GTP-U–PDCP Sequence Mapping for Multicast Handover Retransmission
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Solution Overview
Problem
Data loss occurs during handover of a terminal from a source cell to a target cell in multimedia broadcast and multicast services due to asynchronous data transmission between the two cells.
Innovation Solution
A data retransmission method that involves obtaining a mapping relationship between GTP-U sequence numbers and source PDCP sequence numbers of data packets, enabling targeted data retransmission by the target node or source node to minimize data loss during handover.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If data transmission is performed asynchronously between source node and target node during handover, then handover speed is improved, but data packet loss increases
Solution Approach 1:
The source node performs preliminary actions by determining which data packets need to be retransmitted and forwards their packet identifiers (PDCP sequence numbers) to the target node before the handover is complete. This allows the target node to have the necessary data ready for immediate retransmission to the terminal, preventing data loss during the asynchronous handover process.
Solution Approach 2:
The source node acts as an intermediary by identifying and forwarding information about missing data packets to the target node. This intermediary action enables the target node to reconstruct and retransmit the missing data without requiring synchronous communication between source and target nodes during handover.
2Device complexity
If data retransmission is performed without mapping relationship, then retransmission process is simplified, but data loss cannot be accurately recovered
Solution Approach 1:
The terminal provides feedback to the source node about which data packets have been successfully received and which are missing. The source node uses this feedback information to determine which specific packets need retransmission and forwards their identifiers to the target node, enabling precise recovery of only the missing data without unnecessary complexity.
Data Source
AI summary
Data retransmission method is disclosed. The method includes: obtaining a mapping relationship between GTP-U sequence numbers of N data packets sent by a source node and source PDCP sequence numbers assigned to the N data packets by the source node; and performing data retransmission based on the mapping relationship.