An efficient reliable multicast protocol for 802.11-based wireless LANs

Many applications are inherently multicast in nature. Such applications can benefit tremendously from reliable multicast support at the MAC layer because addressing reliability at the MAC level is much less expensive than handling errors at the upper layers. However, the IEEE 802.11 MAC layer does not support reliable multicast. This void in the MAC layer is a limiting factor in the efficacy of multicast applications. In this paper, we propose a Slot Reservation based Reliable Multicast protocol that adds a novel reliability component to the existing multicast protocol in the 802.11 MAC. Our protocol builds on the existing DCF support in the IEEE 802.11 MAC to seamlessly incorporate an efficient reliable multicast mechanism. Intelligent assignment of transmission slots, minimal control packet overhead and an efficient retransmission strategy form the basis of our protocol. We evaluate the performance of our protocol through extensive simulations. Our simulation results show that our protocol outperforms another reliable multicast protocol, Batch Mode Multicast MAC in terms of delivered throughput in various scenarios.