A downlink non-orthogonal multiple access scheme having physical layer security

In recent years, the standardization for the fifth generation (5G) mobile communication systems has been actively discussed, and it is expected that a large number of wireless communication terminals, and beyond, in the current systems are accommodated in 5G systems. One of the steps in establishing this system is an advanced multiple access technology. In this paper, we propose a chaos non-orthogonal multiple access (C-NOMA) scheme for downlink transmission that offers high capacity allocation and secure wireless multiple access with physical layer security. In 5G systems where many terminals concurrently communicate, it is also important to ensure communication integrity for each user while maintaining large capacity communication. As a secure wireless channel-coded communication scheme, we have proposed a chaos multiple-input multiple-output (C-MIMO) scheme using the principle of chaos communication. By applying C-MIMO into a power-domain non-orthogonal multiple access transmission, we were able to demonstrate the operation and suitability of the C-NOMA configuration for handling both large capacity and physical layer security against eavesdroppers. We also demonstrated its improved performances through numerical simulations, and provided comparisons with those of conventional NOMA and chaos orthogonal frequency division multiple access schemes. In addition, we evaluated the security capability of the proposed technique based on the channel capacity of eavesdroppers and showed that secure transmission can be achieved using floating-point calculations.