A Study on a Set of Media Synchronization Protocols in Wireless Networks

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The research results can be classified into five categories. The first study examines four lip synchronization schemes for stored MPEG video and voice ; two schemes interleave voice and video into a single transport stream, and the others treat them separately. In each kind, one exerts synchronization control at the destination, while the other does not. In addition, we apply a dynamic resolution control scheme of MPEG video to the two schemes with synchronization control. We have implemented those schemes on an ALTAIR wireless LAN.The measured performance shows that heavily loaded networks need synchronization control and that the dynamic resolution control is effective.Secondly, we study media synchronization on live MPEG video and voice as in the first study.Thirdly, we propose a joint synchronization scheme among stored video, live voice and live video streams. The scheme takes advantage of the difference in the feature between live and stored media. We have implemented the scheme on an integrated ATM and wireless LAN and demonstrated its effectiveness.The fourth study measures the quality of stored media synchronization under the slide control in PHS Internet access. A simple experimental system was developed for the transmission of H.263 video and G.726 audio from a media server to PHS mobile terminals. We examine the effects of Rayleigh fading in the PHS channels and the data load in the Internet on the media synchronization quality.Lastly, we study the application of the slide control to interleaved transmission of live video and audio specified by the H.223 Annex in PHS.We also propose a QOS control scheme to control both media synchronization quality and transmission delay. Through simulation, we confirm the effectiveness of the scheme. In addition, we carry out an experiment of live G.728 audio transmission with PIAFS and UDP/IP.