A novel user selection algorithm for multiuser hybrid precoding in mmWave systems

In this paper, a novel user selection algorithm is proposed for downlink multiuser mmWave systems. The base station exploits hybrid precoding and communicates with multiple users simultaneously via spatial multiplexing. The system performance degrades when the spatially multiplexed users are angularly close and thus results in residual interference which is hard to be cancelled out by the hybrid precoding. To obtain an efficient and computably tractable solution, a novel formulation of the user selection problem and the associated algorithm is presented in this paper. The proposed algorithm enables an optimal spatial multiplexing at the base station, where a predefined number of users is selected and simultaneously served to maximise the averaged spectral efficiency per user. Simulation results show that implementing the multiuser hybrid precoding with the proposed user selection algorithm achieves a performance close to the interference-free limit.