A Simulation Study of P_Mul Multicasting Protocol Enhanced by Ideal FEC Code

摘要

Simulation studies have been conducted to determine the benefits of forward error control (FEC) enhancement oh automatic repeat request (ARQ) based reliable multicast protocols, particularly in the wireless environment. As the first step, an ideal FEC code was added to a reliable multicast protocol PJViul as the base protocol. Originally, P_Mul's error control mechanism is based on ARQ where the multicast group members periodically respond with a list of missing packets. Also, in the cases when the loss is independent for different receivers, the entire message often needs to be retransmitted multiple times. With an ideal FEC scheme, improvement in the transmission efficiency has been observed. By ideal FEC, it was assumed that the FEC code provides unlimited number of parity packets, or an arbitrarily low rate erasure code. Every packet from the new round of retransmissions is a parity packet, and can be used to recover any previously lost packet. The simulation study shows throughput improvements especially at the high bit error rates.