Pilot contamination reduction based on MSE performance of channel estimation

We investigate channel estimation mean square error (MSE) performance in Massive multiple-input multiple-output (MIMO) system with pilot contamination. Different from the traditional MSE expressions, the expressions that we derived have algebraic form, which no longer need hard matrix inversion as M, the number of the base station antennas, increasing. From them, we also found that the average transmitted power and length of training sequence almost does not help in enhancing the performance of MSE as M → ∞. Based on this, a scheme to reduce pilot contamination in time division duplexing (TDD) cellular networks is proposed with simple cooperation among base stations. Numerical results finally verify our derivations and the proposed scheme.