RIS does not need to appear in the first 6G release to be commercially relevant. The more useful question is what function the system performs, whether that function requires air-interface standardization, and whether the site conditions make an active RIS relay practical.
This RFCOM original article reviews current RIS standardization discussions, active RIS relay architectures, and practical deployment considerations for coverage engineering teams.
As one of the future industries prioritized in China’s 15th Five-Year Plan, 6G has entered a critical period of standards development. Reconfigurable Intelligent Surface (RIS), with its potential advantages in cost, power consumption, and deployment flexibility, has shown promise as a disruptive technology for 6G and future networks.
However, against the backdrop of Europe’s relatively cautious position and the United States’ differentiated approach to 6G, RIS has encountered some temporary headwinds in the 3GPP standardization process.
Public industry commentary from Yuan Yifei, Chief Expert at China Mobile Research Institute, frames RIS as fundamentally a multi-antenna technology. Relay applications may involve radio-interface standardization, while most other applications are matters of engineering implementation. For that reason, whether 3GPP standardizes RIS is not the only indicator of its deployment prospects. Even if RIS is not included in the first 3GPP release for 6G, that does not mean it cannot be standardized in a later release.
Yuan noted that 3GPP standardized the Network-Controlled Repeater (NCR) in Release 18 and that NCR has already seen deployment at a certain scale. Together with the lessons learned from earlier RIS application trials, this creates an opportunity for RIS relays to move toward industrial deployment. He also cited a recent Hubei Mobile tender for 300 RIS systems as a sign that the industry is beginning to converge around active RIS relays and that RIS has started to meet the conditions for industrialization. To reach large-scale commercial deployment, however, RIS costs still need to fall further.
3GPP Standardization Is Not a Fast Track; Scenario Fit Matters More
Yuan offered a simple analogy: "RIS is like a mirror, and electromagnetic waves are like light. By intelligently controlling the surface, the system can direct the waves precisely without physically rotating the mirror. It can be used to fill coverage gaps and strengthen signals in mobile networks."
RIS can support several functions, including wireless relaying, base-station antennas, sensing and positioning, and electromagnetic energy harvesting.
"Only the relay use case involves standardization, and the extent of standardization depends on whether the system uses semi-static beams, dynamic beam scanning, or millisecond-level precoding, as well as how open the wireless backhaul link between the base station and RIS needs to be," Yuan said. "Air-interface standardization is needed only for dynamic operation that requires an open wireless backhaul interface. Therefore, whether 3GPP standardizes RIS is not the only indicator of its deployment prospects."
Yuan explained that the first release of a 3GPP 6G air-interface standard would mainly define foundational physical-layer functions such as waveform modulation, channel coding, multiple access, and radio-frame structure. Its primary focus would be radio transmission over the link between a base station and a terminal. Communication through relays, or direct communication between terminals, would normally be standardized in a second release.
He also said that 3GPP expects future 6G networks to maintain inter-site distances similar to those of 5G networks, even though major 6G deployment bands may be around 7 GHz or higher, compared with the 2.6 GHz and 3.5 GHz bands commonly used for 5G. Propagation loss is substantially higher at the higher frequencies. More antenna elements can partially compensate for the difference, but a larger share of the network may still require gap-filling coverage than in 5G. That would increase the need for RIS and could support its standardization in later releases.
Yuan added that European and US operators and manufacturers generally take a cautious approach to new technologies. Much of the 3GPP 6G air interface may therefore evolve from 5G air-interface technologies with targeted enhancements. This creates more resistance for comparatively disruptive technologies such as RIS.
Active RIS as an Enhanced Form of NCR
RIS has attracted considerable academic and industry attention as a potential enabling technology for 6G. Its transition from academia toward industry accelerated after an RIS task group was established under the Wireless Technology Working Group of the IMT-2030 (6G) Promotion Group in June 2020.
Yuan said that over the past five years, China’s three major operators, university research teams, and equipment manufacturers have carried out extensive work to explore RIS industrialization.
Millimeter-wave applications are one example. The demand for gap-filling coverage is clear, and the required panel can be relatively small and easy to install. However, the broader millimeter-wave mobile ecosystem remains underdeveloped. China has not issued wide-area millimeter-wave licenses, and hardware cost and antenna-aperture radiation efficiency remain challenges. Whether used as a relay or as a base-station antenna, millimeter-wave RIS is still largely at the prototype stage.
There have also been two approaches to passive RIS relays at low and mid bands. One uses no external power at all. Examples include fully static modes such as radio-frequency transparent films or designs that use specialized semiconductor devices to reduce power consumption significantly. Large-scale customization of transparent RIS films is difficult, however, because glass types and deployment bands vary. In Chinese cities, access to power is often practical enough that a completely unpowered system is not always a decisive advantage.
The other passive approach uses electrical power, but compensating for cascaded-channel loss requires a large RIS aperture. This can reduce deployment flexibility and limit coverage distance.
The turning point came when 3GPP Release 18 standardized the Network-Controlled Repeater and NCR began to see deployment. This provided a new opportunity for RIS relay industrialization.
After several years of large-scale 5G base-station deployment, operators have largely completed wide-area coverage, but many localized areas still need coverage enhancement. Building a macro site or small cell for every such area may not be cost-effective. Commercial NCR is less expensive than a macro site or small cell, but current hardware implementations generally do not provide beam scanning, making inter-cell interference and channel quality harder to control.
"Active RIS can become an important enhancement to NCR," Yuan said.
He cited Hubei Mobile’s recent procurement of 300 RIS systems as another indication that the industry is converging on a practical use case: the active RIS relay. An NCR equipped with an RIS phased array has a near-end unit and a remote unit, responsible for signal reception and transmission respectively. The main targets are small and medium-sized enclosed indoor environments and low-rise residential buildings. The beam is adjusted semi-statically, so the 5G air-interface protocol does not need to be changed.
"Because the number of antenna elements is not very large, the beam is not extremely narrow and retains a degree of robustness as users move," Yuan said.
Cost Remains the Largest Challenge to RIS Industrialization
A 300-unit tender in one province can be viewed as a pilot. It is reasonable to expect that the number of units in a subsequent commercial rollout could be much higher.
Yuan said cost remains the largest barrier to large-scale RIS commercialization. One reason is the use of general-purpose semiconductor components such as PIN diodes. Because these parts are not designed specifically for RIS, they can introduce unnecessary performance overhead and higher power consumption. Control circuits may also depend on expensive devices such as FPGAs, while conventional PCB processes can struggle with the requirements of high-frequency, high-density integration.
Yuan proposed several possible paths forward. One is a low-cost phased array based on reconfigurable surface antenna elements. At mid-band frequencies such as 4.9 GHz and 7 GHz, analog-domain beamforming can reduce the number of RF chains while largely preserving communication and sensing performance. This type of lower-cost phased array could be used in macro and small base stations and could also form a key part of active or passive RIS systems.
Another path is the use of new materials and manufacturing processes. Replacing commonly used PIN diodes with RF switches could reduce power consumption significantly. Semiconductor devices designed specifically for RIS, including customized RF switches, could improve performance and reduce cost. China’s display-glass manufacturing capacity could also support the use of glass substrates instead of conventional epoxy-resin PCB materials and chip substrates, potentially improving integration precision and temperature stability while reducing power consumption.
The industry should also continue exploring scenarios in which RIS solves a hard requirement rather than serving as an optional enhancement. Possible examples include low-altitude coverage, low-altitude drone sensing, and satellite communications. During the Hangzhou Asian Games, a low-cost "static intelligent surface" deployment was reportedly used and validated to improve wireless communication quality in event venues.
The value of a technology is not determined by whether it appears in the first release of a standard. The real test is whether it solves practical problems and creates commercial value. As customized chips and new material processes mature, and as more scaled pilots are deployed, RIS may demonstrate its potential to reshape future wireless-network architectures and become an enabling technology for representative 6G use cases.
Evaluating active RIS for a coverage project? Contact RFCOM with the target area, donor signal conditions, frequency band, and deployment constraints for an initial technical review.
