Lifetime Extension of Wireless Sensor Networks with Energy Harvesting

Abstract

Wireless sensor networks (WSN) consist of a large number of sensor nodes to collect various data such as temperature, humidity, speed, acceleration, and so on. In these networks, sensor nodes are usually driven by battery energy and distributed over extensive and large areas. Thus, running out of battery energy is a serious problem. For this reason, it is important to extend the lifetime of WSN. To extend the lifetime, the method of low-energy adaptive clustering hierarchy (LEACH) has been proposed. In LEACH, a cluster head (CH) is chosen without considering the residual energy of each node. Energy-harvesting technology in WSN has also been proposed. However, energy harvesting has some problems. Equipping energy-harvesting devices increases the system cost. Also, the amount of generated energy is unstable in real situations. To solve these problems, this paper proposes LEACH with partial energy harvesting (LPEH), extended LEACH with energy harvesting (ELEH), and ELEH with a sleep operation. In LPEH, the number of energy-harvesting nodes is limited to avoid increasing cost. In ELEH, a CH is chosen from the energy-harvesting nodes to extend the lifetime effectively. In ELEH with the sleep operation, each node becomes an active mode or sleep mode after consideration of the amount of remaining battery energy. In these methods, the coverage area is not considered. Thus, this paper proposes ELEH with the sleep operation considering node positions (ESNP) and ELEH with the sleep operation considering surrounding area condition (ESSA). In ESNP and ESSA, each node enters the sleep mode depending on the distance from adjacent nodes and the surrounding sensing condition, respectively, to reduce the overlapped sensing area. Thus, the unrequested data collected by other nodes becomes low and the energy consumption is reduced. As a result, the coverage area remains large in the long term.