Reconfigurable intelligent surfaces (RISs) have been considered as a promising technology for the sixth-generation (6G) wireless networks that can control wireless channels in a desirable way and significantly enhance the network performance. Simultaneous transmitting and reflecting-RISs (STAR-RISs) can overcome limitation of reflecting-only RISs by leveraging the higher design flexibility and full-space coverage. Despite the benefits, the modeling and analysis of STAR-RISs are complicated because of various control parameters for both transmission and reflection links. In this article, a general framework to facilitate the design and implementation of STAR-RISs in 6G scenarios and network topologies is presented. We provide a systematic introduction to the STAR-RIS operating protocols for different communication modes and discuss recent efforts to identify the research progress and combination solutions. Finally, we provide the design concepts, research challenges, potential solutions, and future directions related to the channel modeling, channel estimation, hardware implementations, modeling and limitations, and optimization.
翻译:重新配置的智能表面(RIS)被认为是第六代(6G)无线网络的一个大有希望的技术,能够以可取的方式控制无线频道,并大大提高网络的性能;同时传输和反射RIS(STAR-RIS)能够通过利用较高的设计灵活性和全空间覆盖,克服仅反映性RIS的限制;尽管好处很大,但STRA-RIS的建模和分析由于传输和反射联系的各种控制参数而变得复杂;在本条中,介绍了一个总框架,以便利在6G情景和网络结构中设计和实施STAR-RIS。我们系统地介绍了STRA-RIS的不同通信模式操作协议,并讨论了最近为确定研究进展和综合解决办法所作的努力。最后,我们提供了与频道建模、频道估计、硬件安装、建模和限制以及优化有关的设计概念、研究挑战、潜在解决办法和未来方向。