IMS Link State Handling for UE Re-Registration Without Wake-Ups

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Solution Overview

Problem

Current push notification mechanisms in communication networks, particularly for IMS applications, are not compliant with modern operating systems that block wake-up signals, leading to issues with maintaining registration and connectivity, resulting in dropped calls and inefficient battery usage.

Innovation Solution

A platform-agnostic re-registration mechanism where a first communication node, such as a P-CSCF, subscribes to a push notification service to manage the status of the communication link and periodically re-registers with the core network on behalf of the UE, ensuring continuous connectivity without waking up the device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If push notification mechanisms are used to wake up UE for registration maintenance, then connectivity can be restored, but modern operating systems block these wake-up signals causing registration failure and dropped calls

Engineering Contradiction:
Improveregistration maintenanceVSAvoidcompatibility with modern OS
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The P-CSCF acts as an intermediary between the UE and the core network, performing re-registration on behalf of the UE without requiring the UE to wake up. The P-CSCF subscribes to push notification service to monitor link status and automatically re-registers with the core network when needed, eliminating the need for OS-compliant wake-up mechanisms.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system enables self-service by having the P-CSCF autonomously monitor communication link status through push notification subscription and automatically initiate re-registration procedures with the core network when link state changes occur, without requiring UE intervention or wake-up.

Inventive Principle:
Principle #25Self-service

2Reliability

If UE wakes up frequently to maintain registration, then connectivity is maintained, but battery consumption increases

Engineering Contradiction:
ImproveconnectivityVSAvoidbattery consumption
Core Design Contradiction:
ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous UE wake-ups, the system uses periodic push notification subscriptions at the P-CSCF to monitor communication link status. The P-CSCF only initiates re-registration when link state changes are detected, transforming continuous energy-consuming wake-ups into event-driven periodic actions.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The P-CSCF serves as an intermediary that assumes the registration maintenance function, allowing the UE to remain in low-power state. The P-CSCF monitors link status and handles re-registration autonomously, eliminating the need for UE to wake up frequently and consume battery power.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Extent of automation

If P-CSCF subscribes to push notification service for link status monitoring, then automatic re-registration is enabled, but additional network signaling is required

Engineering Contradiction:
Improveautomatic re-registrationVSAvoidsignaling complexity
Core Design Contradiction:
Extent of automationVSDevice complexity

Solution Approach 1:

The P-CSCF leverages its existing multi-functional role in the IMS architecture by adding push notification subscription capability to its portfolio. This existing node performs multiple functions including registration management, session control, and now link status monitoring, avoiding the need for dedicated new components and reducing overall system complexity.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Data Source

PatentEP4046352B1Nodes and methods for handling state change of a communication link in a communications network
Publication Date: 2026.01.14 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP4046352B1 patent drawingFigure 1
  • EP4046352B1 patent drawingFigure 2
  • EP4046352B1 patent drawingFigure 3a

AI summary

The embodiments herein relate to a method performed by a first communication node (503) for handling state change of a communication link (520) in a communications network (500). The first communication node subscribes to state information indicating a state change of a communication link (520) between a UE (101) and a second communication node (513). The first communication node obtains, from the second communications node (513), the state information indicating the state change.