MSC Detach Indication for EPS Network Context Clearing

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Solution Overview

Problem

Current technologies lack a method to detach user equipment (UE) from an evolved packet system (EPS) network, which is essential for efficient handover and providing continuous communication services.

Innovation Solution

A method and device for detaching a UE from the EPS by using a Detach Type message, where the MSC receives a Detach Request indicating EPS detachment only, and subsequently clears the packet switched core network context and connection between the MSC and MME, allowing the UE to select a CS cell for communication.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the UE is registered in both EPS and CS networks using CSFB, then the UE can access both packet switched and circuit switched services, but there is no available method to detach the UE from the EPS network

Engineering Contradiction:
Improvenetwork access capabilityVSAvoiddetachment process complexity
Core Design Contradiction:
Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The detachment process is segmented into two independent operations: EPS detachment and CS network detachment. The patent introduces a specific detach type indicator that allows the network to detach the UE from the EPS network independently while maintaining the CS network registration, thereby solving the problem of inability to selectively detach from EPS without affecting CS services

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Instead of requiring full re-registration when detaching from EPS, the patent inverts the traditional approach by allowing selective detachment from EPS only. The detach type indicator enables the network to send a detach request that specifically targets EPS network resources while preserving CS network context, thus avoiding the complexity of complete re-registration

Inventive Principle:
Principle #13The other way round (Inversion)

2Reliability

If the UE performs standard Attach process in EPS, then the UE can be registered in the EPS network, but the subsequent handover and service provision experience time delays

Engineering Contradiction:
Improveregistration reliabilityVSAvoidhandover time delay
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent applies preliminary action by maintaining the UE's CS network registration and context in advance. When handover is needed, the UE can quickly transition to CS network services without performing a complete re-registration process, as the context is already prepared and stored in the MSC/VLR, thus reducing handover time delay while ensuring service reliability

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3193528B1Method and device for detaching user equipment
Publication Date: 2020.08.12 HUAWEI TECH CO LTD
  • EP3193528B1 patent drawingFigure 1
  • EP3193528B1 patent drawingFigure 2
  • EP3193528B1 patent drawingFigure 3

AI summary

A system and methods for detaching a user equipment (UE) and a corresponding UE are disclosed in the present invention. The UE is registered with a mobility management entity (MME) in a packet switched (PS) network and a mobile switching center (MSC) in a circuit switched (CS) network. When the UE needs to detach from the PS network, the MSC receives a Detach Indication with a Detach Type indicating the detaching from the PS network only; after receiving the Detach Indication, the MSC deletes the context of the PS core network entity and clears the connection between the MSC and the MME. The present invention helps reduce the time delay during the subsequent handover and quickly provide users with communications services, so as to improve user's experience and meet the carriers' requirements.