Reconfigurable intelligent surface (RIS) has been recognized as a promising technique for the sixth generation (6G) of mobile communication networks. The key feature of RIS is to reconfigure the propagation environment via smart signal reflections. In addition, active RIS schemes have been recently proposed to overcome the deep path loss attenuation inherent in the RIS-aided communication systems. Accordingly, this paper considers the secrecy performance of up-link RIS-aided multiple users multiple-input single-output (MU-MISO) communication systems, in the presence of multiple passive eavesdroppers. In contrast to the existing works, we investigate the impact of the RIS phase shift errors on the secrecy performance. Taking into account the complex environment, where a general Rician channel model is adopted for all the communication links, closed-form approximate expressions for the ergodic secrecy rate are derived for three RIS configurations, namely, i) passive RIS, ii) active RIS, iii) active RIS with energy harvesting (EH RIS). Then, based on the derived expressions, we optimize the phase shifts at the RIS to enhance the system performance. In addition, the best RIS configuration selection is considered for a given target secrecy rate and amount of the power available at the users. Finally, Monte-Carlo simulations are provided to verify the accuracy of the analysis, and the impact of different system parameters on the secrecy performance is investigated. The results in this paper show that, an active RIS scheme can be implemented to enhance the secrecy performance of RIS-aided communication systems with phase shift errors, especially when the users have limited transmission power.
翻译:对移动通信网络第六代(6G)而言,可重新配置的智能表面(RIS)被认为是一种很有希望的技术。RIS的主要特征是通过智能信号反射重新配置传播环境。此外,最近还提出了积极的RIS计划,以克服RIS辅助通信系统固有的深度路径损失减弱现象。因此,本文件认为,在多个移动通信网络第六代(6G)存在多个被动式监听器的情况下,由RIS辅助的多个用户提供的多输入单输出(MU-MISO)通信系统的保密性能。与现有的工程相比,我们调查了RIS阶段转换错误对保密性能的影响。考虑到复杂的环境,所有通信连接都采用了通用Rician频道模型,因此,在三个TRIS配置中,即(iS)被动式,(二)主动式的RIS,(三)主动式的RIS,(ERS)和(EH RIS)收集能源的积极性能反应系统(E)的保密性能。然后,根据衍生的表达方式,我们优化了RISS阶段的精确性变换,特别是目标用户在升级阶段的精确度,在升级的系统上可以提高性能。