RF Energy Harvesting With Cooperative Beam Selection for Wireless Sensors

RF energy harvesting is a promising potential solution for providing convenient and perpetual energy supplies to low-power wireless sensor networks. In this letter, we investigate the energy harvesting performance of a wireless sensor node powered by harvesting RF energy from an existing multiuser MIMO system. Specifically, we propose a random unitary beamforming-based cooperative beam selection scheme to enhance the energy harvesting performance at the sensor. Under a constant total transmission power constraint, the multiuser MIMO system tries to select a maximal number of active beams for data transmission while satisfying the energy harvesting requirement at the sensor. We derive the exact closed-form expression for the distribution function of harvested energy in a coherence time over Rayleigh fading channels. We further investigate the performance tradeoff of the average harvested energy at the sensor versus the sum-rate of the multiuser MIMO system.