ETSI is Reimagining Edge Networks with Reconfigurable Intelligent Surfaces
October 30, 2021
ETSI is defining a type of a network node based on smart radio surfaces that dynamically control and shape RF signals to achieve specific goals.
There’s already a lot going on at the edge of 5G networks. And it’s not getting any less crowded.
The connectivity technologies flying around at the edge include everything from Wi-Fi and Bluetooth to cellular and sub-GHz options. And to accommodate that noisy RF environment a decade or more into the future, engineers at the international standards organization ETSI are looking at 6G network architecture options.
They may have found a path forward in the form of reconfigurable intelligent surfaces (RIS).
Introducing Intelligent Surfaces
Reconfigurable intelligent surfaces are currently being investigated in an Industry Specification Group (ISG) at ETSI. And although they are not yet well defined, Arman Shojaeifard, spokesperson for RIS at ETSI explains that they can be thought of as software-defined system nodes comprised of thousands of small antennas or metamaterial elements that dynamically reshape and control radio signals.
“With RIS, we don’t actually take the channel as-is. Rather, we turn a channel into a service, something that you can actually program and reconfigure,” he says.
In other words, RIS essentially proposes the concept of a massively software-defined radio (SDR) network infrastructure components sophisticated enough to transform the entire spectrum of edge RF signals into whatever you want, whenever you want it. And potentially do it on a single piece of hardware (Figure 1).
According to ETSI, “RIS can be configured to operate at any part of the radio spectrum, including frequencies from sub-6 GHz to THz, and may use tools from Artificial Intelligence and Machine Learning to enable systems operation and optimization.”
RISky Network Architectures
RIS represents a paradigm shift compared to the way that networks are designed and built today. That’s largely because the nodes do not create their own signals whatsoever – they just recycle and repurpose the signals from elsewhere.
While this may sound like an extreme undertaking, it helps solve a key challenge emerging in today’s 5G deployments: Maintaining coverage within higher frequency bands. By integrating a RIS component onto indoor or outdoor objects, he said, “what you could do is to dynamically control and shape RF signals in order to improve your coverage performance.”
Shojaeifard added that these surfaces would have to be made of mostly passive components in order to reduce power consumption and deployment and maintenance costs compared to the fully stacked cells we see today. This semi-passive characteristic would mean that RIS nodes could be deployed onto other objects like walls, and perhaps most importantly, be controlled using a low-power microcontroller.
The RIS ISG is currently defining KPIs, deployment and operational scenarios, and other requirements of the reconfigurable networking technology.
On the technical front, the working group is currently evaluating RF characteristics of surface models, channel characterization, and radiation exposure limits, as well as the mechanics of RIS-aided air interface technologies. From there, they will look to define system and network control signaling, architectural framework considerations, and baseline evaluation methodologies for the system and link levels.
The final leg of the ISG roadmap is standardizing prototyping, verification, and validation methods around a series of hackathons, but the ecosystem isn’t waiting for formal invitations. Early working RIS prototypes are planar surfaces of electromagnetic unit cells that harness some amount of real-time network intelligence to control the cells, executed from a basic microcontroller (Figure 2).
Though the ETSI ISG isn’t sure exactly when or how we will see RIS nodes deployed, their composition implies that RIS nodes will be “everywhere” by virtue of being able to interact with basically any RF signal at the edge.
RIS won't be a catch-all solution for every wireless networking challenge, but it could fill in a lot of gaps in current networking technology. With RIS, we may finally be able to fully embrace the diversity of the edge.
[Editor’s Note: ETSI members and non-ETSI members interested in learning more about reconfigurable intelligent surfaces and ways to can participate can visit the ISG webpage at https://portal.etsi.org/TB-SiteMap/RIS/List-of-ISG-RIS-Members-and-Participants]