Signal-strength-aware routing in wireless ad hoc networks

Abstract

The advent of wireless technologies has led to widescale deployment of wireless computer networks. The need to communicate tetherlessly has led to the growth of Ad hoc Networks that do not rely on fixed infrastructure for their operation. The participants in the network need a routing protocol to communicate if they are not within direct transmission range of each other. This thesis focuses on the design, im­plementation, and performance evaluation of a Signal-Strength-Aware version of the Ad hoc On-demand Distance Vector (AODV) routing protocol for multi-hop wireless ad hoc networks. The first part of this thesis surveys existing routing protocols for Ad hoc net­works and critically analyzes them from an implementation perspective. AODV is chosen as a basis for experiments because of its on-demand hop-by-hop approach to routing. The second part of this thesis describes an extension to AODV to incor­porate Signal-Strength-Aware routing. This allows AODV to choose stable routes. The thesis describes the design and implementation of signal-strength-aware routing, based on Uppsala University's implementation of AODV. The thesis concludes with experimental evaluation of the protocol in a small (4 hop) wireless ad hoc network. The experimental results demonstrate the functionality and performance of signal­strength-aware AODV. The results show that TCP throughput decreases significantly with the number of hops in a multi-hop wireless ad hoc network. This property is true for both stationary and mobile clients. Route discovery time varies depending on the wireless channel conditions. The routing protocol overhead increases with the number of hops, but remains below 4.25% in the scenarios studied.