Research On Signal Conditioning Technology In Real-time Optical IM/DD-OFDM System

Optical Orthogonal Frequency Division Multiplexing(OOFDM)is a new technology that has been widely researched and focused in recent years.Due to its high spectral efficiency,high dispersion tolerance and the advantage of easy to channel estimation in time-varying environments,Catering to high-speed,long-distance,high-capacity network transmission performance requirements in the future.This thesis mainly gives research on the real-time Intensity Modulated Directed Detected OFDM(IM/DD-OFDM)system,for which signal conditioning techniques,proposed a transmission system transmitter's Finite Impulse Response(FIR)filter and a suitable real-time system's channel estimation and equalization algorithm respectively.Meanwhile,they also have been implemented on the Field Programmable Gate Array(FPGA)platform,and verified in a real-time optical IM/DD-OFDM testing system.Finally,the transmission performance of the entire system related verification has been demonstrated successfully.The main work of the paper and innovations include:(1)Analyze the influence of signal conditioning technology on the system in optical IM/DD-OFDM system theoretically and make mathematical derivation and theoretical analysis.The results show that FIR filter and channel estimation and equalization are both helpful to improve signal demodulation performance.(2)A FIR digital filter emulation module and a pilot-based channel estimation and equalization emulation module for transmission system are established respectively.The numerical simulation shows that in the IM/DD-OFDM system The signal after the signal can be better demodulation,and is conducive to OFDM signal transmission.(3)The implementation of FIR digital filter based on distributed algorithm on FPGA hardware platform,and the implementation of pilot-based channel estimation and equalization,involved in the construction of real-time optical IM/DD-OFDM system testing platform and system cascading test,in the case of 80km fiber link,the test results show that the two modules designed to work properly,and eventually the data can be correctly demodulated recovery.