The next wave of 5G – 3GPP Release 19
This week we celebrate! The plenary held from 11 to 15 December 2023 marks the 25th anniversary of 3GPP, a standards community that has provided world-leading standards for mobile broadband over the last two-and-a-half decades and thereby established the fastest scaling global technology ecosystem. The meeting concludes Release 18, which introduces 5G Advanced and defines the future direction of 5G Advanced by approving the main scope of Release 19.
As a continuation of 5G Advanced, Release 19 will primarily focus on improving performance and addressing critical needs in 5G commercial deployments. We see that 5G Advanced will continue to evolve within 3GPP during this decade and, in parallel, 6G standardization is expected to ramp up in Releases 20 and 21 starting from 2025, in line with Figure 1.
Evolution of 5G Advanced
5G Advanced will enhance network performance and add support for new applications and use cases. This blog post focuses on how 3GPP Release 18 and 19 will enable high-performance radio access networks (RAN) and new features that allow communication service providers to differentiate their service offerings. It will also explain how automated and sustainable networks are supported by the latest evolutions of the standard.
High performing 5G networks
Advanced antenna systems and massive MIMO are cornerstones of 5G. Release 18 introduces several enhancements:
System capacity is boosted further in both the uplink and downlink, mainly through improvements in 5G multi-user-MIMO. Multiuser MIMO is a technique that enables two or more user equipment (UE) to share the same time and frequency resources, so more UEs can be scheduled on these same resources.
Signal quality is improved by enabling coordinated operation across distributed transmitters. This is an important step on the path towards fully distributed MIMO (D-MIMO) systems.
Data rates in fixed wireless applications are boosted with the support for eight transmit antennas in customer-premises equipment.
To increase the quality of service for mobile users, the MIMO framework is improved to cater for adaptations between beamforming methods depending on the user’s mobility.
In Release 19, 3GPP will support massive MIMO on even larger antenna arrays, giving higher gains and a higher level of beamforming flexibility. This will improve both link and network performance and is vital in new frequency bands in the 6 to 7GHz range.
Release 19 will also introduce enhancements that enable the cost-efficient realization of distributed transmitters and receivers. This is one more step on the path to large-scale D-MIMO deployments.
Finally, Release 19 will speed up the 5G beam management procedures by allowing UE-initiated measurement reporting. This functionality will allow faster beam selection, which is of high relevance for mobile users.
Like MIMO, mobility is a central component of high-performing 5G networks. In 5G Advanced, 3GPP introduces a new handover procedure with shorter service interruption times, known as L1/L2-triggered mobility (LTM). LTM is applicable in all frequency bands and can even be applied for UEs configured to use carrier aggregation. 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. The LTM framework will further include NR-NR dual connectivity across FR1 and FR2. Release 19 will also explore the use of artificial intelligence and machine learning (AI/ML) to improve mobility. As an example, AI/ML can be used to predict the future best-serving cell. A 3GPP study will consider both AI/ML performance and complexity aspects and its conclusions will guide the specification of new mobility features in Release 20.
Dynamic spectrum sharing
Dynamic spectrum sharing (DSS) is a key deployment feature in 5G that facilitates the migration from 4G by allowing 4G and 5G carriers to share the same frequency. Therefore, a base station can serve 4G and 5G devices in the same spectrum.
DSS was introduced in the first version of 5G and has been improved throughout the releases of 5G. Release 18 adds support for handling strong interference from neighboring 4G cells and increases the downlink control channel capacity and coverage. After evolving DSS in Releases 15 to 18, no further enhancements of DSS are considered necessary in Release 19.
Support for new consumer and enterprise services
5G Advanced provides enhanced support for several new consumer and enterprise services that allow communication service providers to differentiate their networks. These include cloud gaming, immersive reality, indoor positioning, and industrial sensor networks.
Extended reality (XR) is an umbrella term that covers a wide area of use cases such as virtual reality (VR), augmented reality (AR), and cloud gaming. The different flavors of XR share strict requirements on low and bounded end-to-end latency. In addition, the market trends point towards reduced device form factors, which imposes constraints on available power and computational resources.
The article Network evolution to support extended reality applications outlines requirements and needed network functionality related to XR.
For Release 18, 3GPP identified and specified enhancements for XR in the 5G RAN and core network. To address the strict latency requirements, low latency low loss scalable throughput (L4S) was introduced. L4S reduces the packet queueing in the network by means of adapting the application data rate. Release 18 also introduces an abstraction of a media unit, which consists of a set of packets that, for example, contributes to the rendering of a video frame. This allows the RAN to perform Active Queue Management (AQM), dropping packets while minimizing the impact on quality of experience.
In addition, Release 18 introduces power-saving features specifically designed for XR devices. To support the use of these features, the specification includes XR awareness in the RAN. This is achieved by new signaling mechanisms to deliver XR application information (like packet periodicity and QoS requirements) from the 5G core network to the RAN.
In Release 19 the work will continue. Improved uplink and downlink scheduling using packet delay information will enable higher XR capacity. The impact of measurement gaps on the downlink and uplink data rate will be reduced by enhancements that allow data transmission to a UE in unused measurement gaps.
Applying AI and ML to improve performance in specific scenarios opens up new possibilities. Release 18 studied the use of AI/ML to boost 5G based positioning accuracy, a valuable service, particularly in indoor environments. Indoors, for example in factories or offices, Global Navigation Satellite Systems such as GPS might not be available. The 3GPP study focused on using AI to identify line-of-sight links between gNBs and UEs because positioning in line-of-sight conditions offers high accuracy.
In Release 19, 3GPP will specify support for AI/ML-powered localization to improve positioning accuracy, based on the Release 18 study.
Internet of Things
Release 17 introduced the low complexity NR Reduced Capability (RedCap) UE facilitating a reduced device price point to support industrial wireless sensor networks, wearables, and wireless cameras. RedCap UEs can be equipped with a single receiver branch to support reduced form factors for wearable devices.
Release 18 specifies positioning and a reduced peak data rate of 10Mbps. The reduced data rate enables further reduction in RedCap complexity. The remaining RedCap aspect that will be addressed in Release 19 is support for satellite communication to achieve truly ubiquitous NR IoT coverage.
Power saving features are important for IoT devices. In Release 18, the merits of a low-power wake-up signal (LP-WUS) were studied. The LP-WUS is designed for reception by a low power-consumption, low-cost wake-up receiver (WUR) – a unit with the sole purpose of waking up the main receiver in a device when it detects the presence of the LP-WUS. Support for LP-WUS and WUR will be included in the standards in Release 19.
In Release 17, NR was adapted to support satellite communication in non-terrestrial networks (NTN). Release 18 includes NR NTN uplink coverage enhancements needed to facilitate robust voice and messaging connectivity. To achieve tighter integration between terrestrial and non-terrestrial networks, mobility procedures between these two network topologies are strengthened as part of Release 18.
NR NTN evolution will continue in Release 19:
- One objective is to increase the downlink coverage provided by a satellite.
- 3GPP will investigate if any changes of the 5G architecture is needed to be able to have a full gNB onboard the satellite.
- UEs with higher output power will be introduced.
- Finally, as already mentioned in the previous section, RedCap device support will be introduced.
From the start, 5G was designed to meet increasing traffic demands while limiting the power consumption of mobile networks. With 5G Advanced, the focus on network energy savings is accelerated. Release 18 defines a network energy consumption model to identify opportunities for improving network energy efficiency. It also specifies methods for dynamic adjustment of the active part of the gNB antenna and the gNB output power.
Further building on the work in Release 18, Release 19 will introduce additional energy-saving functionalities including:
- On-demand Synchronization Signal Block (SSB) transmission in secondary cells.
- Adaption of the periodicity of SSB, paging occasion and random access occasion.
Both these techniques will be based on a new trigger for the on-demand transmission.
In addition, further work is done in the AI/ML area to support network energy saving.
Intelligent network automation
AI and ML have the capability to solve complex and unstructured network problems by analyzing data collected from the networks. 3GPP has selected to investigate how to apply AI and ML in the 5G RAN and in the NR physical layer by working on selected use cases.
AI and ML for next-generation RAN enhancements
The work on AI/ML in Release 18 focused on three use cases:
- AI-powered network energy savings
- Load balancing
- Mobility optimization
The use of AI in these use cases is supported by signaling enhancements on NR interfaces such as the UE to gNB radio interface and the inter-gNB Xn interface. 3GPP has agreed to keep the AI model implementation specific to ensure competition, vendor incentives, and innovation.
A study targeting new use cases will start in Release 19. One new use case included is AI-assisted dynamic cell shaping – in other words, coverage and capacity optimization.
AI/ML for physical layer enhancements
In Release 18, 3GPP studied how AI/ML tools can be used to improve the performance and functionality of the 5G air interface. The study was driven by three use cases:
- Beam management
- Channel State Information reporting
In addition, the study considered issues related to AI Life Cycle Management, including performance monitoring and testing.
Based on the conclusions of the Release 18 study, Release 19 will specify a general framework for using AI/ML on the air interface and will address AI/ML support for use cases such as positioning and beam management. In addition, 3GPP will continue exploring the applicability of AI/ML based solutions for other use cases such as mobility.
Bridge towards 6G
In the Release 19 timeframe, we anticipate that a study on use cases and service requirements for 6G will begin in the Service and System Aspects Working Group 1. It will be followed in Release 20 by an in-depth technical study covering the 6G RAN design. Release 21 will specify the 6G RAN to prepare for commercial launch of 6G in 2030.
In our view, Release 19 will provide a bridge from 5G Advanced to 6G through many of the activities presented in this blog post.
XR will gradually evolve into immersive communication for human-machine interaction and will pose new requirements that 6G should address to provide an even better user experience.
AI and ML will play an important role in the future and are expected to be an important 6G building block from day 1.
Network energy efficiency enhancements in 5G Advanced will provide the baseline for sustainable network design in the 6G era.
The D-MIMO solutions added in Release 18 and 19 will create precursors for D-MIMO in 6G.
In addition, there will be two studies in Release 19 focusing on channel modeling, laying the foundation for future work to come:
- Channel modeling for Integrated Communication and Sensing (ISAC) - a technique wherein the communication network can support both communication and sensing of the surroundings.
- Verification of 3GPP channel models in the range of 7 to 24GHz – particularly looking into support for new 6G spectrum in the cm-wave range.
The end of Release 18 marks the introduction of 5G Advanced. Building on the baseline defined by 3GPP Releases 15, 16, and 17, 5G Advanced represents the aggregated value of the 5G evolution from 2018 and onwards.
As a continuation of 5G Advanced, Release 19 will focus on solutions that promote continuous investments in 5G commercial deployments to improve performance and address critical needs. At the same time, Release 19 will serve as the bridge to 6G, where many solutions in Release 19 will provide the baseline for future 6G systems.
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