End Marker Handling for 5G to LTE Mobility
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Solution Overview
Problem
In next-generation wireless networks, particularly during handovers between 5G and LTE base stations, the core network's lack of awareness of radio bearers leads to challenges in ensuring lossless mobility and efficient end marker signaling, causing issues with packet reordering and resource management.
Innovation Solution
The method involves generating and sending single end marker indications for PDU sessions from the source base station to the target base station, allowing the target station to determine the necessary end markers for each radio bearer and manage data forwarding effectively, even in scenarios where the core network operates on a PDU session basis rather than EPS bearers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If the core network sends a single end marker indication for a PDU session during handover, then the signaling overhead is reduced, but the target base station cannot determine the complete set of end markers needed for each radio bearer
Solution Approach 1:
The patent segments the single PDU session-level end marker indication into multiple bearer-level end marker indications. The source base station receives one end marker for the PDU session, then divides it into separate end markers for each radio bearer mapped to that PDU session, ensuring complete information delivery to the target base station for proper resource management.
Solution Approach 2:
The source base station acts as an intermediary that translates the core network's PDU session-level end marker into bearer-level end markers. It maps the PDU session to its constituent radio bearers using stored mapping information, thereby bridging the information gap between the core network's simplified signaling and the RAN's detailed bearer management requirements.
2Reliability
If the target base station waits for all end markers before switching paths, then packet reordering is prevented, but handover latency increases
Solution Approach 1:
The source base station performs preliminary actions by generating and forwarding all necessary bearer-level end marker indications to the target base station before the path switch is completed. This allows the target base station to have all required information ready in advance, enabling it to switch paths without waiting for additional end markers, thus reducing handover latency while maintaining reliability.
Solution Approach 2:
The system cushions against potential packet reordering issues by having the source base station proactively send all end marker indications for all bearers mapped to the PDU session. This beforehand cushioning ensures the target base station receives complete information before needing to make path switching decisions, preventing delays caused by waiting for missing end markers.
3Loss of information
If the source base station generates separate end marker indications for each bearer, then the target base station receives complete information for resource management, but the signaling overhead increases
Solution Approach 1:
The patent merges multiple bearer-level end marker indications into a single PDU session-level end marker indication sent by the core network. The source base station then performs a one-time expansion of this single indication into multiple bearer-specific indications using its stored mapping information, achieving complete information delivery without requiring the core network to send separate messages for each bearer.
Solution Approach 2:
The source base station uses its own stored mapping information between PDU sessions and radio bearers to self-generate the bearer-level end marker indications from the single PDU session-level indication received from the core network. This self-service approach eliminates the need for additional core network signaling messages, reducing overall signaling overhead while maintaining complete information delivery.
Data Source
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AI summary
Methods and apparatus, including computer program products, are provided for mobility between networks. In some example embodiments, there may be provided a method. The method may include receiving, at a source base station, a single end marker indication for a flow associated with a user equipment being handed over to a target base station; determining, by the source base station and in response to the received single end marker indication, at least one bearer mapped to the flow; generating for each determined bearer, at least one end of marker indication; and sending, over a forwarding path from the source base station to the target base station, the generated at least one end of marker indication. Related systems, methods, and articles of manufacture are also described.