The 3GPP roadmap (see figure below) is continuously evolving to fulfill the larger 5G vision. In this initial 5G wave that began in 2018, 3GPP has already completed three major releases (new releases every 1.5 to 2 years): 15, 16, and 17. Release 17 is included in the ITU-R M.2150-1 recommendation which is the only standard for 5G RIT/SRIT (i.e. 5G RAN interface).
3GPP Release 18 and beyond (often referred to as 5G-Advanced or 5.5G) involve gradual technology improvements aimed at elevating 5G to the next level, creating a foundation for more demanding applications and a broader set of use cases. In addition to performance improvements and support for new applications, sustainability and intelligent network automation are also important building blocks in the broader 5G-Advanced vision (Ericsson).
The scope of 5G Advanced in Release 19 was approved at the December 2023 3GPP Plenary Meeting in Edinburgh, Scotland. Release 19 builds on Release 18 and focuses on enhancing 5G performance while expanding the capability of 5G across devices and deployments. In addition, it will establish the technical foundations for 6G and will include preliminary work on new 6G capabilities. Release 19 will be followed by Release 20, the first 3GPP release for 6G studies.
5G Advanced continues to push the spectral efficiency limits and coverage in both sub-7GHz and millimeter wave spectrum. In addition to continued enhancements to massive MIMO radios and mobility, 3GPP Release 19 provides advancements for new use cases such as XR and Non-Terrestrial Networks.
Massive MIMO Radio – Release 18 introduced improvements to massive MIMO uplink and downlink throughput. Release 19 will boost capacity further by improving multi-user MIMO, which enables more UEs to share the same time and frequency resources.
Release 19 will also enable the cost-efficient realization of distributed transmitters and receivers, thus improving signal quality. This is an important step towards enabling fully distributed MIMO (D-MIMO) systems. Other enhancements include 5G beam management with UE-initiated measurement reporting, thus resulting in faster beam selection.
Mobility – 5G Advanced introduces a new handover procedure known as low-layer (i.e. L2) triggered mobility (LTM). In Release 18, LTM is supported between cells served by the same gNB. In Release 19, the LTM framework will be extended to support handover between cells served by different gNBs.
XR and the Metaverse – Release 19 builds on the low latency and power saving features of Release 18 by enabling higher XR capacity by adding improved uplink and downlink scheduling using packet delay information.
Non-Terrestrial Networks – 5G Advanced combines terrestrial and satellite communications under one standard for the first time. Release 19 will build on the enhancements introduced in Release 18 with a focus on increasing satellite downlink coverage, introducing UEs with higher output power and providing Redcap device support. It will also investigate whether additional support is required for regenerative payloads.
Current priorities with 5G-Advanced include:
More capacity and better performance. Some estimates suggest that MIMO enhancements, better beam management, and full duplex technologies taken together with other advancements, including multi-band serving cell (MB-SC) and Extremely Large Antenna Array (ELAA) will deliver another 20% of efficiency improvements relative to today’s 5G. Enhanced uplink (UL) and multi-cell UL improvements could pave the way for greater data rate and latency improvements in the UL. For reference, Huawei defines 5G-Advanced as a site that can support at least 10 Gbps of cell capacity. ZTE is also targeting 10 Gbps+ with 5G-Advanced.
Expanded coverage. In addition to MIMO and IAB coverage enhancements, 5G-Advanced includes Non-Terrestrial Network (NTN) connectivity improvements, building on the NR/LTE-based NTN support that was introduced with Release 17.
More intelligence. Releases 15-17 already include some AI/ML features. 5G-Advanced will offer AI/ML enhancements in the RAN (including the air interface) and the management layers. In addition, Intelligent RAN and AI-powered analytics will help operators to improve the performance and proactively address network issues before they become a problem.
Energy savings. Release 18 includes a confluence of static and dynamic power-saving enhancements for the radios and the overall RAN. Also, the specification is targeting to define a base station energy consumption model with various KPIs to better evaluate transmission and reception consumption/savings.
Flexible spectrum (FD, DSS, CA). NR is currently based on TDD or FDD spectrum. Full duplex (FD), a 5G-Advanced contender, improves spectrum utilization by allowing UL and DL to share the same spectrum (FD should improve capacity and latency, especially in the UL). Release 18 also includes DSS capacity enhancements (increasing PDCCH capacity by allowing NR PDCCH to be transmitted in symbols overlapping with LTE CRS). Other spectrum-related upgrades with 5G-Advanced include multi-carrier enhancements and NR support for dedicated spectrum bandwidths below 5 MHz.
Critical IoT. 5G-Advanced includes multiple industrial and IoT related advancements. Release 17 included support for Time Sensitive Networking (TSN), which will be expanded in 5G-Advanced to support Deterministic Networking (DetNet).
RedCap IoT. NR-Light or Reduced Capability (RedCap) was introduced with 3GPP NR Release 17. 5G-Advanced will introduce lower-tier RedCap devices, seeking to find a better set of tradeoffs between cost, performance, and power consumption.
Ambient IoT. Passive IoT, sometimes referred to as Ambient IoT, will allow devices/objects to connect without a power source.
Sensing. Harmonized communication and sensing (HCS) is a Release 19 study item.
Positioning. Positioning is already supported in Release 16/17, though 5G-Advanced is expected to improve positioning accuracy and power consumption (Nokia has said sub-10 cm positioning is doable). In addition, Release 18 will include support for RedCap devices.
Role of AI/ML in 5G Advanced:
AI/ML will become a key feature of 5G networks with numerous applications ranging from network planning and network operations optimization to full network automation. Another important application is the use of AI/ML to improve the performance and functionality of the 5G air interface.
3GPP studied the use of AI/ML in the air interface in Release 18 and defined three use cases: channel state feedback (CSF) information, beam management and positioning. Based on the conclusions of Release 18 studies, Release 19 will specify a general AI/ML framework, i.e. actual specifications to support the above three use cases as well as specific support for each individual use case. Release 19 will also explore new areas in the AI/ML air interface such as mobility improvement and AI/ML-related model training, model management and global 5G data collection.
AI/ML is another major focus for Qualcomm. The company has dedicated significant technical resources to develop full-scale demonstrations of the three Release 18 defined use cases. For example, it recently demonstrated CSF-based cross-node machine learning involving E2E optimization between devices and the network. This reduces device communication overheads resulting in improved capacity and throughput. Qualcomm has also demonstrated the use of AI/ML to improve beam prediction on its 28GHz massive MIMO test network and is heavily involved in positioning technologies. For example, it has showcased its outdoor precise positioning technology, which uses multi-cell roundtrip (RTT) and angle-of-arrival (AoA) based technologies, as well as its RF finger printing technology operating in an indoor industrial private network.
Over the next few months, 3GPP will continue exploring the applicability of AI/ML based solutions for other use cases such as load balancing between cells, mobility optimization and network energy savings. For example, there will be support for conditional Layer 2 mobility in Release 19 and a new study item targeting new use cases designed to improve coverage and capacity optimization, such as AI-assisted dynamic cell shaping.
Enhancing Device and Network Sustainability:
5G Advanced focuses on sustainability and introduces energy-saving features for devices and networks as well as exploring end-to-end energy saving opportunities that benefit devices. There are also improved features for RedCap and the study of ambient IoT as a new device type.
Power-optimized devices – Releases 18 and 19 build on existing energy saving features, for example, a new low-power wakeup signal (LP-WUS). A low-complexity, power-optimized receiver is specified to monitor low-power wake-up signals from the network which only wakes-up the main radio when data is available at the device. This avoids the significant power consumption required to keep the main radio monitoring control signals from the network.
Ambient IoT – enables new use cases enabled by very-low power devices that harvest energy from the ambient environment, for example, RF waves. Release 19 will investigate new architectures for ambient IoT devices and will include the development of a harmonized specification. Numerous use cases will be studied, including smart agriculture, industrial wireless sensor networks, smart logistics, warehousing, etc.
Network energy savings – 5G Advanced reduces network energy consumption by dynamically adjusting the network’s operation based on feedback from the device, i.e. shutting down parts of the network when idle and transmitting less power depending on the overall traffic load or using more efficient antennas.
Dell’Oro’s Stefan Pongratz says “one fundamental aspect of 5G-Advanced will be to support more demanding consumer MBB applications. The days of exponential data traffic growth are clearly in the past; however, global mobile data traffic is still projected to increase threefold over the next five years, reaching 0.5 ZB/month by 2028 (mobile plus FWA). While operators are currently in a fairly good position from a capacity perspective, especially those not aggressively pursuing FWA, some of the technology improvements with 5G-Advanced can help to address capacity limitations in hotspot areas.”
Omdia (owned by Omdia) expects leading service providers in Asia and Oceania to leverage the new capabilities and features offered by 5G-Advanced to enhance their network infrastructure and offer innovative services to their customers. These advancements include enhanced performance metrics such as higher data rates, lower latency, improved reliability, and greater network efficiency. During the next few years, 5G Advanced will continue to evolve within 3GPP while the specification of 6G officially starts to ramp up in parallel, leading to the ITU-R IMT 2030 standard.
Setting The Stage For 6G:
Although Release 19 will be the last release focused on 5G, it will also include some longer-term technologies that will become the foundation of 6G, thus setting the direction for Release 20. For example, Integrated Sensing and Communications (ISAC), which combines wireless communications with RF sensing, will enable a raft of new position-based use cases. Release 19 will study channel characteristics suitable for the sensing of various objects, including vehicles, UAVs and humans. Full duplex, another 6G technology, allows transmitters and receivers to operate simultaneously on the same frequency, potentially resulting in a doubling of network capacity. Release 19 will study sub-band full duplex, a type of full duplex, which will improve capacity and latency, particularly for the uplink. Release 19 will also include channel model studies for the upper mid-band spectrum (7-16GHz), which will be supported by “Giga-MIMO” in the 6G timeframe, in order to enable wide-area coverage in this higher band.
Whereas AI/ML is a key pillar of 5G Advanced, it will be a core foundational technology of 6G and will underpin the key features that will make 6G revolutionary. For example, 6G will start to move away from the traditional, model-driven approach of designing communication systems and transition towards a more data-driven design. Indeed, it is likely that the 6G air-interface will be designed to be AI-native from the outset, thus signalling a paradigm change in the way communication systems are designed. An AI-native air interface could offer many benefits. For example, it could refine existing communication protocols by continuously learning and improving them, thereby enabling the air interface to be customized dynamically to suit local radio environments.
References:
5G Advanced – How will it impact the RAN Market?
NGMN issues ITU-R framework for IMT-2030 vs ITU-R WP5D Timeline for RIT/SRIT Standardization
Nokia plans to investment €360 million in microelectronics & 5G Advanced/6G technology in Germany
ZTE and China Telecom unveil 5G-Advanced solution for B2B and B2C services
ABI Research: 5G-Advanced (not yet defined by ITU-R) will include AI/ML and network energy savings
Draft new ITU-R recommendation (not yet approved): M.[IMT.FRAMEWORK FOR 2030 AND BEYOND]