Copula Theory based Investigation of the Physical Layer Security Performances for Downlink Non-Orthogonal Multiple Access(NOMA) Channel with Dependent Fading Coefficients

Abstract In wireless communications, it is often assumed that the channel coefficients are independent, while there physically exists correlations between them. In this paper, considering physical layer security in downlink NOMA channel with dependent coefficients, important wireless performances (the average secrecy rates (ASR) and the secrecy coverage regions (SCR) are investigated, by using Copula theory. Specifically, the effect of channel coefficients correlation on the performances is analyzed. Based on the results of mathematical investigations and numerical results, we found that the effect of correlations between channels can improve performances or be harmful.