| Summary: | 碩士 === 國立屏東科技大學 === 資訊管理系所 === 95 === A wireless local area network (WLAN) is error-prone because the radio signal is easily interfered by the multi-path fading effect. Provision efficient error recovery is important for video multicast in a WLAN. Instead of relying on client’s retransmission, the source-based error correction mechanisms are commonly employed for multicast where the source manipulates the data by adding some extra correction information (e.g., FEC) and the client recovers the errors from the received data. However, in the presence of long burst errors, the effect of recovery becomes limited for videos. This paper presents a replicated multiple descriptor scheme (RMD) where a video stream is encoded into several independent sub-streams and some important video frames in a sub-stream are also replicated in some other sub-streams. Sub-streams are transmitted over different multicast channels by employing some time-offsets. The simulation results reveal that RMD shows great help in immunizing the video stream from long burst errors and achieving an improved visual quality, compared with other schemes.
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