Impact of Phase-Shift Error on the Secrecy Performance of Uplink RIS Communication Systems
Impact of Phase-Shift Error on the Secrecy Performance of Uplink RIS Communication Systems
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DOI：
10.48550/arxiv.2301.00276
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发表时间：
2022-12
期刊：
影响因子：
--
通讯作者：
Abdelhamid Salem;K. Wong;C. Chae
中科院分区：
文献类型：
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作者：
Abdelhamid Salem;K. Wong;C. Chae
可重构智能表面（RIS）已被认为是第六代（6G）移动通信网络的一项有前途的技术。 RIS 的关键功能是通过智能信号反射重新配置传播环境。此外，最近提出了有源 RIS 方案来克服 RIS 辅助通信系统中固有的深度路径损耗衰减。因此，本文考虑了在存在多个被动窃听者的情况下上行链路 RIS 辅助的多用户多输入单输出 (MU-MISO) 通信系统的保密性能。与现有的工作相比，我们研究了 RIS 相移误差对保密性能的影响。考虑到复杂环境，所有通信链路均采用通用莱斯信道模型，针对三种 RIS 配置导出了遍历保密率的封闭式近似表达式，即 i）被动 RIS，ii）主动 RIS，iii）具有能量收集的主动 RIS（EH RIS）。然后，根据导出的表达式，我们优化 RIS 处的相移以提高系统性能。此外，针对给定的目标保密率和用户可用的电量，会考虑最佳的 RIS 配置选择。最后，通过蒙特卡罗仿真验证了分析的准确性，并研究了不同系统参数对保密性能的影响。本文的结果表明，可以实施主动 RIS 方案来增强带有相移误差的 RIS 辅助通信系统的保密性能，特别是当用户的传输功率有限时。
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.