Spectral efficiency enhancement in Massive MIMO system under pilot contamination

摘要

Massive multiple-input, multiple-output (MIMO) system is an effective technique to develop the spectral efficiency of the wireless communication systems. Since the number of users is much higher than the available number of orthogonal pilot sequences, the users in the neighboring cells can reuse the same pilots of the home cell. Thus, pilot contamination occurs, which restricts the system throughput. In this paper, Laplacian centralized scattering-spatially correlated Rayleigh fading channel model with multi-cell minimum mean square error (M-MMSE) combining and precoding to mitigate pilot contamination and enhance cell throughput. This model gives a more accurate description, especially for cell-edge users. It results in an accurate spatial channel correlation matrix calculation that enhances the channel estimation quality under pilot contamination. Simulation results indicate that the proposed Laplacian scattering-spatially correlated Rayleigh fading model achieves better pilot contamination mitigation and larger spectral efficiency, as compared with both the one-ring scattering-spatially correlated Rayleigh fading and the uncorrelated Rayleigh fading channel models for different combining and precoding schemes at different pilot reuse factors. The cost of interference rejection and spectral efficiency enhancement is an increase in the system computational complexity.