Research On Broadcast Algorithm In Ad Hoc Network

Self-organizing wireless network (Ad Hoc) is a new and developed network technology in the field of wireless communications, which is rapidly infiltrated from military communications into the related civilian communications fields.In Ad Hoc networks, broadcasting is extensively used in route discovery, address resolution, and many other network services. In Ad Hoc, it is not the case that every node can directly communicate with all other nodes. A broadcast packet may be rebroadcast at many nodes to guarantee that the packet can reach all nodes in Ad Hoc. An inefficient broadcast approach may generate many redundant rebroadcasting packets. As a result, the efficiency of broadcasting is critical for the performance of Ad Hoc.The premise and key of the research of wireless routing protocol is an excellent broadcast algorithm. Based on the existing broadcast algorithms, both research and discussion are presented in this paper for this topic: the rebroadcasting probability of each node and the distribution of the rebroadcast neighboring hosts around each forwarding host.For the rebroadcasting probability research, it is showed in this paper mainly that adjusting dynamically the probability according to the distance between each node. The improved algorithm is based on the probabilistic algorithm, referring to the distance between each node. It is showed that all kinds of network topology are set the best probability.Through some tests, it confirmed that the basic function of adjusting dynamically the probability according to the distance between each node is implemented. Otherwise, some tests and analysis have been done to show the reachability and the saved rebroadcast. It is provided that adjusting dynamically the probability according to the distance between each node is a reliable and effective solution to reduce the influence of broadcast storm. The distribution of the rebroadcast neighboring hosts around each forwarding host is focused in the paper in order to keep the average area covered by each broadcasting host to be maximum. Referring to the probabilistic algorithm and the counter-based algorithm it is introduced that a method to improve the traditional algorithms. According to the location between the neighboring node and the symmetrical point around the forwarding host and the distribution density of nodes in Ad Hoc network the rebroadcasting probability is dynamically adjusted. The simulation experiment shows that the superiority of those algorithms in Ad Hoc network. Moreover, the simulation implementation and the results of some simulation tests are given and some performance figures of broadcasting algorithm are analyzed by NS2. After selected the neighboring node on the symmetrical point around the forwarding host, network may be obtained better reachability. Network with appropriate probability works well and has less redundant rebroadcasting packets. It is showed that research of the distribution of the rebroadcast neighboring hosts around each forwarding host is the exploration of the geometry-based broadcast algorithm.