Optimum and quasi-optimum relaxation parameters for low-complexity massive MIMO detector based on Richardson method

The low-complexity minimum mean square error detector based on Richardson method for massive MIMO systems was proposed, where the very important relaxation parameter was obtained by intensive simulations for each given massive MIMO channel matrix. Thus, a simple approach is developed to determine the optimum relaxation parameter of Richardson method for any massive MIMO system configuration. Furthermore, by exploiting the massive MIMO channel property of asymptotic orthogonality, a simple way to obtain the quasi-optimum relaxation parameter is proposed, which is given as a function of the number of users and the received base station antennas of a massive MIMO system.