SCMA Secure Communication Scheme for Satellite System Based on Distance Spectrum

We propose a novel physical layer security scheme applied to SCMA communication for satellite system, called SCMA secure communication based on distance spectrum. SCMA is an important alternative of non-orthogonal multiple access (NOMA) in the fifth generation mobile communication system, due to its superior overload transmission. This paper aims at designing SCMA codebooks based on distance spectrum, which involves parameter design, phase rotation, mapping, and sparse spreading. In addition, this paper shows that, in the multi- satellite communication links, the phase of the legitimate user channel is used as the key to be integrated into the satellite SCMA secure communication codebook structure to reduce the probability of being intercepted. Simulation results show that the proposed algorithm effectively improves the safety of satellite communication links on the basis of ensuring that the overload transmission performance is not affected, and provides a valuable reference for the practical application of sparse code division multiple access.