MSC Server Session Transfer Compatibility Verification

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Solution Overview

Problem

Current 3GPP specifications inaccurately indicate support for session transfers from circuit switched to packet switched networks, leading to potential handover failures or call loss due to mismatched user equipment and network capabilities.

Innovation Solution

A method where a control node requests and verifies compatibility between user equipment capabilities and network configurations for session transfers from a circuit switched network to a packet switched network, ensuring accurate indication of support only when both match.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the MSC Server indicates support for session transfer without verifying UE capability compatibility, then the network appears more capable and versatile, but handover failures and call loss occur due to capability mismatches

Engineering Contradiction:

Improvenetwork capability indicationVSAvoidhandover success rate

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent applies preliminary action by having the MSC Server verify UE capability compatibility with the target PS network before indicating support for session transfer. The MSC Server checks whether the UE supports required capabilities (IMS registration, VoIP over PS) and only then sets the CS to PS SRVCC operation possible indication, preventing capability mismatches before they cause handover failures

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by having the MSC Server query the RAN for UE capability information and use this feedback to determine whether to indicate support for session transfer. The RAN provides feedback on UE capabilities, and the MSC Server uses this feedback to make an informed decision about capability compatibility before committing to support the transfer

Inventive Principle:

Principle #23Feedback

2Reliability

If the MSC Server verifies UE capability compatibility before indicating session transfer support, then handover reliability improves, but signaling overhead increases due to additional capability checking

Engineering Contradiction:

Improvehandover success rateVSAvoidsignaling overhead

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent merges the capability verification process with the existing SRVCC session transfer signaling flow. The MSC Server checks UE capabilities as part of the normal session transfer preparation, combining the capability verification function with the existing handover signaling rather than adding separate verification procedures, thus minimizing additional signaling overhead

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS9924414B2Session transfer from a circuit switched network to a packet switched network

Publication Date: 2018.03.20 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)

AI summary

The invention relates to methods and nodes for supporting a session transfer, for a user equipment, from a circuit switched network to a packets witched network. According to one aspect a method for operating a control node of a core network is provided. The method comprises the steps: requesting from a radio access network of the circuit switched network information on whether a capability of the user equipment related to the session transfer are compatible with a network configuration related to the session transfer; receiving from the radio access network an indication whether the capability of the user equipment and the network configuration are compatible; determining whether to indicate that the session transfer is supported by using the received compatibility indication; and setting an indication whether the session transfer is supported according to the determination.