Performance Analysis of RIS-Aided Communications based on Student-T Copula

Reconfigurable intelligent surface (RIS) has received remarkable attention for its potential to improve the capacity and coverage of wireless communication networks. In this paper, we evaluate the performance of RIS-assisted communication systems in the presence of phase noise with the help of Student-T copula in two scenarios. The first one is the cascade link or RIS link and the second scenario involves direct link in conjunction with cascade link. In particular, we first analyze the probability density function and the cumulative distribution function of the signal-to-noise-ratio with/without direct link. Then, we investigate the outage probability and ergodic capacity of the RIS-assisted network by using Student- T copula function to characterize the non-linear dependency among the signal components. Furthermore, we reveal the relation between the Student- T copula dependency parameter and Pearson correlation coefficient. Finally, numerical results are presented confirm the validity of the analytical closed-form expressions.