Reconfigurable Intelligent Surface (RIS) presents a promising solution for achieving a balance between communication quality and power consumption. However, traditional reflecting RIS designs are limited to covering signals within a 180-degree range. Fortunately, the development of Simultaneous Transmitting and Reflecting RIS (STAR-RIS) technology enables the simultaneous transmission and reflection of signals, allowing for 360-degree coverage. In this letter, we investigate the STAR-RIS assisted wireless communications under Nakagami-m fading channels, and the channel state information (CSI) is assumed perfectly obtained. Considering the hardware design complexity, the RIS phase shifts are discretely configured with quantization errors. We derive the closed-form expressions of the outage probability and the ergodic achievable rate under the discrete phase. In addition, the approximations for the special cases including the random phase case, the continuous phase case, the Rayleigh fading case, as well as the high signal-noise ratio (SNR) case are further deduced. Numerical results verify the correctness of the analytical results.

中文翻译：

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STAR-RIS 辅助无线通信，带分立式移相器


可重构智能表面 （RIS） 为实现通信质量和功耗之间的平衡提供了一种有前途的解决方案。然而，传统的反射 RIS 设计仅限于覆盖 180 度范围内的信号。幸运的是，同步传输和反射 RIS （STAR-RIS） 技术的发展实现了信号的同时传输和反射，从而实现 360 度覆盖。在本文中，我们研究了 Nakagami-m 衰落信道下的 STAR-RIS 辅助无线通信，并假设获得了完美的信道状态信息 （CSI）。考虑到硬件设计的复杂性，RIS 相移离散地配置了量化误差。我们推导出离散阶段下中断概率和遍历可实现率的闭式表达式。此外，进一步推导了特殊情况的近似值，包括随机相位情况、连续相位情况、瑞利衰落情况以及高信噪比 （SNR） 情况。数值结果验证了分析结果的正确性。