Home SMF Authorization for Roaming Multicast MBS
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Solution Overview
Problem
Current mobile communication systems lack effective support for roaming in multicast and broadcast services (MBS), leading to unauthorized access and lack of suitable architecture for continuing or preventing MBS sessions during user equipment (UE) roaming.
Innovation Solution
The proposed solution involves a method where a home session management function (H-SMF) in the home public land mobile network (HPLMN) receives a join request from a user equipment (UE) roaming in a visited public land mobile network (VPLMN) to join a multicast MBS session. The H-SMF determines the UE's authorization based on local configurations, information from application functions, or user subscription data, and then transmits an acceptance or rejection response to the V-SMF, ensuring proper authorization and session management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of stationary object
If multicast MBS services are supported during roaming without authorization checks, then service continuity is improved, but security and authorization control deteriorate
Solution Approach 1:
The V-SMF acts as an intermediary between the roaming UE and H-SMF, forwarding join requests to the home network for authorization verification. This mediator approach enables service continuity during roaming while maintaining security through centralized authorization control at the H-SMF.
Solution Approach 2:
The system implements feedback mechanisms where the H-SMF receives join requests from roaming UEs via V-SMF, performs authorization checks based on subscription data, and returns acceptance or rejection responses. This feedback loop ensures that service continuity is maintained only for authorized users.
2Reliability
If individual unicast QoS flows are established for each roaming UE, then authorization control is improved, but network complexity and signaling overhead worsen
Solution Approach 1:
The system segments the QoS management by establishing individual unicast QoS flows for each authorized roaming UE while maintaining the multicast MBS session structure. This segmentation enables precise authorization control per user while preserving the efficiency of multicast delivery for the group.
Solution Approach 2:
The V-SMF and H-SMF interaction framework serves multiple functions: it handles authorization verification, QoS flow establishment, and session management for roaming UEs. This multi-functional approach reduces overall network complexity by consolidating control functions in the home network.
3Reliability
If centralized authorization management at H-SMF is implemented, then security is improved, but signaling overhead and processing time worsen
Solution Approach 1:
The system performs preliminary authorization setup by establishing the H-SMF as the central authorization point before roaming MBS sessions commence. Subscription data is pre-configured and stored at the H-SMF, enabling rapid authorization decisions during actual roaming operations without repeated complex verification processes.
Solution Approach 2:
The V-SMF serves as an intermediary that handles initial request processing and forwarding, reducing the direct signaling burden on the H-SMF. This intermediary approach maintains centralized security control while optimizing processing time by distributing signaling tasks appropriately between visited and home network functions.
Data Source
AI summary
A H-SMF receives, from a V-SMF in a VPLMN, a join request originating from a UE roaming in the VPLMN to join a multicast multicast and broadcast services (MBS) session, and determines whether the UE is authorized to join the multicast MBS session based upon a local configuration in a home public land mobile network, information received from an application function during establishment of the multicast MBS session, and/or user subscription data received from a user data manager. The H-SMF at least one of: transmits to the V-SMF, if the UE is authorized, an acceptance response configured to establish at least one unicast QoS flow corresponding to multicast QoS flow information received from a H-MB-SMF, or, if the UE is not authorized, a rejection response comprising error cause information indicating that the UE is not authorized to join while roaming.