1Cognitive and Energy Harvesting-Based D2D Communication in Cellular Networks: Stochastic Geometry Modeling and Analysis

Abstract—While cognitive radio enables spectrum-efficient wireless communication, radio frequency (RF) energy harvesting from ambient interference is an enabler for energy-efficient wireless communication. In this paper, we model and analyze cognitive and energy harvesting-based device-to-device (D2D) communication in cellular networks. The cognitive D2D trans-mitters harvest energy from ambient interference and use one of the channels, which are allocated to cellular base stations (BSs) for downlink transmissions, to communicate with the corresponding receivers. We investigate two spectrum access policies for the cellular BSs, namely, random spectrum access (RSA) policy and prioritized spectrum access (PSA) policy. In RSA, a cellular BS can access any of the available channels randomly (including the channel used by the D2D transmitters), while in PSA a BS accesses the D2D channel only when all of the other channels are occupied. Each D2D transmitter can communicate successfully with its receiver only when it harvests enough energy to perform channel inversion towards the receiver, the D2D channel is free, and the signal-to-interference-plus-noise ratio (SINR) at the receiver is above the required threshold; otherwise, an outage occurs for the D2D communication. We use tools from stochastic geometry to evaluate the performance of the proposed communication system model in terms of outage probability for D2D and cellular users. We show that energy harvesting can be a reliable alternative to power cognitive D2D transmitters while achieving acceptable performance. With PSA, under the same SINR outage requirements as for the case with RSA, cognitive channel access improves the outage probability for D2D users by more than 150 % when compared to non-cognitive channel access. For D2D users, the PSA policy provides improved performance when compared to the RSA policy. For cellular users, the PSA policy provides almost the same outage performance as the RSA policy