Duplex mode selection for device-to-device communications underlaying the cellular uplink

Abstract

Device-to-device (D2D) communications, which enable nearby mobile devices to communicate with each other, have drawn significant research interests. To further improve the spectral efficiency of D2D communications, we integrate full-duplex (FD) into D2D communications. Since the residual self-interference (SI) will limit the performance gain introduced by the FD mode, we cannot directly determine which duplex mode should be used. Therefore, this paper investigates the duplex mode selection problem for D2D communications underlaying the cellular uplink. Two cases are considered, i.e., the base station (BS) has perfect instantaneous channel state information (CSI) of both cellular link and D2D link and the BS only has user location information. For each case, we give the conditions to use D2D communications and investigate the existence of feasible solutions. When the feasible solutions of both FD mode and HD mode exist, we use power control to further improve system performance and give the duplex mode selection scheme. Numerical results show that the mode selection scheme is determined by the rate requirements and the residual self-interference.