CD and PMD Effect on Cyclostationarity-Based Timing Recovery for Optical Coherent Receivers

Timing recovery is critical for synchronizing the clocks at transmitting and receiving ends of a digital coherent communication system. The core timing to determine reliably current sampling error local digitizer so that circuit may lock stable operation point. Conventional phase detectors need adapt optical fiber channel common effects this channel, such as chromatic dispersion (CD) polarization mode (PMD), on extraction must be understood. Here we exploit cyclostationarity signal derive model studying CD PMD effect. We prove CD-adjusted cyclic correlation matrix contains full information about PMD, determinant detector immune both PMD. also obtain other results completely PMD-independent estimator, etc. Our analysis supported by simulations experiments over field implemented cable.