Channel Time Allocations and Handoff Management for Fair Throughput in Wireless Mesh Networks

In this paper, we study a wireless mesh network (WMN), where a number of access points (APs) form a wireless infrastructure and provide communications to the mobile stations (MSs). Different APs share the same frequency channel. We study how to provide fair long-term throughput for the MSs while efficiently utilizing the channel resources through effective handoff management and channel timeline allocations, where the channel time is allocated at two levels: first among the APs and then among the MSs. An optimization problem is first formulated and solved. The optimum solution is based on the assumption of having global information about the channel conditions of all the MSs and cannot be easily implemented in a practical WMN. Two distributed schemes are proposed by decoupling the handoff management and channel time allocations. The HO-CA scheme performs heuristic handoff decisions for the MSs based on their link gains to nearby APs and then optimizes the channel time allocations through an iterative process. The CA-HO scheme allocates the channel time to individual APs based on interfering relationship of the APs and then allows the MSs to make handoff decisions based on possible utilities from nearby APs. In both schemes, individual APs solve a local optimization problem to allocate channel time for their associated MSs. Numerical results indicate that both the proposed schemes can achieve very good fairness and that the HO-CA scheme achieves higher throughput.