Minimizing Operational Power Cost in Remote-Area Wireless Sensor Networks With a DF Relay and Outage Constraints

For wireless multi-sensor networks with a single decode-and-forward (DF) relay, this letter provides an optimal power allocation that minimizes the total sum of costs of sensor- and relay-transmitting powers and recharging the battery in the sensors, which is referred to operational power cost. We assume a remote-area wireless sensor application and hence that the direct communication between the sensors and a destination does not exist. Motivated by an observation that the proposed power allocation is a function of the location of relay, we also provide a near-optimal location of the relay that minimizes the operational cost. Optimality of the proposed solutions is verified with numerical investigation. Numerical results show that the proposed power allocation saves the total cost by nearly up to 15% compared to the previous source-sum-power minimizing allocation when the relay location is fixed. Furthermore, the proposed relay location is shown to save the cost by about 59-77% compared to randomly-chosen relay locations.