Fault-Tolerant Support for Reliable Multicast in Mobile Wireless Systems: Design and Evaluation

In this paper we present a protocol for reliable multicast within a group of mobile hosts that communicate with a wired infrastructure by means of wireless technology. The protocol tolerates failures in the wired infrastructure, i.e., crashes of stationary hosts and partitions of wired links. The wireless coverage may be incomplete and message losses could occur even within cells, due to physical obstructions or to the high error rate of the wireless technology, for example. Movements of mobile hosts are accommodated efficiently because they do not trigger any interaction among stationary hosts (i.e., there is no notion of hand-off). We evaluate by simulation the impact of fault-tolerance on the performance of the protocol in normal operating conditions, i.e., in the absence of failures. The results obtained show that the increase in the average latency experienced by messages is limited to few milliseconds.