PDU Session Control After S1-to-N1 Change in Restricted Areas
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Solution Overview
Problem
A UE is unable to perform PDU session modification after the first inter-system change from S1 mode to N1 mode when in a restricted service area, leading to contradictory and unpredictable behavior due to service area restrictions.
Innovation Solution
A method and apparatus that allow a UE to perform a PDU session modification procedure by sending a 5GSM message only after leaving a restricted service area or meeting specific conditions, such as being in a normal service state, ensuring consistent and predictable UE behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If service area restrictions are enforced to control network access, then network security and service management are improved, but UE ability to perform PDU session modification is blocked
Solution Approach 1:
The patent changes the parameter of service area restriction enforcement by introducing an exception condition: when the UE is in a non-allowed area but needs to perform PDU session modification to report 5GSM capability, the network should allow this specific operation. This parameter change resolves the contradiction by selectively modifying the restriction rule for capability reporting scenarios.
Solution Approach 2:
The patent introduces an intermediary mechanism where the UE includes an indicator in the PDU session modification request message to explicitly signal that it is reporting 5GSM capability. This intermediary indicator allows the network to distinguish between regular PDU session modifications and capability reporting, enabling selective permission granting in restricted areas.
2Productivity
If UE reports 5GSM capability after inter-system change from S1 to N1 mode, then network service optimization is improved, but service area restrictions prevent the reporting
Solution Approach 1:
The patent applies preliminary action by allowing the UE to perform PDU session modification and report 5GSM capability even before leaving the non-allowed area, provided specific conditions are met. This preliminary permission enables capability reporting to occur earlier than would normally be allowed, improving service optimization efficiency without requiring the UE to first exit the restricted area.
Solution Approach 2:
The patent changes the operational parameter by modifying the service area restriction rule to permit PDU session modification for capability reporting purposes. This parameter change transforms the normally blocked operation into an allowed one under specific conditions, enabling ease of operation for capability reporting while maintaining overall service area control.
3Reliability
If UE is blocked from sending 5GSM messages in restricted areas, then service area control is maintained, but capability reporting fails
Solution Approach 1:
The patent introduces an intermediary indicator in the PDU session modification request message that signals to the network that the UE is reporting 5GSM capability. This intermediary mechanism allows the network to maintain service area control while making an exception for capability reporting, preventing loss of important capability information.
Solution Approach 2:
The patent changes the control parameter by introducing an exception to the service area restriction rule. When the UE includes the capability reporting indicator, the network changes its response from blocking to permitting the message, thereby preventing loss of 5GSM capability information while maintaining overall service area control integrity.
Data Source
AI summary
The disclosure relates to a 5G or 6G communication system for supporting a higher data transmission rate. According to an embodiment, the method comprises establishing at least one PDU connection in an S1 mode; performing an inter system change from the S1 mode to an N1 mode; and in case that a successful UE-requested PDU session modification procedure is not previously performed and the UE is in a 5GMM-REGISTERED.NON-ALLOWED-SERVICE state, performing a UE-requested PDU session modification procedure to report 5G session management (5GSM) capability of the UE after entering a 5GMM-REGISTERED.NORMAL-SERVICE state.