SNPN to PLMN Service Continuity via Backup PDU Session
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Solution Overview
Problem
There is a need to support seamless service continuity between stand-alone non-public networks (SNPN) and public land mobile networks (PLMN) to prevent disruptions in data delivery, especially for services like video, imaging, and audio (VIAPA) that require low latency and high data rates, particularly when user equipment (UE) moves between these networks.
Innovation Solution
A method is implemented where a wireless device establishes a protocol data unit (PDU) session with a non-3GPP interworking function (N3IWF) of the source network, creating a backup user plane connection to enable quick handovers between SNPN and PLMN, allowing data buffering to ensure continuous service delivery by deactivating the initial connection and activating the buffered data transfer through the N3IWF when moving to the target network.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a PDU session is established with N3IWF for SNPN access, then data delivery is enabled, but service continuity is disrupted when UE moves to PLMN
Solution Approach 1:
The patent establishes a backup PDU session with the PLMN's N3IWF in advance while the UE is connected to the SNPN. This preliminary action ensures that when handover occurs, the data path is already prepared, eliminating service disruption and reducing handover latency.
Solution Approach 2:
The patent introduces a backup data path through the PLMN's N3IWF as an intermediary. This alternative path acts as a mediator that can take over data transmission when the primary SNPN path becomes unavailable, ensuring continuous service delivery.
2Speed
If backup user plane connection is established in advance, then handover speed is improved, but network complexity increases
Solution Approach 1:
The backup PDU session is established in advance during SNPN connection, preparing the data path before handover is needed. This preliminary setup enables rapid switching without requiring complex real-time decision-making or additional signaling during the actual handover event.
Solution Approach 2:
The patent creates a copy of the data path through the PLMN's N3IWF that mirrors the SNPN connection. This copied path can be activated instantly during handover, simplifying the handover process while maintaining network reliability.
3Loss of substance
If data buffering is implemented during handover, then data loss is reduced, but buffering overhead increases
Solution Approach 1:
By establishing the backup PDU session before handover, the system eliminates the need for extensive data buffering. The data path is already prepared and can immediately transmit data upon handover, minimizing both data loss and buffering overhead.
Solution Approach 2:
The patent ensures continuous data transmission by maintaining an active backup data path through the PLMN's N3IWF. This continuous readiness eliminates gaps in data delivery during handover, reducing the need for buffering and retransmission.
Data Source
AI summary
A method and apparatus for support of service continuity between stand-alone non-public network (SNPN) and public land mobile network (PLMN) is provided. A wireless device transmits, to an access and mobility management function (AMF) of a source network, a protocol data unit (PDU) session establishment request to establish a PDU session with the source network via a non-3GPP interworking function (N3IWF) of the source network. The PDU session establishment request includes information informing that data delivery is not available via the PDU session. The wireless device determines to move from the source network to a target network, and transmits, to a user plane function (UPF) of the source network, mobility information informing that the wireless device moves from the source network to the target network.