Bandwidth allocation for bi-directional end-to-end paths in a last-mile wireless mesh network

In this paper, we study the bandwidth allocation problem on a bi-directional end-to-end path in a last-mile wireless mesh network. We first propose an analytical model to study the interaction between contending links. Based on this model, we formulate the bandwidth allocation problem as a constrained maximization problem that captures real world complexities such as hidden node collisions, multi-hop flows and maximum packet transmission retry limit. The objective of the optimization problem is to maximize the downlink end-to-end throughput under a predefined uplink end-to-end throughput requirement. The optimal setting of each mesh router's contention windows can be obtained from the solution of the optimization problem. Our approach does not require any hardware modification and application layer rate control. Simulation results show that the proposed methodology works very well, the target uplink bandwidth can be reached and the downlink throughput is increased significantly when compared to the IEEE 802.11 standard.