SMF Data Buffering for 5G Session Continuity
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Solution Overview
Problem
In 4G communications systems, downlink data received by terminal devices can be out of order due to different transmission paths, affecting user experience, and in 5G systems, ensuring in-order data reception is crucial for maintaining service continuity during terminal device movement.
Innovation Solution
A data buffering method where a session management function entity interacts with user plane function entities to notify an anchor user plane function entity to buffer downlink data based on preset conditions, ensuring that the transmission path remains consistent after the session is switched to an active state, without establishing additional forwarding tunnels or releasing existing ones.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If downlink data is transmitted through multiple different transmission paths (SGW1→SGW2 and PGW→SGW2) after terminal device moves to connected state, then service data transceiving can be established, but the downlink data received by terminal device becomes out of order
Solution Approach 1:
The patent applies preliminary action by having the source SGW1 buffer downlink data before the terminal device switches to connected state and before establishing the forwarding tunnel to SGW2. This ensures that data is ready and waiting in the correct sequence position, preventing out-of-order delivery when the terminal reconnects through a different gateway.
2Adaptability or versatility
If terminal device switches from idle state to connected state and selects a new SGW2, then continuous service can be maintained, but additional forwarding tunnel establishment is required which increases signaling interaction
Solution Approach 1:
The patent establishes the forwarding tunnel from SGW1 to SGW2 and buffers data at SGW1 before the terminal device actually needs to receive data after switching to connected state. This preliminary setup avoids the need for complex real-time tunnel establishment and data reordering operations when the terminal reconnects.
Data Source
AI summary
A data buffering method including: a session management function (SMF) interacting with a first user plane function (UPF1) and a second UPF2, such that the UPF1 sends first downlink data of a first session to an access network device via UPF2, where UPF1 is an anchor of the first session; and the SMS releasing UPF2 in a procedure in which a terminal device enters an idle state and a transmission resource associated with the first session in an access network is released, where UPF1 buffers incoming second downlink data of the first session. After the terminal device is switched to a connected state, both a transmission path of incoming third downlink data of the first session and that of the buffered second downlink data pass through UPF1, UPF3, the access network device, and the terminal device successively.