In this article, we investigate the performance of a reconfigurable intelligent surface (RIS)-assisted dual-hop mixed radio-frequency underwater wireless optical communication (RF-UWOC) system. An RIS is an emerging and low-cost technology that aims to enhance the strength of the received signal, thus improving the system performance. In the considered system setup, a ground source does not have a reliable direct link to a given marine buoy and communicates with it through an RIS installed on a building. In particular, the fixed buoy acts as a relay that sends the signal to an underwater destination. In this context, analytical expressions for the outage probability (OP), average bit error rate (ABER), and average channel capacity (ACC) are derived assuming fixed-gain amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols at the marine buoy. Moreover, asymptotic analyses of the OP and ABER are carried out in order to gain further insights from the analytical frameworks. In particular, the system diversity order is derived and it is shown to depend on the RF link parameters and on the detection schemes of the UWOC link. Finally, it is demonstrated that RIS-assisted systems can effectively improve the performance of mixed dual-hop RF-UWOC systems.

中文翻译：

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关于RIS辅助双跳混合RF-UWOC系统的性能

在本文中，我们研究了可重构智能表面 (RIS) 辅助双跳混合射频水下无线光通信 (RF-UWOC) 系统的性能。RIS 是一种新兴的低成本技术，旨在增强接收信号的强度，从而提高系统性能。在所考虑的系统设置中，地源与给定的海洋浮标没有可靠的直接链接，而是通过安装在建筑物上的 RIS 与其通信。特别是，固定浮标充当将信号发送到水下目的地的中继器。在这种情况下，中断概率 (OP)、平均误码率 (ABER)、假设在海洋浮标处采用固定增益放大转发 (AF) 和解码转发 (DF) 中继协议，推导出平均信道容量 (ACC)。此外，还对 OP 和 ABER 进行了渐近分析，以便从分析框架中获得进一步的见解。特别是，系统分集阶数被推导出来，它取决于射频链路参数和 UWOC 链路的检测方案。最后，证明了RIS辅助系统可以有效提高混合双跳RF-UWOC系统的性能。系统分集阶数被推导出来，它取决于射频链路参数和 UWOC 链路的检测方案。最后，证明了RIS辅助系统可以有效提高混合双跳RF-UWOC系统的性能。系统分集阶数被推导出来，它取决于射频链路参数和 UWOC 链路的检测方案。最后，证明了RIS辅助系统可以有效提高混合双跳RF-UWOC系统的性能。