Phase Noise Compensation Using FDM Based Pilot Symbol Assisted EKF for OFDM Based Radio Backhaul Links

This paper proposes an iterative phase noise compensation (PNC) method using an extended Kalman filter (EKF) that employs pilot symbol assisted (PSA) PNC for computing the initial values in the EKF for orthogonal frequency division multiplexing radio backhaul links. In the PSA PNC stage of the proposed method, the phase noise is estimated and compensated using frequency division multiplexing (FDM) pilot symbols that are multiplexed into the data symbols. Based on the decision symbols after the PSA PNC, the time-varying phase noise estimate and variance in the time domain are tracked and updated using the EKF iteratively. The proposed method achieves a low computational complexity because low-density parity-check (LDPC) decoding is conducted only once after the phase noise in the received signal is suppressed by PSA-EKF PNC. Computer simulation results show that the loss in the required received signal-to-noise power ratio (SNR) satisfying the bit error rate (BER) of 10 ^-8 of the proposed method compared to that without phase noise is suppressed to within approximately 1.2 dB for 256QAM with LDPC coding at the coding rate of 8/9.