Abstract
The nonorthogonal multiple access (NOMA) techniques are considered one of the main methods to realize the goals of 5G mobile and wireless systems such as link communication reliability and high user connectivity. Yet, when the amount of simultaneously connected users increases, many concerns will arise regarding the users' data security. Various chaotic systems in the communication field have been presented to mitigate the data security concerns offering a cost-efficient technique to provide physical layer security. This work presents an uplink secure chaos-based NOMA (SCB-NOMA) system by exploiting the power domain. For signal modulation at the transmitters' node, chaos shift keying is used, with controlled transmit power to satisfy the receiver conditions. For multiuser detection, the receiver side employs successive interference cancellation with chaotic demodulation. The efficiency of designed SCB-NOMA is demonstrated by considering different power control factors, system scenarios, and chaotic sequence length compared with different reference systems. It is shown that the efficient selection of the power allocation parameter has a direct effect on the bit error rate (BER) performance. Meanwhile, when the amount of power difference for the successive interference cancellation process is not adequate, the chaotic codes maintain the desired data security and enable robust BER performance for connected users. Besides, the correlation between the utilized chaotic codes has more impact on BER regardless of the considered sequence length.
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