  In this letter, we propose to employ reconfigurable intelligent surfaces
(RISs) for enhancing the D2D underlaying system performance. We study the joint
power control, receive beamforming, and passive beamforming for RIS assisted
D2D underlaying cellular communication systems, which is formulated as a sum
rate maximization problem. To address this issue, we develop a block coordinate
descent method where uplink power, receive beamformer and refection phase
shifts are alternatively optimized. Then, we provide the closed-form solutions
for both uplink power and receive beamformer. We further propose a quadratic
transform based semi-definite relaxation algorithm to optimize the RIS phase
shifts, where the original passive beamforming problem is translated into a
separable quadratically constrained quadratic problem. Numerical results
demonstrate that the proposed RIS assisted design significantly improves the
sum-rate performance.
