Design And Implementation Of Video Telephony Over CDMA/EVDO Mobile Terminal

Video telephony takes integrated multimedia processing to audio, video, data, and so on. By combination of video telephony and mobile communication technology, a dream which mobile users have a real-time audio and video communication in different place will become to true.CDMA2000lx/EVDO Rev A is an important third generation mobile communication system, which not only supports voice call but also offers high speed packet switched data service. Comparing to EVDO Rev0, the ability of packet data processing of EVDO Rev A system is greatly enhanced. On the forward link, the rate of forward peak has upgraded from2.4Mbps to3.1Mbps. On the reverse link, the rate of reverse peak has up from153.6Kbps to1.8Mbps by application of variable packet length and incremental transport, hybrid ARQ and higher order modulation technology. What is more important is that, by optimizing access channels and control channels, introducing low-latency data transfer mode and multi-stream mechanism, EVDO Rev A can guarantee end-to-end quality of service for data transmission, shorten access time and operational delay effectively, optimize throughput of the forward link, improve bandwidth of reverse link and transmission rate. In conclusion, EVDO Rev A can support real-time and non-real-time services simultaneously and provides a solid foundation to apply video telephony over mobile terminal.Therefore, combining demanding of video telephony and characteristics of CDMA20001x/EVDO Rev A, basis of video telephony over CDMA2000lx/EVDO Rev A system is introduced firstly, and then design principle and implementation method of video telephony over CDMA2000lx/EVDO Rev A mobile terminal are studied deeply. Specific content includes:1) Introduced core design ideas, network architecture and role of important network elements of video telephony which based on EVDO Rev A network.2) Combining demands and characteristics of video telephony, performance improvement and key technologies of EVDO Rev A are analyzed and researched. It also elaborated important significance of end-to-end quality of service to packet switched video telephony and implementation method of quality of service in EVDO Rev A.3) Studied software implementation method of video telephony over CDMA/EVDO mobile terminal. It focused on software design concept of video telephony, design and implementation of application layer and service layer in CDMA/EVDO mobile terminal. It also took specific analysis and elaboration to how to apply quality of service assurance mechanisms and SIP protocol of control plane to CDMA/EVDO mobile terminal.4) Analyzed factors which affect performance of video telephony. On basis of the factors, some network elements of EVDO Rev A how to affect performance of video telephony were discussed specifically.Through this thesis, engineers can master basic principle, system architecture, key technologies and factors which affect performance of videophone in EVDO Rev A. They can also take timely and effective treatment to the problems exposed in the video telephony development and application process. The thesis laid solid foundation for use and promotion of video telephony.