Iterative Encrypted OFDM Physical Layer Security Algorithm

With the continuous development of wireless communication system toward broadband and integration, it has faced increasingly serious security threats. In order to make up for the deficiency of traditional security algorithms and meet the new safety requirements of air interface protection in wireless communication system, the research on physical layer security algorithms combined with OFDM modulation has caused more and more attention.In this paper, a physical layer security algorithm combined with OFDM modulation is proposed, in order to overcome the disadvantages of the existing physical layer security algorithms which can not resist plaintext cipher-text attack. The modulation process is controlled by a secret key, namely the iterative interpolation of the transformation step of IFFT-FFT. Through several times of iterative interpolation, the size and location of the original data symbols have changed, making the key and the plaintext cipher-text into a complicated nonlinear relationship. Theoretical analysis and simulation results have showed that the algorithm not only has a large key space, but also can resist plaintext cipher-text attack. With almost no obviously impact on the original system performance except for a small noise SER and PAPR increase, the proposed algorithm has a good effect on encryption and anti-attack ability, which can realize effective air interface protection.