Optimal allocation of packet-level and byte-level FEC in video multicasting over wired and wireless networks

Multicast is an efficient technique to deliver video content over a network. In this paper, we consider such a multicast system to serve both wireless and wireline users when there is error over the wired network and wireless hop. Since packets are likely to be dropped in the wired networks while bit errors are more likely over the wireless hop, a combination of both packet-level and byte-level FEC is required to recover these errors. Given the estimated error and bandwidth characteristics reported by end users, the server needs to optimally allocate the packet-level and byte-level FEC to achieve maximum video quality. We study two schemes pertaining to whether or not the wireless gateway is able to transcode the video packets from the wired network before forwarding it to the wireless users. We first develop a model to analyze the system; and then propose an efficient algorithm for the FEC computation. We finally compare the schemes in terms of the optimal parameters used in the FEC, and the video quality achieved.