Physical Layer Security using Artificial Noise in D2D Underlay Network

In this paper, we investigate secure D2D communications underlay cellular network using artificial noise. In wireless communications where a single eavesdropper is present, artificial noise can effectively degrade the eavesdropper performance and increase the secrecy rate. Since the user and the device share radio resources in an underlay network, it causes interference with each other. Thus, the sum secrecy rate of the user and the device are considered to enhance the entire network. In order to maximize the sum secrecy rate, we designed a precoding signal vector and an artificial precoding matrix and found the optimal power allocation for the signal and the artificial noise. Moreover, given the base station power, we obtained the upper limit of device power for achieving the corresponding secrecy rate.