A groundbreaking revelation in the realm of wireless communications has emerged, presenting a paradigm shift that intertwines cutting-edge metamaterials engineering with sustainable energy harvesting. Researchers have introduced an innovative ambient-energy-driven space-time-coding metasurface (ASTCM), a remarkable technology that seamlessly integrates ambient solar energy harvesting with dynamic electromagnetic (EM) wave manipulation and multi-channel information transmission. Published recently in the prestigious journal Opto-Electronic Advances, this breakthrough promises to redefine the architecture of future wireless communication systems by enhancing capacity, energy efficiency, and user accessibility, all while promoting green and sustainable methodologies.
Programmable metasurfaces, also widely recognized as reconfigurable intelligent surfaces (RIS), have rapidly ascended as pivotal components in the evolution of next-generation wireless communications. Their intrinsic ability to manipulate electromagnetic waves with exceptional precision and flexibility, combined with their advantages such as low cost and integrability, has unlocked unprecedented possibilities. Traditionally, programmable metasurfaces have been employed primarily in two contexts: passive relaying surfaces that optimize channel propagation through spatial beamforming and rudimentary communication systems that modulate information directly on scattered waves. However, the drive towards augmenting transmission capacity and enabling simultaneous multi-user access necessitates more sophisticated multiplexing strategies.
Recent investigations have explored multiplexing schemes built on programmable metasurfaces, utilizing dimensions such as frequency, space, polarization, and combinations thereof to intricately encode and transmit data. Such approaches include frequency-division, space-division, space-frequency-division, and space-frequency-polarization-division multiplexing, all designed to expand the data throughput and user connectivity. Despite these advancements, the full potential of programmable metasurfaces remains underexploited, particularly concerning efficient manipulation across multiple electromagnetic dimensions to multiply independent communication channels, a critical factor in zooming towards ultra-high-capacity systems.
A significant hurdle in the widespread application of programmed metasurfaces has been their reliance on external power sources. Devices dependent on discrete power supplies suffer from increased bulk, operational complexity, and elevated costs, ultimately limiting scalability and deployment flexibility. While the scientific community has recently made strides in self-powered metasurfaces capable of harvesting ambient energy—such as through RF energy, solar power, and mechanical vibrations—these often depend on external, cumbersome energy harvesting peripherals. The result is devices with bulky footprints, poor integration, and difficulty adapting to large-scale metasurface arrays.
The newly proposed ambient-energy-driven space-time-coding metasurface (ASTCM) addresses these challenges innovatively. By heterogeneously integrating miniature solar cell chips directly onto each meta-atom unit of the metasurface, this design marries electromagnetic control and energy harvesting within a unified physical aperture. This dual-purpose integration allows the ASTCM to simultaneously manipulate the reflection properties of EM waves and convert ambient solar energy into electrical power. Such an approach not only slashes device complexity and size but also fosters scalability and practical applicability for future communication infrastructure.
Crucially, the researchers developed an advanced space-time coding scheme enabling the ASTCM to perform independent multi-beamforming across multiple harmonic frequencies simultaneously. Unlike conventional metasurfaces that primarily operate at a single frequency or beam, this capability enables simultaneous steering of different frequency components into distinct spatial directions. By further modulating the phase of each formed beam, the system effectively multiplexes both frequency and spatial resources, constructing numerous independent and parallel channels for information transmission. This multidimensional multiplexing markedly improves communication throughput and serves as a backbone for multi-user access.
To ensure operational autonomy, a solar power management circuit (SPMC) was ingeniously integrated with the ASTCM to store harvested energy and regulate supply to the metasurface and its control electronics. The entire system, including the back-end control circuitry, was designed with low-power consumption principles, drastically reducing energy requirements. This efficient power management framework ensures that the solar energy collected from ambient light not only supports the metasurface’s wave manipulation functions but also maintains continuous system operation without reliance on external electrical sources.
The research team demonstrated the viability of the ASTCM through a sophisticated prototype embodying a self-powered four-channel wireless communication system. This prototype leverages the ASTCM’s multi-frequency multi-beamforming prowess, forming four independent communication channels by combining two harmonic frequencies with two spatial beam directions. Each channel employs quadrature phase shift keying (QPSK) as the modulation scheme, ensuring high data integrity and spectral efficiency. The experimental validation revealed the system’s ability to simultaneously, independently, and in real-time transmit distinct image streams to four receiver terminals, showcasing its practical multi-user communication potential.
Energy efficiency stands out as a paramount achievement of this ASTCM-based communication system. The prototype achieves an exceptionally low power consumption rate of approximately 17.4 milliwatts per bit, setting new benchmarks in energy savings within metasurface-based wireless communication technologies. Concurrently, the device can harvest solar energy at rates up to 12 milliwatts per square centimeter, comfortably exceeding its own power requirements of only 0.66 milliwatts per square centimeter. This surplus energy accrual translates into impressive operational autonomy; under standardized solar irradiance conditions, the ASTCM can amass sufficient energy within roughly 1.3 hours to support continuous 24-hour functionality.
This pioneering research converges ambient energy harvesting, electromagnetic wavefront manipulation, and direct information modulation into a single integrated metasurface platform. The ASTCM not only embodies a technological leap for high-capacity wireless communication systems but also charts a new course toward convergence between green energy utilization and advanced electromagnetic engineering. By enabling simultaneous multi-dimensional multiplexing and fully leveraging ambient solar power, the ASTCM paradigm underscores a sustainable approach to addressing the burgeoning global demand for efficient, reliable, and scalable wireless connectivity.
Led by Professor Tie Jun Cui from Southeast University, the research group has been internationally recognized for their contributions to electromagnetic metamaterials and programmable metasurfaces. The team pioneered the field of digital coding and programmable metamaterials, establishing foundational frameworks in information metamaterials. Their accolades include multiple National Natural Science Awards and the prestigious IEEE Communications Society Marconi Prize, underscoring their leadership in advancing electromagnetic science and engineering. Complementing this, Professor Wei Xiang Jiang’s subgroup has steered developments in light-controlled programmable metasurfaces, enhancing functional diversity and control in metamaterial-based devices.
The publication of this transformative work in Opto-Electronic Advances, a leading, high-impact open-access journal with a 2024 impact factor of 22.4, ensures broad dissemination across the scientific community. This accessible platform supports the accelerated translation of research breakthroughs like the ASTCM into real-world technological advances. As wireless communication continues to evolve toward next-generation 6G and beyond, innovations fostering energy-efficient, high-capacity, and sustainable systems such as reported here will play an indispensable role in underpinning the digital society of the future.
In conclusion, the ambient-energy-driven space-time-coding metasurface represents a monumental advance at the intersection of metamaterials science and sustainable wireless communication. By ingeniously coalescing ambient solar energy harvesting with sophisticated electromagnetic wavefront engineering and multidimensional multiplexed data transmission, this technology mitigates critical limitations in power dependency and bandwidth capacity. It opens promising pathways toward energy-autonomous, scalable communication networks that satisfy the escalating demands of an interconnected world, all while embracing ecological responsibility and technological elegance.
Subject of Research: Ambient-energy-driven space-time-coding metasurface for wireless communication
Article Title: Ambient-energy-driven space-time-coding metasurface for space-frequency-division multiplexing wireless communications
Web References: DOI 10.29026/oea.2026.250229
Image Credits: OEA
Keywords
programmable metasurfaces, space-time-coding metasurfaces, ambient energy harvesting, self-powered, multiplexing wireless communications, energy-efficient
