Stair Matrix and its Applications to Massive MIMO Uplink Data Detection

In this paper, we propose a new approach of using the stair matrix for uplink data detection in massive MIMO systems. We first demonstrate the applicability of the proposed method by showing that the probability (that the convergence conditions are met) will approach one as long as sufficient large number of antennas are equipped at the base station. We then propose an iterative method to perform data detection and show that a much improved performance can be achieved with the computational complexity remaining at the same level of existing iterative methods where the diagonal matrix is adopted. Performance evaluation is conducted in terms of the probability that the convergence conditions are met, the normalized mean-square error of the Neumann series expansion to approach the matrix inverse, the residual estimation error to approach the linear ZF/MMSE detection, and the system bit error rate. Numerical simulations show significant performance enhancement of using the stair matrix over the diagonal matrix in all performance aspects.