Research And Optimization Of Forward Error Correction Technology In Optical Transmission Network

Nowadays,human society is in the information age,and the rapid development and widespread application of computer technology and communication technology have brought about an information explosion.In recent years,the development of optical communication technology has gained rapid momentum.The growth of data traffic and the number of users has increasingly required the bandwidth of optical transmission networks.Optical communication technology also has higher requirements for transmission distance,transmission capacity and transmission rate.Optical Transport Network(OTN)is a next-generation transmission network regulated by the International Telecommunication Union Telecommunications Standardization Sector(ITU-T).It contains both electrical and optical layer networks,combining the advantages of Synchronous Digital Hierarchy(SDH)and Wavelength Division Multiplexing(WDM)technology to support a variety of service signal mapping.However,in high-speed and long-distance optical transmission systems,due to the attenuation,dispersion and nonlinear effects of optical signals in optical fibers,errors will inevitably occur.According to the G.709 launched by ITU-T and other suggestions,we study forward Error Correction(FEC)technology and optimize it to enhance the transmission performance of OTN.The main research of this article is as follows:A complete customer signal mapping simulation link in OTN is built.According to related protocols such as IEEE and ITU-T,the Ethernet data frame format,the General Framing Procedure(GFP),and the OTN standard frame format are studied.The GFP mapping method is used to map the Ethernet frame to the OTN frame to realize the transmission of Ethernet signals in the OTN.The standard FEC technology in OTN and an improved single FEC technology using LDPC(Low Density Parity Check,LDPC)code are studied.The method used by the standard FEC technology in OTN is data interleaving and RS(255,239)code.The implementation process is to interleave and RS encode the first 3824 columns of information bytes in the OTN frame,and generate the last 256 columns of check bytes.Standard FEC technology uses a single RS code.In order to obtain better error correction performance and higher coding gain,we can use LDPC codes with better performance in OTN.Therefore,LDPC(32640,30592)codes with the same redundancy as RS(255,239)codes are proposed.It is used in the OTN signal mapping simulation link built.The simulation results show that its performance is about 1.5 d B higher than that of standard FEC technology.An improved cascading FEC technology for cascading RS codes and LDPC codes is proposed.The performance of LDPC code is close to the Shannon limit,and it has the characteristics of flexible structure and low latency.It is suitable for large-capacity and high-speed transmission systems.Therefore,we can use a cascade pattern with the outer code as RS code and the inner code as LDPC code.The proposed RS-LDPC cascade code is used in the OTN signal mapping simulation link built,and the simulation results show that its performance is about 1.7 d B higher than that of standard FEC technology.