Trellis-Coded Modulation(TCM)for Forward Error Correction In Optical Communication

Trellis-Coded Modulation (TCM) is efficient transmission scheme that does not show the combination of a channel coding and modulation wideband. However, in the multi-use existing TCM convolutional code encoding and decoding. In the high-speed optical communication system, the error correction capability is very limited. LDPC error correction coding technique that introduce high bitrate, adding a small amount of redundant bits to detect error correction. Optical signal-to-noise ratio (OSNR) tolerance significantly reduced in the receiving end.This dissertation mainly researches on forward error correction in optical communication, focuses on trellis-coded modulation(TCM) and low-density parity check codes(LDPC). TCM coding and LDPC coding cascade, comparing with the TCM coding simulation system, obtain the effective coding gain improvement. First of all, in the background proposes Trellis-coded modulation techniques in the course of development in optical communication, research significance and status, and provides an overview of the main components of the optical fiber communication systems and technology indicators. Secondly, through theoretical analysis, nonlinear convolution coding at different state is simulated.Through comparative analysis of the optimal error performance, an improved method of the TCM encoder is designed to improve coding gain. Then, the paper introduces several common coding and decoding algorithm of the LDPC error correction coding is and the structure of the parity check matrix of LDPC is designed. And then proposes400Gb/s LDPC-TCM-32QAM cascade system.Through simulation in Matlab platform to verify the feasibility of its handling, the transmission characteristics of the simulation results and a brief analysis is analyzed. The simulation results shows compared to non-cascade system, this improved algorithm by this paper performs better to a certain extent on system performance improvement. Finally, the full text summary of the whole dissertation and future research work is shown.