Research On Energy Efficient Multicast Routing In Wireless Ad Hoc Networks

With the rapid and extensive development of wireless communication and internet, it has been substantially essential to acquire information and communicate with other people at anytime, anywhere and for anybody. Wireless ad hoc network is a kind of mobile communication combined with computer networks, and it consists of a collection of mobile hosts dynamically forming a temporary network. The ability to be set up quickly and operate without wired infrastructure makes wireless ad hoc network a promising candidate for next generation wireless networks. On one hand, the information exchange of the network has adopted the packets exchange mechanism. The organization of the network is not restricted by the communication infrastructure and the geographical position. It can organize the network independently, and link other networks directly. On the other hand, the user terminal is a terminal station can move and each user terminal has two kinds of functions of a router and host computer concurrently.Wireless ad hoc networks are convenient for emergency situations, temporary conferences and so on, due to their minimal configuration, absence of infrastructure and quick development. These applications all involve multicast. It makes the multicast research even more important.In wireless ad hoc network, a communication session can be achieved either through a single-hop transmission or through some relaying nodes. Thus, how to select relaying nodes is a major issue in routing algorithm design. Since mobile hosts are powered by batteries, another crucial issue is the energy efficiency.The main work and contributions of the thesis include:1. Discuss the current multicast routing protocols and deeply analyze the tree-based multicast routing algorithms. Study the disadvantage of these algorithms and proposed some improvement.2. Research on minimum energy broadcast routing. In wireless ad hoc network, mobile hosts are powed by batteries, so the crucial issue is the energy efficiency. This problem was modeled by the graph theory and a special case where the number of nodes is 3 was discussed. Then extend it to the general case. In this thesis, a greedy algorithm called greedy maximum-branch replacement(GMBR) algorithm was proposed. This algorithm can be developed to distributed one easily. Compared with the previous algorithms, GMBR was proved to have better performance in energy efficiency, especially when the propagation loss exponent and the network size become larger. Finally, the algorithm was extended to the multicast case.3. Research on maximum lifetime broadcast routing. In wirless ad hoc networks, achieving the minimum total energy may lead to reducing network lifetime. The hosts are powed by batteries, so the entire network may be partitioned because of the drainage of a small set of batteries. Therefore, the crucial issue is to improve the energy efficiency, with an objective of prolonging the lifetime. This thesis discusses the broadcast tree construction with different initial energy reserves. A greedy algorithm called weighted minimum spanning tree(WMST) has been proposed. This algorithm takes into account the initial energy of each node and energy consumption of each communication. Experiments have demonstrated that the performance of the peoposed algorithm prolongs the lifetime.4. Research on load-balanced broadcast routing. Prove that maximum the lifetime doesn't assure the total energy consumption is minimal. Based on analyse of the previous algorithm, an improved one - Improved WMST -was proposed. The objective is balancing the goal of achieving the minimum total energy and prolonging the lifetime. Experiments have demonstrated that the performance of the proposed algorithm improved the load balance. At last, the proposed algorithm was extended to the case of the limited resource.