Joint Channel Estimation and Phase Noise Suppression for OFDM Systems

The joint channel estimation and phase noise suppression scheme for orthogonal frequency-division multiplexing (OFDM) systems is proposed for a case where channel estimation is needed symbol by symbol. In the proposed scheme, channel estimation and phase noise suppression are performed iteratively via the expectation-maximization (EM) algorithm. The proposed algorithm mitigates the performance degradation due to phase noise effectively while providing the accurate channel estimate with comparatively few pilot subcarriers so that the spectral efficiency of an OFDM system is improved

Joint Channel Estimation with Phase Noise Suppression and Soft Decision Decoding Scheme for OFDM-based WLANs

In orthogonal frequency-division multiplexing (OFDM)-based wireless local area networks (WLANs), phase noise (PHN) and channel estimation errors can degrade the performance of the system. This letter provides a soft decision decoding scheme analysis for OFDM-based WLANs in the presence of PHN and channel estimation errors. Basing on this analysis, we propose a novel iterative scheme for joint channel estimation with PHN suppression and soft decision decoding. In addition, the soft decision decoding metric for QAM OFDM systems is modified to mitigate the effects of PHN and channel estimation errors. The simulation results show that the proposed scheme mitigates the performance degradation due to PHN and channel estimation errors effectively

Channel, Phase Noise, and Frequency Offset in OFDM Systems: Joint Estimation, Data Detection, and Hybrid Cramer-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 present the signal model for the estimation problem and derive the hybrid Cramer-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 and outperforms the existing estimation algorithms at moderate-to-high signal-to-noise ratio (SNR). In addition, the combined estimation algorithm and iterative receiver are more computationally efficient than existing algorithms and result in improved average uncoded and coded bit error rate (BER) performance

On Phase Noise Suppression in Full-Duplex Systems

Oscillator phase noise has been shown to be one of the main performance limiting factors in full-duplex systems. In this paper, we consider the problem of self-interference cancellation with phase noise suppression in full-duplex systems. The feasibility of performing phase noise suppression in full-duplex systems in terms of both complexity and achieved gain is analytically and experimentally investigated. First, the effect of phase noise on full-duplex systems and the possibility of performing phase noise suppression are studied. Two different phase noise suppression techniques with a detailed complexity analysis are then proposed. For each suppression technique, both free-running and phase locked loop based oscillators are considered. Due to the fact that full-duplex system performance highly depends on hardware impairments, experimental analysis is essential for reliable results. In this paper, the performance of the proposed techniques is experimentally investigated in a typical indoor environment. The experimental results are shown to confirm the results obtained from numerical simulations on two different experimental research platforms. At the end, the tradeoff between the required complexity and the gain achieved using phase noise suppression is discussed.Comment: Published in IEEE transactions on wireless communications on October-2014. Please refer to the IEEE version for the most updated documen