The Physical Layer Encryption Algorithm Based On Artificial Noise Spectrum Coverage In OFDM System

With the development of wireless communication technology in the field of broadband,integration,intelligence and ubiquitization,the security problems are becoming more and more serious,thus making traditional link layer encryption algorithm being challenged a lot.So,physical layer encryption algorithms become popular these days.However,a large number of existing physical layer encryption algorithms are based on baseband symbol operation of the physical layer.And they don't take much attention to the spectrum leakage in RF domain.Therefore,the system can be easily attacked.In this paper,a anti-attacking method was discussed based on the analyses of OFDM signal spectrum characteristics.And two successful attacking cases was presented.Furthremore,a physical layer encryption algorithm is designed by adding artificial noise to suppress carrier leakage.These noises are ruled by encryption key and have special sprectrum.After adding them to original OFDM signals,two kinds of spectrum can interact with each other in frequency domain,which can ensure the security of original OFDM signals and to some extent,noise spectrum can also be protected.The results of theoretical analyses and simulation show that the noise can effectively destroy the orthogonality between subcarriers,and can cover and interfere with the spectrum of the original system.At the same time,it reaches the purpose of suppressing the leakage of information carrier.The algorithm has high robust performance and lower space complexity.It also brings little impact on the original system bandwidth,peak ratio and bit error rate.