Joint Equalization of RSOP and PMD Impairments Based on Square-root Cubature Kalman Filter for PDM-16QAM System

In this paper, a polarization demultiplexing scheme based on Square-root cubature Kalman filter (SCKF) is proposed, which can compensate polarization mode dispersion in the frequency domain and track the rotation of state of polarization (RSOP) in the time domain. The performance of the SCKF scheme has verified by 28 GBaud PDM-16QAM system. The simulation results demonstrate that the proposed scheme can handle ultra-fast RSOP up to 55 Mrad/s, and still has a compensation capability of about 90 ps for different group delay (DGD) under the extreme RSOP variation of 15 Mrad/s. It achieves a higher performance than the conventional Extended Kalman filter (EKF) and has a higher OSNR tolerance of about 1dB. The time complexity of SCKF is O(NlogN).