Channel Estimation for Extremely Large-Scale Massive MIMO Systems

Abstract

Extremely large-scale massive multiple-input multiple-output has shown considerable potential in future mobile communications. However, the use of extremely large aperture arrays will lead to near-field and spatial non-stationary channel conditions, which result in changes in transceiver design and channel state information acquisition. This letter focuses on the channel estimation problem and describes the non-stationary channel through a mapping between subarrays and scatterers. We propose subarray-wise and scatterer-wise channel estimation methods to estimate the near-field non-stationary channel from the views of the subarray and the scatterer, respectively. Numerical results demonstrate that the subarray-wise method can derive accurate channel estimation results with low complexity, whereas the scatterer-wise method can accurately position the scatterers and identify almost all the mappings between subarrays and scatterers.