Sink repositioning for enhanced performance in wireless sensor networks

Most of the energy aware routing approaches for unattended wireless sensor networks pursue multi-hop paths in order to minimize the total transmission power. Since almost in all sensor networks data are routed towards a single sink (gateway), hops close to that sink become heavily involved in packet forwarding and thus their batteries get depleted rather quickly. In addition, the interest in optimizing the transmission energy tends to increase the levels of packet relaying and thus makes queuing delay an issue, especially for real-time traffic. In this paper we investigate the potential of gateway repositioning for enhanced network performance in terms of energy, delay and throughput. We address issues related to when should the gateway be relocated, where it would be moved to and how to handle its motion without negative effect on data traffic. We present two approaches that factor in the traffic pattern for determining a new location of the gateway for optimized communication energy and timeliness, respectively. The gateway movement is carefully managed in order to avoid packet losses. The proposed approaches are validated in a simulated environment. (c) 2005 Elsevier B.V. All rights reserved.