5G UPF Handover Packet Loss Prevention via SMF End Marker Control
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Solution Overview
Problem
In 5G communications networks, during user equipment (UE) movement and handover, data packet loss occurs due to premature discarding of downlink data packets on secondary branches after an end marker is received, leading to a degraded user experience.
Innovation Solution
A method where the session management function network element sends session modification requests to multiple anchor user plane function network elements, indicating only the last updating element to send an end marker, ensuring that packet transmission on old paths is completed before switching to new paths, thereby avoiding data packet loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the end marker mechanism is used to indicate the last downlink data packet on the old path, then the target RAN can switch to sending data packets on the new path, but data packets on secondary branches may be discarded prematurely causing data packet loss
Solution Approach 1:
The patent implements a feedback mechanism where the SMF monitors the transmission status of downlink data packets across multiple branches and provides feedback information to control the sending of end markers. The SMF determines whether all branches have completed data packet transmission before triggering the end marker mechanism, ensuring that the target RAN switches to new paths only when all old path transmissions are complete, thus preventing data packet loss while maintaining handover efficiency
Solution Approach 2:
The SMF acts as an intermediary between the anchor UPFs and the target RAN. It coordinates the end marker sending process by receiving information from anchor UPFs about data packet transmission status and controlling which anchor UPF sends the end marker based on this information. This intermediary role ensures that the complex multi-branch transmission coordination is managed centrally, preventing premature switching and data packet loss
2Device complexity
If multiple anchor user plane function network elements send end markers, then each branch can be independently managed, but the target RAN cannot determine which end marker indicates complete transmission across all branches
Solution Approach 1:
The SMF implements a feedback-based control mechanism where it receives transmission status information from multiple anchor UPFs and provides feedback to determine which anchor UPF should send the end marker. This feedback loop ensures that only the appropriate anchor UPF (typically the last one to complete transmission) sends the end marker, allowing the target RAN to correctly interpret the transmission completion signal without confusion from multiple end markers
Solution Approach 2:
The patent segments the end marker sending function by assigning it to a specific anchor UPF based on transmission status, rather than having all anchor UPFs send end markers simultaneously. This segmentation is controlled by the SMF which divides the coordination task by monitoring each branch and determining the optimal timing and source for the end marker, thus preventing information loss while maintaining branch management flexibility
Data Source
Figure 1A~2A
Figure 2B~3B
Figure 4A
AI summary
This application provides a transmission control method, including: in a re-allocation process of a first user plane function network element to a second user plane function network element, a session management function network element sends a respective session modification request to each anchor user plane function network element of a plurality of anchor user plane function network elements, where each session modification request includes information about the second user plane function network element; and indicates to only a first anchor user plane function network element in the plurality of anchor user plane function network elements to send an end marker; or sends the end marker to only the first anchor user plane function network element. Using the solution can resolve a packet loss problem for a downlink data packet in a scenario of re-allocating a user plane function network element, improving user experience.