Study On The Implementation Of Videophone Based On HSDPA

In recent years, as the quick development of the multimedia technology andwireless communication technology, communication of single voice media canno longer meet the needs of the information age. People need to improve themeans of communication. In the arrival of 3G of domestic area, as the high-endapplications of 3G mobile phones, mobile phone has become a hotspot in recentyears.This paper presents and researchs the development of HSDPA Mobile DataNetwork, the character of 3G-324M protocol stack and the entire softwareplatform architecture based on the Real-time Operating System-REX (RealTime Excutive) It gives the main design thoughts, architecture andimplementation methods of the videophone system software of a cellphone. Inthe part of center control, it uses the mechanism of state machines to achieve UI(HMI), the encoder and decoder, wireless communications equipment, callcontrol based on the circuit switched, the interaction between 3G-324M protocolstack and others so that the completion of the related functions.It does further research of Call Connection of 3G-324M protocol stack andpresents the idea of reducing the number of exchange of information. It usesinformation control, payload segmentation and reassembly, flag emulationavoidance and other techniques, so that to achieve quick connection of a callestablishment. Experimental results show that the time of connection of call isshortened.Synchronization of audio and video is an important criterion for measuringmultimedia communication systems. Through the analysis of the audio and video bit stream of videophone of 3G-324M, this paper presents a algorithm ofsynchronization control between the medias, which use the frame rate of H.263video bit streams, control the time of broadcast of video frame and based on thetime of playing of audio. Using the algorithm in the actual Videophone won'tincrease communication redundancy, the method of adjusting is easy, and itsignificantly enhanced the P_QoS of video playing of multimedia systems.Thereby, the theory and design methods that discussed in this paper arevery important reference and valuable guide to domestic 3G terminal designscurrently.