Turbo Equalization with Convolutional and LDPC Codes as well as Analytically Computed Metrics

This paper compares advanced electrical equalization schemes for intensity modulated high speed fiber optic transmission. The treated equalization schemes are based on the Turbo principle and apply convolutional as well as low-density parity-check (LDPC) codes with a forward error correction (FEC) overhead of 6.7%. A bit error rate (BER) and EXIT chart analysis based on a sophisticated channel model and analytically computed branch metrics for the BCJR and Viterbi equalizers give detailed insight into the performance and into the iterative equalization process, respectively.