A mobility-based framework for adaptive dynamic cluster-based hybrid routing in wireless ad hoc networks

This dissertation presents the (α, t)-Cluster—a framework for routing in wireless ad-hoc networks—a class of network architecture that is characterized by its dynamic topology and limited resources. Routing in ad-hoc networks is a difficult challenge that involves a tradeoff between efficiency and response. An ad-hoc network routing algorithm must adapt rapidly enough to topology changes to meet the performance demands of users, without over-utilizing network resources. The fundamental tenet of this research is that this tradeoff should be dynamically balanced in response to changing network conditions. It is assumed that mobility is the central challenge to routing; however, the framework is generalizable to account for other factors.; The (α, t)-Cluster-framework presents a unified strategy designed to sense and adapt dynamically to changing environments. It utilizes adaptive clustering to organize nodes into clusters in which the probability of path failure due to node movement can be bounded over time Mobility-based clustering provides the basis for an adaptive hybrid routing strategy which dynamically balances routing responsiveness and efficiency according to localized mobility characteristics. The objective is to achieve scalability and support robust, efficient routing subject to a wide range of mobility rates. Based on the (α, t)-Cluster scheme, routes within clusters are maintained on a proactive basis; whereas, hierarchical routing between clusters is managed on a demand-basis.; The (α, t)-Cluster-framework addresses several important problems with respect to routing in ad-hoc networks. Specifically, the first well-defined mobility-based routing metric is developed. The metric provides the basis for the cluster characterization. Next, an efficient distributed clustering algorithm is developed that maintains clusters with characteristics determined by the mobility of the local nodes. Finally, it is shown how the cluster organization enables mobility to adaptively balance the proactive and reactive components of the routing algorithm. Simulation results show that the cluster organization can be effectively adapted to node mobility and that routing is both more robust and efficient than routing in fully proactive, reactive or fixed-hybrid schemes.