DAPS Handover Reporting for Duplicate Packet Discard
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Solution Overview
Problem
Existing wireless communication systems face challenges in achieving seamless and lossless handovers with minimal interruption time, particularly in scenarios requiring dual active protocol stacks, due to issues such as packet duplication and resource inefficiencies during handover processes.
Innovation Solution
The implementation of Dual Active Protocol Stack (DAPS) handover, where the user equipment maintains connections with both the source and target cells during the handover process, allowing simultaneous data transmission and reception, and includes mechanisms for early and late packet forwarding to minimize duplication and latency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If traditional handover is used, then protocol stack simplicity is maintained, but handover interruption time increases and packet loss occurs
Solution Approach 1:
The protocol stack is segmented into source and target stacks during handover, allowing both to operate simultaneously. The source protocol stack maintains existing connections while the target protocol stack establishes new connections, enabling parallel processing of handover tasks and reducing interruption time without requiring a single monolithic complex stack.
Solution Approach 2:
The target protocol stack is prepared and activated before the actual handover execution. Measurement reports are collected, target cell selection is performed, and the target protocol stack is pre-configured in advance, so that when handover is triggered, the stack is already ready to receive and process packets immediately, minimizing handover interruption time.
2Reliability
If dual active protocol stacks are used, then handover continuity is improved, but packet duplication increases
Solution Approach 1:
PDCP status information including sequence numbers and transmission status is transferred from the source protocol stack to the target protocol stack before handover execution. This preliminary transfer of status information enables the target stack to identify and discard duplicate packets that would otherwise be transmitted, maintaining handover continuity while preventing packet duplication.
Solution Approach 2:
The system implements feedback mechanisms where the target protocol stack receives status information about already transmitted packets from the source stack. This feedback loop allows the target stack to adjust its packet transmission behavior, discarding duplicates that have already been successfully transmitted, thereby maintaining reliability while reducing substance loss from packet duplication.
3Productivity
If early packet forwarding is implemented, then handover latency is reduced, but packet duplication risk increases
Solution Approach 1:
PDCP status information is transferred in advance to the target protocol stack before packets are forwarded. This preliminary preparation of status information enables the target stack to be ready to receive and validate packets immediately, allowing early packet forwarding to occur with minimal latency while the status information is already in place to prevent duplication.
Solution Approach 2:
The system dynamically adjusts packet forwarding timing based on real-time conditions. The protocol stack monitors transmission status and can forward packets at optimal moments, balancing the need for speed with the need to avoid duplication. This dynamic control allows the system to maximize productivity while minimizing substance loss through intelligent timing rather than rigid fixed schedules.
Data Source
AI summary
A method performed by a wireless device includes obtaining User Plane (UP) information comprising at least one Handover (HO) interruption time. The at least one HO interruption time is associated with a first packet of a plurality of duplicate packets received by the wireless device. The wireless device transmits, to a network node, a report associated with a handover of the wireless device, the report comprising the UP information comprising the at least one HO interruption time associated with the first packet of the plurality of duplicate packets received by the wireless device.