Significant breakthrough in 6G technology at Xidian University

In the process of advancing 6G wireless communication toward ubiquitous connectivity, there is a significant demand for highly integrated, low-power, and multifunctional networks. Reconfigurable intelligent surfaces (RIS), as a core technology for optimizing wireless environments, have long faced bottlenecks such as limited functionality and low resource utilization—existing RIS solutions are mostly confined to single modes of scattering or radiation, making it difficult to simultaneously meet the needs of multiple scenarios like communication, sensing, and power supply. Additionally, their complex hardware structures and large phase quantization errors severely constrain their potential applications in 6G networks.  

The breakthrough achieved by Professor Li Long's team from Xidian University, titled "Electromagnetically Multidimensional Integrated Radiative-Scattering Reconfigurable Intelligent Surfaces," published in *National Science Review*, addresses these pain points. The 6G official account (ID: sixgmobile) reported that the team has realized multifunctional (communication, sensing, power supply) integration on a unified hardware platform, providing a key solution for advancing RIS technology.

Overall, the relevant achievements have systematically solved the core problems of traditional RIS, such as single function, high cost, limited polarization, and difficulty in multifunctional fusion, through sophisticated hardware integration design and framework innovation. For the first time, radiation scattering mode switching, arbitrary polarization control, multi initial phase integration, and "communication sensing energy supply" integration have been achieved on a unified platform. The proposed electromagnetic integrated RIS design not only reduces hardware costs and volume, The 6G official account has noticed that it has filled in the technical gap of electromagnetic radiation scattering system, provided a low-cost and highly integrated technical paradigm for 6G wireless communication, and opened up a new path for the construction of intelligent electromagnetic environment, the global coverage of the Internet of Things and other fields. The multidimensional evolution of this' smart mirror 'is laying a solid foundation for the intelligent connectivity of all things in the 6G era.

Solve the limitation of single mode and realize the hardware integration of radiation and scattering

The core weakness of traditional RIS is the inability to integrate both radiation and scattering core modes on a single platform, resulting in it being only suitable for specific scenarios - scattering mode is mostly used for non line of sight (NLOS) communication signal relay, while radiation mode can only be used as a phased array to achieve signal transmission. Multi scenario applications require the deployment of multiple hardware, which increases costs and occupies space.

The electromagnetic integrated RIS proposed in this achievement solves this problem through the superatom design of "radiation patch+3dB coupler": the radiation patch is responsible for defining the polarization characteristics, the 3dB coupler is loaded with a PIN diode, and flexible switching between the two modes is achieved through diode state switching (00/11 state corresponds to radiation mode, 01/10 state corresponds to scattering mode). In this design, radiation and scattering functions are integrated into a single hardware for the first time. The 6G official account noticed that RIS can not only form a cost-effective phased array in radiation mode, but also complete NLOS blind spot coverage in scattering mode, without the need to deploy multiple devices, greatly improving resource utilization.

Cracking the contradiction between accuracy and cost, emphasizing both error suppression and hardware simplification

The existing integrated radiation scattering RIS faces a dilemma: either low phase control accuracy (1-bit control can easily generate gate lobes, reducing transmission efficiency), or complex structure (requiring multiple PIN diodes or varactor diodes, resulting in high losses and high costs). For example, some schemes require 3 PIN diodes to achieve 1-bit phase control, or the accuracy of radiation and scattering phase control is inconsistent, making it difficult to meet practical application requirements.

This achievement solves the above contradiction through two major innovations.

One is to load different capacitors on the radiation patch and design four types of superatoms with distinct initial phases. For the first time, the four initial radiation phases (0 °, 45 °, 90 °, 135 °) and scattering phases (0 °, 90 °, 180 °, 270 °) are integrated into a single structure, effectively suppressing the grating lobes caused by 1-bit phase quantization and improving beam scanning efficiency;

The second is that only two PIN diodes can be used to achieve 1-bit phase control of radiation and scattering. If replaced with varactor diodes, continuous phase control can also be achieved, which simplifies the hardware structure, reduces costs, and ensures the flexibility of phase control.

Actual testing shows that the 12 × 12 array has a sidelobe level of ≥ 10dB within the ± 45 ° beam scanning range, and the gain fluctuation is controlled within a reasonable range, balancing accuracy and economy.

Breaking through polarization and functional limitations, supporting multifunctional integrated applications

The demand for RIS in 6G networks has extended from single communication to "communication sensing power supply" integration, but the existing RIS design framework is complex and can only support single line polarization, and cannot achieve multifunctional integration on the same platform. This makes it difficult for RIS to adapt to diverse scenarios such as radar detection and wireless energy harvesting (WEH), limiting its application in intelligent electromagnetic environments.

The antenna circuit decoupling design framework proposed in this achievement breaks this limitation: the front-end antenna can be designed as linear polarization, circular polarization or dual frequency polarization according to the demand, and the back-end circuit can adjust the amplitude and phase through the 3dB coupler. The 6G official account learned that the radiation scattering super atom design with different polarization characteristics can be achieved without modifying the circuit. At the same time, the RIS can be used as a phased array to achieve high-definition video transmission in radiation mode (stable constellation under 16-QAM modulation), complete NLOS communication blind spot coverage in scattering mode (power density increased by 3-8dB in L-shaped corridor scenarios), and achieve WEH when the PIN diode is in the 00 state, converting RF energy into DC energy for use by itself or other devices. This integrated capability of "communication sensing power supply" does not require additional hardware modules.