Mobile Network RAN Failure Notifications for AMF-SMF Coordination

Solution Overview

Problem

Current mobile network architectures face issues with synchronization and collision of messaging between Access and Mobility Management Function (AMF) and Session Management Function (SMF) due to per-UE session management context update idle mode entry messaging upon Radio Access Network (RAN) failures, leading to connectivity glitches and user experience degradation.

Innovation Solution

Implementing a subscription mechanism where the SMF subscribes to receive notifications from the AMF regarding RAN failures, allowing the AMF to notify the SMF about RAN node resets instead of sending per-UE session management context updates, thereby avoiding unnecessary messaging on the N11 interface.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If per-UE session management context update idle mode entry messaging is sent upon RAN failure, then session management is updated for each user equipment, but messaging collisions and delays occur on the N11 interface

Engineering Contradiction:

Improvesession management update reliabilityVSAvoidmessaging delay

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent merges multiple per-UE session management context update messages into a single aggregated notification message. Instead of sending separate idle mode entry messages for each UE when RAN failure occurs, the AMF consolidates these updates and sends one unified notification to the SMF, which then distributes the information to relevant UEs. This reduces messaging collisions and delays on the N11 interface while maintaining reliable session management updates.

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If per-UE session management context update idle mode entry messaging is sent upon RAN failure, then session management is updated for each user equipment, but messaging collisions occur on the N11 interface

Engineering Contradiction:

Improvesession management update reliabilityVSAvoidmessaging collision complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges multiple per-UE session management context update messages into a single aggregated notification message. Instead of sending separate idle mode entry messages for each UE when RAN failure occurs, the AMF consolidates these updates and sends one unified notification to the SMF, which then distributes the information to relevant UEs. This reduces messaging collisions and delays on the N11 interface while maintaining reliable session management updates.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If AMF sends per-UE session management context updates upon RAN failure, then session state is updated, but connectivity glitches occur for users

Engineering Contradiction:

Improvesession state update reliabilityVSAvoidconnectivity glitch

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent implements preliminary action by having the AMF send a notification to the SMF before actually executing the idle mode entry for UEs. This preliminary notification allows the SMF to prepare and coordinate the session management changes in advance, ensuring that all UEs are properly handled before connectivity changes are applied. This prevents connectivity glitches by avoiding simultaneous or conflicting session management operations.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent establishes a feedback mechanism where the AMF notifies the SMF about RAN failure conditions, and the SMF responds with appropriate session management actions. This feedback loop ensures that session management decisions are made with full awareness of the RAN state, allowing for coordinated and conflict-free updates that prevent connectivity glitches while maintaining reliable session state management.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS20250267477A1Techniques for handling radio access network failures in a mobile network environment

Publication Date: 2025.08.21 CISCO TECHNOLOGY INC

AI summary

Provided herein are techniques to facilitate handling Radio Access Network (RAN) failures in a mobile networking environment. In one example, a method may include obtaining, by an access management node from a session management node of a mobile network, a subscription request for the session management node to be notified regarding reset of a radio node of a wireless wide area (WWA) radio access technology (RAT) type; determining, by the access management node, that a particular radio node of the WWA RAT type has been reset; and providing, by the access management node to the session management node, a notification indicating that the particular radio node of the WWA RAT type has been reset.