On the Spectral Efficiency for Massive MIMO Systems With Imperfect Spacial Covariance Information
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This paper studies the impact of imperfect channel covariance information on the uplink and downlink spectral efficiencies of a time division duplexed (TDD) massive multiple-input multiple-output (MIMO) system. Specifically, we derive analytical lower bounds on the uplink and downlink spectral efficiencies of a user with imperfect knowledge on channel vectors, as well as that of the channel covariance matrices, of the users. We consider a linear minimum mean squared estimator (LMMSE) and element-wise LMMSE channel estimation for the unknown channel in this paper. These analytical bounds enable us to choose the sample size for covariance matrix estimation to meet spectral efficiency requirements. The accurate agreement between derived bounds and simulated bounds based on random samples of channel vector and covariance matrices is shown.
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