This blog is a repost from IWCE’s Urgent Communications, originally published on October 15, 2024.

This blog post is part of the "Tech Talk" series focused on the First Responder Network Authority’s (FirstNet Authority) standards development activities to support public safety. This post recaps discussions linked to public safety and other related topics from the 3GPP plenary meetings that were conducted in September 2024. The FirstNet Authority represented public safety interests at the plenary meetings.

The 3GPP Plenary meetings took place September 9-13, 2024, in Melbourne, Australia. 3GPP Radio Access Network (RAN), Service and System Aspects (SA) and Core Terminal (CT) groups continued to focus on the Release 19 (R19) work, while officially approving a study on 6G.

The 6G work represents the next generation of wireless communications. While the industry remains very active in deploying 5G technologies, the standards organizations have been working on high-level visions and use cases for 6G. The approval of this 6G study item is the first step for 3GPP towards 6G standardization. The goal of this study is to start capturing use cases and high-level requirements. This will lead to more detailed work and eventually to normative 3GPP specifications for 6G. The timing for the initial 6G specifications has not been finalized, but based on the initial discussions, it is expected to be completed in late 2029.

The functional freeze date for R19 remains on track for the planned final completion date of December 2025.

The following Technical Specification Group (TSG) reports include details on each of the Plenary TSG meetings focused on progressing features important to public safety. The FirstNet Authority and government agencies of other nations continue to represent public-safety interests in these meetings.

The Radio Access Network (RAN) TSG Plenary

There were over 350 in-person attendees at the TSG RAN Plenary meeting. The RAN Plenary is responsible for defining the requirements, functions, and interfaces of the 3GPP radio access network.

The FirstNet Authority continues leading and championing the advancements of public-safety communications, including successfully incorporating a new critical public-safety relaying feature — dubbed “NR (new radio) sidelink multi-hop relay”— into the global standards of 3GPP R19.

The normative work for this feature will add support for as many as two additional relays on top of present R17/R18 single hop relay in User Equipment (UE) to network relaying. The normative work started, and it is on track for completion by December 2025. Multi-hop relaying is critical to extend off-network coverage for public-safety users.

Additionally, the plenary approved modifications to the RAN5 working group Terms of Reference (ToR) to extend its scope/responsibility to include mission-critical services (MCS) server conformance testing (further discussion below). MCS server conformance test specifications are important for the FirstNet Authority and the public-safety community to reduce implementation cost and rollout time for MCS.

RAN1 working group—responsible for the specification of the physical layer of the radio interfaces — reported steady progress on the R19 study and work items addressing high-priority features for public safety. These items included the study of the Artificial Intelligence (AI)/Machine Learning (15% completed) and the channel modeling study for Integrated Sensing and Communication (ISAC) for New Radio (NR, a.k.a. 5G) (about 5% completed).

The ISAC allows the network to collect data on the range, velocity, position, size, and the materials of objects in coverage areas to meet public safety’s situational-awareness needs.

Additionally, progress also was reported on the Ambient Internet of Things (IoT) feature that lets wireless sensors derive energy from solar and/or wind power, eliminating the need for frequent change of batteries (60% completed). Ambient IoT is designed to let connected wireless sensors be embedded in personal protection equipment (PPE) of public-safety users, without the need for frequent change of batteries for these sensors.

The working group also approved an introduction of network-level support for Half Duplex operation mode in Narrow Band-IoT Non-Terrestrial Networks (NTN, a.k.a. satellite direct to device). This work should support an accelerated rollout for this feature.

The RAN2 working group is responsible for defining the Radio Interface architecture and protocols. The working group started R19 work on the FirstNet Authority-championed feature of NR (new radio) sidelink multi-hop relay, with 15% completed progress to date.

RAN2 also reported solid progress on other high-priority R19 public-safety features such as NTN for NR (45% completed), NTN IoT (30% completed), and inter Radio Access Technology (RAT) mode for supporting mobility between LTE Terrestrial Network (TN) to NR-NTN (95% completed).

NTN for NR enhancements expand coverage beyond terrestrial mobile networks (e.g., to rural and remote unserved and underserved areas). IoT NTN enhancements are important to provide connectivity beyond coverage of terrestrial networks for IoT sensors and devices that can be integrated with and relied upon by public-safety systems.

RAN3 working group is responsible for the overall LTE and NG-RAN architecture and the specification of protocols for the related network interfaces.

In the context of dense 5G deployments — particularly when operating on mmWave spectrum — the backhaul connectivity poses an economical challenge. To address this, integrated access and backhaul was developed leveraging the use of same spectrum for both user access and network backhaul.

To further evolve backhaul solutions, 3GPP defined a new architecture named Wireless Access Backhaul (WAB). The WAB solution consists of a full base-station function and UE function, where the base-station function is used to communicate with UEs for access service. The UE function is used to communicate with another base station for backhauling purposes. During this meeting, the RAN Plenary approved the development of normative specifications for this feature.

The RAN4 working group is responsible for work on the Radio Frequency (RF) aspects, including performing simulations and deriving the minimum requirements for transmission and reception parameters for UE devices.

The group reported solid progress on R19 NR Power Class 2 (PC2 = 400 milliwatts) Reduced Capability (RedCap) UE (over 20% completed). This is a different work item than a previously defined PC2 UE smartphone/router power-class work item. This feature will support reduced capability devices making it a suitable candidate for equipping PPE of public-safety personnel.

The RAN5 working group — responsible for the development of UE conformance-test specifications — typically works one to two releases behind the other working groups. The group reported completion of LTE Conformance Test Aspects — Protocol enhancements for MCS for R16 (Mission Critical Push to Talk (MCPTT, MCVideo, MCData) and approval of a new work item UE Conformance — Protocol enhancements for MCS for R17 for LTE and NR.

RAN5 also reported revision of its ToR extending RAN5 scope/responsibility to include MCS server-conformance testing in 3GPP specifications that public-safety supports. For the first time, the public-safety community is developing 3GPP conformance-test specifications for server MCS conformance testing, which facilitates interoperability testing across interconnected MCS systems from various vendors. The RAN5 scope was previously limited to UE conformance testing only.

The other significant public-safety-related UE conformance-test specifications development includes R17 NR Sidelink single-hop UE to Network relay (30% completed), UE Conformance Solutions for R17 NR NTN (over 80% completed), and R18 UE Conformance for IoT NTN (over 25% completed).

The Service and System Aspects TSG Plenary

There were more than 275 in-person attendees at the TSG SA Plenary meeting. TSG SA is responsible for the overall architecture and service capabilities of 3GPP-based systems.

3GPP SA work continued to focus primarily on progressing the R19 features. The meeting also dedicated time planning for R20 and beyond, as 6G technology is becoming more of a focus in the SA1 working group. The SA working groups reported that many of the R19 work items are nearing 100% completion.

The highlight of the weeklong SA plenary meeting was the formal approval of the study item for 6G, which allows work to begin on 6G use cases and requirements.

As discussed in previous blogs, the SA1 working group is responsible for the 5G services and system requirements, and typically works one release ahead of the other 3GPP working groups.

SA1 has focused on R20 for the last two quarters, splitting into two focus areas. The first area was on 5G advance enhancements, and the second on 6G use cases and requirements. Many of the 5G-Advance features are continued enhancements to existing features, like satellite access, network sharing, and energy efficiency.

The 6G work started with the opportunity for members to present their views on what they envision for 6G. Based on these presentations and discussions, SA1 reported using their August 2024 meeting to develop an initial study item for 6G. The key area of focus will define potential requirements to enable the 3GPP system to support the needs of new and enhanced services and scenarios.

The SA2 working group — responsible for the 5G System and Evolved Packet System Architectures — reported steady progress on R19 architectural studies and technical specifications on high-priority features for public safety. These studies included some of the top-priority features for the FirstNet Authority, which are the Proximity Services (ProSe) enhancements. SA2 reported 100% completion of the technical report and 70% completion of the technical specifications (0% from the previous report).

The ProSe enhancements include the support for multi-hop UE-to-Network relay and multi-hop UE-to-UE relay. These enhancements will increase communications coverage and throughput in weak-coverage and off-network areas.

Most of the other studies for public-safety high-priority features were reported as completed, while technical specifications for these features have reached 40% completion on average. These features include enhancements to the vehicle-mounted relay to include backhaul support over NTN, Femtocell enhancements, Ambient IoT, artificial intelligence, and machine learning. Additionally, a phase 3 enhancement for Uncrewed Aerial Vehicles will improve detection and avoidance capabilities, as well as improve communication.

The SA3 working group is responsible for 5G Security Aspects. The working group reported the completion of the study about enabling the 5G system to support use of cryptographic algorithms with 256-bit key sizes to provide enhanced security. SA3 also reported that the security study for R19 to address enhancements for ProSe has reached 60% completion. This work evaluates and addresses security issues introduced with the new multi-hop relaying capabilities.

The SA6 working group develops the architectures for most MC features. The working group reported solid progress for R19 studies. The current R19 study for the MC architecture has been completed, and the work item reportedly is 75% complete.

This work item is a general work item including several features. The most significant public-safety feature is the MCS support for single-hop relay services for both UE-to-UE and UE-to-Network connectivity. This feature is 100% complete.

A feature designed to support sharing of administrative configuration between MC service systems will let different MC organizations share administrative information and allow easier user migration between systems is now 100% complete. The study of enhancements for application enablement over satellite is now 100% complete, and the normative work item has started. This work includes the impact of MC services support over satellite communications.

A new study item was included at the May 2024 SA6 meeting for a generic isolated operation for public safety (IOPS) mode for communication for 5G. This study will examine the issues and needs to provide MCPTT and MCData services when connectivity to the core network is not available or is highly degraded. SA6 also started an associated generic IOPS work item. Both the study and the work items are scheduled to be completed in December 2024 as part of R19.

The Core Network and Terminals (CT) TSG Plenary

There were more than 225 in-person attendees at the TSG CT Plenary meeting. This group covers the protocol details that follow and support the requirements and architectural work defined by the TSG SA groups.

The CT group completed R18 work last quarter; however, there remain a few late-change requests submitted for protocol corrections. R18 included the completion of notable features for public safety such as enhancements to MCPTT, ProSe, MC services over 5G broadcast (5MBS), and ad-hoc communications.

The meeting focused on starting work on Release 19 protocols. The group currently has 11 work items in progress and 12 new study/work items. Of these 23 projects, six are related to public safety.

Two of these projects were existing projects and are enhancements to mission-critical location work (10% completed) and protocol enhancements for mission-critical services (10% completed). Several of the new projects have not started yet, including ProSe for NTN, ProSe enhancements to support multi-hop relays, and railway specific enhancements for MCS. The railway-specific enhancement project was named as a new project for phase 2 of the vehicle-mounted relays.

Further information on the 3GPP’s work and organization can be found at: www.3gpp.org.

Dean Prochaska is the FirstNet Authority’s senior director of standards. Contributors to this article: FirstNet Authority Senior Standards Engineers Jeff Cichonski, Ihab Guirguis, Satish Jha, Mark Lipford, and Eshwar Pittampalli.