Research On Several Key Techniques Of Coherent Optical Transmission System Based On OFDM Technology

Coherent optical OFDM (CO-OFDM) system not only perfectly inherits the advantages of the wireless OFDM technology which has high transmission rate, high spectrum efficiency, high immunity to dispersion and simple DSP, but also has the advantages of coherent optical receiver technology with high sensitivity and long distance transmission. The CO-OFDM system is able to compatible with the existing optical transmission system, and can construct a high speed, large capacity, low cost and long distance transmission system for the next generation1. Based on the study of OFDM technology and coherent optical receiver technology, this paper investigates the basic principles and key technologies about the CO-OFDM system. Combined with the current status of domestic and foreign research, the paper deeply studies the theory of each component part in CO-OFDM system and analyzes the advantages, disadvantages and potential prospect.2. Based on the CO-OFDM simulation platform, which is constructed by Matlab simulation software, the paper analyzes thecommon synchronization algorithm and concludes the defects of the S&C algorithm and Minn algorithm in optical communication system. For the residue optical carrier interference, we proposed a new improved algorithm based on pilot sequence. For the low bandwidth utilization, we proposed anther new improved algorithm based on super-imposed sequence.3. This paper analyzes the necessity and feasibility on physical layer security mechanism of CO-OFDM system and proposes a CO-OFDM system by frequency hopping at physical layer to enhance system security. Simulation results show the proposed scheme has excellent anti-jamming and anti-intercept capability.