Wi-Fi PPDU Null Tone Transmission for Low-Latency Urgent Data

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Solution Overview

Problem

The introduction of frame aggregation in Wi-Fi networks, while increasing overall throughput, results in higher worst-case latency for time-sensitive frames due to longer transmission times, particularly when the channel is occupied by long PPDU transmissions from other devices within the same or overlapping BSS.

Innovation Solution

Utilization of null tones within the PPDU for transmitting urgent data, determined based on the PPDU's bandwidth and transmission mode, allowing for orthogonal frequency domain transmission of time-sensitive traffic alongside regular data.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If frame aggregation is used to increase throughput, then overall data transmission efficiency is improved, but latency for time-sensitive frames increases

Engineering Contradiction:

ImprovethroughputVSAvoidlatency

Core Design Contradiction:

ProductivityVSLoss of time

Solution Approach 1:

The patent segments the frequency spectrum by utilizing null tones (specific subcarriers) within the aggregated PPDU structure to create a separate transmission channel for urgent data. This allows time-sensitive frames to be transmitted independently without waiting for the complete aggregated frame to finish, thereby reducing latency while maintaining high throughput for regular data.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a new dimension for data transmission by using the frequency domain (specific null tone subcarriers) as an additional channel within the existing time-domain aggregated frame structure. This enables parallel transmission of urgent data alongside regular aggregated data, effectively solving the latency-throughput tradeoff.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Quantity of substance

If longer PPDU transmission time is used for frame aggregation, then more data can be transmitted, but channel occupancy increases causing delays for other devices

Engineering Contradiction:

Improvedata payload sizeVSAvoidchannel occupancy time

Core Design Contradiction:

Quantity of substanceVSLoss of time

Solution Approach 1:

The patent ensures continuous useful action by utilizing the null tones that would otherwise be wasted during the entire PPDU transmission period. This allows urgent data to be transmitted continuously alongside regular data without requiring additional channel occupancy time, maximizing the utilization of the available transmission window.

Inventive Principle:

Principle #20Continuity of useful action

3Loss of time

If null tones are utilized for urgent data transmission, then latency for time-sensitive frames is reduced, but complexity of PPDU structure increases

Engineering Contradiction:

Improvelatency for urgent dataVSAvoidPPDU structure complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The patent applies self-service by having the transmitting device automatically identify and utilize the null tones within the existing PPDU structure without requiring external coordination or complex additional signaling. The receiver similarly self-adapts by detecting the null tone positions and extracting urgent data, simplifying the overall system complexity despite the enhanced functionality.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12567937B2Utilization of null tones for urgent data transmission in Wi-Fi network

Publication Date: 2026.03.03 INTEL CORP

AI summary

The present application provides an apparatus including RF interface circuitry; and processor circuitry coupled with the RF interface circuitry and configured to: generate a PPDU carrying urgent data to be transmitted by the apparatus; provide the PPDU to the RF interface circuitry for transmission to a receiver of the PPDU. The urgent data may be carried over one or more null tones in the PPDU.