Examples relate to a Forward Error Correction (FEC) encoder, an FEC decoder, Passive Optical Network (PON) systems, an Optical Line Terminal (OLT), an Optical Networking Unit (ONU), and to corresponding methods and computer programs. A forward-error-correction (FEC) encoder that is suitable for generating FEC data for use with hard-decision input at a receiver and for use with soft-decision input at the receiver is configured to generate the FEC data based on payload bits using a Low-Density Parity-Check (LDPC) code. The generated FEC data is generated using a single LDPC code that is suitable for use with soft-decision input and hard-decision input at the receiver or using one of two LDPC codes that are suitable for soft-decision input and hard-decision input, respectively.