In this paper, we focus on the reconfigurable intelligent surface (RIS)-enhanced two-way device-to-device (D2D) multi-pair orthogonal-frequency-division-multiplexing (OFDM) communication systems. Specifically, we maximize the minimum bidirectional weighted sum-rate by jointly optimizing the sub-band allocation, the power allocation and the discrete phase shift (PS) design at the RIS. To tackle the main difficulty of the non-convex PS design at the RIS, we firstly formulate a semi-definite relaxation problem and further devise a low-complexity solution for the PS design by leveraging the projected sub-gradient method. We demonstrate the desirable performance gain for the proposed designs through numerical results.
@article{arxiv.2005.01910,
title = {Reconfigurable Intelligent Surface (RIS)-Enhanced Two-Way OFDM Communications},
author = {Chandan Pradhan and Ang Li and Lingyang Song and Jun Li and Branka Vucetic and Yonghui Li},
journal= {arXiv preprint arXiv:2005.01910},
year = {2020}
}