Simultaneously Transmitting And Reflecting Surfaces (STARS) for Multi-Functional 6G

TL;DR

The paper surveys Simultaneously Transmitting And Reflecting Surfaces (STARS) as a versatile enabler for multi-functional 6G, classifying STARS by power amplification, reciprocity, and element density; it outlines three sensing architectures (monostatic, bistatic, and target-mounted STARS) and investigates STARS-enabled computing (MEC and AirComp) and caching (caching-at-STARS). It discusses design trade-offs between passive and active, reciprocal and non-reciprocal, and patch-array versus metasurface implementations, and provides quantitative insights into SNR scaling. The article also highlights practical deployments, potential use cases, and state-of-the-art standardization efforts (ITU, ETSI) shaping future integration. Overall, STARS offer a path to 360° coverage, enhanced DoFs, and cross-functional capabilities that could significantly improve communication, sensing, computation, and content delivery in 6G, while also presenting hardware, synchronization, and modeling challenges to be addressed.

Abstract

Simultaneously transmitting and reflecting surface (STARS) empowered multi-functional 6G wireless networks are investigated. Starting with the communication functionality, various types of STARS are introduced in terms of power amplification capabilities, reciprocity features, and spatial density of elements. Then, three STARS-empowered wireless sensing architectures are proposed, namely STARS-aided monostatic sensing, STARS-enabled bistatic sensing, and sensing with target-mounted STARS, where the representative benefits and application challenges are identified. Furthermore, promising applications of STARS for computing and caching functionalities are explored to improve the computation efficiency and reduce the content delivery latency. Finally, recent standardization progress for reconfigurable intelligent surfaces is presented for motivating the employment of STARS in multi-functional 6G.

Figures (6)

• Figure 1: Applications of STARS in multi-functional 6G.
• Figure 2: Different types of STARS employed in wireless communications.
• Figure 3: SNR scaling laws achieved by active and passive STARS for transmitted/reflected (T/R) users. The simulation parameters can be found in 10163896.
• Figure 4: Conceptual illustration of three proposed sensing architecture utilizing STARS: (a) (a) STARS-aided monostatic sensing, where the transmission sensing node also serves as the reception node; (b) STARS-enabled bistatic sensing, where STARS functions as the reception node with the aid of active sensors; and (c) Sensing with target-mounted STARS, where STARS controls signal reflection at the target and enhances the communication service inside the target.
• Figure 5: STARS for Computing in 6G.