PDU Session Reporting for URSP Compliance in LBO Roaming
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Solution Overview
Problem
In a local breakout (LBO) roaming environment, there is a need for a method by which a visited-policy control function (V-PCF) of a visited public land mobile network (VPLMN) can transfer a report on a UE route selection policy (URSP) enforcement rule to a home-policy control function (H-PCF) of a home PLMN, and ensure compliance with the URSP even when slice or DNN replacement occurs.
Innovation Solution
The V-PCF transmits a terminal policy control request message to the H-PCF, receives a policy control request trigger (PCRT) for capability information related to the URSP, and communicates with an SM-PCF to obtain and transmit capability information including DNN and S-NSSAI, potentially modifying S-NSSAI to HPLMN S-NSSAI.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the V-PCF transfers URSP enforcement rule reports to the H-PCF in an LBO roaming environment, then the H-PCF can identify compliance with URSP, but the complexity of the policy control system increases due to multiple PCF interactions
Solution Approach 1:
The patent segments the policy control function into multiple PCFs (V-PCF and H-PCF) with distinct responsibilities. The V-PCF handles local policy enforcement and report generation, while the H-PCF performs compliance verification. This segmentation allows precise compliance identification without requiring a single complex PCF to handle all functions, thus resolving the contradiction between measurement precision and device complexity.
Solution Approach 2:
The V-PCF acts as an intermediary between the UE and the H-PCF. It collects URSP enforcement rule reports from the UE and forwards them to the H-PCF for compliance verification. This intermediary role simplifies the overall system architecture by distributing functions across multiple components, reducing the complexity burden on any single element while maintaining high compliance identification accuracy.
2Reliability
If the V-PCF monitors and reports URSP enforcement rules, then compliance can be verified, but the signaling load and processing time increase
Solution Approach 1:
The patent implements preliminary action by having the V-PCF proactively collect and forward URSP enforcement rule reports to the H-PCF before compliance verification is needed. The V-PCF continuously monitors UE behavior and maintains an up-to-date record of enforcement rule compliance, so when the H-PCF needs to verify compliance, the information is already available, reducing signaling processing time while maintaining high verification reliability.
3Adaptability or versatility
If the system supports slice and DNN replacement, then network flexibility improves, but maintaining URSP compliance becomes more difficult
Solution Approach 1:
The patent implements a feedback mechanism where the V-PCF continuously monitors URSP enforcement rule compliance and reports status to the H-PCF. When slice or DNN replacement occurs, the feedback loop ensures that the H-PCF receives updated information and can verify whether the replacement maintains compliance with URSP. This feedback mechanism enables the system to adapt to network changes while maintaining policy enforcement consistency, resolving the contradiction between network flexibility and manufacturing precision.
Data Source
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AI summary
The present disclosure relates to: a communication technique of a 5G communicaiton system for supporting higher data transmission rates than 4G system, and the system. According to the presnet dsiclosure, a method performed by a visited-policy control function (V-PCF) of a visited public land mobile network (VPLMN) in a local breakout (LBO) roaming situation includes the steps of: transmitting a terminal policy control request message to an H-PCF of a home PLMN (HPLMN); receiving, from the H-PCF, a policy control request trigger (PCRT) for capability informaiton about a terminal related to a UE route selection policy (URSP); transmitting a subscription request for the URSP-related terminal capability information to an SM-PCF managing a packet data unit (PDU) session, receiving the URSP-related terminal capability information from the SM-PCF, and transmititng the URSP-related terminal capabiltiy information to the H-PCF.