5G Handover QoS Flow Mapping for In-Sequence Data Delivery
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Solution Overview
Problem
In 5G communications, ensuring data units are submitted in sequence during handover processes is challenging due to changes in Quality of Service (QoS) flow mappings between data radio bearers, leading to potential out-of-order data transmission.
Innovation Solution
A handover method where the target base station receives a handover request from the source base station, establishes a PDU session or DRB tunnel, and allocates addresses to ensure that data units are transferred in sequence by buffering and reordering data units at the SDAP layer, using indication information to manage changes in QoS flow mappings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If QoS flow to DRB mapping is changed during handover, then service adaptability is improved, but data transmission order is disrupted
Solution Approach 1:
The source base station performs preliminary actions by determining the QoS flow to DRB mapping relationship before handover and notifying the target base station in advance through the handover request message. This allows the target base station to prepare the correct mapping configuration before actually receiving data, ensuring that data units are forwarded in the correct order even as mappings change during handover.
Solution Approach 2:
The patent introduces an intermediary mechanism where the source base station acts as a mediator that determines the QoS flow to DRB mapping relationship and communicates it to the target base station. This intermediary role ensures that the mapping information is accurately transmitted and applied, maintaining data order during the handover process while allowing flexible mapping changes.
2Reliability
If data units are buffered at SDAP layer during handover, then data order is maintained, but handover time is increased
Solution Approach 1:
The source base station determines the QoS flow to DRB mapping relationship before handover and notifies the target base station in advance. This preliminary action allows the target base station to prepare the correct forwarding configuration, reducing the need for extensive buffering and reordering operations during handover, thereby minimizing handover time while maintaining data order.
Solution Approach 2:
The target base station uses the QoS flow to DRB mapping information received from the source base station to automatically configure its own data forwarding behavior. This self-service approach allows the target base station to immediately begin correct data forwarding without requiring complex coordination or extended buffering, thus reducing handover time while maintaining reliability.
3Manufacturing precision
If QoS flow mapping information is transmitted during handover, then data forwarding accuracy is improved, but signaling overhead is increased
Solution Approach 1:
The patent extracts only the essential QoS flow to DRB mapping information from the complete handover signaling process and includes it specifically in the handover request message. This selective extraction approach ensures that the most critical information for maintaining data forwarding accuracy is transmitted without including unnecessary signaling overhead, thus improving data forwarding accuracy while minimizing information loss.
4Productivity
If multiple QoS flows are mapped to same DRB, then resource efficiency is improved, but QoS differentiation is reduced
Solution Approach 1:
The patent applies local quality by configuring QoS flow to DRB mapping relationships specifically for each handover scenario and each QoS flow type. Instead of using a universal mapping rule, the source base station determines and notifies the target base station of the specific mapping relationship appropriate for each local context, allowing multiple QoS flows to be efficiently mapped to the same DRB when appropriate while maintaining QoS differentiation when required.
Data Source
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AI summary
A handover method is used by a source base station and a target base station to transmit, through a tunnel, a data unit obtained after a DRB corresponding to a QoS flow changes to a second DRB. The method in embodiments of this application includes: receiving, by a target base station, a handover request sent by a source base station, where the handover request includes first indication information, and the first indication information is used to indicate that a data radio bearer DRB corresponding to a quality of service flow QoS flow of the source base station changes from a first DRB to a second DRB; and sending, by the target base station, information about a tunnel to the source base station, where the tunnel is used by the target base station to receive a data unit sent by the source base station, and the data unit is a data unit obtained after the DRB corresponding to the QoS flow changes to the second DRB.