Distributed Intelligent Reflecting Surfaces-Aided Device-to-Device Communications System

Intelligent reflecting surface (IRS) is a revolutionizing and promising technology to improve the high transmission rate of the wireless communication systems. Specifically, an IRS consists of a great amount of low-cost passive reflecting elements, which reflect the incident signals to the desired user by collaboratively using passive beamforming. This paper introduces IRSs into a device-to-device (D2D) underlying cellular system to enhance transmission rate performance of the D2D pairs. We formulate an optimization problem of maximizing the transmission rate of the D2D pairs while satisfying the minimum required rate of the cellular users. We address this problem by jointly optimizing the reuse indicator, received beamforming, power allocation, and phase shift matrices. Block coordinate descent (BCD) algorithm is adopted to decouple the original problem into four subproblems. Closed form solutions are obtained by solving the sub-problems of optimizing the received beamforming and power allocation. Then, Kuhn-Munkres (KM) algorithm and minimization-majorization (MM) algorithm are adopted to solve the sub-problems of optimizing the reuse indicator and phase shift matrices, respectively. Simulation results demonstrate that IRSs can effectively improve the transmission rate of the D2D pairs and our proposed distributed IRSs scheme outperforms the other benchmark schemes.