NAS Message Separation in 5G Session Establishment
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Solution Overview
Problem
Current 5G network technologies face limitations in separating NAS message transfer from session user plane establishment, particularly in non-3GPP access networks like fixed networks, which restricts terminal access to 5G core networks due to unsupported NAS message transfer capabilities.
Innovation Solution
A method and system that allow NAS message transfer to be separated from session user plane establishment by using different access technologies, where a terminal sends NAS messages to an access network device using one technology and initiates a session with a user plane function network element using another technology, facilitated by identifiers like IP addresses or FQDNs for session establishment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If one access network device performs both NAS message transfer and user plane establishment, then the device can handle both functions, but the system lacks versatility for different access technologies
Solution Approach 1:
The patent segments the access network device into two separate functional entities: a control plane device that handles NAS message transfer and a user plane device that handles user plane establishment. This segmentation allows different access technologies to be supported independently - the control plane device can forward NAS messages while the user plane device establishes sessions, enabling fixed networks and other non-3GPP accesses to connect to the 5G core network even though they cannot natively support NAS message transfer.
2Reliability
If fixed network access is deployed, then user plane processing capability is available, but NAS message transfer is not supported
Solution Approach 1:
The patent introduces a control plane access network device as an intermediary that forwards NAS messages between the terminal and the core network. This intermediary enables fixed network access to utilize the 5G core network by relaying control plane messages, while the user plane function is established directly between the terminal and the core network, allowing fixed networks to access 5G services despite lacking native NAS message transfer capabilities.
3Ease of operation
If NAS message transfer and user plane establishment are combined in one device, then the process is simplified, but application in some scenarios is limited
Solution Approach 1:
The patent divides the session establishment process into two independent phases: NAS message transfer handled by the control plane device and user plane establishment handled by the user plane device. This segmentation maintains operational simplicity within each phase while dramatically expanding scenario applicability, enabling fixed networks, non-3GPP accesses, and heterogeneous network environments to establish sessions with the 5G core network.
Data Source
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AI summary
Embodiments of this application provide a session establishment method and system, and a device, to resolve a prior-art problem that NAS message transfer cannot be separated from session user plane establishment and application in some scenarios is limited. The method includes: sending, by a terminal, a first non-access stratum NAS message to a first access network device corresponding to a first access technology, where the first NAS message is used to request to establish a session; receiving, by the terminal, a second NAS message from the first access network device, where the second NAS message carries an identifier of a user plane function network element; and initiating, by the terminal, a session establishment procedure between the terminal and the user plane function network element based on the identifier of the user plane function network element by using a second access technology.