Time-frequency-multiplex preamble design for joint I/Q imbalance, CFO and channel estimation in OFDM systems

In this paper, a novel time-frequency-multiplex preamble design is proposed to estimate the in-phase and quadrature-phase (I/Q) imbalance, carrier frequency offset (CFO) and channel impulse response parameters for the zero-IF receiver of orthogonal frequency-division multiplexing (OFDM) systems. First, the contiguous time-multiplex preamble is designed to estimate CFO. Then, the two CFO compensators of the positive and negative subcarriers are proposed to separate and estimate I/Q imbalance and channel parameters. Finally, the image signal cancellation via the estimated parameters is designed to enhance the receiver performance. The advantage of the proposed time-frequency-multiplex preamble design is low computational complexity and robust performance. Simulation results confirm that the proposed estimator can provide reliable performance over the severe I/Q imbalance, CFO, and multipath fading channel environment.