New MMSE Downlink Channel Estimation for Sub-6 GHz Non-Line-of-Sight Backhaul

The minimum mean square error (MMSE) channel estimator employs the second-order statistics of the channel condition to minimize the mean square error. The major disadvantage of the MMSE estimator is its high complexity. In this paper, a new technique based on a one-dimensional MMSE method using frequency-domain interpolation followed by time-domain interpolation is proposed. Also, an energy efficient channel estimator based on power-delay-profile tracking and noise/interference power estimation method for sub-6 GHz backhaul link is analysed. The proposed algorithm is evaluated using a high delay spread Stanford University Interim SUI-5 and SUI-3 channel NLOS models for fixed backhaul wireless applications and small cells.