Energy Harvesting-Based D2D Communications in the Presence of Interference and Ambient RF Sources

This paper considers a device-to-device (D2D) network with time-splitting protocol, where a D2D transmitter ( $ \text {T}_{\text {x}}$ ) first harvests energy from a multiple-antenna power beacon (PB) and ambient radio frequency sources, and then uses that harvested energy to transmit data to the D2D receiver ( $ \text {R}_{\text {x}}$ ). To improve the energy transfer efficiency, the PB is equipped with multiple antennas for energy transfer, and $ \text {T}_{\text {x}}$ is equipped with multiple antennas for energy harvesting. Two beamforming techniques, called best antenna-based beamforming and optimal beamforming vector, are proposed to use at the PB. We derive novel analytical expressions for the average harvested energy, power outage probability, and the outage probability of the information transfer link, considering the effect of co-channel interference from homogeneous Poison distributed interferes and the short-range propagation model for the path loss. We show that by deploying multiple harvesting energy antennas at $ \text {T}_{\text {x}}$ and by implementing optimal beamforming vector scheme at the PB, the system performance improves substantially. Furthermore, Monte-Carlo simulations are provided and verify the accuracy of our analytical results.