Adaptive routing in dynamic wireless mobile ad hoc networks

Following the recent developments in the wireless communication and computing technology, progress has been made to connect them all together to form a computing and communication system with or without fixed base stations for networking support. This has led to the concept of wireless mobile ad-hoc networks. By allowing a group of mobile units to migrate around in a certain terrain, yet maintaining the connection among each other, it would offer a lot of convenience in situations where it is difficult or too costly to build fixed support facilities. However, there are several challenges arising from the inherent basic characteristics of the wireless mobile computing networks. These include migratory nature of mobile units, limited bandwidth of transmission channels, limited battery power, and even the weather. Taking the mobility factor into consideration, when the mobility increases, not only the complexity of message routing in a wireless mobile ad-hoc network increases, but also the routing failure. Therefore, dealing with route failure during message transmission becomes an important issue.; Efficient route switching is important in connection-oriented communication systems to maintain a route for a certain period of time. This dissertation presents a new approach to ease the route switching problems in a network with high migration rate of units. By monitoring the signal strength of messages, a unit in a route that receives an incoming message can detect possible route fluctuations locally. As the average signal strength declines into a dangerous level, the unit that receives the message will send an advance-warning message to the route source unit. If the source unit can find more stable routes locally, it will adapt a substitute route and will complete the process of adaptation before the breakdown of the original route. If the route source unit cannot adapt a new route locally, the source unit will be forced to search for a new route by considering the entire network. A routing architecture is proposed to implement and to simulate our proposed routing algorithms. For this architecture with the inherent expandability of modular design, it is possible to adapt future routing factors such as the delay, cost, fairness, throughput, and security. The routing architecture, evaluation and simulation are presented to show the feasibility of this new approach.