Device-to-device (D2D) communication in MU-MIMO cellular networks

In this paper, we address a resource allocation problem, where a pair of device-to-device terminals are integrated into a time division duplex (TDD) cellular network. By introducing an incremental relay transmission scheme for the D2D communication, the D2D transmitter, traditionally believed to be the source of interference, are coordinated with other cellular user equipments (CUEs) in the uplink session. In consequence, both the D2D receiver and the central base station (CBS) are able to decode the message sent from the D2D transmitter. The CBS, in the following downlink session, may forward this message to the D2D receiver if the direct D2D link is in outage. We formulate and solve the cell throughput maximization problem for three transmission modes: cellular, underlay transmission, and incremental relay mode. Simulation results show that the proposed incremental relay is not only with higher spectral efficiency, but also provides more reliable D2D transmission than the cellular relay and the underlay scheme.