Physical Layer Security Technology Based on Nonorthogonal Multiple Access Communication

Abstract

NOMA (nonorthogonal multiple access) technology is an effective technical means to improve spectral efficiency and system capacity. At present, due to the proliferation of access devices and other reasons, the network security communication is facing very serious challenges. This research combines TAS (antenna selection) technology and AN (artificial noise) technology, applies them to NOMA system, and proposes a physical layer optimized security transmission scheme in which AN signals are superimposed at the base station. In this scheme, a part of the total power is divided into the AN signal, and the AN signal and the useful information are superimposed and encoded for transmission. The exact solution of SOP and the asymptotic solution under high signal-to-noise ratio are obtained by mathematical derivation. Moreover, the influence of the power allocation coefficient and target rate of legitimate users on the security performance of the physical layer is explored. The study found that when the solution proposed in this study is adopted, when the fixed SOP size is 10−2, taking the ideal SOP curve as the benchmark, it can be observed that the RHI only occurs when the user node is eavesdropped, and performance improvement of about 2 dB can be obtained. This is because only the system eavesdropping user performance is degraded at this time, so the security performance is improved. In addition, under the same SOP performance, the user is closer to the legal node and can obtain a better channel to resist fading and eavesdropping. The scheme proposed in this study effectively improves the security performance of the NOMA scenario and provides some theoretical guidance for the design process of the secure communication system.