Research Of Physical Layer Encryption Technology Based On The Characteristics Of Wireless Channels

Nowadays,wireless communication technology is widely used,and new security threats and vulnerabilities are also increasing.Due to the broadcast characteristics of the wireless channel and the rapid development of the interception technology,the eavesdropper can obtain the information which can not be protected by the traditional security policy such as the modulation method and the channel coding type of the legal communication by certain means,and then use this information to guess the communication intention,and even infer the plaintext information.Physical layer security encryption technology aims to use the nature of the wireless channel characteristics to achieve security protection for modulation signal and coding information in the physical layer.This paper studies the two levels of modulation and channel coding respectively,Firstly,the physical layer encryption algorithm based on multi-dimensional modulation in Orthogonal Frequency Division Multiplexing(OFDM)system is studied for the security of modulation layer.Based on the basic principle of physical layer modulation,the phase randomization signal is used to detect the channel and extract the equivalent channel phase information.The information of the constellation is protected and the receiver decrypts the demodulation.The proposed scheme makes full use of the randomness,reciprocity and location sensitivity of the phase response of the wireless channel,and uses this feature to enhance the security of the physical layer signal.Theoretical analysis and computer simulation results show that the algorithm can achieve high security,and the three-dimensional constellation modulation is about 2.5dB better on bit error rate(BER)performance compared to the traditional quadrature phase shift keying(QPSK)modulation.Secondly,a physical layer coded cryptographic transmission algorithm based on chaotic sequence is proposed for the security of channel coding layer.On the basis of fully analyzing the ECBC(Error Correction Based Cipher)system,the proposed algorithm is used to extract the binary key by using the wireless channel and transform it into the initial value of the chaotic system,and generate the chaotic sequence to realize the protection of the physical layer coding information.In addition,the idea of soft XOR is proposed to ensure the reliability of the system.Theoretical analysis and simulation results show that the proposed encryption algorithm can restore the error correction performance of channel coding,and compared to the ECBC algorithm,it can achieve higher security.What's more,the proposed algorithm can improve the key quantity and ensure the security of data transmission.Finally,on the basis of summarizing the research work,the paper points out the aspects to be improved,and looks forward to the follow-up research direction of the physical layer encryption technology based on wireless channel.