LAUSR

Underlay device-to-device (D2D) communication in a cellular network is expected to improve spectrum utilization as well as to enable the use of new proximity-based applications. However, deploying D2D communications in a cellular network poses some challenges in the system design due to the potential interference between the cellular links and the D2D links. In this paper, we consider a scenario where a D2D device equipped with multiple antennas attempts to reuse the downlink resources of an active cellular user. Two strategies are proposed to handle the interference that the D2D link may cause to the cellular link. Interference nulling (IN), the first strategy, completely eliminates the interference, while interference constraining (IC), the second strategy, intends to limit the amount of residual interference such that the signal-to-interference-plus-noise ratio (SINR) for the cellular user is ensured to be higher than a certain threshold. Both methods do not produce additional overhead at the base station (BS), since the D2D side autonomously determines the transmit signals without involvement of the BS. The results of a numerical analysis are then presented to compare the performance of these two strategies under various environments.