Performance Analysis of RIS Assisted D2D Communication Systems Under Beamforming and Interference Cancellation

Reconfigurable intelligent surface (RIS) is envisioned as a potential technology to improve spectrum efficiency with low energy consumption. Moreover, the spectrum reuse technologies are also extensively applied in various networks, such as vehicle-to-vehicle (V2V) in transportation system, machine-to-machine (M2M) in industrial Internet of Things (IIoT) system and so on. In this paper, we investigate the performance of the general RIS-assisted device-to-device (D2D) communication. We consider the limited feedback system where the channel state information (CSI) is imperfectly known. The analytical expression of the ergodic achievable rate (EAR) for beamforming (BF) strategy and interference cancellation (IC) strategy are derived. For exploring engineering design, we investigate the tight bounds of EAR with much simpler form. Then, the EAR gain brought by RIS compared to the traditional D2D system is analyzed. Further, four specific scenarios are discussed in detail, including the weak interference case, the high SNR case, the large number of BS antennas case and the large number of reflective elements case. We derive the EAR approximations of these four cases and explore a series of insights. Numerical Results shows the perfect agreement between the analytical results and simulations.