By moving from massive antennas to antenna surfaces for software-defined wireless systems, the reconfigurable intelligent surfaces (RISs) rely on arrays of unit cells to control the scattering and reflection profiles of signals, mitigating the propagation loss and multipath attenuation, and thereby improving the coverage and spectral efficiency. In this paper, covert communication is considered in the presence of the RIS. While there is an ongoing transmission boosted by the RIS, both the intended receiver and an eavesdropper individually try to detect this transmission using their own deep neural network (DNN) classifiers. The RIS interaction vector is designed by balancing two (potentially conflicting) objectives of focusing the transmitted signal to the receiver and keeping the transmitted signal away from the eavesdropper. To boost covert communications, adversarial perturbations are added to signals at the transmitter to fool the eavesdropper's classifier while keeping the effect on the receiver low. Results from different network topologies show that adversarial perturbation and RIS interaction vector can be jointly designed to effectively increase the signal detection accuracy at the receiver while reducing the detection accuracy at the eavesdropper to enable covert communications.
翻译:通过从大型天线向软件定义的无线系统天线表面移动,可重新配置的智能表面依靠单元细胞阵列来控制信号的散射和反射剖面,减少传播损耗和多路衰减,从而提高光谱效率。在本文中,在RIS面前考虑隐蔽通信。虽然有RIS推动的不断传输,但预定接收器和窃听器都个别地试图利用它们自己的深神经网络分类器探测这种传输。RIS互动矢量通过平衡两个(可能相互冲突)目标来设计,即将传输信号集中到接收器并保持传送信号远离电子窃听器。为了促进隐蔽通信,在发射机的信号中添加了对抗性扰动干扰,以愚弄电子窃听器的分解器,同时保持对接收器的影响低。不同网络的表象显示,对对敌性扰和IRS互动矢量可共同设计,以有效提高电子接收器的信号探测准确度,同时降低接收器的精确度。