User Plane Positioning Connection Management

Description

User Plane Positioning Connection Management (UPP-CM) is a Rel-19 feature that governs how a User Equipment (UE) establishes, maintains, and releases a user-plane connection dedicated to positioning operations. In legacy 5G positioning (introduced in Rel-16/17), location services were predominantly handled through the control plane via the LTE Positioning Protocol (LPP) transported over NAS and RRC signaling. While functional, this approach can introduce latency and signaling overhead, especially for continuous or high-rate positioning. UPP-CM addresses this by defining procedures that allow positioning data — such as assistance data, measurement reports, and location estimates — to flow over the user plane, leveraging the data radio bearer and the 5G core user plane path.

The architecture of UPP-CM spans both the access network and the core network. In the core network, the specification 24.572 defines the UE-to-network protocols for user plane positioning, while 29.518 covers the corresponding service-based interface procedures for the Location Management Function (LMF) and related network functions. The UE interacts with the LMF through a user-plane connection that may be anchored at a User Plane Function (UPF) or a dedicated positioning server. UPP-CM defines the connection states, the triggers for establishing or releasing the user-plane positioning session, and the mapping between positioning session identifiers and the underlying transport connection.

Key components include the UE, the Next Generation Radio Access Network (NG-RAN), the UPF, the LMF, and the Access and Mobility Management Function (AMF) which may still be involved for authorization and policy. The UPP-CM procedures define how the UE requests a user-plane positioning connection, how the network authorizes and configures it, and how the connection is maintained during mobility events such as handovers. The management aspect includes monitoring connection health, re-establishment after radio link failure, and release when the positioning session ends or when resources are needed for other services.

From a protocol perspective, UPP-CM relies on the User Plane Positioning Protocol (UPPP) or similar mechanisms defined in 24.572. This protocol carries positioning messages that would otherwise be sent via LPP over the control plane. The user-plane approach allows for higher throughput and potentially lower latency, which is beneficial for applications such as augmented reality, autonomous vehicles, and industrial IoT where frequent or real-time location updates are required. It also enables positioning to be treated as a data service, subject to QoS differentiation and network slicing.

UPP-CM is significant because it represents a shift in how positioning is integrated into the 5G system. By decoupling positioning transport from control-plane signaling, it reduces the burden on signaling radio bearers and the AMF, and it allows positioning to scale with user-plane traffic. It also facilitates new business models where positioning is offered as a value-added service with specific QoS guarantees. As Rel-19 continues to evolve, UPP-CM is expected to be a foundational enabler for advanced location-based services in 5G-Advanced and beyond.

Purpose & Motivation

UPP-CM exists to overcome the limitations of control-plane-only positioning in 5G. In earlier releases, positioning protocols such as LPP were transported over NAS and RRC, which constrained the frequency and volume of positioning messages and added latency due to signaling overhead. For emerging applications like V2X, drone navigation, and industrial automation, these constraints are unacceptable. UPP-CM was created to allow positioning traffic to use the user plane, which is optimized for high-throughput, low-latency data transport.

Another motivation is the desire to treat positioning as a first-class service that can be managed with QoS and network slicing. By establishing a dedicated user-plane connection for positioning, operators can apply specific QoS profiles, monitor performance, and integrate positioning with other data services. This also simplifies the core network architecture by reducing the dependency on control-plane signaling for high-rate positioning.

Historically, the 3GPP has progressively enhanced positioning accuracy and availability from Rel-16 onwards. UPP-CM in Rel-19 is a natural evolution that aligns positioning transport with the broader trend of user-plane-centric service delivery in 5G-Advanced. It addresses the need for scalable, efficient, and flexible positioning support in diverse deployment scenarios.