Frame synchronization and joint estimation of IQ imbalance and channel response for OFDM systems

In this paper, we first introduce a new method for joint estimation of IQ imbalance and channel response in OFDM systems under the assumption of perfect frame synchronization. The proposed method needs only one OFDM block for training and the solution is given in closed form. Then the method is applied to the scenario when the OFDM frame is not synchronized. A reduced complexity algorithm is derived. With a relatively low complexity, the proposed method can accurately estimate the frame starting position, the IQ imbalance and the channel response simultaneously. Simulation results show that the bit error rate (BER) performance of the proposed method is very close to the ideal case when all these parameters are known perfectly at the receiver.