Reconfigurable intelligent surface empowered underlaying device-to-device communication

Funding Information: ACKNOWLEDGMENT This work of Gang Yang, Yating liao, and Ying-Chang Liang was supported by the National Natural Science Foundation of China (Grant No. 61631005, 62071093 and U1801261), the National Key Research and Development Program of China under Grant 2018YFB1801105 , the Fundamental Research Funds for the Central Universities under Grant ZYGX2019Z022, and the Programme of Introducing Talents of Discipline to Universities under Grant B20064. This work of Olav Tirkkonen was supported by Academy of Finland under Grant 319484. Publisher Copyright: ©2021 IEEE. Reconfigurable intelligent surfaces (RIS) are a new and revolutionary technology to achieve spectrum-, energy- and cost-efficient wireless networks. This paper studies the resource allocation for RIS-empowered device-to-device (D2D) communication underlaying a cellular network, in which an RIS is employed to enhance desired signals and suppress interference between paired D2D and cellular links. We maximize the sum rate of D2D users and cellular users by jointly optimizing the resource reuse indicators, the transmit power and the RIS’s passive beamforming. To solve the formulated non-convex problem, we first propose an efficient user-pairing scheme based on relative channel strength to determine the resource reuse indicators. Then, the transmit power and the RIS’s passive beamforming are jointly optimized by an iterative algorithm, based on the techniques of alternating optimization, successive convex approximation, Lagrangian dual transform and quadratic transform. Numerical results show that the proposed design outperforms the traditional D2D network without RIS.