Resume Failure Fallback Using S-TMSI for Signaling Overhead Reduction

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Solution Overview

Problem

Current 3GPP LTE systems face challenges in efficiently managing resume failure fallback mechanisms, particularly in cellular Internet of Things (CIoT) devices, due to issues with context information availability and stale data, leading to increased signaling overhead and resource usage inefficiencies.

Innovation Solution

The implementation of a resume failure fallback mechanism that utilizes the System Architecture Evolution (SAE) Temporary Mobile Subscriber Identity (S-TMSI) to enable optimized fallback to legacy RRC connection setups, allowing for reduced signaling overhead and efficient resource management by transitioning from user plane to control plane solutions when resume procedures fail.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If resume failure fallback mechanism is implemented using S-TMSI, then signaling overhead is reduced, but device complexity increases

Engineering Contradiction:
Improvesignaling overheadVSAvoiddevice complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent uses S-TMSI as a simplified copy or alternative identifier instead of full context information. When context is unavailable, the system falls back to using S-TMSI for resume procedures, reducing signaling overhead while maintaining functionality through this lighter-weight identifier copy.

Inventive Principle:
Principle #26Copying

2Reliability

If fallback to legacy RRC connection setups is enabled, then reliability is improved, but productivity decreases

Engineering Contradiction:
ImprovereliabilityVSAvoidproductivity
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The system dynamically selects between optimized resume procedures and legacy RRC connection setups based on context availability. When context is available, it uses the optimized path for higher productivity; when context is stale or unavailable, it falls back to legacy procedures for reliability, creating a dynamic adaptation mechanism.

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The system prepares fallback mechanisms in advance by maintaining the ability to use S-TMSI and legacy RRC procedures. This prior cushioning ensures that when context information becomes stale or unavailable, the system can immediately switch to reliable legacy procedures without service interruption.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Ease of operation

If context information is retained for resume procedures, then ease of operation is improved, but loss of information increases

Engineering Contradiction:
Improveease of operationVSAvoidcontext information availability
Core Design Contradiction:
Ease of operationVSLoss of information

Solution Approach 1:

The system implements feedback mechanisms to detect when context information becomes stale or unavailable. Based on this feedback, it automatically switches from using stored context to using S-TMSI for resume procedures, ensuring that ease of operation is maintained while avoiding the use of invalid context information.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP3437425B1Devices and computer readable medium for resume failure fallback
Publication Date: 2021.09.15 APPLE INC
  • EP3437425B1 patent drawingFigure 1
  • EP3437425B1 patent drawingFigure 2
  • EP3437425B1 patent drawingFigure 3

AI summary

Devices, methods, user equipment (UE), evolved node B (eNB), and storage media are described for resume failure fallback mechanisms. Various embodiments are implemented in LTE systems or systems for cellular Internet of Things (CIoT) device communications. In one embodiment, a UE encodes a request to resume a radio resource control (RRC) connection using a resume identity information element. The UE then decodes an RRC connection setup response indicating that an RRC connection resume has been fallbacked. In response, the UE encodes an RRC connection setup complete message with a System Architecture Evolution (SAE) Temporary Mobile Subscriber Identity (S-TMSI). In various embodiments, the resume is fallbacked due to the resume identity being stale, previously deleted, or otherwise insufficient to establish a UE identity for a corresponding eNB.