Richardson method based linear precoding with low complexity for massive MIMO systems

For massive MIMO system with hundreds of antennas at the base station (BS), zero forcing (ZF) precoding can achieve the near-optimal capacity due to the asymptotically orthogonal channel, but it involves complicated matrix inversion of large size. In this paper, we propose a Richardson Method (RM) based precoding to avoid the complicated matrix inversion in an iterative way, which can reduce the complexity by one order of magnitude. We also prove that the optimal relaxation parameter to RM can be approached by a simple and quantified value to maximize the convergence rate of RM-based precoding, which only depends on the number of BS antennas and the number of users. Simulation results show that RM-based precoding can achieve the near-optimal performance of ZF precoding with only a small number of iterations.