How 6G Is Being Shaped for Mission Critical Communications

Mission critical communications have been evolving within 3GPP for more than a decade. Beginning with Mission Critical Push-to-Talk in Release 13, the standards have expanded to include mission critical video, data, location, interworking, recording, non-terrestrial network support and many other capabilities.

At Critical Communications World 2026 in London, two presentations provided complementary views of how this work will continue into the 6G era. Ricardo Blasco from Ericsson looked at the relevance of the emerging 6G Radio Access Network standards, while Jukka Vialén from Airbus, speaking as 3GPP SA6 Vice Chair, explained how the mission critical application layer is being prepared for 6G.

The important message from both presentations was that 6G mission critical communications will not be created from scratch. It will build on the extensive work already completed for LTE, 5G and 5G-Advanced, while introducing new radio, network, security and application capabilities where they offer real operational benefits.

The initial 6G standards are being developed as part of 3GPP Release 21. The current schedule targets the Stage 2 freeze in June 2028 and the Stage 3 freeze in December 2028, with the Release 21 completion milestone expected around March 2029. This aligns with the wider industry expectation that the first commercial 6G systems could become available around 2030.

One of the proposed principles for 6G is to minimise complexity while maximising performance. Rather than repeating the gradual transition from 4G to 5G Non-Standalone and then 5G Standalone, 6G is expected to use a standalone architecture from the beginning. The 6G Core would be based on an evolved version of the 5G Core, supported by a programmable and intent-based architecture, selected open interfaces and the ability to operate across existing 3GPP spectrum as well as new centimetre-wave bands.

Spectrum sharing between 5G and 6G is also expected to be important. This would allow operators and public safety organisations to introduce 6G capabilities gradually without immediately replacing existing networks, devices and spectrum allocations.

For mission critical users, coverage remains more important than extreme peak data rates. Emergency services, railways, utilities, defence organisations and other critical users need connectivity inside buildings, tunnels, remote regions, disaster areas and locations where parts of the terrestrial network may have failed.

Several possible 6G radio enhancements are therefore directly relevant. These include improved uplink waveforms, higher power user equipment, more efficient power amplifiers, uplink and downlink decoupling and AI-assisted receivers that can improve channel estimation while reducing reference signal overhead.

Non-terrestrial networks are also expected to become a more deeply integrated part of the system. A common design across terrestrial and non-terrestrial access could allow devices to move more smoothly between mobile networks, satellites and potentially other aerial platforms. Native support for unmanned aerial vehicles could be valuable for temporary coverage, surveillance, search and rescue and communications during major incidents.

Reliability alone is not enough for critical communications. The network must also be resilient when infrastructure, spectrum, positioning systems or application servers fail.

The proposed 6G radio design includes enhanced protocol robustness and mechanisms for recovering quickly from failures using mobility and carrier aggregation. A device could, for example, detect a problem with one carrier or access node and rapidly move to another available connection.

Other areas being considered include non-terrestrial connectivity that does not depend completely on Global Navigation Satellite Systems, greater privacy protection for physical-layer channels and signals, early failure detection using new network observability tools and mechanisms for making better use of redundancy within each deployment.

This is particularly relevant for public safety networks. During a major emergency, congestion, equipment failures, power outages and physical damage to sites can happen at the same time. A future mission critical network will therefore need to identify degradation before services fail completely and select alternative radio, transport, core or application resources automatically.

Artificial Intelligence and Machine Learning are expected to operate at several levels of the 6G RAN. Within the air interface, they could assist with channel estimation, digital post-distortion and reducing Channel State Information overhead. At cell level, AI could predict traffic, measurements and network events. Across the wider network, it could support load balancing, mobility optimisation, energy management and service quality.

For mission critical communications, however, introducing AI is not simply about allowing an algorithm to make decisions. The network must be able to monitor model performance, activate or deactivate models, switch between models and fall back to conventional non-AI mechanisms when required.

The proposed 6G AI lifecycle management framework would therefore support data collection, training, inference, monitoring, retraining and root cause analysis. Fast switching and fallback mechanisms will be particularly important where an AI model behaves unexpectedly or conditions differ significantly from the data on which it was trained.

Integrated Sensing and Communications, generally known as ISAC, could add another dimension to mission critical services. While initial 5G work has focused mainly on detecting and tracking UAVs using signals transmitted and received from the same site, 6G could support sensing involving multiple sites and user devices.

This could enable the detection and tracking of passive objects, improve situational awareness and allow sensing information to assist communication performance. Potential applications include locating people or equipment, detecting drones, monitoring restricted areas and supporting emergency operations where conventional sensors are unavailable.

The application-layer work is being studied separately within 3GPP SA6. The Study on Mission Critical Architecture Evolution and 6G Capabilities for Mission Critical Services began in March 2026 and is scheduled to continue until June 2027.

The study is analysing how 6G capabilities could enhance existing mission critical services and how those services could transition from the 5G System to a future 6G transport network. Thirty-two use cases from the wider 3GPP study on 6G use cases and service requirements have already been identified as potentially affecting the mission critical application layer.

Some of the first issues identified include session connectivity, Quality of Service characteristics, network slicing, migration between network generations and maintaining mission critical service continuity during failures.

The work is also considering improvements that may be useful regardless of the underlying radio generation. These include handling mission critical server or network-function failure and overload, using sidelink for positioning and ranging between mission critical devices and developing a converged user profile across mission critical services.

Security will be another important part of the transition. 3GPP SA3 is studying next-generation mission critical security, including the impact of post-quantum cryptography. Existing identity-based encryption mechanisms such as MIKEY-SAKKE cannot simply be assumed to meet future post-quantum requirements.

The current intention is to retain much of the existing mission critical security architecture, including its client-to-server and server-to-server procedures, while reviewing the underlying encryption algorithms, key-management mechanisms, hashes, signatures, authentication and service-authorisation processes.

In parallel, 5G-Advanced is continuing to provide capabilities that will form part of the journey towards 6G. Release 20 work includes Proximity Services multi-hop relays, logging and recording, Future Railway Mobile Communication System enhancements, the ability to disable and re-enable mission critical services on specific devices, and improvements to ambient listening. Discreet listening and monitoring has been moved into Release 21.

Multi-hop relay is especially relevant to difficult environments. Devices can relay communications through intermediate devices to extend coverage into tunnels, underground locations, buildings and other dead zones. Such features demonstrate why 6G mission critical communications should be viewed as an evolution of work already taking place rather than as a completely separate future system.

The overall objective is to maintain a broad and unified 3GPP ecosystem. Mission critical users should be able to continue using LTE, 5G and 5G-Advanced while adopting selected 6G capabilities when suitable networks and devices become available.

An evolutionary approach based on an evolved core, spectrum sharing and support for multiple radio generations should reduce market fragmentation. It should also improve the commercial viability of specialised capabilities such as sidelink, broadcast, non-terrestrial connectivity and high-resilience communications, which might otherwise struggle to achieve sufficient scale.

Although 6G is often associated with new consumer experiences and very high data rates, its most important contribution to critical communications may be something less visible: networks that maintain coverage, recognise failures, use multiple forms of connectivity, recover automatically and continue delivering essential services under extremely difficult conditions.

The foundations are now being studied. The challenge for 3GPP and the wider critical communications community will be to turn these capabilities into a common, interoperable and commercially sustainable platform without losing the reliability and operational control that mission critical users require.

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