Low-complexity Calibration Scheme of Channel Reciprocity for Massive MIMO-OFDM System with IQ Imbalance

Massive multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) is one of the promising technology for the fifth generation of wireless communications. As a major radio-frequency impairment, in-phase and quadrature-phase (IQ) imbalance tends to destroy the channel reciprocity and degrade the performance of time division duplex (TDD) massive MIMO-OFDM system. In this paper, a calibration scheme is proposed to restore the channel reciprocity for TDD massive MIMO-OFDM system with IQ imbalance. Two calibration matrices are designed to compensate the uplink and downlink transmission respectively. A low-complexity estimation method of calibration matrices is also proposed in this paper. Numerical results confirm that the proposed scheme can restore the channel reciprocity and provide reliable performance.