A Comparative Study of Forward Error Correction and Frame Accumulation for VoIP over Congested Networks

摘要

We compare Forward Error Correction (FEC) and frame AC-Cumulation (ACC) to see which of the two schemes most effectively reduce frame loss rate for an aggregate of VoIP flows, sharing a network bottleneck. We model this bottleneck by a M/M/1/K queue and we analytically show that given certain assumptions, FEC is the best choice for low initial load at the bottleneck. Then, as the initial load increases, a crossing point is reached after which applying ACC is the better choice. We study this crossing point through numerical examples. Furthermore, we present numerical examples indicating that ACC is better than FEC in bandwidth limited network scenarios, while performance is more equal for packet processing limited scenarios, with FEC being the slightly better choice. Finally, we introduce more general queue models, e.g. the MMPP/M/1/K queue, to model traffic scenarios like the aggregate of ON/OFF VoIP traffic.