The challenge

Background and context

The public safety and defence communities have critical needs for resilient, secure, interoperable, and ubiquitous communications to support operations in complex environments such as natural disasters, public safety emergencies, and large planned events. These stringent and unique communications needs extend beyond those of commercial users, and include continuous connectivity, security, prioritization and dynamic user profiles. These needs can benefit greatly from the use of mobile broadband technologies such as 4G and 5G, due to their very high levels of performance (speed, latency, densification of devices) and their pervasiveness.

With the emergence of 5G, the number of mobile broadband network instances continues to grow rapidly and add to the already vast global mobile broadband communications landscape. With this increased number of networks, including commercially and privately operated, user connectivity and interoperability across all networks will become more challenging. This is because users will increasingly connect to multiple mobile broadband networks over the course of a day, and connectivity needs to be re-established with the new network during each transition (roaming). The number of re-connections will only increase with the future emergence of 6G.

Unfortunately, this need to reconnect also causes a break in the communication session since user devices need to re-authenticate to the new network (each distinct network has a unique Public Land Mobile Network Identifiers (PLMN ID)). Understandably, this is not ideal for any user group, but the negative impact of this on operations within the public safety and defence communities will be very problematic, where continuous, uninterrupted communications is of the utmost importance. The need to reconnect and cause a break in communication each time a first responder or defence personnel changes networks is a significant capability gap, and such network interworking, and interoperability gaps and challenges need to be resolved.

At the forefront of capabilities required to resolve these gaps is session persistence (service continuity) which would enable uninterrupted connectivity while devices hand off from one PLMN ID network to another in a seamless manner. This in turn will enable continuous, uninterrupted mobile communications over multiple networks for first responders and defence personnel and could lead to the development of a whole range of new capabilities that require session persistence without loss of connectivity such as:

• Real-time situational awareness
• Command, Control, Communications, Computers, Intelligence, Surveillance and Reconnaissance (C4ISR)
• Control of Uncrewed Ground Vehicles (UGVs), Uncrewed Aerial Vehicles (UAVs), and telerobotics

Essential outcomes

We are seeking innovative solutions that can enable the delivery of seamless inter-PLMN ID network interworking and service continuity.

The proposed solutions must:

• Include core network to core network configuration;
• Include radio access network (RAN) configuration;and,
• Address network interworking scenarios that deliver session persistence (service continuity) between distinct Third Generation Partnership Project based (3GPP-based) mobile broadband networks. This would allow for defence, security, and public safety users to experience full user connectivity in a complex multi-network mobile broadband communications environment.

Desired outcomes

The proposed solutions should consider one or more of the following scenarios for network interworking with session persistence (service continuity).

• Between distinct 5G networks.
• Between distinct 5G and private (non-commercial) 5G networks.
• Between distinct 4G and 5G networks.
• Between distinct 4G and private (non-commercial) 5G networks.
• Between terrestrial-based 4G networks and Low Earth Orbit (LEO)-based 5G networks.
• Between terrestrial-based 5G networks and LEO-based 5G networks.
• Between Internet of Things (IoT) machine-type communications (fixed or mobile) and 5G.

Proposals should include a test plan for over-the-air testing.