Routing Area Update Determination in MOCN Handover

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Solution Overview

Problem

In FULL-Multi-Operator Core Networks (MOCN), handover procedures often result in unnecessary Routing Area Updates (RAUs) due to PLMN continuity issues, leading to resource consumption and suboptimal network performance, especially when Mobile Stations (MS) change cells between different Public Land Mobile Networks (PLMNs).

Innovation Solution

Implementing a method where the source RAN sends a handover request message to the target RAN with the selected PLMN ID, allowing the target RAN to determine if a RAU is needed by comparing the source and target cell's Routing Area Identity (RAI), and using a RAU_FLAG to inform the MS whether to perform a RAU, thus avoiding unnecessary updates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the MS performs a routing area update (RAU) after handover to ensure proper network registration, then the MS maintains accurate routing information, but unnecessary RAUs consume network resources and reduce handover efficiency

Engineering Contradiction:
Improverouting area update accuracyVSAvoidhandover efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The target RAN performs the routing area update determination in advance during the handover preparation phase, before the MS completes handover. By proactively comparing source and target RAI values and setting the RAU_FLAG, the system eliminates the need for the MS to perform unnecessary RAU procedures, thus improving handover efficiency while maintaining routing accuracy.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system enables the MS to autonomously determine whether a RAU is needed by providing it with the RAU_FLAG and relevant RAI information through the handover command. The MS can then make its own decision on whether to initiate a RAU procedure, reducing unnecessary network signaling while ensuring proper routing updates when required.

Inventive Principle:
Principle #25Self-service

2Adaptability or versatility

If the MS changes PLMN during handover in a FULL-MOCN environment, then the MS can access different operator networks, but this causes RAI changes that trigger unnecessary RAU procedures

Engineering Contradiction:
ImprovePLMN switching capabilityVSAvoidnetwork resource consumption
Core Design Contradiction:
Adaptability or versatilityVSLoss of energy

Solution Approach 1:

The invention extracts the essential information needed for RAU determination (source RAI, target RAI, and RAU_FLAG) from the complex FULL-MOCN handover process. By providing the MS with pre-computed RAI comparison results and a clear RAU_FLAG indicator, the system separates the RAU decision logic from the PLMN switching capability, allowing the MS to change PLMNs without triggering unnecessary RAU procedures while still consuming minimal network resources.

Inventive Principle:
Principle #2Taking out (Extraction)

3Loss of information

If the network sends complete system information messages (SI3, SI1, SI13) containing PLMN, RAC and LAC to the MS during handover, then the MS has all necessary information for RAU determination, but this increases signaling overhead and bandwidth consumption

Engineering Contradiction:
Improverouting area information completenessVSAvoidsignaling overhead
Core Design Contradiction:
Loss of informationVSQuantity of substance

Solution Approach 1:

The invention extracts only the critical RAI components (PLMN, RAC, LAC) and the RAU_FLAG from the complete system information messages. By providing the MS with a filtered set of essential routing area information rather than complete system information, the system maintains all necessary data for accurate RAU determination while significantly reducing signaling overhead and bandwidth consumption in FULL-MOCN environments.

Inventive Principle:
Principle #2Taking out (Extraction)

Data Source

PatentEP2929720B1Determining the need for a routing area update for packet switched handover in multi-operator core network
Publication Date: 2021.09.08 TELEFONAKTIEBOLAGET LM ERICSSON (PUBL)
  • EP2929720B1 patent drawingFigure 1
  • EP2929720B1 patent drawingFigure 2
  • EP2929720B1 patent drawingFigure 3

AI summary

A method implemented by a MS for controlling handover of the MS from a source cell of a source RAN operating in PS domain to a target cell of a target RAN operating in PS domain where the target RAN supports MOCN. The method includes receiving SI transmitted by a node of the source RAN. The SI includes a selected PLMN, LAC of the target cell, and RAC of the target cell. The MS executes handover to the target RAN. A target RAI is determined using the selected PLMN, LAC of the target cell, and RAC of the target cell from the SI transmitted by the node of the source RAN. The target RAI is compared to a registered RAI of the MS. The MS determines whether a RAU is needed in the target RAN based on the comparison of the target RAI to the registered RAI.