Secure OFDM-Based NOMA for Machine-to-Machine Communication

Machine-to-machine communication (M2M) has obtained increasing interest in recent years. However, its enhancement and broadcasting characteristics produced a new security challenge. We have suggested a novel dynamic Quadrature Amplitude Modulation (QAM) scheme for a totally elastic and dynamic mapping of user data by using chaos. This paper analyses physical layer security methods in Orthogonal Frequency Division Multiplexing-based Nonorthogonal Multiple Access (OFDM-NOMA) and introduces a secure data transmission mechanism created by dynamic QAM. The security robustness given by the suggested encryption scheme is assessed, where an overall keyspace of ~ 10163 is achieved, which is sufficient to provide security against exhaustive attacks. The result of the scheme is verified through MATLAB simulation, where the bit error rate performance of our proposed scheme is compared with an unencrypted OFDM signal, and the performance of our proposed scheme is analyzed for an illegal user. The suggested dynamic mapping fulfills the fundamental obligations of cryptography for data security. Moreover, it enhances the level of security in OFDM-NOMA.