A Distributed Topology Control Algorithm in the Presence of Multipath Propagation

Each node in a wireless multihop network can adjust the power at which it makes its transmissions and thus change the topology of the network by choosing the neighbors with which it directly communicates. Many previous algorithms for distributed topology control have assumed an ability at each node to deduce some spatial information such as the direction and the distance of its neighbor nodes with respect to itself. However, such a deduction of spatial information cannot be relied upon in a multipath environment where different paths of a signal may have different loss characteristics and none of the paths may be line-of-sight. In this paper, we present Step Topology Control (STC), a simple distributed topology control algorithm which reduces power consumption while preserving the connectivity of a heterogeneous sensor network in a multipath environment. The STC algorithm avoids the use of GPS devices and also makes no assumptions about the distance and direction between neighboring nodes. We provide analytical proofs of the relationship between the STC algorithm and a cone-based topology control algorithm. We present a detailed simulation- based comparative analysis of the energy savings achieved by the STC algorithm and previously known algorithms that also seek to reduce power consumption while preserving connectivity. The results show that the STC algorithm performs significantly better than other algorithms, especially in the presence of radio irregularities and multipath propagation. In addition, the STC algorithm scales better than other algorithms in performance and in fact, is more effective with increasing numbers of nodes.