Capacity Enhancement for D2D Relay Communications Based on UE-specific RIS

Traditional device-to-device (D2D) communication improves the power consumption, communication delay and resource efficiency, but limited to communication range of devices. To this end, this paper proposes a novel UE-specific reconfigurable intelligent surface (RIS) aided D2D relay communication approach to enhance the network capacity by exploring the degrees of freedom of time, space and reuse mode. The capacity enhancement problem is formulated to maximize the overall spectral efficiency of cellular users (CUs) and D2D users (DUs) to find out the optimal reuse partners i.e., CUs and power control with a decoupling algorithm. Simulation results show that the proposed approach significantly improves the access rate and increases the total spectrum efficiency by 45.6% compared with the direct D2D communication, and outperforms traditional D2D relay scheme in terms of higher 35.2% total spectrum efficiency and less 29.3% power consumption.