eNodeB PLMN Selection for CSFB Handover

Solution Overview

Problem

During the circuit switching fallback (CSFB) process in Evolved Packet System (EPS) networks, the eNodeB fails to perceive the Public Land Mobile Network (PLMN) ID of the MSC/VLR selected by the Mobility Management Entity (MME), leading to increased processing delays and reduced service success rates due to unnecessary location area updates and roaming retries when the UE switches to a different PLMN.

Innovation Solution

The method involves the Mobility Management Entity (MME) sending an S1 interface application protocol request message to the eNodeB, including the PLMN identity of the MSC/VLR, allowing the eNodeB to select a target cell within the same PLMN, thereby avoiding additional processing delays and improving service success rates.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the eNodeB selects a target cell without perceiving the MSC/VLR's PLMN ID, then the handover procedure can be executed, but the UE may be redirected to a different PLMN causing additional location area update and roaming retry procedures

Engineering Contradiction:

ImproveCSFB processing efficiencyVSAvoidprocessing delay

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The MME performs preliminary action by selecting the target MSC/VLR and determining its PLMN ID before initiating the CSFB procedure. This PLMN ID information is then provided to the eNodeB in advance, enabling the eNodeB to pre-determine the target cell within the same PLMN, thereby avoiding subsequent location area updates and roaming retries.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary information exchange mechanism between the MME and eNodeB. The MME provides the PLMN ID of the selected MSC/VLR to the eNodeB through message transmission, serving as an intermediary that bridges the information gap and enables coordinated PLMN selection across different network elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the eNodeB does not have PLMN ID information from the selected MSC/VLR, then the handover can proceed with available information, but the service success rate is reduced due to unnecessary roaming procedures

Engineering Contradiction:

Improveservice success rateVSAvoidinformation exchange complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The MME performs preliminary action by selecting the target MSC/VLR and determining its PLMN ID before initiating the CSFB procedure. This PLMN ID information is then provided to the eNodeB in advance, enabling the eNodeB to pre-determine the target cell within the same PLMN, thereby avoiding subsequent location area updates and roaming retries.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary information exchange mechanism between the MME and eNodeB. The MME provides the PLMN ID of the selected MSC/VLR to the eNodeB through message transmission, serving as an intermediary that bridges the information gap and enables coordinated PLMN selection across different network elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If the UE camps to a target cell with different PLMN ID, then the handover to the selected MSC/VLR is completed, but additional location area update and roaming retry procedures are required

Engineering Contradiction:

Improvehandover executionVSAvoidprocessing delay

Core Design Contradiction:

Ease of operationVSLoss of time

Solution Approach 1:

The MME performs preliminary action by selecting the target MSC/VLR and determining its PLMN ID before initiating the CSFB procedure. This PLMN ID information is then provided to the eNodeB in advance, enabling the eNodeB to pre-determine the target cell within the same PLMN, thereby avoiding subsequent location area updates and roaming retries.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent introduces an intermediary information exchange mechanism between the MME and eNodeB. The MME provides the PLMN ID of the selected MSC/VLR to the eNodeB through message transmission, serving as an intermediary that bridges the information gap and enables coordinated PLMN selection across different network elements.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP3697130B1Method for selecting public land mobile network

Publication Date: 2021.09.22 HUAWEI TECH CO LTD

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AI summary

The embodiments of the present invention relate to a method, an apparatus, and a system for selecting a public land mobile network. The method includes: acquiring, by an eNodeB, PLMN information about a CSFB; and determining, by the eNodeB, a target cell of a packet switching handover according to the PLMN information about the CSFB. In the embodiments of the present invention, the eNodeB acquires the PLMN information about the CSFB, and the eNodeB determines the target cell of the packet switching handover according to the acquired PLMN information about the CSFB, so as to switch to the PLMN where the MSC/VLR attached by the UE in the EPS network is located, thereby avoiding an additional processing delay of the CSFB procedure caused when an eNodeB selects a different PLMN for failing to perceive the PLMNwhere the MSC/VLR attached by the UE in the EPS network is located in the CSFB procedure, and improving the service success rate.