Visited-Network AM Policy Retrieval for Subscriber-Specific Roaming

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Solution Overview

Problem

Existing public land mobile networks (PLMNs) lack the capability to provide access and mobility policy control at a per-subscriber level during roaming, as they typically apply the same policies to all subscribers based on their PLMN ID, failing to account for individual subscriber-specific agreements.

Innovation Solution

Implementing a system that allows the visited network to retrieve subscriber-specific access and mobility policies from the home network by communicating with the home AM-PCF, using a modified N24 interface or APIs, to dynamically derive policies based on individual subscriber profiles.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a visited network applies the same access and mobility policies to all subscribers based on PLMN ID, then network management is simplified, but individual subscriber-specific agreements cannot be honored

Engineering Contradiction:

Improvesubscriber-specific policy controlVSAvoidpolicy management complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent segments the policy control function by introducing a separate AM-PCF (Access and Mobility Policy Control Function) that operates independently from the SM-PCF. This AM-PCF specifically handles access and mobility policies for roaming subscribers, allowing subscriber-specific policy differentiation without complicating the entire network management system. The segmentation enables targeted policy control at the access level while maintaining overall system simplicity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces the AM-PCF as an intermediary component between the visited network and the home network. This intermediary retrieves subscriber-specific policies from the home network's AM-PCF and applies them locally in the visited network. The intermediary approach allows the visited network to honor individual subscriber agreements without requiring complex direct coordination between home and visited networks for each subscriber case.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If a visited network retrieves subscriber-specific policies from the home network, then personalized service is enabled, but network communication overhead increases

Engineering Contradiction:

Improvesubscriber-specific policy enforcementVSAvoidpolicy retrieval time

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent implements preliminary action by having the AM-PCF retrieve and cache subscriber-specific access and mobility policies before they are needed for actual service provision. The policy retrieval is performed in advance during network setup or when the subscriber first connects, so that subsequent service decisions can be made using the pre-fetched policies without causing delays. This caching mechanism eliminates the need for real-time policy retrieval during active service sessions.

Inventive Principle:

Principle #10Preliminary action

3Adaptability or versatility

If traditional PLMN roaming agreements are used, then network coverage is extended, but per-subscriber service differentiation is lost

Engineering Contradiction:

Improveservice differentiation capabilityVSAvoidroaming operation simplicity

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent enables self-service by allowing the AM-PCF to automatically retrieve and apply subscriber-specific policies without requiring manual intervention or complex configuration in the visited network. The system autonomously queries the home network for the appropriate policies based on subscriber identification and applies them automatically to the active session. This self-service mechanism maintains roaming operation simplicity while enabling sophisticated per-subscriber service differentiation.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS20250310750A1Systems and methods for deriving access and mobility policy in visited networks

Publication Date: 2025.10.02 VERIZON PATENT & LICENSING INC

AI summary

A method, a device, and a non-transitory storage medium provide an enhanced access and mobility policy service. A network device in a visited network receives a roaming request to connect to the visited network for a user equipment (UE) device. The network device determines, based on a first access and mobility (AM) policy association request, whether a home network for the UE device has a subscriber-specific roaming policy. When the home network for the UE device has a subscriber-specific roaming policy the network device sends a second AM policy association request to the home network; receives, from the home network, the AM policy for the roaming UE device; and sends an AM policy association response to the first AM policy association request.