Date Added: Aug 2009
Codes on graphs of interest for next generation Forward Error Correction (FEC) in high-speed optical networks, namely turbo codes and Low-Density Parity-Check (LDPC) codes are described in this invited paper. The authors describe both binary and nonbinary LDPC codes, their design, and decoding. They also discuss an FPGA implementation of decoders for binary LDPC codes. The authors then explain how to combine multilevel modulation and channel coding optimally by using coded modulation. Also, they describe an LDPC-coded turbo-equalizer as a candidate for dealing simultaneously with fiber nonlinearities, PMD, and residual chromatic dispersion.