PLMN Identity Management in Inter-PLMN Handover
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Solution Overview
Problem
Current mobile communication systems face issues with communication disruption and security concerns during handovers between Public Land Mobile Networks (PLMNs) due to inconsistencies in PLMN-related information, especially when user equipment transitions from one Radio Access Technology (RAT) area to another with a different PLMN, such as from UTRAN or GERAN to E-UTRAN, leading to potential communication cutoffs and security failures.
Innovation Solution
A method is introduced that activates Idle-state Signaling Reduction (ISR) and performs a routing area update process, constructing a Tracking Area Identity (TAI) from the new PLMN identity and Tracking Area Code (TAC) to ensure seamless communication by transmitting a Tracking Area Update (TAU) request message to the Mobility Management Entity (MME), which determines the PLMN identity based on a globally unique temporary identity, thereby maintaining secure and efficient communication during handovers between PLMNs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If ISR is activated and routing area update is performed during handover between PLMNs, then signaling reduction is achieved, but PLMN identity inconsistency occurs causing communication cutoff
Solution Approach 1:
The MME performs preliminary actions by allocating a new GUTI that includes the correct PLMN identity before the handover is completed. This preliminary allocation ensures that when the UE performs routing area update with ISR activated, it receives the correct PLMN identity in advance, preventing the identity inconsistency problem while maintaining signaling reduction benefits
Solution Approach 2:
The system implements feedback mechanisms where the MME monitors the handover status and PLMN identity consistency. When inconsistency is detected or anticipated, the MME sends corrective GUTI reallocation commands to the UE, ensuring the PLMN identity is updated correctly. This feedback loop maintains communication reliability while preserving ISR benefits
2Speed
If PLMN identity is not updated during handover between different PLMNs, then handover speed is maintained, but security authentication fails
Solution Approach 1:
The MME performs preliminary GUTI allocation containing the correct PLMN identity before the handover completes. This ensures that when security authentication is required, the UE already has the correct PLMN identity, enabling immediate authentication without delaying the handover process
Solution Approach 2:
The GUTI serves as an intermediary that carries the PLMN identity information. By embedding the PLMN identity within the GUTI structure, the system enables security authentication to proceed smoothly during handover without requiring separate identity update steps, thus maintaining both speed and security
3Loss of information
If GUTI is reallocated during handover, then PLMN identity consistency is improved, but additional signaling overhead is generated
Solution Approach 1:
The system changes the parameters of the GUTI by embedding the PLMN identity within its structure. This parameter change allows the GUTI to serve dual purposes: as a temporary identifier and as a carrier of PLMN identity information. By doing so, the system achieves PLMN identity consistency without requiring separate signaling messages for identity updates, thus minimizing additional signaling overhead
Data Source
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AI summary
The present disclosure relates to a communication method between a terminal and a network during an inter PLMN (public land mobile network) handover in a mobile communication network that shares an E-UTRAN (evolved universal terrestrial radio access network), and a mobile communication system thereof. According to the present invention, the terminal performs E-UTRAN registration through a base station (eNB) and an MME (MME), updates a routing area, activates ISR (idle state signaling reduction), receives a handover command to the previous PLMN or another PLMN and transmits a location update request message to the MME while the handover is being executed. As such, a communication disconnect or any authentication or security failure during the inter PLMN handover of the terminal can be avoided.