In the rapidly evolving landscape of wireless communication, the situation is continuously changing as researchers strive toward more advanced, efficient technologies. One of the most promising frontiers lies in the integration of reconfigurable intelligent surfaces (RIS). These surfaces, capable of dynamically manipulating electromagnetic waves, herald a significant leap forward in 5G-Advanced and 6G communications. They promise not only to enhance connectivity across networks, devices, and applications but also to facilitate integrated sensing and communication.
The ambitious objective of interconnecting all entities capable of network interaction defines the quest for a more intelligent global ecosystem. Behind this vision resides a challenge: the existing architectures of RIS systems often struggle with centralized control mechanisms, leading to inadequate use of hardware resources. These limitations pose critical barriers to the anticipated capabilities of future wireless networks, demanding innovations that reflect high integration and low power consumption.
Recent groundbreaking research published in the prestigious National Science Review has introduced a new paradigm in electromagnetic design. A team led by Professor Long Li from Xidian University in China has conceptualized an all-in-one radiation-scattering RIS. This innovative design provides a unified framework for manipulating electromagnetic properties, thus leading to enhanced functionality in automatic control of radiation and scattering states. This evolution facilitates the on-demand design of RIS technologies, significantly shaping the future of sixth-generation wireless communications.
Central to the functionality of this new RIS architecture is a specially designed meta-atom that combines a radiating patch with a 3 dB coupler. The radiating patch serves to establish the desired polarization and frequency characteristics essential for effective communication. Integrating PIN diodes on the coupler allows the structure to switch between radiation and scattering modes seamlessly—an essential feature for versatile communication applications. This development efficiently combines initial radiation and scattering phases, marking the first time such integration has been realized within a single structure.
Experimentation has revealed that the meta-atoms exhibit remarkable amplitude control, phase control, and customizable initial phase characteristics. Functionally, the system can be switched to operate in either radiation or scattering modes, with optimal performance achieved via the inclusion of different capacitors on the radiating patches. This intricate design enables a wide array of potential applications in wireless sensor networks as well as enhancing overall communication efficiency.
The research team’s detailed exploration of the meta-atom began with a linearly polarized 1-bit radiation-scattering configuration drawing focus to a U-slot patch interconnected with a specialized 3 dB coupler. The crucial aspect of controlling the state of the PIN diode facilitates two distinct modes of operation. States of ’11’ or ’00’ allow for 1-bit radiation phase control, while states of ’10’ and ’01’ enable 1-bit scattering phase control. However, quantization errors in these 1-bit controls lead to grating lobes, which could compromise operational performance.
To mitigate these issues, the researchers incorporated capacitors into their initial design, associating varied capacitors with specific initial phases. This experimental approach culminated in the design of four prototype U-slot patches, each capable of generating unique scattering and radiation phases. The calculated initial phase distribution remains pivotal for accurate beam steering, which underpins the RIS’s capability for effective communication, showcasing a successful mapping of initial phase distributions onto a configured 12×12 radiation-scattering RIS.
The implications of this advanced RIS extend far beyond mere technical efficiency. An integrated approach to communication, sensing, decision-making, and power supply introduces a comprehensive hardware platform which simplifies system architecture and enhances functionality. The metasurface operates in transmit mode to relay predefined signals, subsequently routing commands to sensor nodes that respond by transmitting data back to the core network.
In receiving mode, the RIS can autonomously analyze electromagnetic environmental changes and localize sensor nodes, further initiating wireless power transfers. This represents an innovative stride towards real-time decision-making capabilities within wireless sensor networks. In addition to its sensing capabilities, the metasurface can also capture and rectify energy from wireless sources, providing an inherent self-sufficient power solution that could be vital for numerous applications in IoT and beyond.
In practical implementations, a 12×12 metasurface was manufactured and verified for low-cost phased array applications in radiation mode. The experimental data showed that the metasurface achieved single-beam scanning across a ±45° coverage range without the interference of grating lobes. The sidelobe levels were consistently maintained below a threshold of 10 dB, illustrating exceptional communication efficiency. Additionally, under ’00’ conditions during radiation mode, the system also showcased proficiency in wireless energy harvesting, opening possibilities for empowering sensor nodes and devices in the evolving technological landscape.
Transitioning to function in scattering mode further underscored the practical applications of this RIS technology. Field tests in conditions that typically hinder communication, such as in L-shaped corridors prone to blind zones, resulted in successfully controlling the direction of the reflected beam and achieving significant gains in signal strength. Signals reflecting off the metasurface within these challenging environments experienced an average boost in power density of around 7 dB, suggesting dramatic improvements in communication quality even under adverse conditions.
As the race to unlock cutting-edge wireless communication capabilities accelerates, innovations such as the all-in-one radiation-scattering RIS exemplify the potential of future networks. This research not only offers tangible solutions to current limitations but also provides invaluable insights into the comprehensive integration of sensing, communication, and decision-making in a single platform. The shift towards self-sustaining systems capable of real-time data processing could very well define the next generation of interconnected technologies, paving the way for smarter, more resilient networks equipped for challenges yet unseen.
In conclusion, the work presented by Professor Long Li and his team illustrates a critical step in realizing the vision of comprehensive connectivity in 6G networks. By providing both a theoretical framework for effective electromagnetic control and a practical platform for diverse applications, this advancement holds the capacity to redefine what interconnected systems can achieve. The future is poised for a revolution in wireless communication that intertwines technology and everyday life in unprecedented ways, placing the capabilities of our devices firmly in the hands of transformative scientific progress.
Subject of Research: All-in-One Radiation-Scattering Reconfigurable Intelligent Surfaces
Article Title: Innovative All-In-One Radiation-Scattering Technology Enhances 6G Communication
News Publication Date: Expected in Late October 2023
Web References: National Science Review
References: National Science Review
Image Credits: ©Science China Press
Keywords
Reconfigurable Intelligent Surfaces, Wireless Communication, 6G Technology, Electromagnetic Waves, Integrated Sensing and Communication, Power Supply, Energy Harvesting, Metasurfaces, Communication Networks, Smart Devices, Internet of Things, Beam Steering
