Fig. 1. Flow chart of proposed phase noise compensation algorithm based on UKF

Fig. 2. (a) BER variation versus laser linewidth in 16QAM, 32QAM systems when iterating one, two, three times by proposed UKF algorithm; (b) BER variation versus laser linewidth in 16QAM system using proposed UKF and LS algorithms when the pilot signal subcarrier intervals are 32 and 64; (c) BER variation versus laser linewidth in 32QAM system using proposed UKF and LS algorithms when the pilot signal subcarrier intervals are 32 and 64; (d) BER variation versus system transmission rate in 32QAM system u

Fig. 3. Signal constellation diagrams obtained by receiver with laser linewidth of 700 kHz, 32QAM and pilot signal subcarrier interval of 64. (a) Without using any equalization algorithm; (b) using initial CPE phase noise compensation; (c) using Avg-BL phase noise compensation algorithm; (d) iteration one times by UKF algorithm; (e) iteration two times by UKF algorithm; (f) iteration three times by UKF algorithm