As 5G continues to be rolled out, the 3rd Generation Partnership Project (3GPP) organization is hard at work in developing standards for 5G Advanced and is beginning to talk about what may be included in the first release of 6G.
It is exciting to think about the start of 6G, but we, as an industry, still have a lot of work to do on 5G and 5G Advanced. Articles and presentations at recent wireless industry events have been quick to criticize the rollout of 5G and lackluster reception from consumers. In reality, many consumers have only experienced the non-standalone (NSA) version of 5G.
The most exciting and promising features of 5G need standalone 5G (SA 5G) to be deployed and realized, which isn't widely available outside of India and China today. The next several years of 5G Advanced development and deployment will give communications engineers an opportunity to reinvigorate consumers and the larger wireless ecosystem by delivering much-anticipated features and upgrades to networks.
The 6G roadmap
Research and development into the foundations for 6G will happen in parallel. The timeline in Figure 1 shows where we are today in relation to 3GPP releases and the International Telecommunication Union – Radiocommunications Sector’s (ITU-R) timeline to approve a first version of the 6G standard.
The major focus for 2023 has been completing work and finalizing Release 18, which is the first official release supporting 5G Advanced. According to Wanshi Chen, chairman of the 3GPP Radio Access Network (RAN) plenary, Release 18 aims to drive a balanced 5G evolution across key technology areas while also taking into consideration the ways 5G Advanced will evolve in Release 18, Release 19, and beyond. This evolutionary approach has led to many study items being defined and set up as work items in later releases.
Major topics covered in Release 18 include MIMO enhancements, in particular for uplink and mobility scenarios, NR-Light (RedCap) evolution, evolved duplexing, and artificial intelligence (AI) and machine learning (ML) data-driven designs. The MIMO enhancement uplink improvement aims to improve the user experience when trying to upload content in crowded locations, a common pain point for customers. And RedCap looks to provide a low-power solution for devices like sensors and wearables.
In parallel to the work being done in Release 18, the first plenary meeting was held in June 2023 to discuss the package of projects that will be included in Release 19. This package will be approved at the December ’23 RAN plenary (RAN #102) with a target timeframe of 18 months for the duration of Release 19. The primary focus of Release 19 will be 5G-Advanced, and again, this release will be all about balance.
A 6G plan of action
When deciding what is included, the 3GPP chairman is looking to strike a balance between short-term fixes and long-term feature development, mobile broadband evolution versus the expansion of vertical use cases, and device evolution versus network evolution. Release 19 is important because it will also serve as a bridge to 6G. Release 20 is anticipated to be the first official release to include 6G study items, but there is strong interest in initiating some studies sooner for important topics like channel modeling for 7-24 GHz and integrated sensing and communications (ISAC).
An initial list of topics for consideration for Release 19 was drafted in June and further narrowed down at the RAN plenary in September 2023 (Figure 2). After the September meeting, seven items were identified for RAN Working Group 1 (RAN1), five for RAN Working Group 2 (RAN2), and three for RAN Working Group 3 (RAN3). The full list of all items and more details can be found in the RAN chair’s guidance (RP-231540).
The RAN1 topics include AI and ML for the air interface, ambient IoT, network energy savings, and an exploration of new spectrum (7-24 GHz). AI/ML and the inclusion of items related to improving energy efficiency are obvious inclusions based on current industry trends. And like energy savings items, ambient IoT could also be considered part of the green movement for wireless. An ideal ambient IoT device would be a device that could harvest energy from the RF radiation in the atmosphere and would not need a battery.
These devices are still a research concept, but the 3GPP is looking for ways to construct the protocol to allow for minimal up time, the most efficient design of a wake-up signal, and the lowest overall power required for the device to communicate with the network.
The most time units (TUs), or the estimated amount of time that the 3GPP will dedicate to focusing on a specific item, in RAN1 is four for AI/ML for the air interface. This makes sense, given the efforts to look at AI/ML in Release 18, which included AI for channel state information (CSI) enhancements, beam management, and positioning. This work will be carried into Release 19, and some new topics are likely to emerge as well. Network energy savings remain a significant effort and are likely to be carried forward into Release 19. The largest effort in Release 18 was the MIMO evolution, and again, to no surprise, MIMO evolution is listed for Release 19, although with only 1-2 TUs reserved.
RAN2’s topics include enhancements for extended reality (XR) and non-terrestrial networks (NTN) evolution for NR and IoT. There will also be overlap and cross-working group efforts needed between RAN1 and RAN2 for ambient IoT and AI/ML for the air interface. RAN3 items include AI/ML for next-generation RAN (NG-RAN), self-organizing networks (SON) / minimization of drive test (MDT) enhancements, and additional topological enhancements, as well as cross-working group efforts for ambient IoT. The development cycle for RAN Working Group 4 (RAN4), which focuses on radio performance and protocol aspects, trails RAN1, 2, and 3 by a few months. A similar discussion will be had to look at candidate items for RAN4 during the December plenary.
A final word on 5G Advanced and 6G
While these study and work items are intended for 5G Advanced, they can be used to get an early idea of what might be included in 6G. AI and ML will clearly be major areas of focus and will impact all parts of the wireless ecosystem and affect design decisions and implementation methods for 6G. Ambient IoT, or the idea of IoT devices that don’t need a battery to operate, compliments the push for power efficiency and green communications in 6G and could anchor the topic of network sustainability. While we are still several years away from beginning work officially on 6G, 3GPP’s Release 19 looks like it will pave the way for a quick and efficient start to the 6G standard.
Sarah LaSelva is the Director of 6G Marketing at Keysight.