RAN-Initiated Tunnel Setup for Low-Latency UE Handover
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Solution Overview
Problem
Existing 5G communications networks experience significant delays in handling uplink data packets during UE mobility due to the selection of a new User Plane Function (UPF), which is unacceptable for ultra-reliable low-latency communications (URLLC) services.
Innovation Solution
Introduce a new identifier system for wireless device connections, allowing radio access network (RAN) nodes to directly transmit an identifier to a shared data storage layer accessible by multiple UPFs, enabling the selected UPF to retrieve the context without SMF signaling, and implement a UPF selection mechanism in the RAN node to reduce latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If SMF-controlled UPF selection is performed during UE mobility, then network control and management are maintained, but significant delays occur in handling uplink data packets
Solution Approach 1:
The RAN node performs UPF selection in advance during handover preparation, before the actual handover executes. The selected UPF identifier is included in the handover request message, so when handover occurs, the UPF is already selected and ready to receive data immediately, eliminating the delay of post-handover UPF selection
Solution Approach 2:
The UPF selection function is extracted from the SMF and relocated to the RAN node. This allows the RAN node to independently select and initiate connection to the appropriate UPF without waiting for SMF signaling, thereby reducing latency while maintaining network control through other SMF functions
2Reliability
If traditional handover signaling flow is used with SMF updating, then proper session management is ensured, but latency increases due to multiple signaling steps
Solution Approach 1:
The RAN node selects the UPF and establishes the user plane connection before the handover actually occurs. By including the UPF identifier in the handover request, the signaling flow is optimized so that when the handover executes, the data path is already prepared, reducing the number of sequential signaling steps
Solution Approach 2:
The RAN node autonomously performs UPF selection and initiates the user plane connection without requiring SMF intervention at the moment of handover. This self-service capability allows the RAN node to handle UPF selection independently, reducing dependency on multi-step SMF signaling while maintaining proper session management through other control plane procedures
Data Source
AI summary
One aspect provides a method performed by a radio access network node in a telecommunications network. The method comprises: responsive to detection of a trigger event associated with a wireless device having a connection to the telecommunications network via the radio access network node or seeking to establish a connection to the telecommunications network via the radio access network node, transmitting a message directly to a user plane core network node providing functionality for the connection via the radio access network node, the message comprising one or more of: an indication of an identifier of the wireless device; and an indication of an identifier of a session for the wireless device. The user plane core network node has access to a data storage layer shared between a plurality of user plane core network nodes, the data storage layer storing respective contexts for the sessions of a plurality of wireless devices, including the wireless device.