapter3,3,3.1 Review of relevant requirements,To evaluate how well existing network technologies match the multimedia application requirements derived last chapter, we will use following categories as evaluating p
3、arameters. Throughput: 64Kbps; 384Kbps; 1.4 Mbps quality level. Transmission delay: 150 ms end-to-end delay for interactive application. Multipoint communication: multicast and broadcast. Reliability: error control or recovery mechanism integrated in the network.,2019/5/24,MMCN-Chapter3,4,3.2 Multim
4、edia transmission over WAN,Qestions The ability of the various traditional WAN technologies to carry multimedia traffic, in particular audio and video traffic. Can circuit switched network support multimedia traffic?,2019/5/24,MMCN-Chapter3,5,3.2 Multimedia transmission over WAN,Circuit switched ser
5、vices ISDN Packet switched services Internet IP Multicast and MBone Internet 2 initiative,2019/5/24,MMCN-Chapter3,6,3.2.1 Circuit Switched Services,1. POTS-Plain Old Telephone Service Telephone network is called Public Switched Telephone Network (PSTN). Part of the PSTN that looks after simple phone
6、 connections is called the POTS. Modems have to be used for data transmission. Its speed can be 28.8 Kbps, 38.4 Kbps, or 57.6 Kbps for download way. The rates are adequate for text and audio, but fall short of the bandwidth for good quality video transmission in real-time. Video Phone over POTS use
7、low frame rate and small picture size.,2019/5/24,MMCN-Chapter3,7,3.2.1 Circuit Switched Services,2. Leased lines Analog leased line An analog leased line is like a phone connection that never hangs up. It provides better quality than that of a dialup connection, because a higher SNR is obtained. Swi
8、tched 56 service: provides a bandwidth of 56 Kbps over switched lines. It can be used for low resolution video conferencing as an alternative to the POTS network.,2019/5/24,MMCN-Chapter3,8,3.2.1 Circuit Switched Services,Digital leased line Fractional T1: 384Kbps; video transmission by using H.261 (
9、Px64) or MPEG-4. T-1: 1.544 Mbps; (E-1: 2.048 Mbps for Europe); high quality compressed video transmission. T-2: 6.312Mbps; can sustain multiple video conferencing connections and video stream. T-3: 44.7Mbps;TV-quality video transmission. T-4: 274 Mbps; the highest bandwidth leased line.,2019/5/24,M
10、MCN-Chapter3,9,3.2.1 Circuit Switched Services,QoS and cost of digital leased lines leased lines are excellent for providing the required QoS for the transmission of multimedia stream. Because of the end-to-end connection, the SAS factors can be controlled very well. However, the cost of leased line
11、s might be un-economical.,2019/5/24,MMCN-Chapter3,10,3.2.1 Circuit Switched Services,3. SDH-Synchronous Digital Hierarchy SDH is a data transmission service based on optical transmission (optical fiber). SDH is a transport service that can be used for advanced network services such as B-ISDN, FDDI.
12、Bandwidths available in the SDH are defined with STM (Synchronous Transport Mode), e.g. STM-1 is 155.52 Mbps, and STM-3 is 466.56 Gbps.,2019/5/24,MMCN-Chapter3,11,3.2.2 ISDN,ISDN started in the 1980s as an alternative to digital leased lines. To provide higher data rates, the original ISDN was exten
13、ded to Broadband-ISDN (B-ISDN). The original ISDN can thus be called Narrowband-ISDN (N-ISDN). Two key aspects of ISDN: integrated services: voice, data, text, video, etc. digital networking. ISDN was designed to be multimedia enabled.,2019/5/24,MMCN-Chapter3,12,3.2.2 ISDN,1. ISDN channel A-channel:
14、 analog; 3-4Khz; analog voice, compatible with the current analog POTS. B-channel: digital; 64kbps; digitized voice or data. A single B-channel is not adequate for high quality video traffic, so a number of B channel can be used in a single user interface. C-channel: digital; 16Kbps; low speed data.
15、 D-channel: 16 or 64Kbps; signaling or data.,2019/5/24,MMCN-Chapter3,13,3.2.2 ISDN,2. ISDN interfaces ISDN services are provided to the users as ISDN interface. Widely used interfaces in ISDN are the BRI(basic rate interface) and PRI (primary rate interface). BRI: 2B+D; 144-192Kbps; digital voice an
16、d data, low quality video. PRI: 23B+D 1.544Mbps or 30B+D 2.048 Mbps; adequate for video transmission at VCR quality.,2019/5/24,MMCN-Chapter3,14,3.2.2 ISDN,Evaluation: ISDN was a massive attempt to replace the analog telephone system with a digital one suitable for both voice and non-voice traffic. Unfortunately, the standardization process took years and the technology in this area moved very rapidly, so that once the standard was finally agreed upon, it was obsolete. Oddly enough, ISDN is still
