Research On Physical Layer Encryption Performance Of Optical OFDM Based On DNA Encoding

Orthogonal frequency division multiplexing(OFDM)technology has strong anti-multipath interference ability and can effectively resist chromatic dispersion in optical communication.Therefore,the integration of OFDM and optical communication makes optical communication system have the characteristics of large-capacity,high-speed,and long-distance transmission.Meanwhile,the physical layer security of optical OFDM is also worthy of attention.As an irregular motion in nonlinear dynamic system,chaos has the characteristics of initial sensitivity,randomness,and boundedness,which is related to the cryptography.Thus,in recent years,there are many researches on the combination of chaos and physical layer encryption.In this paper,an improved DNA encoding,combined with chaotic encryption,is applied to optical OFDM communication system.Through theory analysis,simulation and experimental verification,the feasibility and reliability of each encryption scheme are discussed,and corresponding conclusions are drawn.The main research contents are given as follows:(1)An improved DNA encoding encryption is presented,and a hybrid encryption method based on orthogonal frequency division multiplexing passive optical network(OFDM-PON)is proposed.In this scheme,the binary data are encrypted by the improved DNA encoding,and then the symbols are encrypted by the spiral scrambling method.The chaotic sequences generated by the spatial generalized Logistic system are used as the encryption parameters,which can provide the key space of1?10^{13 5} and guarantee the security of the system.The simulation results show that the BER performance of the encrypted OFDM signal on 60km standard single mode fiber(SSMF)has about 1d B improvement than that of the traditional unencrypted scheme.(2)Based on the improved DNA encoding encryption,a secure transmission scheme in filter OFDM(F-OFDM)PON is proposed.In this scheme,the data are scrambled by subband-interleaved scrambling and the encryption process is controlled by the chaotic system.The proposed encryption scheme can obtain the key space of1?10^{14 2},and the security performance of the system is significantly improved.Experiments show that,after 20km SSMF transmission,the BER performance of the encrypted multi-subband F-OFDM signal has an improvement of about 0.8d B compared with the traditional F-OFDM.(3)A secure transmission scheme of radio-over-fiber(Ro F)system based on cellular neural network(CNN)and dynamic resource allocation is proposed.A seven-dimensional CNN chaotic system is constructed,and the spectrum resources are optimized by dynamic allocation.In addition,encryption mechanism is used to ensure the security of the system and the analysis shows that the proposed scheme can achieve a key space of1?10^{11 2}.The encrypted F-OFDM signal is successfully transmitted in the Ro F system of 50km SSMF and 5m wireless channel,and the experimental results show that the proposed scheme can improve the BER performance by approximately0.3d B compared with the traditional one.