SMF-gNB Direct Control via N3-C Interface
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Solution Overview
Problem
In 5G mobile and wireless networks, the separation of session management function signaling from the Access and Mobility Management Function (AMF) is incomplete, leading to inefficiencies in error handling and communication security, as session management functions still rely on the AMF for relaying communications with user equipment (UE) and gNBs, which complicates troubleshooting and network performance.
Innovation Solution
Establishing a dedicated control plane between the Session Management Function (SMF) and the gNB using the N3-C interface, independent of the N2 interface used by the AMF, allowing SMF to handle NAS signaling and session management directly with the UE and gNB, and using a security key from the Security Anchor Function (SEAF) for encryption, thereby separating session management from mobility management functions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If session management functions rely on AMF for relaying communications with UE and gNBs, then communication can be maintained through unified interface, but error handling efficiency deteriorates and troubleshooting complexity increases
Solution Approach 1:
The patent segments the control plane by establishing a separate N3-C interface between SMF and gNB, independent from the N2 interface used by AMF. This segmentation allows session management signaling to be handled directly between SMF and gNB without relaying through AMF, improving error handling efficiency while reducing communication relay structure complexity.
2Productivity
If session management functions rely on AMF for relaying communications, then interface unification is maintained, but network performance and efficiency deteriorate
Solution Approach 1:
The patent divides the control plane into separate interfaces: N2 for AMF mobility management and N3-C for SMF session management. This segmentation enables direct SMF-gNB communication for session management, eliminating unnecessary relaying through AMF and improving network efficiency without significantly increasing interface structure complexity.
Solution Approach 2:
The patent extracts session management signaling from the AMF relay path and establishes a direct N3-C interface between SMF and gNB. This extraction removes the bottleneck of AMF relaying for session management, improving network efficiency while the interface structure remains manageable through standardized protocols.
3Reliability
If SMF uses AMF relay for communications, then unified security management is maintained, but communication security deteriorates
Solution Approach 1:
The patent segments security management by introducing separate security contexts for N2 (AMF) and N3-C (SMF) interfaces. The SMF derives its own security keys (K_SMF, K_UPF) from the initial authentication key, enabling independent security management for session management communications, thereby improving communication security while keeping key management structured and manageable.
4Adaptability or versatility
If session management and mobility management are combined through AMF, then architecture simplicity is maintained, but functional independence deteriorates
Solution Approach 1:
The patent segments mobility management (AMF via N2 interface) and session management (SMF via N3-C interface) into independent functional paths. This segmentation enables each function to operate independently with dedicated interfaces, improving functional independence while the overall architecture remains structured and manageable through standardized protocol definitions.
Data Source
AI summary
The disclosed technology separates session management function signaling from the AMF. In particular, an SMF key is created for each SMF following the AMF generating an SM context request that contains gNB information and UE subscription information. Each PDU session creates a direct connection between the SMF and a local gNB. The gNB communicates with each SMF directly over a new interface (N3-C) for session management that is independent of the N2 interface used by the gNB to communicate with the AMF for mobility management. In this way, each SMF independently handles NAS signaling with the UE, using the SMF key and gNB related session-management signaling over an independent interface with the gNB. This removes the burden of relaying these communications through the AMF, which is then freed up to solely to handle mobility management signaling, resulting in an improved architecture.