A divide-and-conquer precoding scheme for sub-connected massive MIMO systems

The hybrid beamforming strategy that applies a combination of analog and digital precoders has attracted much attention recently for its ability to reduce both hardware complexity and energy consumption. However due to the large number of antennae, the determination of hybrid precoders usually involves a large amount of computation, which may take much time and potentially risk the low-latency demand. In this paper we propose a novel divide-and-conquer precoding scheme where the precoding problem for the sub-connected architecture is divided into a series of independent subproblems. These subproblems can be solved simultaneously to save time. To deal with the subproblems, we propose a semidefinite relaxation based approach. By dividing the precoding problem, computational complexity can be reduced, and simulation results show its comparable performance with existing works, and robustness against potential saddle points with poor performance.