Load-aware multicast routing metrics in multi-radio multi-channel wireless mesh networks

Efficient multicast routing metric is critical for one-to-many communications in wireless mesh networks. The existing unicast routing metrics do not perform well in multicast due to the distinctive differences between unicast and multicast routing in frame exchange manners in the link layer. It is thus necessary to propose specialized routing metrics for multicast. The focus of this paper is to investigate multicast routing metrics in multi-radio multi-channel wireless mesh networks. We first solve multicast throughput optimization problem in concurrent multicast flows and show that the throughput can be improved by seeking the multicast route with lower channel congestion degree. Then, the multicast routing metrics and protocol are designed by considering this aspect. The main contribution of our work is to propose two load-aware multicast routing metrics named FLMM and FLMMR. Both metrics account for channel diversity, interference and wireless broadcast advantage. FLMM aids in finding multicast route that are better in terms of reduced intra-flow and inter-flow interference and exploits channel diversity to improve bandwidth usage and network throughput. Compared with FLMM, FLMMR further considers the unreliability of MAC multicast. The effectiveness of the two metrics is empirically examined through simulations. Finally, we present the further work from two aspects: the joint multicast routing and channel assignment problem for optimal multicast and the practicality of proposed metrics.