Proximity Services-enabled Public Safety User Equipment

Description

The ProSe-enabled Public Safety UE is a specific type of User Equipment (UE) defined in 3GPP specifications to support proximity-based services for public safety applications. Introduced in Release 12, this UE is configured by the Home Public Land Mobile Network (HPLMN) to be authorized for public safety use and is capable of executing ProSe procedures and capabilities tailored for public safety scenarios. Unlike regular UEs, a ProSe-enabled Public Safety UE can participate in ProSe Group Communication, ProSe UE-to-Network Relay, and other ProSe services even when network coverage is unavailable, by using direct device-to-device communication. The UE may optionally have a USIM with special access classes {12, 13, 14}, which are reserved for public safety personnel and grant priority access to the network during congestion or emergencies.

Architecturally, the ProSe-enabled Public Safety UE is a standard UE with additional software and hardware capabilities to support ProSe. It must support the PC5 interface for direct communication with other UEs and the Uu interface for communication with the network. The UE is provisioned with ProSe-related parameters, such as ProSe Group IDs, security keys, and relay selection policies, by the ProSe Function in the network. The ProSe Function also authorizes the UE for specific ProSe services based on its subscription and configuration. The UE may also interact with a ProSe Application Server for group management and application-level services. The special access classes {12, 13, 14} are stored on the USIM and are used by the network to prioritize access for public safety users during radio resource congestion.

Key components of the ProSe-enabled Public Safety UE include the ProSe protocol stack, which handles discovery, connection establishment, and data transfer; the security module, which manages encryption and integrity protection for ProSe communication; and the application layer, which provides public safety applications such as push-to-talk, video streaming, and location sharing. The UE must support both network-controlled and autonomous operation modes. In network-controlled mode, the network manages resource allocation and mobility; in autonomous mode, the UE uses pre-configured parameters to communicate directly with other UEs without network assistance. The UE also supports relay functionality, allowing it to act as a relay for other UEs or to connect via a relay to the network.

The operation of a ProSe-enabled Public Safety UE involves several procedures: ProSe discovery, where the UE discovers other UEs or relays; ProSe communication establishment, where the UE sets up a direct or relayed communication path; and ProSe communication maintenance, where the UE manages mobility and resource allocation. The UE may also perform ProSe UE-to-Network Relay procedures, acting as a relay for remote UEs or connecting to a relay to reach the network. The 3GPP specifications 23.303, 23.703, 32.277, 32.844, and 36.300 define the architecture, service requirements, management, and radio aspects of the ProSe-enabled Public Safety UE.

The ProSe-enabled Public Safety UE is a cornerstone of mission-critical communication, enabling first responders to communicate reliably and efficiently in all scenarios. It leverages the benefits of proximity services to provide group communication, relay connectivity, and priority access, ensuring that public safety personnel can perform their duties effectively. As 3GPP evolves towards 5G, the capabilities of the ProSe-enabled Public Safety UE continue to expand, with enhancements in security, interoperability, and support for new services such as mission-critical video and data.

Purpose & Motivation

The ProSe-enabled Public Safety UE was created to meet the unique communication needs of public safety organizations, such as police, fire, and emergency medical services. These organizations require highly reliable, secure, and feature-rich communication systems that can operate even when network infrastructure is unavailable or congested. Traditional public safety communication systems, such as Land Mobile Radio (LMR), provided basic voice group communication but lacked advanced data capabilities and interoperability with commercial networks. The ProSe-enabled Public Safety UE addresses these limitations by leveraging cellular technology to provide advanced services such as group video, file sharing, and location tracking, while also enabling direct device-to-device communication for off-network operation.

The motivation for this UE type stems from the need for priority access and authorization. During emergencies, cellular networks can become congested, and public safety users must be able to communicate without being blocked by commercial traffic. The special access classes {12, 13, 14} on the USIM allow the network to identify and prioritize public safety users, ensuring they get access to radio resources. Additionally, the HPLMN configuration ensures that only authorized UEs can use ProSe services, preventing misuse and ensuring security. The ProSe-enabled Public Safety UE also supports interoperability, allowing different agencies to communicate seamlessly, which is critical for coordinated emergency response.

Furthermore, the ProSe-enabled Public Safety UE is designed to support the evolution towards 5G and mission-critical services. It enables new use cases such as real-time video surveillance, drone control, and IoT sensor integration. The UE can also act as a relay, extending coverage for other public safety UEs in challenging environments. As 3GPP continues to develop, the ProSe-enabled Public Safety UE will remain a key enabler for advanced public safety communication, ensuring that first responders have the tools they need to save lives and protect communities.