Effective routing in wireless mobile ad hoc networks

Mobile Ad hoc NETworks (MANETs) have received much attention and are gaining popularity because of their flexible application environments and ubiquitous information access capabilities. However, the deployment of MANETs presents many challenges. As the essential step, finding paths for multi-hop message forwarding, or routing, becomes the crucial and fundamental service support for MANETs. Routing, nevertheless, is not a trivial task in this architecture due to frequent topology changes, scarce bandwidth and power resources, and the unreliability of radio transmission. This dissertation focuses mainly on how to handle these difficulties effectively.; Location tracking is required by some applications and also provides facilities for routing implementation. We propose a LOcation Trace Aided Routing (LOTAR) protocol that utilises the mobile users' location information to improve routing performance. In summary, we use location information to reduce the control overhead in the route discovery phase, to search quickly for a feasible path in the case of link breakage, and to hand off a flow to a stable path if the active one breaks based on prediction. Keeping "always-on" end-to-end connectivity once a flow is established is the distinctive advantage of LOTAR.; It is well-known that multipath routing can increase end-to-end throughput and provide load balancing in wired networks. However, its advantage is not obvious in MANETs because the traffic flows along the multiple paths may interfere with each other. In addition, without accurate knowledge of topology, finding multiple disjoint paths is difficult. We present the challenges of deploying multipath methods in mobile ad hoc networks and propose two on-demand methods to search for multiple node-disjoint paths effectively. Simulation studies present the advantages as well as some important lessons for utilising multipath routing in MANETs.; Since mobile hosts are usually battery-powered, distributing the routing tasks fairly has obvious advantages. We propose a load-sensitive on-demand routing approach that utilises the network load information as the main route selection criterion. Compared with Dynamic Source Routing (DSR), our protocol provides better performance in terms of packet delivery ratio and average end-to-end delay. At low mobility, these benefits are gained without an increase in the control overhead.; To deploy a MANET for a particular realistic system, the information about end-users' behaviours, or profiles, can be used to simplify the implementation and enhance network performance. We point out a possible direction for the commercial evolution of MANETs and present a scheme to simplify routing strategies in MANETs with the help of end-users' mobility profiles. We also study how the routing strategy improves network performance in a realistic city transportation system.