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

研究成果可分为五类。第一项研究探讨了四个唇同步方案存储的MPEG视频和语音，两个方案交织成一个单一的传输流的语音和视频，和其他对待他们分开。在每种类型中，一个在目的地施加同步控制，而另一个不施加。此外，我们将MPEG视频的动态分辨率控制方案应用到具有同步控制的两个方案中。我们在ALTAIR无线局域网上实现了这些方案，测试结果表明，在高负载的网络中需要同步控制，动态分辨率控制是有效的。其次，我们研究了MPEG视频和语音流的媒体同步问题。第三，我们提出了一种视频、语音和视频流的联合同步方案。该方案利用了实时媒体和存储媒体之间的特征差异。我们已经实现了一个综合的ATM和无线局域网的方案，并证明了其有效性。第四个研究措施的质量下的滑动控制PHS互联网接入的存储媒体同步。开发了一个简单的实验系统，用于从媒体服务器向PHS移动的终端传输H.263视频和G.726音频。研究了PHS信道中瑞利衰落和Internet上的数据负载对媒体同步质量的影响，研究了滑动控制在PHS中H. 223协议中实时视频和音频交织传输中的应用，并提出了一种QOS控制方案来控制媒体同步质量和传输延迟。通过仿真验证了该方案的有效性。此外，本文还利用PIAFS和UDP/IP协议实现了G.728音频的实时传输。

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.