Qualified route search in wireless ad hoc networks

Abstract

There are currently two variations of mobile wireless networks. One is a cellular network and the other is an ad hoc network. In a cellular network, a mobile node should be directly connected to the base station that is within its communication radius. Hence, the communication coverage of the network is limited around base stations. Moreover, the service rate is high because the construction of infrastructures takes large cost and long time. In an ad hoc network, our major concerns, a mobile node randomly moves and communicates with each other over radio. Hence, an ad hoc network does not require any infrastructure and reduces overall costs. But, it’s hard to provide stable communications in an ad hoc network because network topology changes dynamically. The primary objective of this thesis is to provide a route for high quality communications. This objective can be achieved by providing a quality estimation model and a route search algorithm. Hence, this thesis proposes both a link stability estimation model and qualified route search algorithms. Firstly, an enhanced link stability estimation model for wireless ad hoc networks is presented. Most routing algorithms for ad hoc networks find the shortest hop route that is, however, very unstable especially in highly dense networks. Some routing protocols such as Signal Stability based Adaptive routing (SSA) and Associativity Based Routing (ABR) were proposed to find more stable route by considering the link stability. SSA determines link stability from the current link state, and ABR determines from link history. In this thesis, we will propose Advanced signal Strength Based estimation Model (ASBM) and compare the proposed model with previous models. In the comparison, the route with ASBM has the longest lifetime with little increase in hop-length. The ASBM route has 2 times longer lifetime than the shortest path route. Secondly, two distributed route search algorithms will be presented to search a qualified rou...