Performance of PSA Kalman Filters for Phase Noise Compensation in High-Order QAM OFDM Systems

Abstract

This paper presents an iterative phase noise compensation (PNC) method that utilizes pilot symbol assisted (PSA) PNC and subsequently an iterative Kalman filter in orthogonal frequency division multiplexing radio backhaul links. There are two options for the presented iterative PNC depending on the type of Kalman filter employed. One is an extended Kalman filter (EKF) and the other is an unscented Kalman filter (UKF). The latter is expected to perform better than the former since the PNC problem is nonlinear. We compare the bit error rate (BER) performance of iterative PNC employing the EKF and UKF. Computer simulation results show that no distinct difference in the BER is observed between the EKF PNC and UKF PNC associated with PSA PNC for 256QAM and 1024QAM schemes, where a low-density parity-check (LDPC) code with the coding rate of 8/9 is used for error correction. We also show that PSA-EKF and PSA-UKF PNC are effective in achieving a low BER such as 10 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−8</sup> in a time-varying phase noise channel for LDPC-coded 256QAM and 1024QAM schemes.