The Research Of Admission Control Mechanism And QoS Routing Protocol In Wireless Mesh Networks

As one of the most important access techniques for the next generation wireless networks, Wireless Mesh Networks have attracted more and more attention in the last decade. The capability of self-organization in WMNs reduces the complexity and cost of deployment and maintenance of wireless network. Due to such advantages, WMNs have covered a variety of applications in our daily life. While more and more multimedia applications are expected in WMNs, supporting Quality-of-Service (QoS) for these real-time traffics is still a challenging and important task because of the shared media and limited resource in wireless networks.Admission control mechanism and QoS routing protocol are the two key components for the QoS assurance mechanism in WMNs. The former is the base of all the QoS assurance mechanisms and the latter usually cooperates with the former to find a QoS guaranteed routing path.In this thesis we first introduce the characters and architecture of WMNs, we also introduce the basic QoS assurance method in the wireless networks. Then we analyze the relationship, characters and key problems of the admission control mechanism and QoS routing protocol in WMNs in depth.The accurate estimation of the available bandwidth of a wireless mesh node is a fundamental step to all admission control mechanisms. The existing bandwidth estimation schemes in WMNs seldom consider the channel reuse caused by parallel transmissions which would influence the accuracy of the estimation results. In chapter 3, with the deep analysis of this problem, we propose a novel bandwidth estimation scheme used in admission control mechanism for WMNs, named BEPTC (Bandwidth Estimation with Parallel Transmission Consideration) scheme. Furthermore, a distributed admission control mechanism is proposed based on the combination of BEPTC and AODV routing protocol. The simulation results demonstrate that our admission control mechanism with the use of BEPTC can effectively control the amount of traffic in the network and increase the resource utilization and system throughput. The traditional QoS routing protocols in multi-hop wireless networks usually flood the routing packets in the network to find the QoS guaranteed path for flows. But the hub-based traffic pattern in WMNs, especially the multi-gateway WMNs, will make such routing method generate too much routing packets and decrease the performance of the networks. In chapter 4, in the light of the hub-based traffic pattern in multi-gateway WMNs, we propose a Tree Based Domain Routing protocol--TBDR. TBDR firstly divides the network into many gateway management domains. And in each domain, the protocol constructs and maintains a bandwidth-best routing tree. In order to find a QoS guaranteed routing path, the admission control mechanism will send the routing request packets according to the routing tree and make the admission control decision in each node of the path. The simulation results demonstrate that in the multi-gateway WMNs, our protocol TBDR can effective decrease the routing load and improve the performance on arrival rate of packets and flow accepted rate. It can also do some load balance between different nodes in one domain.