Relay Path Switching with PDCP Status to Reduce Packet Loss

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Solution Overview

Problem

When a remote terminal device switches from a path involving a relay terminal device to another path, a large quantity of data packets are lost.

Innovation Solution

Implement a data transmission method that includes PDCP re-establishment, RLC re-establishment, and MAC resetting to minimize data packet loss during path switching in communication scenarios involving relay terminal devices.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a remote terminal device switches from a path including a relay terminal device to another path, then communication path flexibility is improved, but data packet loss increases

Engineering Contradiction:
Improvecommunication path flexibilityVSAvoiddata packet loss
Core Design Contradiction:
Adaptability or versatilityVSLoss of information

Solution Approach 1:

The patent applies preliminary action by having the network device forward data packets that are currently being transmitted on the relay path to the target network device before the path switch is completed. This pre-forwarding ensures that when the remote terminal device switches paths, the data packets are already available at the target end, preventing packet loss during the transition.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent uses the source network device as an intermediary to coordinate the path switching process. The source network device receives the path switch request, identifies the data packets being transmitted, and forwards them to the target network device. This intermediary role ensures smooth transition and prevents data loss during the handover process.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Loss of time

If path switching is performed quickly, then service continuity is improved, but data packet loss increases

Engineering Contradiction:
Improveservice continuity timeVSAvoiddata packet loss
Core Design Contradiction:
Loss of timeVSLoss of information

Solution Approach 1:

The patent implements preliminary action by pre-forwarding data packets to the target network device before the path switch is executed. This allows the switching process to be completed quickly without waiting for data packet transmission to finish on the old path, thus reducing service interruption time while preventing packet loss.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent maintains continuity of useful action by ensuring that data packet forwarding continues uninterrupted during the path switch. The source network device forwards data packets to the target network device while the remote terminal device is switching paths, ensuring that data transmission remains continuous and no packets are lost during the transition.

Inventive Principle:
Principle #20Continuity of useful action

Data Source

PatentEP4329372B1Data transmission method and apparatus
Publication Date: 2026.02.25 HUAWEI TECH CO LTD
  • EP4329372B1 patent drawingFigure 1(a)~1(b)
  • EP4329372B1 patent drawingFigure 2(a)~3
  • EP4329372B1 patent drawingFigure 4(a)

AI summary

This application provides a data transmission method and an apparatus, and relates to the field of communication technologies. According to the method, a first network device sends a first message including first information to a remote terminal device. The first message indicates the remote terminal device to switch from being connected to the first network device through a first path to being connected to a second network device through a second path. The first path includes at least one relay terminal device. The second path includes at least one relay terminal device or does not include a relay terminal device. The first information indicates a receiving status of a first PDCP entity of the first network device. The first information is carried in a switch command, so that the remote terminal device can receive the first information as soon as possible, to avoid or reduce packet loss when data is transmitted on the second path based on the first information.