Multicast overlay spanning trees in ad hoc networks: Capacity bounds, protocol design and performance evaluation

We study the benefits of multicast routing in the performance of wireless ad hoc networks. In particular we show that if a node wishes to communicate with n distinct destinations, multicast can reduce the overall network load by a factor O (sqrt(n)), when used instead of unicast. One of the implications of this scaling property consists in a significant increase of the total capacity of the network for data delivery. Hence, we show that the aggregate multicast capacity of wireless ad hoc networks is O (sqrt(n)) larger than the unicast capacity, when the group size n is small compared to the total number of nodes in the network. We discuss how these information theoretic results can be taken into consideration in the operation of a multicast protocol for wireless mesh networks using Multicast Overlay Spanning Trees (MOST). We perform simulations of the MOST protocol to compare with the theoretical results, and we present a fully working implementation for real network environments.