Mobile Intelligence

2.1 INTRODUCTION

In wireless ad hoc networks that are formed by autonomous mobile devices communicating through radio, topology control plays an important role in the performance of the protocols used in the network, such as routing, clustering, and broadcasting. There are two approaches for topology control in ad hoc networks—transmission range control and hierarchical topology organization (clustering). The goal of this technique is to control the topology of the graph representing the communication links between network nodes, with the purpose of maintaining some global graph property (such as connectivity) while reducing energy consumption. Moreover, topology control has the positive effect of reducing contention when accessing wireless channels. In general, when the nodes' transmission ranges are relatively short, many nodes can transmit simultaneously without interfering with each other, and the network capacity is thus increased. Ideally, the nodes' transmission ranges should be set to the minimum value such that the communication graph is connected.

As mentioned above, transmission range control is a general approach for topology control in ad hoc networks. The construction of hierarchical topology (clustering) is another effective solution. Cluster-based constructions are commonly regarded as a variant of topology control in the sense that energy-consuming tasks can be shared among the members of a cluster. The basic idea of clustering is to group the network nodes that ...