A novel IQ imbalance and channel estimation algorithm for Alamouti OFDM systems

This paper shows that the unwanted In-phase/quadrature (IQ) imbalance can be exploited to achieve a diversity gain for Alamouti space-time coding orthogonal frequency division multiplexing (AL-OFDM) systems. In addition, we propose a novel iterative algorithm to jointly estimate the channel impulse response (CIR) and IQ imbalance occurring at both the transmitter and receiver. A pilot sequence is employed for initial estimation and detection. Then, soft information is exchanged between the detector and the estimator iteratively in order to enhance the system performance. Simulation results confirm the effectiveness of the proposed algorithms.