This letter considers the secure communication in a reconfigurable intelligent surface (RIS) aided full duplex (FD) system. An FD base station (BS) serves an uplink (UL) user and a downlink (DL) user simultaneously over the same time-frequency dimension assisted by a RIS in the presence of an eavesdropper. In addition, the artificial noise (AN) is also applied to interfere the eavesdropper's channel. We aim to maximize the sum secrecy rate of UL and DL users by jointly optimizing the transmit beamforming, receive beamforming and AN covariance matrix at the BS, and passive beamforming at the RIS. To handle the non-convex problem, we decompose it into tractable subproblems and propose an efficient algorithm based on alternating optimization framework. Specifically, the receive beamforming is derived as a closed-form solution while other variables are obtained by using semidefinite relaxation (SDR) method and successive convex approximation (SCA) algorithm. Simulation results demonstrate the superior performance of our proposed scheme compared to other baseline schemes.
翻译:本信考虑在可重新配置的智能表面(RIS)辅助的全复式(FD)系统中的安全通信。FD基地站(BS)同时服务于同一时间频度的上链(UL)用户和下链(DL)用户,同时由RIS协助,在窃听器面前进行窃听器;此外,人工噪音(AN)还用于干扰窃听器的频道。我们的目标是通过联合优化传输波束成型、在BS接收波形和AAN共变矩阵、在IRS接收被动成型矩阵,最大限度地提高UL和DL用户的总保密率。为了处理非连接问题,我们将其分解为可移动的子方案,并根据交替优化框架提出高效的算法。具体地说,接收波形是作为一种封闭式解决办法产生的,而其他变量则通过使用半定式放松(SDR)法和连续的同源化(SCA)算法获得。模拟结果显示我们拟议方案与其他基线方案相比的优性表现。