The Effect of Channel Estimation Errors on the Energy Efficiency of Downlink Massive MIMO Systems

In this paper the effect of channel estimation errors on the energy efficiency of a downlink massive multiple-input multiple-output system is investigated and analyzed. The required downlink transmit power of the zero forcing (ZF) and maximum ratio transmission (MRT) precoding schemes are derived and analyzed under imperfect channel state information condition. Analytical and simulations results show that, as the reliability of the estimation increases from zero, power increases to a certain point and begins to decrease. The value of reliability where the power begins to decrease depends on the number of base station antennas and the number of users within the cell.