IQ-Code for PDL and Crosstalk Mitigation in Nyquist-WDM Transmission Based on DSC

Nyquist wavelength-division-multiplexing transmission based on digital sub-carrier, emerges as a promising solution to address the growing network traffic demand. However, this system is impacted by the crosstalk between sub-bands resulting from laser drift. In addition, the transmission capacity is restricted by polarization-dependent loss (PDL), which classical digital signal processing (DSP) techniques at the receiver side are not able to mitigate. In this work, we propose a digital multiple-input-multiple-output coding technique, labelled as IQ-code, aimed at enhancing transmission performance in dual polarized wavelength-division multiplexing (WDM) systems affected by PDL. Furthermore, it demonstrates resilience against crosstalk and non-linearity. A key advantage lies in the use of a single time interval, reducing decoding complexity compared to alternative spatial coding techniques. Our findings demonstrate versatility across various sub-bands, achieving notable improvements up to 1.5dB gain in different scenarios over a transmission distance of 1000 Km.