Joint charging and rate allocation for utility maximization in sustainable sensor networks

A sensor network deployed for long-term monitoring shall sustain meanwhile provide as much useful sensory information (i.e., as high network utility) as possible. We propose a JCRA (Joint Charging and Rate Allocation) scheme to maximize the network utility while satisfying the network sustainability requirement. JCRA is designed based on the observation that the energy repository of a sensor node is co-affected by three factors: uncontrollable ambient energy harvesting, controllable wireless charging, and controllable sensory data generation. It jointly controls the charging, communication, and sensing activities while guaranteeing non-empty energy repositories at all sensor nodes. JCRA is a low-cost solution, as neighbor sensor nodes collaborate with each other to adjust their data generation rates in a distributed manner, based on the status of ambient energy supply and the wireless charging schedule planned by the base station. Extensive simulations have verified the effectiveness of JCRA in achieving the stated goals: JCRA can always guarantee network sustainability, while the achieved network utility is close to that by a centralized (1 - ϵ) approximate solution to the same optimization problem, in most simulation settings.