PCF Selection for Direct AMF-SMF Policy Association
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Solution Overview
Problem
In 5G communication systems, the lack of a direct connection interface between the AM PCF and SM PCF leads to complex implementation and unnecessary signaling overheads when forwarding SM policy results through the UDR, complicating the UDR's role as a database node.
Innovation Solution
Implement methods for determining policy control network elements by using mobility and session management network elements to select and associate the same PCF for access and mobility management and session management, utilizing first and second indication information to ensure consistent policy control network element selection based on DNN and S-NSSAI, and leveraging network repository functions for discovery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the SM PCF pushes SM policy results to the AM PCF through the UDR, then the AM PCF can perform policy adjustment, but the UDR implementation becomes excessively complex and unnecessary signaling overheads are generated
Solution Approach 1:
The patent extracts the policy result forwarding function from the UDR by introducing a dedicated N15 interface between AM PCF and SM PCF. This removes the burden of policy forwarding from the UDR, allowing it to focus solely on its database function, thereby reducing UDR implementation complexity while maintaining reliable policy control
Solution Approach 2:
The patent introduces a direct communication interface (N15) as an intermediary channel between AM PCF and SM PCF. This dedicated interface enables efficient policy result forwarding without involving the UDR, reducing signaling overhead and avoiding the complexity of making the UDR serve dual purposes
2Adaptability or versatility
If the AM PCF and SM PCF are separate network elements, then specialized policy control is achieved, but direct communication between them is blocked and additional signaling overhead is required
Solution Approach 1:
The patent introduces a direct N15 interface as an intermediary communication channel between AM PCF and SM PCF. This dedicated interface enables efficient direct communication while preserving the functional separation and specialization of AM PCF and SM PCF, thereby maintaining adaptability without sacrificing communication efficiency
3Productivity
If the UDR is used for forwarding policy information, then existing database functionality is utilized, but the UDR's role becomes overly complex beyond its database function
Solution Approach 1:
The patent extracts the policy forwarding function from the UDR and assigns it to a dedicated communication interface (N15). This allows the UDR to maintain its simple database functionality while policy forwarding is handled separately, preventing functional complexity from accumulating in the UDR
Solution Approach 2:
The patent segments the policy control system into distinct functional components: the UDR handles only data storage, while the N15 interface handles policy forwarding. This segmentation ensures that each component performs its specialized function without being burdened by additional responsibilities, optimizing resource utilization while maintaining simplicity
Data Source
AI summary
A method for determining a policy control network element, in which a mobility management network element obtains first indication information, where the first indication information indicates to select a same policy control network element as a policy control network element for access and mobility management and a policy control network element for session management; the mobility management network element receives a session establishment request from a terminal for establishing a first session; and the mobility management network element sends second indication information and information about a first policy control network element to a session management network element based on the first indication information, where the second indication information indicates to select a same policy control network element as a policy control network element used for access and mobility management and a policy control network element used for session management of the first session.