Rate allocation and qos support in wireless mesh networks

Wireless mesh networking (WMN) is an emerging technology that uses multi-hop communications to provide cost-efficient broadband Internet access for community or enterprise users. With the increasing popularity of content distribution and multimedia applications, efficient rate allocation and QoS support become essential for the wide deployment of wireless mesh networks. In this dissertation we discuss several research topics related to rate allocation and QoS support in wireless mesh networks. First we propose a framework named QUOTA for QoS support and fair rate allocation in CSMA/CA based wireless mesh networks. Our framework uses contention graphs and Network Utility Maximization (NUM) to perform admission control and rate allocation. Simulation results show that our framework successfully guarantees the QoS of real-time flows and fairly, efficiently allocates bandwidth for elastic flows in different wireless mesh network scenarios. Second we propose a framework that performs rate allocation for multicast and unicast traffic in TDMA based wireless mesh networks using Network Utility Maximization. In addition, a graph coloring based scheduling algorithm is proposed to realize the allocated rates. Simulation results show that our framework provides guaranteed throughput and low delay for both multicast and unicast traffic. Furthermore, our framework significantly outperforms a previously published framework that has a similar objective. Third we propose a routing algorithm for minimum length schedule in multi-channel TDMA based wireless mesh networks. We consider network scenarios where multiple orthogonal channels are available. With a channel assignment algorithm to eliminate secondary interference, we are able to use a scheduling algorithm that yields the minimum length schedule given a specific routing tree. We then propose a heuristic routing algorithm that aims to build the routing tree that results in the minimum length schedule. Our routing algorithm performs significantly better than simple routing algorithms, which are based on Breadth First Search or Dijkstra algorithms. Fourth we propose a path selection metric for mobile stations in IEEE 802.16 Mobile Multihop Relay (MMR) networks to select appropriate paths to the base station. The proposed path selection metric, Normalized Number of Minislots (NNM), effectively takes all the factors that affect the end-to-end achievable throughput into consideration. Simulation results demonstrate that our metric yields better performance in terms of throughput and delay compared to existing path selection metrics, especially when networks have high traffic load.