Efficient link-heterogeneous multicast for wireless mesh networks

A wireless mesh network (WMN) is a type of communication network made up of wireless devices and organized in a mesh topology. Multicast is a fundamental service in WMNs because it efficiently distributes data among a group of nodes. Multicast algorithms in WMNs are designed to maximize system throughput and minimize delay in order to satisfy the end users’ requirement. Previous work has unrealistically assumed that the underlying WMN is link-homogeneous. We consider one important form of link heterogeneity: different link loss ratios, or equivalently different ETX. Different from other work addressing multicast in wireless networks, we point out that the local broadcast quality relies on the worst involved link. We model different link loss ratios by defining a new graph theory problem, Heterogeneous Weighted Steiner Connected Dominating Set (HW-SCDS), on an edge-weighted directed graph, where the edge weights model ETX, the reciprocal of link loss ratios. We minimize the number of transmissions in a multicast by computing a minimum HW-SCDS in the edge-weighted graph. We prove that HW-SCDS is NP-hard and devise a greedy algorithm for it. To improve the effectiveness of our algorithm, we design a dedicated channel assignment algorithm. Simulations show that our algorithm significantly outperforms the current best WMN multicast algorithm by both increasing throughput and reducing delay.