Orthogonal Polarizations Based Channel Estimation for Dual-polarized Massive MIMO Under Pilot Contamination

Pilot contamination limits the accuracy of channel state information (CSI). In this paper, we propose an orthogonal polarizations based channel estimation algorithm in multi-cell multi-user dual-polarized massive multiple-input multiple-output (MIMO) system. The algorithm exploits orthogonal polarizations effectively reduce the mean square error (MSE) under pilot contamination. Meanwhile, for the high complexity of the minimum mean square error (MMSE) channel estimation, the algorithm uses unbiased estimation for the combination term of interference caused by pilot contamination and the noise. Then we deduce and evaluate the approximate MSE analytical expression of the proposed channel estimation. Finally, the simulation results show that the proposed algorithm is simpler than the MMSE estimation, and more practical than least squares (LS) channel estimation.