Soft-FEC Implementation for High-Speed Coherent Optical OFDM Systems

Nowadays one of the discussed solutions for optical transmission systems at 100 Gbit/s (N x 100 Gbit/s) and beyond is coherent optical orthogonal frequency division multiplexing (CO-OFDM). Commonly hard-decision forward error correction (FEC) with the redundancy of 7% is assumed. Recently the improvement of the receiver sensitivity was analyzed by using a low density parity check (LDPC) code that is one of the promising candidates for 100 Gbit/s soft-FEC. In this work we assess the efficiency and investigate the implementation of soft-FEC with LDPC codes with overheads between 7% and 50% in coherent optical OFDM systems.