Proximity Services identifier

Description

The ProSe identifier (Proximity Services identifier) is a key concept in 3GPP Proximity Services (ProSe), which enables direct device-to-device communication and discovery. Introduced in Release 19 for 5G ProSe, the ProSe identifier is used to indicate the ProSe Application associated with ProSe operations, specifically in 5G ProSe Direct Discovery and 5G ProSe Direct Communication. It serves as a link between the ProSe application layer and the underlying 3GPP network procedures. According to TS 23.304 and TS 32.277, the ProSe identifier can be associated with one or more ProSe applications, and a ProSe application can be associated with one or more ProSe identifiers. This many-to-many relationship allows flexible mapping between applications and identifiers, which is essential for supporting diverse use cases and service models.

In the context of ProSe Direct Discovery, the ProSe identifier is equivalent to the 'Application ID' defined in TS 23.303. This means that when a UE performs discovery, it uses the ProSe identifier to announce or query for specific applications. For example, a UE might use a ProSe identifier to discover nearby UEs running a particular application (e.g., a social networking app). The identifier is included in discovery messages, allowing UEs to filter and respond to discovery requests based on application interests. For ProSe Direct Communication, the ProSe identifier helps determine the appropriate communication parameters, such as security and QoS, by associating the communication with a specific application. The network can use the ProSe identifier to apply policies, charging, and authorization.

The architecture for ProSe involves several network functions, including the ProSe Function, which manages ProSe identifiers and their mappings to applications. The ProSe Function may interact with the Unified Data Management (UDM) or Policy Control Function (PCF) to retrieve subscriber-specific ProSe policies. The ProSe identifier is typically provisioned in the UE and can be dynamically updated. In 5G, ProSe is integrated with the 5G Core (5GC), leveraging network slicing and edge computing for enhanced performance.

In Release 20, the definition was revised to emphasize global uniqueness and explicitly refer to 5G ProSe. The new definition states: 'A globally unique identifier used to identify the ProSe Application associated with the ProSe operation in 5G ProSe Direct Discovery and 5G ProSe Direct Communication. In this Release, the 'Application ID' defined in TS 23.303 can be used as the ProSe identifier in 5G ProSe Direct Discovery and in a consequent 5G ProSe Direct Communication.' This change clarifies that the identifier is globally unique, which is important for interoperability across networks and for avoiding conflicts. It also aligns with the 5G ProSe architecture and ensures backward compatibility with the Application ID from TS 23.303.

The ProSe identifier is a critical enabler for proximity-based services, which are expected to play a significant role in 5G for applications like public safety, social networking, and IoT. Its design ensures that applications can be uniquely identified and that network policies can be applied correctly.

Purpose & Motivation

The ProSe identifier exists to solve the problem of identifying and managing ProSe applications in direct discovery and communication scenarios. Before its introduction, ProSe in LTE (4G) used the Application ID, which was defined in TS 23.303. However, with the evolution to 5G, there was a need for a more robust and globally unique identifier that could support the enhanced capabilities of 5G ProSe, such as higher data rates, lower latency, and massive connectivity. The ProSe identifier provides a standardized way to map applications to network procedures, enabling consistent treatment across different UEs and networks.

The many-to-many relationship between ProSe identifiers and applications addresses the flexibility required by diverse service models. For instance, a single application might use multiple identifiers for different contexts (e.g., public vs. private discovery), or multiple applications might share a common identifier for a specific service (e.g., a group of apps for a particular venue). This flexibility is essential for operators to offer customized ProSe services.

The introduction in Rel-19 reflects the maturity of 5G ProSe and the need for a formal identifier in the 5G ecosystem. The Rel-20 update further refined the definition to emphasize global uniqueness and explicit 5G context, addressing potential ambiguities and ensuring interoperability. The ProSe identifier is expected to facilitate new business models and use cases, such as proximity-based marketing, emergency communications, and vehicular communications.