Mobility-Based Clustering for Scalable and Responsive Routing in Ad-Hoc Networks

University Of Pittsburgh, Pittsburgh PA

Investigators

Abstract

In this study, the researchers propose to develop a mobility-based framework for adaptive clustering and routing in wireless ad-hoc networks-an emerging class of network architecture that is characterized by its highly dynamic topology and its limited resources. Within this framework, the researchers will address several key, as yet unanswered questions, which have been raised with respect to the routing problem in ad-hoc networks. Specifically, it has been argued that to achieve acceptable routing performance, multiple routing strategies may need to act cooperatively in the same network. However, this raises the question as to what those strategies should be, and how to effectively toggle between them. Furthermore, it has been proposed that mobility information can be used to select longer-lived routes, and to improve the efficiency of route creation and maintenance. However, no well-defined mobility based metric has been proposed that reflects a quantitative measure of path stability. In this study, the researchers explore novel and significant ideas which address each of the shortcomings described above, and builds them into a unified routing framework. Specifically, the researchers propose to develop a well-defined mobility based routing metric, referred to as path availability. This metric is used for adaptive cluster characterization and routing in ad-hoc networks. The mobility-based cluster characterization provides the basis for an efficient distributed clustering algorithm which adaptively maintains a cluster organization-the size and membership in each cluster is determined dynamically by the mobility characteristics of the local nodes. Using this metric, the researchers propose to investigate pro-active intra-cluster and inter-cluster routing strategies: intra-cluster routing will be based on table-driven routing protocols that maintain up-to-date routing information regarding all cluster destinations, whereas inter-cluster routing is managed on a demand-basis by constructing routes in a dynamic hierarchical fashion as a sequence of relatively stable clusters between the source and the destination. More efficient route search is enabled by the proactive maintenance of routes within each cluster, and reactive route repair is only needed if the source or destination depart their original clusters, or if the next cluster along a route becomes unreachable. Most of the reaction to node mobility is handled locally within the clusters, hence, the far-reaching effects of topological changes are minimized. By adapting the characteristics of the cluster organization to localized node mobility patterns, the strategy is expected to perform well over a wide range of conditions. Furthermore, this framework can be extended to address the need to support QoS requirements for mutlimedia communications. Very few clustering strategies have defined either an adaptive clustering technique, or have factored mobility information into the clustering decision process. Hence, this work represents a significant, and sustainable contribution to the field.