Analysis of wired short cuts in wireless sensor networks
R. Chitradurga, Ahmed Helmy · 2004
Abstract In this paper we investigate the use of wired short cuts in large-scale location aware sensor networks. This new paradigm augments a sensor network with a very limited wired infrastructure to improve its overall energy-efficiency. A wire can be thought of as a short cut between two nodes in the sensor networks. Energy-efficiency is obtained mainly by reducing the average path length by the introduction of the short cuts. This borrows from the concept of small worlds in which adding a few random short cuts to highly clustered networks decreases the degrees of separation (i.e., the average path length) drastically, resulting in a degree of separation similar to that of random graphs. In our work we show how to systematically add these short cuts in order to construct a small world. The aim of the study is to find the limits on the gain that can be achieved by using these short cuts in sensor networks with a sink. This would also give us an understanding about how these short cuts can be placed, and how many are required. We have developed an analytical model to analyze the gain in path length reduction by using short cuts, for arbitrary positions of the sink. We also conducted extensive simulations to validate our analysis. Our results show that there is an optimal wire length for which the path length reduction is at its maximum, beyond which it decreases. The optimal length is only a small fraction (37.8-50%) of the network diameter. In a network with 1000 nodes uniformly distributed on a disk the path length reduction saturates at 60-70 % with 5-24 wires, depending on the location of the sink. Also, we find that restricting the knowledge about the wires to 2 hops does not degrade the performance from the case when we have global knowledge of all wires. These results show promise of the new paradigm.