Next 3GPP standard tees up 5G Advanced

The next 5G specification is teed up at global standards body 3GPP and aims to set the stage for both short-term and long-term evolutions of the wireless technology.  

Known as Release 18, it’s the fourth standard for 5G and the first to be dubbed "5G Advanced." 3GPP recently approved the Rel-18 package, which includes flagship projects that could help underpin future systems in the run up to 6G, as well improvements to things like integrated access backhaul (IAB) and MIMO to make ongoing deployments more fruitful and cost effective with better performance.

Presentations from over 500 company and partner organizations were considered to identify topics for the next standard, with the first 3GPP Rel-18 workshop held in July. Work on Rel-18 officially starts after Release 17 is completed, with the latter expected in the first half of 2022.

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With the 5G Advanced moniker, this release has a little bit more to live up to, says Qualcomm VP of Technical Standards Juan Montojo, who has been at the tech giant for 25 years and involved in 3GPP since 2003. He became the overall 3GPP 5G technical standards lead at Qualcomm this summer taking over from Lorenzo Casaccia.

Unlike Release 16 and 17, which helped extend 5G to new verticals, for the newest release “there was a purpose to really find a good balance between not only the evolution mobile broadband with other verticals, but also evolution or edification of shorter-term goals with a little bit of a longer term 5G vision” with exploration into next-generation type projects, Montojo told Fierce.

Artificial Intelligence and Machine Learning (AI/ML) is one of the four flagship Rel-18 projects outlined by Montojo and the top category in terms of defining the “Advanced” aspect.

3GPP is looking at AI/ML with two different lenses, one for the network and one for the air interface.

“The one for the air interface starts effectively with a clean sheet of paper, where 3GPP is going to try and define how basically we could embrace any resolution or any problem-solving for air interface involving AI/ML,” Montojo explained.  

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He described how the organization has chosen three use cases where AI/ML can deliver improved support for air interface functions, including channel state information (CSI) and feedback enhancements, positioning, and beam management 

The work will try to identify several aspects such as what the framework is, common parts versus use case-specific aspects, and KPIs, and “and basically try to see how much AI/ML-based techniques can shine versus these traditional techniques,” Montojo said. That then funnels into work to define what 3GPP has to do to embrace those in the specifications.

Ericsson has also called out AI/ML as a key component of 5G Advanced, with the technology expected “trigger a paradigm shift in future wireless networks” and used to improve the radio interface by optimizing performance for multi-antenna systems for applications like XR.

“AI/ML-based solutions will be used to introduce intelligent network management and solve multi-dimensional optimization issues with respect to real-time and non-real-time network operation,” wrote Ericsson authors in an October article (PDF) for the Ericsson Technology Review.

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A second priority Montojo cited is evolving duplexing on the road to full duplexing. Currently with TDD (Time Division Duplexing) deployments, transmission and reception (or send/receive) happens in the same channel but alternates based on time. In FDD transmit/receive is separated by frequency channels. Full duplexing looks to enable transmission and reception at the same time within the same channel.

“One simplification 3GPP is taking to make this more palatable for implementation is creating what we call a non-overlapping frequency where transmission and reception, even though they’re in the same channel they would actually occur adjacent in frequency,” he noted. Montojo described it as something like a hole opening in one direction, but where signals could travel the path in either direction – downlink to uplink or vice versa.

XR proliferation

The two other flagship 5G Advanced projects for Release 18 focus on energy savings and XR improvements on the radio side.

Monjoto said extended reality (XR) has always been a prime use case for 5G but until now there wasn’t a way to tangibly model traffic for different type and applications like head XR monitor displays versus glasses, where data and latency needs change.

“Now we have a suite of traffic models for all of those applications including online gaming,” he said, so 3GPP can ask “what could the radio do differently to better suite those traffic models?”

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3GPP is targeting specific improvements on power consumption on the terminal, capacity to support more XR traffic than possible today and overall efficiency.

“For example, having the radio aware that there is an XR application running, so that actually how could the radio adapt, and vice versa – how could the application adapt to different radio conditions,” Montojo said. He pointed to a scenario where there’s a mobility event and features could be throttled down at the application layer, such as lowering the resolution or graphics during that time, and when the event concludes full resolution is restored.

Improvements for current 5G deployments

The Release 18 scope covers several other enhancements, which Montojo categorized as representing a nice spectrum of project continuations.

Some are focused on network operations improvements, with advanced uplink/downlink for 5G massive MIMO for better performance, as well dynamic spectrum sharing and carrier aggregation.  Then there are enhancements to help enable easier NR deployments and extend coverage such as advancing integrated access backhaul (IAB) and smart repeaters.

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IAB allows operators to use existing 5G air interface for backhaul as well as access, allocating a portion of bandwidth instead of needing a wired fiber link for what serves essentially as a base station. IAB was introduced in Release 16, evolved in Rel-17 and now Montojo said Release 18 will take it mobile to extend the relay capability for transportation like cars and trains. Repeaters, seen as a cost-effective way to increase network coverage, also are getting a boost. 3GPP wants to take them from “dumb” to “smart repeaters” that amplify signal selectively based on time, frequency or direction without creating unnecessary interference by turning off when not needed.

“Some operators, particularly the millimeter wave operators are really looking into cost effective ways to improve their coverage and I think that will really help,” Montojo said. Others like China Mobile are interested in it for sub-7 GHz for smart repeaters as well, he noted, but said 3GPP will likley first focus on mmWave use cases.

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Rel-18 projects also look to extend 5G to satellites and drones. Low-earth orbit satellite broadband has gained attention and interest with several companies working to deploy LEO constellations. The 3GPP satellite focus is on making NR-based satellite communications suitable for regular form factor smartphones, with the goal of enabling voice.

As for timelines, those 6G-type projects like AI/ML won’t become a commercial reality with Release 18, Montojo noted, as they’re mainly up for study throughout the whole release.

Energy savings and XR are among some of those he believes will have a more near-term impact, as well as NR-Light (RedCap)which enables bandwidth for reduced capability user devices to possibly scale down to as little as 5 MHz and topology improvements like IAB and repeaters.

Work on Rel-18 is expected to continue through 2023.