Joint Power Control and Routing for Rechargeable Wireless Sensor Networks

Wireless sensor networks (WSN) that are powered by energy harvested from the environment, also known as rechargeable WSNs, typically experience wide variations of energy availability across the network. Such variations can cause frequent node outages at specific locations where energy availability is low, whereas the remaining nodes may receive sufficient energy for continuous operation. The energy availability also varies over time due to environmental factors, which exacerbates the problem. To minimize the impact of such spatial and temporal variations of energy resources, we propose a joint Power COntrol and Routing scheme (PCOR) that adapts the energy consumption in the sensor nodes according to its available energy resources in order to facilitate uninterrupted operations. The scheme is applied to data collecting WSNs with a MAC that utilizes asynchronous duty-cycling for energy conservation. PCOR achieves its objective by reducing the energy consumption at energy-critical sensor nodes, i.e. nodes that have comparatively lower energy resources, using network-wide cooperative power control and route adaptations. This is accomplished by reducing the overhearing at energy-critical nodes, which is a key cause of energy consumption in such networks. We demonstrate through simulations and experimental results that PCOR reduces overhearing at energy-constrained nodes by up to 75% without significantly affecting the end-to-end packet delivery rates.