Efficient multicasting for multi-channel multi-interface wireless mesh networks

Multicasting can be an useful service in wireless mesh networks (WMNs), which have gained significant acceptance in recent years due to their potentials of providing a low-cost wireless backhaul service to mobile clients. Many applications in WMNs require efficient and reliable multicast communication, i.e., with high delivery ratio but with less overhead, among a group of recipients. However, in spite of its significance, there has been little work on providing such a multicast service in multi-channel mesh networks. Traditional multicasting protocols for wireless multi-hop networks mostly assume that all nodes (equipped with a single interface) collaborate on the same channel. The single-channel assumption is not always true for WMNs that often provide the nodes with multiple interfaces for the purpose of substantial performance enhancement. In multi-channel/interface mesh environments, the same multicast data needs to be sent multiple times by a sender node if its neighboring nodes operate on different channels. In this paper, we try to tackle this challenging issue of how to design a multicast protocol more suitable for multi-interface and multi-channel WMNs. Our multicasting protocol builds multicast paths while inviting multicast members, and allocates the same channel to each of neighboring members in a bottom up manner. This mechanism can reduce message overheads and delivery delays while guaranteeing successful message deliveries. For the performance evaluation, we have implemented the proposed scheme on a multi-channel/interface mesh network test-bed with two IEEE 802.11a cards per node.