Green device-to-device communication with harvesting energy in cellular networks

The concept of mobile user equipment (UE) relay (UER) has been introduced to support the relaying transmission using device-to-device (D2D) communications for enhancing communication reliability. However, as the UER needs to use its own power for the other UE's data transmission, the D2D communication can be unfair to the UER. To overcome this issue, motivated by the recent advance in energy harvesting (EH) techniques, we consider the D2D communication provided EH cellular network (D2D-EHCN) where the UERs harvest RF energy from a base station (BS) and use the harvested energy for D2D communications. We first derive the UER distribution by taking into account the EH parameters, and propose the transmission mode selection scheme including the UER selection method. After deriving the outage probability of the D2D-EHCN, we explore the effects of the network parameters on the outage probability. Particularly, we show that the outage probability of D2D-EHCN is smaller than that of the cellular network without D2D communication, and their difference becomes more significant when the density of BSs is small.