Robust transceiver optimization for underlay device-to-device communications

In this paper, we study robust transceiver optimization for device-to-device (D2D) communications that aims for signal-to-interference-plus-noise-ratio (SINR) fairness among D2D users. We assume that the multi-antenna D2D users in the cellular network employ interference alignment (IA) for their communication. In addition to an interference power constraint that is set by the primary network (i.e., macrocell) in the underlay cognitive transmission, we also consider channel state information (CSI) imperfectness to obtain a robust transceiver design for the D2D users. Due to the non-convexity of the design problem, we resort to an alternating minimization technique. Numerical simulations demonstrate the performance of the proposed transceiver compared to the benchmark case of an IA system without primary network/macrocell (non-cognitive). It is observed that at low SNR and high CSI error with relaxed interference power constraint, the worst-case stream data rate of the D2D users are close to that of the users in non-cognitive IA system but performance degrades significantly with stringent interference power constraint.