I/Q imbalance aware widely-linear channel estimation and detection for uplink massive MIMO systems

In this paper, we propose an in-phase/quadrature-phase imbalance (IQI) aware widely-linear minimum mean square error (IQA-WLMMSE) receiver for uplink single-cell massive multiple-input multiple-output (MIMO) systems with imperfect channel state information (CSI). In our system model, IQI is present at the base station and user terminals and affects both channel estimation and data detection. The proposed IQA-WLMMSE receiver processes the real and imaginary parts of the received signal separately and mitigates both multiple-access interference (MAI) and IQI. Our analytical and simulation results show that the proposed IQA-WLMMSE receiver performs significantly better than the conventional IQI unaware MMSE (IQU-MMSE) receiver, and its sum rate closely approaches the sum rate of the ideal system with no IQI.