Research On Forward Error Correction Technology In Coherent Optical Communication System Based On Micro-Element Noise Encryption

With the rapid development of new technologies for optical layer transmission,switching and networking,the transmission rate and transmission distance of optical communication are greatly improved,and the open capacity of optical network infrastructure has been significantly enhanced.However,the existing optical communication system does not have security,the optical fiber transmission process is basically in an unfortified state,the optical signal can be directly eavesdropped from the optical cable or the optical amplifier and analyzed and intercepted.As the physical layer security threats and impacts become increasingly prominent,and the traditional cryptosystem based on computational complexity can no longer cope with the powerful ciracking ability from quantum computers,the information content transmitted in optical communication will face"transparent,copied,and tampered.In this paper,the micro-element signal intrusion noise transmission mechanism is based on the physical layer encryption technology,and adopts various methods of optical signal processing and electrical signal processing to realize an optical communication physical layer security scheme integrating encryption and concealment functions.It provides a reliable guarantee for meeting the requirements of high transmission speed and high safety strength.This paper concludes some research work and innovations which are as follows:(1)This paper is based on the new theoretical Micro-element in the field of optical communication physical layer secure transmission namely the smallest signal state that can be determined due to the in fluence of noise in optical fiber channel transmission.This paper analyzes in detail the security signal model of large-scale multi-dimensional and multi-order modulation,which divides the signal state by'dimension' and 'order' and uses noise to hide the signal.Finally,the process of transmitting and receiving the security decision after the micro-noise encryption is described.(2)To ensure the quality of the optical signal in the coherent optical system after long-span non-relay transmission,the encoding and decoding algorithms of the RS code and the LDPC code are analyzed in detail,and the ber of traditional QPSK signal and the post-high-order QAM signal which encrypted by micro-element noise are simulated under the Gaussian white noise channel.A forward error correction coding suitable for the micro-noise-encrypted coherent optical communication system is selected.(3)The experimental platform of micro-element noise encryption coherent optical transmission system was built.The optical signal transmission experiment was carried out in 200km standard single-mode fiber,and the quality and security of the signal after long-distance transmission were analyzed.The experimental results show that due to the superior error correction performance of the LDPC code,the optical signal has a very low bit error rate even after long-distance transmission.In the case of eavesdropping,the optical signal after the micro-element noise is still very good safety.