Real-time burst-mode digital signal processing for passive optical networks

Driven by ever-increasing capacity demands, the 50G passive optical network (PON) is maturing gradually. One of the main challenges for the 50G PON is implementing burst-mode digital signal processing (BM-DSP) for the burst upstream signal. This paper demonstrates a real-time BM-DSP for burst reception of a 25 Gbit/s on-off keying signal to meet the asymmetric-mode 50G PON demand. The real-time BM-DSP includes BM frequency-domain timing recovery and a BM frequency-domain equalizer, which can be fast converged based on the ${\sim}42\;\text{ns}$ designed preamble. Meanwhile, the simplified implementations for fast Fourier transform, minimum mean square error, and decision-directed least-mean-square-error algorithms decrease the DSP resources by 28.57% compared to the conventional implementation without optimization, enabling the loading of real-time BM-DSP in a field programmable gate array with limited DSP resources. The real-time implementation of BM-DSP can guide the design of application-specific integrated circuits for 50G PON.