802.11ax Preamble Structure for Reliable Protocol Version Detection

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Solution Overview

Problem

The challenge of rapidly and reliably auto-detecting the 802.11ax protocol version in wireless local area networks using preambles is not adequately addressed by existing technologies, leading to compatibility and interoperability issues.

Innovation Solution

A data transmission method and apparatus that generates and processes preambles with multiple OFDM symbols, ensuring the same input information bits for rapid and reliable auto-detection of the 802.11ax version by using distinct interleaving and modulation techniques for different OFDM symbols, maintaining compatibility with existing protocol versions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a mixed format preamble is used to ensure backward compatibility with legacy devices, then interoperability between different 802.11 standard versions is improved, but the ability to rapidly and reliably auto-detect the 802.11ax protocol version deteriorates

Engineering Contradiction:
ImproveinteroperabilityVSAvoidprotocol version auto-detection
Core Design Contradiction:
Adaptability or versatilityVSDifficulty of detecting and measuring

Solution Approach 1:

The preamble is segmented into legacy field and non-legacy field parts, with the non-legacy field containing version-specific training fields and signal fields that enable protocol version detection while the legacy field maintains compatibility with older devices

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Version detection signal fields are introduced as intermediary elements between the legacy preamble structure and the new 802.11ax protocol features, allowing receiving devices to identify the protocol version without disrupting legacy compatibility

Inventive Principle:
Principle #24Intermediary (Mediator)

2Difficulty of detecting and measuring

If distinct interleaving and modulation techniques are used for different OFDM symbols in the non-legacy field, then rapid and reliable auto-detection of 802.11ax version is improved, but the complexity of the preamble structure increases

Engineering Contradiction:
Improveprotocol version auto-detectionVSAvoidpreamble structure
Core Design Contradiction:
Difficulty of detecting and measuringVSDevice complexity

Solution Approach 1:

Different interleaving and modulation techniques are applied locally to specific OFDM symbols within the non-legacy field, allowing version detection through localized signal characteristics without requiring complete restructuring of the entire preamble

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent changes physical signal parameters (interleaving patterns, modulation schemes) of specific OFDM symbols to encode protocol version information, enabling detection through parameter comparison while maintaining overall structure consistency

Inventive Principle:
Principle #35Parameter changes

3Quantity of substance

If multiple OFDM symbols with different input information bits are used in the non-legacy field, then the information carrying capacity is improved, but the reliability of auto-detection through bit comparison deteriorates

Engineering Contradiction:
Improveinformation carrying capacityVSAvoidauto-detection reliability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

Certain information bits are periodically repeated across multiple OFDM symbols in the non-legacy field, allowing receiving devices to perform reliability checks through comparison while still maintaining high information carrying capacity through the overall multi-symbol structure

Inventive Principle:
Principle #19Periodic action

Data Source

PatentEP4224807B1Data transmission method and apparatus
Publication Date: 2026.03.18 HUAWEI TECH CO LTD
  • EP4224807B1 patent drawingFigure 1~2
  • EP4224807B1 patent drawingFigure 3
  • EP4224807B1 patent drawingFigure 4~5

AI summary

Embodiments of the present invention provide a data transmission method and an apparatus, so as to implement rapid and reliable auto-detection of a preamble of an 802.11ax version. The method includes: generating a preamble for a protocol version of a wireless local area network, where the preamble includes a legacy signal L-SIG field and a high efficiency signal HE-SIG field that are arranged in order, the HE-SIG field includes a first orthogonal frequency division multiplexing OFDM symbol and a second OFDM symbol that are arranged in order, and an input information bit of the first OFDM symbol is the same as that of the second OFDM symbol; and sending the preamble to a receive end device, so that the receive end device restores the preamble, and when determining that input information bits obtained after restoring the first OFDM symbol and the second OFDM symbol are the same, determines that the preamble is the preamble of the protocol version.