Secrecy Capacity Analysis Using Nonlinear Transmissions for Physical Layer Security

In this paper, physical layer security is investigated, which is characterized by utilizing the physical layer characteristics to achieve secure transmissions without adopting encryption or decryption. In order to acquire the secrecy capacity, we propose to employ the nonlinear transmission, where the operating point of the power amplifier is set to be relatively high, so that the transmitted signal displays obvious nonlinear property. At the receiver side, the legitimate user can carry out the nonlinear reception scheme utilizing the predesigned training information, which is unavailable for the wiretap channel. Consequently, the eavesdropper could hardly decode the messages correctly from the received nonlinearly distorted signal, leading to an effective enhancement of secrecy capacity. To validate the secrecy performance of this approach, nonlinearity cancellation algorithm is employed at the confidential receiver, while OFDM and single carrier systems are exploited in the simulations. Numerical results show that the proposed nonlinear transmission method has the capability in achieving the secrecy capacity for physical layer security.