| （英） |
In addition to a traditional use case of high-capacity communication, the fifth generation mobile communications system (5G) includes the new use case of massive machine type communications (mMTC), that accommodates many Internet of things (IoT) device connections. To enhance the frequency efficiency of 5G systems, a non-orthogonal multiple access (NOMA) scheme that exploits a nonlinear signal processing has been proposed. In particular, as a NOMA scheme for mMTC, code-domain NOMA has been proposed in which user signals are non-orthogonally superposed in the spreading code domain, and an energy-efficient and grant-free transmission can be conducted. We have proposed a grant-free sparse chaos code multiple access (GF-SCCMA) scheme for mMTC, which applies chaos secure communication scheme into NOMA to achieve a large-capacity transmission and the physical layer security. The quality of output log-likelihood ratio (LLR) of the proposed scheme is improved because of the use of Gaussian modulated codebooks, and the performance of Gaussian belief propagation (GaBP)-based decoding improves, resulting in the realization of a large-scale transmission. In this paper, we introduce the advantage of the nonlinear signal processing of GF-SCCMA. |