Maximizing Lifetime per Unit Cost in Wireless Sensor Networks

Abstract — This paper proposes a new performance metric, called the lifetime per unit cost, to measure the utilization effi-ciency of the sensors in a wireless sensor network. The lifetime per unit cost is defined as the average network lifetime divided by the number of sensors enabled in the network. We analyze the average lifetime per unit cost of an event-driven linear wireless sensor network with different transmission schemes and different sensor placement schemes. We find that forwarding packets to the nearest neighbor toward the gateway node is the optimal transmission scheme for the network employing the greedy sensor placement. Unlike the network lifetime, which increases monotonically as the number of sensors increases, the lifetime per unit cost of the network decreases when the number of sensors is large. Numerical results show that the optimal number of sensors, which maximizes the lifetime per unit cost of the network, increases as the event arrival rate increases or the sensing energy consumption decreases