Modeling and analysis of directional energy harvesting and spectrum sharing communications in massive D2D networks

This paper considers both Energy Harvesting and Spectrum Sharing in Massive Device-to-Device Networks (EH-SS-MD2D Nets) to realize resource-utilization efficiency, where massive D2D networks consist of a large number of low-power devices that sporadically transmit a small volume of data. In contrast to previous study investigating EH-SS networks equipped with omni-directional antennas, we employ directional antennas in our EH-SS-MD2D Nets (namely directional EH-SS-MD2D Nets) to improve network performance. In particular, we develop a theoretic model to analyze both the transmission probability and connection probability of Second Users (SUs) in directional EH-SS-MD2D Nets. Our theoretic model is general for both EH-SS-MD2D Nets equipped with directional antennas and omni-directional antennas. All of our theoretic results are presented in closed-form solutions. Our analytical model is verified by extensive simulations. Numerical results indicate that EH-SS-MD2D Nets equipped with directional antennas can significantly improve the connection probability compared with omni-directional antennas. In addition, results show that the connection probability can be maximized by choosing an optimal density of PTs. Moreover, the connection probability of directional EH-SS-MD2D Nets can be improved by decreasing the antenna beamwidth of the main lobe of SUs. Our model and results can offer beneficial implications for constructing directional EH-SS-MD2D Nets.