Research On Key Technologies Of Channel Coding In Optical Fiber Communication

As one key technologies servicing for the future,optical fiber communication has the advantages of long distance transmission and ultra-high capacity.Most of the data on the Internet must be transmitted based on optical fiber communication.In recent years,with the emergence and popularization of online video,live broadcasting,cloud disk downloading and other emerging large data services,as the basis of information network,optical fiber communication will further play a vital role in the field of information because of its large capacity advantages.In the process of signal transmission,optical fiber communication system will be disturbed by various factors such as noise,dispersion,polarization mode dispersion and so on.Channel coding technology is the most direct and effective technology to resist channel interference.Forward error correction(FEC)technology has attracted much attention for its advantages of no feedback channel,small delay and good real-time performance.How to get high performance and low complexity FEC codes and apply them to existing optical fiber communication technology has great value to be researched.Focused on the channel coding,Intensity-modulated/direct-modulation,high-order modulation and multi-carrier technologies widely used in short-and medium-distance optical fiber communication systems,this dissertation proposed a variety of short-and medium-range optical fiber communication systems,including a V-band radio over fiber system based on adaptive Reed-Solomon coding and envelope detection,asymmetric clipped optical single carrier frequency division multiplexing system based on Layered Low Density Check Codes(LDPC),a generalized frequency division multiplexing system based on LDPC on optical IM/DD system.In this dissertation,FEC coding combined with multi-carrier technology has been innovatively applied in low-cost,low-complexity IM/DD systems and optical wireless communication(OWC)systems.The main research work and innovations of this dissertation are as follows:1.A RoF system scheme based on rate-adaptive RS codesThis dissertation proposed a single carrier 16QAM-ROF system scheme with rate-adaptive RS coding based on the research of Reed-Solomon coding and envelope detection technology.The scheme adjusts the coding efficiency of the system flexibly by using the feedback information of the receiver and adaptive RS coding technology,so as to achieve higher information rate and receiver sensitivity under the premise of the error rate requirement of the receiver.The dissertation experimentally demonstrates the transmission of 60 GHz 16-ary quadrature amplitude modulation(16QAM-modulated)vector signal with adaptive RS coding and precoding technology over 20 km standard single mode optical fiber and 2 m wireless distance.The results show that the proposed scheme can simplify the system,reduce the cost,improve the spectral efficiency and enhance the robustness of millimeter wave signal transmission to dispersion,phase noise and other disturbances,and achieve ultra-low bit error rate.2.Layered/Enhanced asymmetric clipped optical single carrier frequency division multiplexing system scheme based on Layered LDPCThis dissertation proposed a L/E-ACO-SCFDM system scheme based on layered LDPC codes,which is based on a variety of coding and decoding methods of quasi-cyclic LDPC codes and the research of asymmetric clipped optical single carrier frequency division multiplexing(ACO-SCFDM)system.Aiming at the characteristics that the non-linear tailoring noise produced at the low level of L/E-ACO-SCFDM system will superimpose on the high-level signals,the scheme allocates high bit rate LDPC coders at the low level and low bit rate LDPC coders at the high level,and adopts the fast coding method of check matrix and belief propagation(BP)decoding method.In this dissertation,the channel model is built by using matlab,and the excellent performance of the proposed scheme in Gauss additive white noise channel(AWGN)and OWC channel is simulated and analyzed.The results show that the system has not only high power efficiency,high frequency spectral efficiency,low PAPR and anti-transmitter non-linear tailoring and high frequency damage performance of L/E-ACO-SCFDM system,but also the performance of anti-transmitter non-linear tailoring and high frequency damage.It has excellent BER performance and low computational complexity.3.A generalized frequency division multiplexing system scheme based on LDPC using for optical IM/DD systemBased on the GFDM technology of advanced multi-carrier modulation,a scheme of LDPC-coded GFDM-modulated optical IM/DD system cascaded high-order QAM modulation format is proposed in this dissertation.This scheme can achieve more flexible and advanced multi-carrier modulation,with high spectral efficiency and excellent bit error rate performance.This dissertation experimentally demonstrated the transmission of 16QAM-GFDM system based on LDPC codes on short-distance standard single-mode optical fiber link,verifies the feasibility and superiority of the scheme in short-distance optical access network,and compares the applicability of Turbo code and LDPC code in this scheme.This dissertation has also proposed a LCO-GFDM system scheme based on cascaded trellis-coded modulation,which can guarantee the high spectral efficiency of the system and have a certain error-correcting performance at the same time.Then a multi-band 16QAM modulated LCO-GFDM optical IM/DD system is simulated and compared with the LCO-OFDM technology.The results show that the multi-band LCO-GFDM system has lower out-band power and better BER performance,which proves that the proposed scheme has good application prospects in future short-and medium-distance optical fiber communication systems.