Isolated Operation for Public Safety Mission Critical System

Description

The IOPS MC system is a Rel-19 architectural concept defined in 3GPP TS 23.180 and TR 23.700. It represents the collection of application functions and enabling capabilities that are necessary to deliver Mission Critical (MC) services—such as MCPTT (Mission Critical Push-to-Talk), MCVideo, and MCData—while the network is operating in IOPS (Isolated Operation for Public Safety) mode. In this mode, the backhaul connection between the local radio access network and the central core network is disrupted, and the system must autonomously sustain a defined level of service for first responders and other MC users.

The IOPS MC system builds upon the existing 3GPP MC service architecture (defined in TS 23.280 and related specs) but adapts it for isolated operation. It includes functional entities such as the MC service server(s) that are deployed locally or embedded within the IOPS network, along with supporting functions like group management, location management, and security. These functions are hosted on a Local EPC or a dedicated edge computing platform that remains reachable by the eNodeBs in IOPS mode. The system ensures that MC users can continue to communicate with each other within the isolated network, and it may also support limited connectivity to external networks if a satellite or other backup link is available.

Key components of the IOPS MC system include the MC service application servers (e.g., MCPTT server, MCVideo server), the group communication enablers (GCSE), and the underlying IP connectivity, QoS, and policy functions. The system must handle user authentication, authorization, group affiliation, and floor control locally, without relying on the central core network. It also needs to manage service continuity when the backhaul is restored, including synchronization of user data and session states with the central MC system.

The IOPS MC system operates in close coordination with the IOPS network (the radio access part) and the IOPS mode of operation. When the backhaul is lost, the IOPS network detects the isolation and triggers the activation of the IOPS MC system. The system then takes over the MC service delivery, ensuring that critical communication (e.g., group calls, emergency alerts) continues with minimal disruption. The level of service may be reduced compared to normal operation—for example, only voice and low-rate data may be supported—but the essential mission-critical functions remain available.

From a standards perspective, the IOPS MC system is specified in 3GPP TS 23.180, which defines the architecture, procedures, and information flows for MC services in IOPS mode. TR 23.700 provides the study and rationale. The system is designed to be interoperable with existing MC deployments and to leverage common enablers, ensuring that users experience a consistent service even when isolated. This capability is crucial for public safety scenarios such as natural disasters, remote operations, or large-scale incidents where the central network infrastructure may be damaged or unreachable.

Purpose & Motivation

The IOPS MC system exists to solve a critical problem in public safety communications: the loss of backhaul connectivity between the local radio access network and the central core network. In such situations, first responders still need to communicate, but traditional cellular networks would fail because all service logic and user data reside in the central core. The IOPS MC system provides a self-contained, local implementation of mission critical services that can operate autonomously, ensuring that vital communication links are maintained.

Historically, isolated operation was addressed for LTE in Rel-13 with the IOPS network concept, which allowed a local EPC to serve eNodeBs when backhaul was lost. However, that early work focused primarily on basic IP connectivity and voice services, not on the full suite of mission critical applications. As MC services became standardized (MCPTT in Rel-13, MCVideo and MCData in later releases), it became clear that these services also needed to survive isolated operation. The IOPS MC system was introduced in Rel-19 to fill this gap, extending the IOPS concept to the MC service layer.

The motivation is to provide a seamless experience for MC users: when the backhaul fails, the system should automatically switch to IOPS mode and continue to deliver MC services with as little degradation as possible. This requires local hosting of MC servers, local group management, and procedures for synchronizing with the central system once connectivity is restored. The IOPS MC system thus enhances the resilience and reliability of public safety networks, which is a key requirement for mission critical communications.