Adaptive resource allocation of secured access to intelligent surface enhanced satellite–terrestrial networks with two directional traffics

In this paper, we study the secured access to the satellite–terrestrial networks of 6G with two directional traffics. Both access point (AP) and the sensor node in the terrestrial networks simultaneously transmit messages to each other. The passive reflection surface technique is employed to assist both directional traffics. Meanwhile, the satellite as the eavesdropper is keeping on receiving both messages by equipping multiple antennas on this illegal receiver. Specifically, we formulate the adaptive power design problem for both AP and the sensor node, respectively, as the transmitter of the downlink and the uplink traffic in terrestrial networks. The objective function is the energy efficiency maximization and the constraint is the maximum overall data rate of the illegal eavesdropper over the satellite networks. The closed form expression is mathematically derived for the optimum solution. The obtained approach achieves the best performance for the terrestrial networks from the energy efficiency point of view. Moreover, it assures any quality of service requirement concerning the security of the whole satellite–terrestrial networks of 6G. Our approach is numerically verified by the Monte Carlo simulations.