Analysis of low-bit soft-decision error correction in optical front ends

A novel methodology for analyzing the advantageous decoding performance of multibranch configurations of low-bit optical soft-decision forward error correction receivers is presented. The decoding performance and noise behavior of three front-end schemes are evaluated and compared. Arising from a multiple-branch configuration, the concept of inconsistency in the decoder (thermometer code) is presented and used to optimize decoding performance. The experimentally validated methodology considers both optically amplified long-haul and short-reach applications.