Interference Exploitation-Based Hybrid Precoding With Robustness Against Phase Errors

Hybrid analog-digital precoding significantly reduces the hardware costs in massive multiple-input multiple-output (MIMO) transceivers when compared with fully digital precoding at the expense of increased transmit power. In order to mitigate the above-mentioned shortfall, we use the concept of constructive interference-based precoding, which has been shown to offer significant transmit power savings when compared with the conventional interference suppression-based precoding in fully digital multiuser MIMO systems. Moreover, in order to circumvent the potential quality-of-service degradation at the users due to the hardware impairments in the transmitters, we judiciously incorporate robustness against such vulnerabilities in the precoder design. Since the undertaken constructive interference-based robust hybrid precoding problem is nonconvex with infinite constraints and thus difficult to solve optimally, we decompose the problem into two subtasks, namely, analog precoding and digital precoding. In this paper, we propose an algorithm to compute the optimal constructive interference-based robust digital precoders. Furthermore, we devise a scheme to facilitate the implementation of the proposed algorithm in a low-complexity and distributed manner. We also discuss the block-level analog precoding techniques. The simulation results demonstrate the superiority of the proposed algorithm and its implementation scheme over the state-of-the-art methods.