This work peruses a simultaneous transmitting and reflecting reconfigurable intelligent surface (STAR-RIS) based wireless system wherein untrusted energy harvesting nodes wiretap the legitimate signal. The achievable secrecy rate and the harvested energy for multicast communication are computed as functions of STAR-RIS transmission and reflection coefficients (TARCs). Thus, to maximize the secrecy rate while satisfying the minimum required harvested energies, the non-convex optimization problem is investigated. By using the Dinkelbach transformation and semi-definite relaxation technique, the optimization problem is transformed into a convex problem. Eventually, the numerical results are reported to specify the effects of the size of the STAR-RIS and optimizing its TARCs elements on magnifying the secrecy rate-energy harvesting region.

中文翻译：

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能量收集窃听者存在时STAR-RIS的保密率分析

这项工作细读了基于同时发射和反射可重构智能表面 (STAR-RIS) 的无线系统，其中不受信任的能量收集节点窃听合法信号。多播通信的可实现保密率和收集的能量被计算为 STAR-RIS 传输和反射系数 (TARC) 的函数。因此，为了最大化保密率，同时满足所需的最小收集能量，研究了非凸优化问题。通过使用丁克尔巴赫变换和半定松弛技术，将优化问题转化为凸问题。最终，报告了数值结果，以指定 STAR-RIS 的大小和优化其 TARC 元素对放大保密率-能量收集区域的影响。