CS Fallback Indicator Handling During Wireless Handover

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Solution Overview

Problem

Existing wireless communication networks face challenges in effectively handling concurrent handover and circuit switched fallback procedures, leading to disruptions in service, such as dropped calls or failed CS call setups during handovers.

Innovation Solution

A robust CS fallback procedure is implemented, where a mobility manager sends a CS fallback indicator to the serving access point and resends it to the target access point upon detecting handover initiation, ensuring continuous CS fallback and maintaining service by informing the target access point to complete the CS fallback process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If handover is initiated during CS fallback procedure, then mobility and signal quality are improved, but CS fallback completion fails causing service disruption

Engineering Contradiction:

ImproveCS fallback completion reliabilityVSAvoidhandover capability during CS fallback

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The source access point transmits CS fallback indication information to the target access point before the handover is completed. This preliminary action ensures that the target access point is already aware of the ongoing CS fallback procedure when the access terminal switches to it, allowing the CS fallback to be properly completed without service disruption.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The source access point acts as an intermediary by forwarding the CS fallback indication information to the target access point through the network. This intermediary action ensures that the critical CS fallback state information is transferred along with the handover, enabling the target access point to maintain the CS fallback procedure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of information

If CS fallback indicator is only sent to source access point, then message complexity is reduced, but information transfer completeness deteriorates during handover

Engineering Contradiction:

ImproveCS fallback information transferVSAvoidmessage resending mechanism

Core Design Contradiction:

Loss of informationVSDevice complexity

Solution Approach 1:

The system ensures continuous transmission of the CS fallback indication information by sending it to both the source and target access points. This continuous action guarantees that the critical information is not lost during the handover transition, as the target access point receives the information directly from the source access point.

Inventive Principle:

Principle #20Continuity of useful action

Solution Approach 2:

The source access point provides feedback to the network about the ongoing CS fallback procedure by including this information in the handover request message sent to the target access point. This feedback mechanism ensures that the target access point is informed of the CS fallback state without requiring a separate message exchange.

Inventive Principle:

Principle #23Feedback

Data Source

PatentEP2494818B1Method, aparatus and computer program product for completing circuit switched fallback in case of handover

Publication Date: 2018.10.03 QUALCOMM INC

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AI summary

A CS fallback procedure handles conflict that may arise when handover operations occur during CS fallback. If CS fallback is initiated for an access terminal and handover of that access terminal is then initiated before the CS fallback completes, the target for the handover is informed of the CS fallback so that the target may perform the appropriate CS fallback operations.