V2X Control Function

Description

The V2X Control Function (VCF) is a logical function defined within the 3GPP architecture to support the authorization and policy control for V2X communications over the 3GPP network. It operates as part of the service layer for V2X, interacting with other core network functions like the Policy Control Function (PCF) and the Unified Data Management (UDM). The VCF is responsible for determining whether a User Equipment (UE), such as an onboard unit in a vehicle, is authorized to use V2X services. It validates the UE's subscription and the specific V2X service parameters requested, such as the type of V2X communication (e.g., Vehicle-to-Vehicle, Vehicle-to-Infrastructure) and the associated geographical areas where communication is permitted.

Architecturally, the VCF is specified to support both LTE-based V2X (introduced in Release 14) and 5G NR-based V2X (enhanced in subsequent releases). It interfaces with the PCF to obtain V2X-specific policy decisions, which may include parameters for quality of service (QoS), data routing, and network slice selection for V2X traffic. The VCF also interacts with the UDM to fetch subscription data related to V2X services. In scenarios involving roaming, the VCF in the visited Public Land Mobile Network (VPLMN) may communicate with the VCF in the home PLMN (HPLMN) to verify authorization, ensuring consistent service delivery across network boundaries.

The role of the VCF is critical for the security and management of V2X ecosystems. It prevents unauthorized vehicles from participating in safety-critical communications, which could lead to hazardous situations or network congestion. By centralizing the authorization logic, the VCF enables network operators to enforce policies, manage resources, and support advanced V2X applications like cooperative awareness, dynamic map updates, and platooning. Its specifications in 3GPP TS 33.185 and TS 33.885 focus on security aspects, detailing procedures for credential management, authorization, and the protection of V2X signaling messages.

Purpose & Motivation

The V2X Control Function was created to address the specific security and policy management requirements of cellular-based Vehicle-to-Everything communication. Traditional cellular authorization mechanisms were designed for human-centric services like voice and internet browsing and lacked the granularity and low-latency demands required for machine-type, safety-critical V2X communications. The VCF provides a dedicated function to authorize V2X communications, ensuring that only legitimate and properly equipped vehicles can send and receive safety messages, which is paramount for road safety and the prevention of malicious attacks on the V2X system.

Its development was motivated by the automotive industry's push towards connected and autonomous vehicles, which rely on reliable, secure, and instantaneous data exchange. Without a standardized control function like the VCF, each operator or automotive OEM might implement proprietary authorization systems, leading to fragmentation and interoperability issues, especially for vehicles roaming across different countries and network operators. The VCF, standardized by 3GPP, provides a unified framework that enables scalable, secure, and interoperable V2X services on a global scale, facilitating the deployment of advanced driver assistance systems and autonomous driving functionalities.

Key Features

• Authorizes UE for V2X communication based on subscription and service parameters
• Provides V2X-specific policy control in conjunction with the PCF
• Supports authorization for both LTE-V2X and NR-V2X communication modes
• Enables roaming scenarios by interacting with HPLMN and VPLMN VCF instances
• Manages security credentials and parameters for V2X message protection
• Facilitates service provisioning for different V2X application types (e.g., safety, traffic efficiency)

Evolution Across Releases

Defining Specifications