Peak-to-Average Power Ratio Reduction for an Artificial Noise Aided Secure Communication System

To solve the peak-to-average power ratio (PAPR) problem of the artificial noise (AN) aided secure communication system, we propose a PAPR reduction algorithm based on the rotation invariant of AN subspaces in this paper. High peaks of the transmit signal caused by in-phase superposition between information subspace and AN subspaces is cancelled by rotating AN subspaces appropriately. Furthermore, the differential evolution (DE) algorithm is also employed to search the optimum rotation angle of each AN subspace. Simulation results show that the proposed algorithm reduces the transmit signal PAPR property effectively on the premise of keeping the security capacity of this AN aided secure communication system.

I. Introduction

Because of the broadcast nature of wireless channel, the issues of privacy and security have taken on an increasingly important role in wireless communication, especially in military and homeland security applications. Traditionally, secure communication was achieved by using cryptographic technologies such as encryption. However, the perfect secrecy cannot be guaranteed if the eavesdroppers have infinite computational power such as quantum computation. Information theoretic results showed that it is possible to secure the information by employing physical layer strategy, when the desired receiver has a better channel than the eavesdropper [1].