Multi-AP Downlink Retransmission for Low-Quality Wi-Fi Links

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Solution Overview

Problem

In multi-Access Point (AP) cooperation scenarios, existing methods fail to efficiently handle downlink data retransmissions, leading to increased transmission delays and packet loss, particularly for stations with low channel quality.

Innovation Solution

A data retransmission method where a first access point device requests a second access point device within the same operation set to retransmit data frames, reducing the number of downlink retransmissions and transmission delays by leveraging multi-AP cooperation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single access point device performs downlink data transmission, then the device complexity is low, but the transmission delay increases and reliability decreases when channel quality is poor

Engineering Contradiction:
Improvedownlink data transmission reliabilityVSAvoidmulti-AP cooperation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines multiple access point devices into a cooperative transmission system where multiple APs work together to transmit downlink data to a station. This merging of resources improves transmission reliability and reduces delay by providing redundant transmission paths and selecting optimal APs based on channel conditions.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The access point devices in the multi-AP system are designed to perform multiple functions: primary transmission, retransmission, and coordinated cooperation. Any AP in the set can serve as a transmission source, making the system versatile and adaptable to different channel conditions without requiring dedicated specialized devices.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Loss of time

If traditional retransmission methods are used in multi-AP scenarios, then the system structure is simple, but the transmission delay increases due to additional retransmission rounds

Engineering Contradiction:
Improvetransmission delayVSAvoiddownlink data transmission efficiency
Core Design Contradiction:
Loss of timeVSProductivity

Solution Approach 1:

The patent implements preliminary action by having the access control device pre-arrange the retransmission process. When the primary AP fails to transmit successfully, the AC device has already identified and prepared a secondary AP from the operation set to perform retransmission, eliminating the need for the station to request retransmission and reducing overall transmission delay.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system uses feedback mechanisms where the access control device monitors transmission status between APs and stations. Based on this feedback, the AC device dynamically selects appropriate APs for retransmission from the operation set, optimizing transmission efficiency while managing system complexity.

Inventive Principle:
Principle #23Feedback

Data Source

PatentEP4216470B1Data retransmission method and access point device
Publication Date: 2026.01.07 GUANGDONG OPPO MOBILE TELECOMMUNICATIONS CORP LTD
  • EP4216470B1 patent drawingFigure 1~2
  • EP4216470B1 patent drawingFigure 3~5
  • EP4216470B1 patent drawingFigure 6~9

AI summary

The embodiments of the present disclosure provide a data retransmission method and an access point device, capable of achieving downlink data retransmission in a multi-AP cooperation scenario, which can reduce the number of downlink data retransmissions and transmission delay, thereby improving user experience. The data retransmission method includes: transmitting, by a first access point device, first request information when the first access point device fails to transmit a first data frame to a station device, the first request information requesting a second access point device to retransmit the first data frame, and the first access point device and the second access point device belonging to one operation set.