Terminal Device HARQ Buffer Management for Random Access Data Loss

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Solution Overview

Problem

Existing technologies fail to address the issue of data loss during transmission as the MAC PDU of the MAC PDU is flushed when the network side device is not addressed in the HARQ buffer, resulting in the HARQ procedure, leading to specific type of the technical area.

Innovation Solution

A method to improve the success rate of random access by using a contention-based random access procedure, where the network side device is selected based on the reference symbol received power (RSRP) of every downlink signal.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the HARQ buffer is flushed when random access is successful, then the random access procedure can be completed, but data packets are lost

Engineering Contradiction:
Improvedata transmission reliabilityVSAvoiddata packet loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent applies preliminary action by determining whether to flush the HARQ buffer before completing the random access procedure. The terminal device checks if the random access is successful, and only flushes the buffer after confirming success, thereby preventing premature data loss while ensuring proper buffer management.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent changes the state parameter of the HARQ buffer from a fixed flush operation to a conditional operation based on random access success. The buffer is maintained in a non-flushed state during the random access procedure and only flushed when the success condition is met, thus preventing data loss while maintaining system reliability.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If the MAC PDU is buffered in the HARQ buffer for retransmission, then data transmission reliability is improved, but buffer management complexity increases

Engineering Contradiction:
Improvedata transmission reliabilityVSAvoidbuffer management complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent applies self-service by enabling the terminal device to autonomously determine whether to flush the HARQ buffer based on the random access success condition. This self-determination mechanism eliminates the need for complex external control signals or additional network coordination, thereby improving reliability while keeping buffer management straightforward.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3836713B1Random access method and terminal device
Publication Date: 2025.12.24 VIVO MOBILE COMM CO LTD
  • EP3836713B1 patent drawingFigure 1~3
  • EP3836713B1 patent drawingFigure 4

AI summary

The present disclosure provides a random access method and a terminal device. The method includes: reserving a first MAC PDU buffered in a HARQ buffer or buffering a second MAC PDU in a HARQ buffer if a random access procedure is successful, where the first MAC PDU is a PDU that is buffered in a Msg3 buffer in a contention random access procedure, the second MAC PDU is a PDU that includes at least data content of the first MAC PDU and is buffered in a target buffer, and the target buffer and the Msg3 buffer are different buffers.