Research On The Routing Algorithm For Wireless Mobile Ad Hoc Networks

An ad hoc network is a wireless mobile communication network made of a group of mobile nodes with wireless transmitter-receiver sets. Because it can be easily and neatly deployed, easy to operate, at present has already received increasing attentions from international academic circles and industry, is obtaining more and more widespread applications, has became an important direction which the mobile communication technology moves forward. These characters of ad hoc networks make routing protocol based on traditional networks can't be used at ad hoc networks. So IETF established a special MANET working group to study and develop the routing algorithm of ad hoc networks. The emphasis of this article is also routing protocols of ad hoc networks.The paper first introduced background, the development history, the present situation as well as the research significance of ad hoc networks, also described their concept, the characteristic, the application, the essential technology and the system structure. Then, we put emphasis on routing protocols of ad hoc networks, categorized and introduced several kinds of routing protocols issued by the MANET working group and published by researchers, carried on the performance analysis and comparison of several kinds of typical routing protocols with the software simulation method. Meanwhile, we deeply researched the dynamic source routing(DSR), a routing protocol with great application prospect, analysed its performance, found the insufficiency in routing request process– flooding, proposed a kind of improved expanding ring search technology to solve flooding.This article applies expanding ring search to DSR routing protocol for the first time. Expanding ring search as a kind of effective technology of controlling network load can control flooding effectively, has great use value in the routing protocol. This article researched expanding ring search, improved original expanding ring search, applied it to DSR, compared performance of original DSR and improved DSR with the software simulation method. The simulation results indicated compared to original DSR, this technology can reduce routing load,increase packet delivery fraction,reduce average end-to-end delay of data packet, thus improves performance of ad hoc networks. This article compiles script with ns to define the network topology,dispose production and receival of network information current as well as collect statistic information. The output is a series of data recordings to the entire simulation process. We pick up useful information with data processing tool gawk, present the data by the graph form to readers with cartography tool gnuplot.