Limited retransmission of real-time layered multimedia

In contrast to multimedia applications that involve human-to-human communication, streaming media over the Internet enjoys relaxed delay constraints. Thus, streaming media servers are at liberty to retransmit missing packets to avoid unnecessary signal corruption. While state-of-the-art media servers employ such strategies, no work to date has proposed an optimal strategy for delay-constrained retransmissions of streaming media. In this paper, we propose a framework for streaming media retransmission based on layered media representations and explore the performance advantage of integrating layered signal structure into the retransmission strategy. In our approach, the source must choose between transmitting an older layer that expires sooner and a newer layer that expires later but is more important. To arrive at the proper mix of these two extreme strategies, we derive an optimal strategy for transmitting layered data over a binary erasure channel with instantaneous feedback. To provide a quantitative performance comparison of different transmission policies, we conduct a Markov-chain analysis, which shows that the best transmission policy is time-invariant and thus does not change as the layers approach their expiration times.