Performance Investigation of Low-Resolution Coherent Optical Communication System with Low-Complexity Adaptive Equalizer

Coherent optical communication systems are essential for modern high-speed data transmission. However, these systems face challenges related to high cost and complexity, especially in short-reach coherent optical communication systems. To address these issues, we present a low-resolution coherent optical communication system with low-complexity adaptive equalizer. The system's performance is evaluated in a 5 km 28 GBaud 16 QAM transmission scenario. The simulation results indicate that error-feedback noise shaping (EFNS) is highly effective in suppressing digital-to-analog converter (DAC) quantization noise, thereby reducing resolution demands on the DAC. Furthermore, the adaptive equalizer, based on a Stokes-domain depolarization scheme (SS-AEQ), achieves a 45% reduction in the complexity of the equalization algorithm. Compared with the 8-bit resolution DAC and the traditional 2 × 2 MIMO AEQ scheme, the system, employing 4-bit DAC for low-resolution transmission, achieves low-complexity equalization while maintaining comparable transmission performance.