Public-Safety 5G Direct Mode, Broadcast Mode Standards Move Forward at December 3GPP Meetings
By Dean Prochaska
Tuesday, December 22, 2020 | Comments
The fourth quarterly Third Generation Partnership Project (3GPP) plenary e-meetings of 2020 recently concluded. At these December meetings, 3GPP momentum continued with more Release 17 (R17) progress.

Mission-critical (MC) features continue to progress. A major plus for public safety was the continued inclusion and clarification of important 5G direct mode and broadcast mode communications in R17. Many public-safety agencies from across the globe cosigned two contributions authored and led by the First Responder Network Authority (FirstNet Authority) to emphasize the importance of these R17 features.

The schedule for R17 was a major topic in 3GPP. At this set of plenary meetings, it was decided that a new six-month slip of schedule will occur for R17. The completion of the stage three work is now set for March 2022. As 3GPP continues to operate with e meetings instead of meeting in person, work is significantly slowed, especially for more controversial topics. Delegates cannot confer in person to find the compromises that standards are frequently built on.

Testing of a new online voting tool at these plenary meetings was successful. This new tool will allow voting in the March 2021 plenary meetings on chair and vice-chair positions that would normally occur at face-to-face meetings. Some positions have been extended due to the pandemic, but now elections can resume.

The following Technical Specification Group (TSG) reports provide details on each of the plenary meetings with a focus on public-safety activities. Representatives from nearly all major mobile equipment vendors, chip manufacturers, software vendors and network operators from about 35 countries participated, as well as the FirstNet Authority and other government agencies representing public-safety interests.

The Radio Access Network (RAN) Plenary
There were more than 700 registrants for the radio access network (RAN) TSG plenary meeting. RAN is responsible for defining the functions, requirements and interfaces of the 3GPP radio network.

Study items that were completed during the fourth quarter included reduced capability/capacity (RedCap) user equipment (UE), enhanced positioning for industrial internet of things (IIoT), 5G New Radio (NR) coverage enhancements, and solutions to support non-terrestrial networks (NTN) such as satellites.

The RAN plenary approved a new work item to support low-cost devices, such as sensors and wearables, with low complexity and compact form factor. These RedCap UEs are expected to support all frequency bands for both frequency division duplex (FDD) and time division duplex (TDD). When embedded in personal protection equipment, sensors and wearables are important safeguards for public safety.

With the completion of the study item on NR positioning enhancements, the RAN plenary also approved a new work item that will create specifications for positioning enhancements in R17, targeting higher resolution positioning requirements for both commercial and IIoT use cases. The FirstNet Authority has been involved in advancing these positioning enhancements for the benefit of first responders.

Additionally, the study item for NR coverage enhancements is completed, and the RAN TSG has approved a new work item that will pursue the specification work to support further NR coverage enhancements. As a part of this work item, enhancements will be specified for the physical uplink shared channel and the physical uplink control channel.

A new work item was approved for support of NTN, including low earth orbit and geo-synchronous orbit satellites. The work will include core specifications to support FDD, UEs with global navigation satellite system (GNSS) capabilities and commercial handheld devices using sub-6 GHz frequencies.

To increase coverage, integrated access and backhaul (IAB) was previously defined to allow a mobile cell to connect back to the core through a fixed cell using part of the NR channel capacity. To support IAB, radio frequency (RF) repeaters for NR are needed. In response, the RAN plenary approved “NR Repeaters” as a new work item to leverage existing RF specifications for IAB and LTE repeaters.

The Service and Systems Aspects (SA) Plenary
There were over 400 registrants in the plenary meeting for the SA TSG, which is responsible for the overall architecture and service capabilities of 3GPP-based systems. The meeting continued its primary focus of progressing R17 architecture specifications and Release 18 (R18) requirements.

Technical studies for 5G multicast-broadcast services (5MBS) and 5G proximity services (ProSe) have reached 90% completion and were sent to the SA Plenary "for information". As the technical studies are concluding, new work item descriptions to start the technical specification work for 5MBS and ProSe were approved. Technical specification work continues for satellite access in 5G. Native 5G support by satellites holds great promise for increasing coverage for public safety.

In SA working group one, new MC requirements were added to enhance floor control queuing. Studies also continued regarding off-network operation for railways and the sharing of MC administration configuration between interconnected MC systems. In SA working group six, normative work is now in progress on defining MC services (MCS) over 5G, while 5G MC enablers, such as sidelink and 5MBS are still under development in other working groups. The plan is to complete work on the first phase of MCS over 5G in R17 with a scope of on-network, unicast operation.

Progress on architecture issues and solutions for an MC gateway UE function continues. This work would support multiple non-3GPP devices connected to 3GPP MCS via the gateway UE. Finally, significant enhancements were made to mission-critical data (MCData) including the addition of a field that allows organization-specific metadata to be carried with MCData transmissions.

Normative work is underway in working group three (SA3) on enhancements to improve security for MC media content storage, ProSe, 5MBS and unmanned aerial vehicles. This normative work is intended to keep the MC security architecture aligned with architecture features being defined in SA6. Technical studies for the security aspects of enhancement of proximity-based services have started in SA3. This work will address security issues that other groups highlighted, including security and privacy aspects of UE-to-network relay, security aspects of UE-to-UE relay, and security aspects based on the Layer-2 or Layer-3 relay architecture.

The Core Network and Terminals (CT) Plenary
There were nearly 225 registrants for the plenary meeting of the CT TSG, which covers the protocol details and follows the requirements and architectural work performed in the SA TSG.

Solutions for several R17 MC features were approved at this meeting. Support for inclusion of the Z-axis location measurement and for a location timestamp now exist in mission-critical push-to-talk (MCPTT), MCData and mission-critical video (MCVideo). Unicast media stop/resume was also approved. This feature will allow a user to block delivery of streaming services that are not being used because of higher priority activities that require the user's attention, thus saving radio resources. A new study item, “Minimization of Service Interruption (MINT),” was approved that may benefit first responders.

Interruption of communications, while not completely avoidable in a radio environment, can cause delays and require speakers to repeat themselves. Any interruption minimization possible can be valuable in a mission-critical situation. The FirstNet Authority will be following this work to ensure maximum benefit for public safety.

Of the 24 issues found with MC standards during past European Telecommunications Standards Institute (ETSI) Plugtest events to test MC implementations against each other in a lab environment, only five issues now remain unresolved. The FirstNet Authority continues leading work in 3GPP to ensure that these issues result in fixes/clarifications.

The difficulties of agreeing on complex technical issues in these e-meetings was evident in this CT plenary meeting. Several 5G issues were given significant attention, time and work toward resolution, but they still needed to be remanded back to the responsible working groups for further discussion and compromise. In contrast, MC issues were all resolved at the working group level due to concerted cooperation by companies and organizations interested in MC aspects.

Find further information on the 3GPP’s work and organization here.

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Dean Prochaska is senior director of standards for the First Responder Network Authority (FirstNet). He serves as a FirstNet representative during the 3GPP meetings.



 
 
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