Channel, Phase Noise, and Frequency Offset in OFDM Systems: Joint Estimation, Data Detection, and Hybrid Cramer-Rao Lower Bound

摘要

Oscillator phase noise (PHN) and carrier frequency offset (CFO) can adverselyimpact the performance of orthogonal frequency division multiplexing (OFDM)systems, since they can result in inter carrier interference and rotation ofthe signal constellation. In this paper, we propose an expectation conditionalmaximization (ECM) based algorithm for joint estimation of channel, PHN, andCFO in OFDM systems. We present the signal model for the estimation problem andderive the hybrid Cramer-Rao lower bound (HCRB) for the joint estimationproblem. Next, we propose an iterative receiver based on an extended Kalmanfilter for joint data detection and PHN tracking. Numerical results show that,compared to existing algorithms, the performance of the proposed ECM-basedestimator is closer to the derived HCRB and outperforms the existing estimationalgorithms at moderate-to-high signal-to-noise ratio (SNR). In addition, thecombined estimation algorithm and iterative receiver are more computationallyefficient than existing algorithms and result in improved average uncoded andcoded bit error rate (BER) performance.