Influence of Spatial Correlation Over the Channel Estimation in 6G Cell-Free Massive MIMO Network

Within this paper, we use the Bayesian Minimum mean square error channel estimation (CE)to handle the uplink pilot-based channel estimate procedure in a cell-free (CF) Massive multiple-input multiple-output MIMO (M-MIMO) grid that runs under the TDD protocol. Moreover, we consider the spatial correlation (SC) between channels, as it describes a more practical scenario. Furthermore, we describe the SC using the Gaussian local scattering model. In addition, we investigate the influence of SC over CE in a CF grid using the eigenvalues decomposition. We also examine the performance of a small-cell (SCell) grid, where the SCell grid is only a particular case of a CF grid, in which the user is served by one access point. To back up our results, numerical results are provided.