FLCS PON - An Opportunistic 100 Gbit/s Flexible PON Prototype with Probabilistic Shaping and Soft-Input FEC: Operator Trial and ODN Case Studies [Invited]

FLCS-PON is a prototype of a flexible passive optical network (PON), where the modulation and coding parameters (MCP) of the downstream signal: modulation order, code rate and probabilistic shaping entropy can be adjusted on a timeslot basis, to opportunistically achieve mean net bitrate increase. The system exploits unused margins of transceivers and optical distribution networks. In this work we describe the architecture of FLCS-PON, which is designed to be a potential extension of the recently published ITU T G.9804 Recommendation (50G PON) series. In this work we report more accurate performance metrics for FLCS-PON LDPC code subfamily derived from the G.9804.2 LDPC mother code. We then report on the operator trial of the FLCS-PON system prototype carried out jointly with Vodafone and demonstrate maximum achievable net bitrates as a function of the optical path loss for five different transmitter configurations (NRZ, PAM-4 and probabilistically-shaped PAM-4 with three different entropy values). On the receiver side we test four different configurations: FFE23+DFE5 or FFE16+DFE1 equalizers, each followed by either a hard- or soft-input LDPC decoder. Finally, we perform case studies, mapping net bitrates achieved during the operator trial to the actual Vodafone's ODN OPL distribution, or an ensemble of simulated ODNs. We show that in majority of cases FLCS-PON can provide a significant improvement of mean net bitrate, as well as it can allow to support links which do not comply with requirements of the default G.9804 downstream signal.