Joint Association, Routing and Bandwidth Allocation for Wireless Mesh Networks

Abstract

In multi-hop infrastructure wireless mesh networks (WMNs), the association mechanism, by which a client station (STA) affiliates with a mesh access point (MAP), and the routing algorithm, through which MAPs form a multi-hop backhaul for relaying STAs' traffic, determine a two-tier logical topology. Apparently the STA-MAP association mechanism and the backhaul routing impact the available bandwidth that can be allocated to each STA. In this paper, we formulate a joint optimization problem of STA-MAP association, backhaul routing and bandwidth allocation. Our rigorous framework maximizes the network throughput while guaranteeing network-wide fairness among STAs, taking into account the bandwidth constraints of both access and backhaul links, as well as the wireless interference. We then develop approximation algorithms for efficiently solving the joint optimization problem. A method to decouple topology construction and bandwidth allocation is proposed to simplify the optimization problem under integral association and single- path routing, which is NP hard in the original formulation. We also use the clique approximation to alleviate the complexity for constructing the wireless interference constraints. Furthermore a scheduling algorithm is proposed, which coordinates channel access to provide bandwidth guarantee and can recover certain performance loss due to the clique approximation. Our evaluation demonstrates that constructing a good logical topology can improve throughput while enhancing fairness, and our algorithms can achieve performance close to the optimal solution to the joint association, routing and bandwidth allocation problem.