July 2026, London — The TCCA (The Critical Communications Association) has released a new technical white paper examining the theoretical performance of Off-network Mission Critical Services (MCX), providing the critical communications industry with a comprehensive framework for evaluating 5G direct device-to-device (D2D) communications when network infrastructure is unavailable.

Titled "Theoretical Performance of Off-network MCX," the July 2026 publication explores how 3GPP-defined NR Sidelink (PC5) technology can deliver mission-critical voice, video and data services beyond cellular coverage. The white paper is expected to serve as a technical reference for public safety agencies, railway operators, utilities, critical infrastructure operators, equipment manufacturers and mobile network operators planning next-generation mission-critical broadband deployments.

As governments and industries worldwide accelerate the migration from legacy narrowband technologies such as TETRA, P25 and DMR to broadband mission-critical communications, maintaining operational communications outside network coverage remains one of the most important requirements. The report addresses this challenge by analysing the theoretical capabilities of Off-network MCX and identifying the key parameters that influence communication range, reliability, latency and service quality.

According to the white paper, Off-network MCX leverages the 5G NR Sidelink interface to enable direct communications between user equipment without relying on base stations or core network infrastructure. Beyond supporting Mission Critical Push-to-Talk (MCPTT), the technology also enables Mission Critical Video (MCVideo) and Mission Critical Data (MCData), significantly extending the capabilities traditionally offered by direct mode communications in conventional land mobile radio systems.

The study evaluates a broad range of performance factors, including maximum coupling loss (MCL), user equipment transmission power, antenna configuration, operating spectrum, synchronization methods, mobility, interference, signal quality and environmental conditions. It also examines how these parameters affect communication range and operational resilience under a variety of mission-critical scenarios.

Among its key findings, the paper highlights the advantages of low-frequency spectrum for extending communication range, the benefits of high-power user equipment and external antennas for improving coverage, and the importance of synchronization and interference management in maintaining reliable Off-network MCX performance. The report also outlines theoretical optimisation strategies for balancing coverage, latency, spectrum efficiency and reliability in autonomous 5G Sidelink deployments.

The publication comes as international standardisation work on 3GPP Mission Critical Services and the Future Railway Mobile Communication System (FRMCS) continues to gain momentum. With increasing demand for resilient broadband communications across emergency services, transportation, utilities and industrial sectors, the white paper provides a valuable technical foundation for future Off-network MCX deployments and the broader evolution of mission-critical broadband ecosystems.

The full white paper forms part of TCCA's ongoing efforts to support industry understanding of 3GPP Mission Critical Services and the evolution of interoperable broadband communications for critical operations worldwide.

Read the full whitepaper here