Impact of Frequency Selectivity on the Information Rate Performance of CFO Impaired Single-Carrier Massive MU-MIMO Uplink

In this letter, we study the impact of frequency-selectivity on the gap between the required peruser transmit power in the residual carrier frequency offset (CFO) scenario i.e., after CFO estimation/compensation at the base-station (BS) and that in the ideal/zero CFO scenario, for a fixed per-user information rate, in single-carrier massive MU-MIMO uplink systems with the time-reversal maximum ratio combining receiver. Information theoretic analysis reveals that this gap decreases with increasing frequency-selectivity of the channel. Also, in the residual CFO scenario, an O(√M) array gain is still achievable (M is the number of BS antennas) in frequency-selective channels with imperfect channel estimates.