UTRAN Position Radio Co-ordination Function

Description

The UTRAN Position Radio Co-ordination Function (U-PRCF) is a pivotal management entity within the UTRAN positioning subsystem, residing in the Radio Network Controller (RNC). Its primary role is to coordinate all radio-related activities necessary for determining a UE's location. When a positioning request is received (e.g., from the U-PCF or core network), the U-PRCF determines the required measurement type (e.g., OTDOA, UE-assisted or UE-based A-GNSS) and orchestrates the procedure. This involves commanding the relevant Node Bs to transmit positioning reference signals (e.g., for OTDOA), instructing the UE to perform specific measurements, and collecting the resulting measurement data. The U-PRCF manages the radio resources dedicated to positioning, ensuring that positioning activities do not unduly disrupt normal communication services. It interfaces with the U-PCF to receive calculation requests and provide the gathered measurement data. It also interacts with the UTRAN Position Radio Resource Management (U-PRRM) function for resource allocation decisions. Essentially, the U-PRCF translates a positioning calculation requirement into a series of concrete radio layer commands and data collection tasks, abstracting the radio complexity from the calculation engine.

Purpose & Motivation

The U-PRCF was created to address the complexity of gathering radio measurements for positioning in a coordinated and resource-efficient manner within UTRAN. Without a dedicated coordination function, positioning requests would require ad-hoc, disruptive interactions with multiple radio network elements (UE and Node Bs), leading to potential conflicts, inefficient resource use, and increased latency. The U-PRCF provides a centralized control point for all positioning-related radio procedures. It solves the problem of how to efficiently obtain synchronized measurements from multiple cells (for OTDOA) or manage UE-based GNSS assistance data delivery. By separating radio coordination from position calculation (U-PCF) and resource management (U-PRRM), the 3GPP architecture achieves a clean functional split, enhancing modularity, scalability, and the ability to introduce new positioning methods. Its creation was motivated by the need for reliable, low-latency positioning to meet emergency service mandates and support commercial LBS applications.

Key Features

• Coordinates radio procedures for different positioning methods (OTDOA, A-GNSS)
• Commands Node Bs to transmit positioning reference signals (PRS) for OTDOA measurements
• Instructs the UE to perform and report specific radio measurements (e.g., RTT, GNSS data)
• Collects and assembles measurement data from the UE and multiple Node Bs
• Interfaces with the U-PCF to fulfill positioning requests and deliver measurement sets
• Interacts with the U-PRRM for the allocation and management of radio resources for positioning

Evolution Across Releases

Defining Specifications