Mobile Ad Hoc Network Topology Discovery Technology Research And Realization

Mobile Ad Hoc network is a multi-hop, temporary autonomous and distributed network with non-fixed infrastructure. It is self-organized by nodes which have wireless communication and routing function. The mobility of the network nodes, results in network topology constantly changing. Thus, knowing the network topology clearly plays a vital role in optimizing our network, improving network performance, increasing network robustness and realizing network management. The thesis studies in terms of hierarchy mobile Ad Hoc network topology discovery, and the research work are as follow:On the basis of existing Ad Hoc network topology discovery protocol, the MAMD protocol has been proposed for hierarchic mobile Ad Hoc network. It discovers the topology by using mobile agents mixed with datagrarms. In a cluster, cluster member nodes send topology information to a cluster head by datagrams. Meanwhile in cluster head class, mobile agents are used for collecting and reporting topology information.Base on MAMD protocol, the AHB-MAMD protocol is proposed by utilizing the adaptive heart beat algorithm. Through calculating the neighbor change rate of nodes, the interval of cluster member report to cluster head can be adjusted dynamically according to the neighbor set change of nodes, in order to achieve the purpose of reducing the number of topology discovery datagrams.The simulations of MAMD protocol and AHB-MAMD protocol have been realized on OPNET simulation platform. Simulation analysis indicate that, AHB-MAMD protocol significantly reduces the number of datagrams with maintaining high link average connectivity, low fail report ratio and low false report ratio. Then, it is proved that the performance of AHB-MAMD protocol is better than NLPC-NCR-MATD protocol by comparison. Finally, in order to measure the influence of parameters, the speed of nodes, the number of mobile agents and the migration frequency of mobile agents are changed. According to the simulation result, AHB-MAMD protocol can work not only in low speed environment, but in high speed environment.The topology discovery software is implemented by Java language, MySQL database and Python scripting language with 30 PCs and laptops on Linux platform. This software can show the entire network topology to the manager and count the topology discovery time of each node. Because of the portability of Java language and MySQL database, this topology discovery software can also work in Windows system.