Coded-Orthogonal Frequency Division Multiplexing in Hybrid Optical Networks

Future Internet should be able to support a wide range of services containing large amount of multimedia over different network types at a high speed. The future optical networks will therefore be hybrid, composed of different Single-Mode Fibre (SMF), Multi-Mode Fibre (MMF) and Free-Space Optical (FSO) links. In these networks, novel modulation and coding techniques are needed that are capable of dealing with different channel impairments, be it in SMF, MMF or FSO links. The authors propose a coded-modulation scheme suitable for use in hybrid FSO - fibre-optics networks. The proposed scheme is based on polarization-multiplexing and coded - Orthogonal Frequency Division Multiplexing (OFDM) with Large girth quasi-cyclic low-Density Parity-Check (LDPC) codes as channel codes.