Multi-sink Relocation with Constrained Movement in Wireless Sensor Networks

Sensor networks are dense wireless networks where information is gathered by sensor elements spread out in an interest area. The main deficiency of sensors is their finite source of energy. Therefore, an efficient utilization of this energy resource conditions the network lifetime. In order to enhance the performance of these networks, some research efforts have focused on the mobility of a single sink node. The mobility of sink introduces a tradeoff between the need for frequent re-routing to optimize energy consumption and the minimization of the overhead resulting from this topology management. In this paper, we propose a new dynamic approach to extend the lifetime of a sensor network based on both mobility and multiplicity of sinks. The optimal multi-sink positioning problem is NP-complete, therefore we propose a heuristic approach in which sink are moved toward active nodes to achieve energy savings by reducing the transmission distance as well as the number of hops on the shortest paths from each node to the nearest sink. In addition, to avoid transitional effect and costly intermediate configurations during the sink movement, we propose a constrained local search approach to achieve a multiple-step movement of the sink. Simulation results show the efficiency of our approach in terms of energy gain when compared to the basic static sinks solution.