First Real‐Time Softwarization of Complete Coherent DSP Stack with Gardner Timing and Clock Recovery

This work demonstrates the first fully softwarized coherent receiver digital signal processing stack implemented on a general‐purpose graphic processing unit (GPU) platform. By introducing a data‐parallel GPU implementation for Gardner‐based timing and clock recovery (TCR), the system achieves complete real‐time receiver operation without requiring an external clock reference. The 80‐km transmission experiment on 5‐Gbit/s dual‐polarization quadrature phase shift keying (DP‐QPSK) signals resulted in an approximately 1‐dB sensitivity penalty at a target bit error rate of 10 −3 .