Ad Hoc Network Routing Protocols And Optimization,

A mobile Ad hoc network is an autonomous system of mobile hosts connected bywireless links. Such networks are useful in military and other tactical applications, e. g., emergency rescue or exploration missions, where cellular infrastructure isunavailable or unusable. In such a network, each mobile node operates not only as ahost but also as a router. This network has a series of the strengths, for example:MANET can be built rapidly and easy, and it is not set measures to by wired network, and so on.Because of constantly changing topology, Ad hoc networks can't adopt traditional protocols. Research of routing protocols becomes the most important part of the research of Ad hoc. This dissertation presents a comparative simulation study of on-demand protocols with the more traditional proactive protocols on a common platform across a range of traffic and mobility scenarios. This simulation cover a range of design choices: AODV, DSR, DSDV, TORA. The simulation results show that on-demand protocols indeed demonstrate low routing overheads, but over-reliance on query flooding can actually cause on-demand protocols to lose most of this overhead advantage at high loads.As a countermeasure, we develop and evaluate two techniques that reduces the routing overhead for on-demand protocols. The first technique, called query localization, uses certain routing histories to prevent network-wide query flood. It effectively limits the query to a small region where the route is very likely to be found.Query localization techniques can use two kinds of information, one is path information, the other is position information of node. Simulation results show that the query localization techniques can reduce routing overhead notably, and the routing overheads are smaller when using path information. The second technique, called multipath routing, focuses on reducing the frequency of query flooding by exploring multiple, disjoint routes per flood operation. This provides the routing protocol with alternate routes when the primary route breaks. Two variations were explored. In the first, only the source gets multiple alternate routes. In the second, each intermediate node on the primary route gets an alternate route (aside from the source). Simulation results show that either of these techniques can reduce routing overheads significantly. When each intermediate node on the primary route gets an alternate route, the routing overheads are smaller. At present, the research about Ad hoc network routing protocols has just started, and the routing protocols concerns the keyfor whether Ad hoc network could run, So this paper is not merely significant to the research and optimization of the route agreement in Ad hoc network in theory, and also offer scientific basis for its application.