Study On Qos Multicast Routing Protocol In Wireless Ad Hoc Networks

Wireless Ad Hoc networks are formed automatically via wireless connection by mobile nodes and can work without the support of a fixed network infrastructure or a central system. In the mean time, there are increasing business requirements of interactive group communication. Hence, the supports of simple and efficient multicast routing technique are required. On the other hand, numerous multicast applications are multi-media oriented, and require quality of service (QoS) support over multicast routing for a network.How to choose QoS constrait metric is one of the critical issues due to the large number of destination nodes and uneven paths in wireless Ad Hoc networks. But QoS parameters are related with each other. Consider the same network scenario, the delay will be smaller and the ratio of packet loss will be lower when the bandwidth requirement of a data flow is less. On the contrary, when the packets collide frequently in the networks, the delay and the ratio of packet loss increases rapidly. For this reason, bandwidth is considered as the primary QoS parameter in most QoS multicast routing protocols currently.In order to provide unicast routing in wireless Ad Hoc networks, more available bandwidth than the bandwidth requirement of a session is usually needed for a node, ranging from one to four times, due to the effect of neighbour nodes and hidden nodes. This problem also exists in multicast routing. Therefore, we need to consider the effect of neighbour nodes and hidden nodes when we investigate the issues of multicast routing with QoS requirement. However, QoS multicast routing protocols which have been proposed seldomly consider this effect. In this thesis, a distributed bandwidth-satisfied multicast routing protocol in wireless Ad Hoc networks (BCMR) is proposed, considering the effect of neighbour nodes and hidden nodes. This protocol is considered from the side of the node, and differentiates from other multicast routing protocols in the following aspects. Firstly, it uses resource reservation when it calculates the bandwidth. Every node has a resource reservation table which records the bandwidth that the node needs to accommodate the session in real time. Besides, the node will record the bandwidth requirement of the data flows which access its neighbour nodes and hidden nodes into the resource reservation table, and calculate the remaining available bandwidth by deducting the bandwidth reserved in the resource reservation table from the total available bandwidth. Secondly, BCMR distributedly searches the paths with the shortest delay on the basis of bandwidth-satisfied, instead of calculating the paths with the minimum hops. It is a distributed on-demand multicast routing protocol based on local information, and is suitable for the self organized wireless Ad Hoc networks.In this thesis, the bandwidth calculation method and the design of BCMR are introduced in detail. Brief analysis and the simulation results demonstrate the good performance of BCMR in terms of packet delivery reliability and the delay. BCMR can satisfy the requirement of real time communication and can be used in the multicast environment with low mobility.