Channel, Phase Noise, and Frequency Offset in OFDM Systems: Joint Estimation, Data Detec- tion, and Hybrid Cramér-Rao Lower Bound

Oscillator phase noise (PHN) and carrier frequency offset (CFO) can adversely impact the performance of orthogonal frequency division multiplexing (OFDM) systems since they can result in inter carrier interference and rotation of the signal constellation. In this paper, we propose an expectation conditional maximization (ECM) based algorithm for joint estimation of channel, PHN, and CFO in OFDM systems. We outline the signal model for the estimation problem and derive the hybrid Cramér-Rao lower bound (HCRB) for the joint estimation problem. Next, we propose an iterative receiver based on an extended Kalman filter for joint data detection and PHN tracking. Numerical results show that compared to existing algorithms, the performance of the proposed ECM-based estimator is closer to the derived HCRB. In addition, the combined estimation algorithm and iterative receiver are more computationally efficient than existing algorithms and result in improved average bit-error rate performance.