Uplink Channel Estimation in Massive MIMO Systems Using Factor Analysis

In this letter, we consider the channel estimation problem under pilot contamination in massive multiple-input multiple-output (MIMO) systems. We propose a novel channel estimation scheme, which decomposes the space supported by the covariance matrix of the received signals into three subspaces using factor analysis. For a large number of base station antennas, a practically interference-free subspace is created, in which an accurate channel estimate can be obtained. The proposed factor analysis based scheme exploits spatial correlation to significantly reduce the computational complexity. Simulation results are provided to show the efficacy of the proposed scheme.