DAPS Handover for URLLC Packet Duplication Continuity
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Solution Overview
Problem
Existing 5G NR wireless devices configured for PDCP packet duplication face challenges in maintaining Ultra-Reliable and Low Latency Communication (URLLC) Quality of Service (QoS) requirements during inter base station handovers, particularly due to the incompatibility of DAPS handover with PDCP packet duplication, leading to potential service disruptions and reliability degradation.
Innovation Solution
The wireless device transitions from PDCP packet duplication with the source base station to DAPS and back to PDCP packet duplication with the target base station, maintaining dual active protocol stacks during the handover to ensure continuity of data transmission and reliability, by preserving RLC entities and configuring dual logical connections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If DAPS handover is performed to maintain connection continuity during inter base station handover, then service disruption is reduced, but compatibility with PDCP packet duplication is lost leading to reliability degradation
Solution Approach 1:
The system dynamically switches between PDCP packet duplication mode and DAPS handover mode based on operational context. During normal operation, PDCP packet duplication provides redundancy. During handover, the system transitions to DAPS mode to maintain connection continuity, then returns to PDCP duplication mode after handover completion, optimizing both reliability and adaptability at different stages.
Solution Approach 2:
The system performs preliminary configuration of dual active protocol stacks before actual handover execution. This preliminary setup ensures that when handover is needed, the infrastructure is already in place to maintain connection continuity without sacrificing PDCP packet duplication compatibility in the surrounding operational phases.
2Reliability
If PDCP packet duplication is maintained during handover to ensure reliability, then redundant transmission paths are preserved, but handover compatibility issues arise causing service disruption
Solution Approach 1:
The system prepares dual active protocol stacks in advance before handover execution, ensuring that the infrastructure for maintaining redundant transmission paths is already configured. This preliminary action allows seamless transition during handover without service disruption, as the system can immediately switch to using the pre-configured stacks.
Solution Approach 2:
The system maintains continuous data transmission throughout handover by keeping both source and target base station protocol stacks active simultaneously. This continuity ensures that redundant transmission paths remain functional during the transition, preventing service disruption while maintaining reliability.
3Reliability
If dual active protocol stacks are configured during handover to maintain connection, then feedback to source base station is lost requiring additional signaling, but connection continuity is maintained
Solution Approach 1:
The system uses the target base station as an intermediary during handover. The target base station receives and forwards necessary control information and feedback, compensating for the loss of direct feedback path to the source base station. This intermediary role maintains connection continuity while preserving essential information flow.
Solution Approach 2:
The system implements feedback mechanisms through the dual active protocol stacks where the target base station provides acknowledgment and status information back to the wireless device. This feedback loop compensates for the loss of direct feedback to the source base station, maintaining reliable communication during handover.
Data Source
AI summary
Techniques for inter base station handovers are provided for the case where a wireless device is operating in a PDCP packet duplication mode. The handover techniques enable the wireless device to transition from PDCP packet duplication with the source cell to DAPS and to transition back to PDCP packet duplication with the target cell when the handover is complete. In some embodiments, the RLC entities established with the source cell are preserved during the inter base station handover. The handover techniques ensure that QoS requirements for URLLC can be met during the inter base station handover.