Cross-layer framework for rate allocation in heterogeneous wireless multicast

Heterogeneous multicast is an efficient communication scheme especially for multimedia applications running over multihop networks when multicast receivers in the same session require service at different rates commensurate with their capabilities. In this paper, we address the problem of resource allocation for a set of heterogeneous multicast sessions over multihop wireless networks. We propose a framework that achieves the optimal rates for a set of heterogeneous multicast sessions such that the aggregate utility for all sessions is maximized. We present the formulation of the multicast resource allocation problem as a non-linear optimization model and highlight the cross-layer framework that can solve this problem in a distributed ad hoc network environment with asynchronous computations. Our simulations show that the algorithm achieves optimal resource utilization, guarantees fairness among multicast sessions, provides flexibility in allocating rates over different parts of the multicast sessions and adapts to changing conditions such as dynamic channel capacity and node mobility. Our results show that the proposed framework not only provides flexibility in allocating resources across multicast sessions, but also increases the aggregate system utility and improves the overall system throughput compared to homogeneous multicast.