Mobile Station Mobility Management for Registration State Mismatch

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Solution Overview

Problem

In wireless communication networks, user equipment (UE) can miss mobile terminated (MT) calls due to state mismatches between the UE and the network, particularly after an intersystem change when routing area updates (RAU) fail and generic location updating procedures are not successfully performed, leading to registration state mismatches and missed paging.

Innovation Solution

A method is introduced for a mobile station (MS) to detect intersystem changes from S1 mode to A/Gb or Iu mode, identify failed RAU attempts, and trigger a mobility management (MM) specific procedure, which corresponds to a location area update (LAU), ensuring that the UE is correctly registered and can receive MT calls by sending an LAU request when the RAU attempt counter exceeds 5 or the normal RAU procedure is not accepted by the network.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the UE performs RAU after intersystem change to UTRAN/GERAN, then the UE attempts to update its routing area, but the RAU fails due to network failure at SGSN, resulting in registration state mismatch between UE and network

Engineering Contradiction:

ImproveRAU success rateVSAvoidregistration state synchronization

Core Design Contradiction:

ReliabilityVSLoss of information

Solution Approach 1:

The UE performs a location area update (LAU) procedure before attempting RAU after intersystem change. This preliminary action ensures that the network has accurate location information about the UE in the circuit switched domain, which helps prevent registration state mismatches when RAU is subsequently attempted or fails.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE monitors RAU attempt counters and detects when RAU fails. Based on this feedback, the UE triggers a LAU procedure to synchronize its registration state with the network. This feedback mechanism ensures that the UE responds adaptively to RAU failures and maintains accurate location information.

Inventive Principle:

Principle #23Feedback

2Device complexity

If the UE does not perform LAU after intersystem change when in same LAI, then the MM assumes registered area and avoids LAU, but this causes the UE to miss MT paging messages

Engineering Contradiction:

Improvemobility management procedure complexityVSAvoidMT call reception reliability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The UE performs LAU as a preliminary action after intersystem change to UTRAN/GERAN, even when in the same LAI. This ensures that the network is informed of the UE's location change and can properly route paging messages, preventing missed MT calls while maintaining manageable procedure complexity.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE uses feedback from RAU failure detection (when attempt counter reaches threshold) to trigger LAU. This feedback-driven approach ensures LAU is performed when necessary to maintain reliable MT call reception without unnecessarily increasing procedure complexity in all cases.

Inventive Principle:

Principle #23Feedback

3Productivity

If the UE attempts multiple RAU after intersystem change, then the UE tries to register with the network, but repeated RAU failures consume time and resources without resolving the registration state mismatch

Engineering Contradiction:

Improveregistration attempt efficiencyVSAvoidtime to achieve proper registration

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The UE performs LAU as a preliminary action before or instead of repeated RAU attempts after intersystem change. This preliminary location update ensures the network has current location information, increasing the likelihood of successful registration and reducing wasted time from repeated failed RAU attempts.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The UE monitors RAU attempt counters and uses feedback from failed attempts to trigger LAU. When the counter reaches a threshold, the UE switches strategy from repeated RAU to performing LAU, which resolves registration state mismatches more efficiently and reduces overall registration time.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS11012870B2Technique for triggering mobility management specific procedure to avoid registration state mismatch between user equipment and network

Publication Date: 2021.05.18 SAMSUNG ELECTRONICS CO LTD

AI summary

A method in a mobile station (MS) and an MS in a wireless communication network are provided. The method includes detecting an intersystem change from an S1 mode to one of an A/Gb mode and an Iu mode, detecting that a routing area update (RAU) has failed detecting that a successful generic location updating procedure has not been performed since the detected intersystem change, and triggering an MM specific procedure based on detecting that the RAU has failed and the successful generic location updating procedure has not been performed. The MM specific procedure corresponds to a location area update (LAU).