By CT WG3 Delegates Abdessamad El Moatamid (Huawei), Zhenning Huang (China Mobile), Yue Sun (China Telecom)

First published June 2025, in Highlights Issue 10

Access and Mobility (AM) Policy Management and UE (User Equipment) Policy Management are the key components of the so called "non-session management" related policy control framework in 5G. They enable policies to be derived and enforced that control how UEs access the network, how UEs interact with both the network and each other and how both the users and the network manage their mobility within and when roaming outside of the boundaries of the network of a Mobile Network Operator (MNO).

The management and enforcement of policies is ensured primarily by the Policy Control Function (PCF), specifically called the "PCF for the UE", and the Access and Mobility Function (AMF). The main AM Policy management functionalities are the following:

• Service Area Restrictions management, which consists basically on a list of areas within the network (e.g., list of (non-)allowed Tracking Areas) within which the UE is restricted access to network services.
• RFSP Index (RAT/Frequency Selection Priority Index) management, which enables the network to control and influence how the UE performs radio resource management.
• UE-AMBR (UE Aggregate Maximum Bitrate) and UE-Slice-AMBR (UE per-slice Aggregate Maximum Bitrate) management and enforcement, i.e., control the usage of network resources (and per network slice resources) by a particular UE.
• Network Slice Replacement management, which consists on allowing the replacement of a network slice with another network slice, e.g., when the initial network slice becomes unavailable or congested, and based on a local decision at the PCF and/or using inputs from e.g., the O&M system, the NWDAF, etc.
• SMF selection management information management, which allows the PCF to interact and control/influence to some extent the SMF selection functionality of the AMF so as to achieve an overall optimized data traffic management.

The requirements related to all these functionalities may be part of the user's network subscription, provisioned by an application through the 3GPP Network Capability Exposure framework (see [1]) and/or be derived or updated by the PCF based on operator policies and/or other information available to the PCF such as UE location information, network analytics data provided by the Network Data Analytics Function (NWDAF), etc. The control of these functionalities is achieved via the establishment (e.g., during UE registration) and management by the AMF of an "AM Policy Association" (on a per-UE basis) at the PCF, which enables the latter to provision AM policies to the AMF, which in turn provisions these policies to the RAN and/or UE that take care of enforcing them and reporting the related events to the AMF and PCF.

For more details, see also [2], [3], [7], [5] and [6].

UE Policy management is a framework to control how UEs access and interact with the network and how UEs may interact with each other. The management and enforcement of these policies is ensured primarily by the Policy Control Function (PCF), also specifically called the "PCF for the UE", and the Access and Mobility Function (AMF). The main UE Policy management functionalities are the following:

• ANDSP (Access Network Discovery & Selection Policy) management, which consists on the rules and policies to control how the UE selects non-3GPP accesses (e.g., WiFi, WLAN).
• URSP (UE Route Selection Policy) management, i.e., the rules and policies to control how the UE routes outgoing traffic, e.g., to an established PDU Session, offloading to a non-3GPP access (e.g., WiFi) outside the scope of a PDU Session, using a new PDU Session to be established, via a ProSe Layer-3 UE-to-Network Relay outside the scope of a PDU Session.
• V2XP (V2X Policy) management, which enables to provision the configuration parameters and policies for the UE to manage V2X (Vehicle-to-Everything) communications.
• ProSeP (ProSe Policy) management, which enables to provision the configuration parameters and policies for the UE to manage ProSe (Proximity based Services) services.
• RSLPP (Ranging/Sidelink Positioning Policy) management, which enables to provision the configuration parameters and policies for the UE to manage Ranging/Sidelink Positioning services.
• A2XP (A2X Policy) management, which enables to provision the configuration parameters and policies for the UE to manage A2X (Aircraft-to-Everything) communications.

The requirements related to all these functionalities may be derived based on existing UE Policies at the UE (e.g., pre-configured at the UE side), provisioned requirements by an application through the 3GPP Network Capability Exposure framework (see [1]) and/or be derived or updated by the PCF based on operator policies and/or other information available to the PCF such as network analytics data provided by the Network Data Analytics Function (NWDAF), etc. The control of these functionalities is achieved via the establishment (e.g., during UE registration) and management by the AMF of an "UE Policy Association" (on a per-UE basis) at the PCF, which enables the latter to provision UE policies to the AMF, which in turn provisions these policies to the UE that takes care of enforcing them and reporting the related events to the AMF and PCF.

For more details, see also [4], [3], [7], [5] and [6].

Unlocking the potential of 5G AM and UE Policy Management – Examples & Use Cases

Use case #1: AM/UE Policy control based on spending limits

In 3GPP Rel-18, a new functionality was introduced to allow the PCF for the UE to perform AM/UE policy decisions based on the available spending limits information (e.g., the daily/weekly/monthly spending limits for mobile data are reached or are close to be reached for a subscriber) in non-roaming scenarios. This functionality exemplifies how the operator policies at the PCF for AM/UE Policy Management can be implemented.

For this purpose, the PCF interacts with the CHF (Charging Function) to request and/or subscribe to receive spending limits related reporting for one or several "policy counters" (i.e., spending limits indicators). Once this is in place, the CHF notifies the PCF of any changes in the current or pending statuses of the subscribed policy counter(s), and optionally the activation time(s) for the case of pending statuses (e.g., due to a billing period that will expire). The PCF then uses all these dynamically collected statuses of policy counter(s) and the related information as inputs to its internal policy decisions to apply related pre-configured operator-defined actions.

With this functionality, operators can dynamically configure, establish and enforce AM/UE Policy decisions (e.g., downgrade or upgrade the UE-AMBR, change the URSP rules, update the service area restrictions) based on the spending limits information. In 3GPP Rel-19, this functionality was further extended to roaming scenarios to enable dynamic change of UE Policies based on spending limits related information.

Use case #2: Network assisted performance level upgrade using frequency management suggestions

AM Policy management can play a highly important role in enhancing network performance by acting on the improvement of the RFSP Index management. The PCF can enable by that more dynamic and differentiated mobility control strategies. The PCF can provision RFSP Index values to the AMF to assist with frequency selection and enable more specific radio resource management at the UE. The PCF determines the RFSP Index values to be provisioned based on various factors such as the accumulated usage information (e.g., used volume, used time or both), network analytics data from the NWDAF on the current load levels at the concerned network slice instance or the UE Communication related information, UE communication behavior information, user data congestion information, the perceived service experience, etc.

This flexible Policy framework for frequency selection and mobility management enhances user experience, optimizes network efficiency, and supports differentiated service delivery across various users' segments and network conditions.

Conclusion

With the introduction of 5G-A (3GPP Rel-18 onwards) and AI technologies, these capabilities will be further enhanced to enable more autonomous, dynamic and intelligent network management, thus paving the way for the enhanced control of how UEs are treated by the network, e.g., real-time policy management based on an AI-Native network architecture and intent-driven automation, finer-grained UE differentiation for tailored experiences, efficient connecting of more and more types of UEs with greatly more massive numbers (e.g., IoT devices, sensors), etc. We look forward to the introduction of these exciting new functionalities and use cases in the future.

For more on WG CT3 see: www.3gpp.org/3gpp-groups

[1] "3GPP Capability Exposure Frameworks and APIs", Pages 08-09, 3GPP Highlights Newsletter, Issue 09, December 2024

[2] 3GPP TS 29.507: "Access and Mobility Policy Control Service; Stage 3"

[3] 3GPP TS 29.513: "5G System; Policy and Charging Control signalling flows and QoS parameter mapping; Stage 3"

[4] 3GPP TS 29.525: "5G System; UE Policy Control Service; Stage 3"

[5] 3GPP TS 23.501: "Technical Specification Group Services and System Aspects; System Architecture for the 5G System"

[6] 3GPP TS 23.502: "Procedures for the 5G System; Stage 2"

[7] 3GPP TS 23.503: "Policy and Charging Control Framework for the 5G System"