User Requested Application Priority

Description

User Requested Application Priority is a concept introduced in Release 19 for Mission Critical Video (MCVideo) services. It represents the priority level that a user requests for a particular application or communication session. This priority is defined in 3GPP TS 23.280, which specifies the common functional architecture for mission-critical services. The User Requested Application Priority is used by the MCVideo server to determine the actual priority of the communication, taking into account the requested priority and other factors such as user role, resource availability, and operator policies. The server's implementation determines how these factors are combined, providing flexibility for different deployment scenarios.

In the context of MCVideo, priority is crucial for ensuring that critical communications are delivered with the appropriate quality of service, especially in emergency situations where network resources may be scarce. The User Requested Application Priority allows users to indicate the importance of their communication, which can be used to prioritize resource allocation, scheduling, and admission control. For example, a first responder requesting a video stream from an incident scene may request a high priority to ensure timely delivery. The MCVideo server then evaluates this request against other factors, such as the user's role (e.g., incident commander vs. regular responder) and the current network load, to assign the final priority.

The technical implementation of User Requested Application Priority involves several steps. First, the user's device (UE) includes the requested priority in the session establishment request sent to the MCVideo server. This priority may be based on user input or pre-configured settings. Second, the MCVideo server receives the request and extracts the requested priority. Third, the server applies its internal logic to determine the final priority, which may involve mapping the requested priority to a standardized priority level (e.g., from TS 23.280) and considering other factors. Fourth, the server communicates the final priority to the underlying network functions, such as the Policy Control Function (PCF) and the Session Management Function (SMF), which enforce the priority through QoS mechanisms. This may involve setting the appropriate 5QI (5G QoS Identifier) or allocating dedicated resources.

The User Requested Application Priority is part of a broader priority framework in mission-critical services. 3GPP TS 23.280 defines a set of priority levels, often ranging from emergency to low priority, which are used across MCPTT, MCVideo, and MCData. The User Requested Application Priority is one input to the priority determination process, which also includes the user's authorized priority (based on subscription) and the application's default priority. The MCVideo server acts as the decision point, ensuring that the final priority aligns with the operator's policies and the mission-critical requirements.

This concept is particularly important for MCVideo because video communications consume significant bandwidth and are sensitive to latency and jitter. By allowing users to request priority, the system can better manage resources and ensure that critical video streams are not degraded. The flexibility given to the server implementation allows operators to tailor the priority logic to their specific needs, such as prioritizing certain user roles or incident types. As mission-critical services evolve, the User Requested Application Priority will continue to play a key role in ensuring reliable and timely communication for public safety and other critical users.

Purpose & Motivation

The User Requested Application Priority was created to provide a mechanism for users to indicate the importance of their communication in Mission Critical Video (MCVideo) services. In mission-critical scenarios, such as public safety operations, the ability to prioritize communications can be life-saving. However, network resources are finite, and not all requests can be granted the highest priority. The User Requested Application Priority allows users to express their needs, while the MCVideo server balances these requests against other factors to make informed decisions.

Historically, mission-critical services like MCPTT and MCVideo have relied on pre-configured priority levels based on user roles and subscriptions. While effective, this approach lacked the flexibility for users to dynamically request higher priority for specific situations. For example, a first responder at an incident scene might need to send a high-priority video stream to command, even if their default priority is lower. The User Requested Application Priority addresses this by allowing the user to request a priority level, which the server can consider along with other factors.

The motivation for this concept also stems from the need for efficient resource management. In a large-scale incident, many users may request high priority simultaneously, leading to contention. By having the server determine the final priority based on multiple factors, the system can avoid over-allocation and ensure that the most critical communications are prioritized. This approach also allows operators to implement policies that reflect their operational procedures, such as giving precedence to incident commanders or specific agencies. The User Requested Application Priority is therefore a key enabler for flexible and efficient priority management in MCVideo.