QUEUEING LOSSES AND ADAPTIVE RELIABLE MULTICAST IN WIRELESS LANS

摘要

Wireless local area networks pose new challenges to error recovery and flow control in reliable multicast protocols. Limited wireless bandwidth, as well as queuing losses caused by the asymmetric wired/wireless interactions, demands more effective approaches for reducing packet losses. Moreover, a protocol must dynamically adjust its behavior to changing environmental conditions. In this paper, we propose and evaluate such a protocol, called the Adaptive FEC-based Reliable Multicast (AFRM) protocol. The protocol uses both proactive FEC and reactive FEC, adapting relevant parameters to current conditions. Both local and global NACK suppression are applied, but in a manner that accommodates delays due to access point queuing. Finally, the AFRM flow control strategy uses a novel method to differentiate propagation-related packet losses from queueing losses. Experimental and simulation results show the protocol has good performance in terms of throughput in most cases. Those factors that negatively affect performance are highlighted as topics of future research.