Low-Complexity OFDM Channel Estimation in the Presence of I/Q Imbalance and Phase Noise

In this paper, we derive the maximum likelihood (ML) channel estimate in the presence of phase noise (PHN) and I/Q imbalance for OFDM systems. Since it is estimated jointly with I/Q and PHN, the channel estimate is more robust to these RF impairments compared to the conventional schemes. The complexity of the joint estimator is reduced using an approximate cost functions for both PHN and I/Q imbalance. The performance of the proposed estimator in terms of both channel mean squared error (MSE) and bit error rate (BER) is also presented and compared to the case of perfect channel knowledge.