Two-Way Cognitive Network supported by Reconfigurable Intelligent Surface

In this paper, we propose an underlay two-way (UTW) scheme in which two secondary sources transmit simultaneously their data to each other through the Reconfigurable Intelligent Surface (RIS). The proposed scheme is designed to operate in the full-duplex mode under an interference constraint of a primary receiver (PR). The exact closed-form expressions of outage probabilities are considered to evaluate the system performance. The results show that the secondary system performance increases as the number of reflected elements, the distances between PR and secondary sources, the maximum interference power-noise ratio at primary receivers (Q dB), and the maximum signal-noise ratio at the secondary sources (γ
0
dB) increase. Moreover, if the value of the Q or the γ
0
is large enough, the outage probabilities of the secondary network will fall into a saturation state. Finally, the Monte Carlo simulation results are collected to evidence the validity of the analytical expressions of the outage probabilities.