Reliable Multicast via Satellite

Abstract

Many different reliable multicast protocols have been proposed and analyzed in the current literature. With advances in satellite technology,satellites have become more used within commercial networks. Since satellites are naturally a broadcast medium, multicast communications havethe potential to greatly benefit from their wide-scale deployment.<p>The performance of reliable multicast protocols needs to be studied and well understood over networks including satellite links. Most of the analysis performed on these protocols has dealt with bandwidth usage, buffer requirements and processing delay. Very few studies address the transmission delay incurred from using reliable multicast protocols. As delay becomes a larger issue in reliable multicast applications, performance evaluation with respect to this metric becomes important.<p> An existing hybrid error control protocol that combines packet level parity retransmissions with ARQ type feedback was studied under a variety of different conditions. Additionally, several modifications were made to the protocol and their performance in terms of bandwidth and delay were studied. The protocols were studied both with and without local recovery schemes. For non-local recovery schemes, the use of autoparity wasexamined and was shown to decrease recovery latency at the cost ofadditional bandwidth usage. The effects of different estimation schemes coupled with autoparity usage were investigated and results were compared. Simplistic adaptive mechanisms where the parity provided during each transmission is adjusted based upon observed packet loss statistics used with a local recovery scheme were found to offer the best overall results in terms of reducing recovery latency and satellite bandwidth usage.