DAPS Handover Packet Retransmission for Reliable Data Transfer
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Solution Overview
Problem
In dual active protocol stack (DAPS) handover, there is a risk of packet loss due to unacknowledged data packets not being transmitted to the target base station during the handover process, leading to increased mobility interruption times and reduced service reliability in ultra-reliable and low-latency scenarios.
Innovation Solution
The terminal device is configured to retransmit data packets sent to the source base station to the target base station after successful connection, using unacknowledged mode radio link control (UM RLC) bearers, reducing packet loss by maintaining dual active communication links during the handover process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the terminal device does not retransmit data packets to the target base station after handover, then the handover process is simple and fast, but packet loss occurs and service reliability deteriorates
Solution Approach 1:
The terminal device performs preliminary actions by identifying and buffering data packets that were sent to the source base station before handover completion. These packets are marked for potential retransmission to the target base station, ensuring that no data is lost during the handover transition while maintaining a manageable process through structured preprocessing
Solution Approach 2:
The patent introduces an intermediary mechanism where the terminal device acts as a mediator between the source and target base stations. It maintains temporary data packet buffers and determines which packets need retransmission, effectively bridging the gap during handover and preventing packet loss without requiring complex coordination between base stations
2Reliability
If the terminal device retransmits all data packets to the target base station, then packet loss is minimized, but transmission time increases and mobility interruption time worsens
Solution Approach 1:
Instead of retransmitting all data packets, the terminal device applies partial action by selectively identifying only those packets that were successfully sent to the source base station but need to be forwarded to the target base station. This avoids unnecessary retransmission of already delivered packets, reducing time loss while ensuring reliable data transfer
Solution Approach 2:
The patent implements feedback mechanisms where the terminal device receives acknowledgments from the source base station about which data packets were successfully received. This feedback information is used to determine which packets require retransmission to the target base station, optimizing the retransmission process and minimizing mobility interruption time
3Stability of the object's composition
If the terminal device maintains dual active communication links during handover, then service continuity is improved, but device complexity and energy consumption increase
Solution Approach 1:
The terminal device dynamically manages communication links during handover, transitioning from a static single-link mode to a dynamic dual-active mode only when necessary. The device activates the target base station link while maintaining the source link temporarily, then smoothly transitions to exclusive use of the target link, optimizing energy consumption while ensuring service continuity throughout the process
Data Source
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Figure 3a~3b
AI summary
This application provides a data transmission method and a communication apparatus. The data transmission method includes: A terminal device receives first information from a first access network device, where the first information indicates the terminal device to be handed over and connected to a second access network device. The terminal device sends a first data packet to the second access network device after the terminal device successfully accesses the second access network device, where the first data packet is a data packet that has been sent by the terminal device to the first access network device before the terminal device successfully accesses the second access network device. According to the data transmission method, after the terminal device is handed over from the first access network device and connected to the second access network device, the terminal device can retransmit, to the second access network device, data that has been sent to the first access network device, thereby improving data transmission reliability of the terminal device in a handover process.