CU Bearer Context Modification for QoS Flow Remapping
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Solution Overview
Problem
Current 5G communication systems face challenges in efficiently managing Quality of Service (QoS) flow remapping, particularly during handovers and when SDAP end markers are not received, leading to potential packet mixing and lossless transmission issues.
Innovation Solution
The proposed solution involves a method and apparatus where a base station's centralized unit (CU) transmits a bearer context modification request message to its user plane (UP), including PDCP sequence number status and QoS flow information, and the UP responds with a bearer context modification response message, ensuring proper remapping and handling of SDAP end markers to prevent packet mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If QoS flow remapping is performed during handover, then service continuity is improved, but packet mixing and lossless transmission issues occur when SDAP end markers are not received
Solution Approach 1:
The source base station performs preliminary actions by determining the PDCP sequence number status before handover and including it in the handover request message sent to the target base station. This preliminary information exchange enables the target base station to properly handle packet reordering and prevents packet mixing during QoS flow remapping, while maintaining service continuity.
2Productivity
If DRBs are released during handover, then resource efficiency is improved, but data transmission completeness deteriorates when SDAP end markers are not received
Solution Approach 1:
The target base station sends a handover request acknowledgment message back to the source base station, providing feedback on whether the PDCP sequence number status matches the expected value. Based on this feedback, the source base station decides whether to release the DRB or maintain it for potential data forwarding, thus balancing resource efficiency with data transmission completeness.
3Manufacturing precision
If PDCP sequence number status is exchanged between base stations, then packet order is maintained, but signaling overhead increases
Solution Approach 1:
The patent extracts only the essential PDCP sequence number status information needed for packet reordering into the handover request and acknowledgment messages. By taking out only this specific parameter rather than exchanging complete packet buffers or detailed sequence information, the solution maintains packet order while minimizing signaling overhead between base stations.
Data Source
AI summary
A method performed by a base station in a wireless communication system is provided. The method includes transmitting, by a control plane (CP) of a centralized unit (CU) of the base station, a bearer context modification request message to a user plane (UP) of the CU of the base station, wherein the bearer context modification request message includes information associated with a request for a packet data convergence protocol (PDCP) sequence number (SN) status, and transmitting, by the UP of the CU of the base station, based on the bearer context modification request message, a bearer context modification response message to the CP of the CU of the base station, wherein the bearer context modification response message includes information associated with the PDCP SN status and information associated with at least one QoS flow, of which a service data adaptation protocol (SDAP) end marker is not received by the UP of the CU.