AP Unavailability Signaling for Protected rTWT Wi-Fi Slots

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Solution Overview

Problem

Existing Wi-Fi networks face inefficiencies due to interference from legacy devices that do not support Restricted Target Wake Time (rTWT), which disrupt scheduled transmission periods for latency-sensitive applications.

Innovation Solution

Implementing a protocol where all STAs, regardless of rTWT support, initiate transmissions with an initial control frame, followed by an AP response providing scheduling information to harmonize with rTWT schedules, and incorporating new signaling rules in the 802.11 standard to ensure efficient network operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If legacy devices transmit without rTWT awareness, then network compatibility is maintained, but interference with scheduled rTWT transmissions occurs

Engineering Contradiction:

Improvenetwork compatibilityVSAvoidinterference with rTWT transmissions

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The AP sends an unavailability indication to legacy devices before the rTWT transmission period begins, warning them to refrain from transmitting. This preliminary warning prevents legacy devices from causing interference while maintaining their simple operation mode, thus resolving the contradiction between compatibility and interference prevention.

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The unavailability indication acts as an intermediary signal between the AP and legacy devices. It conveys the scheduled rTWT information to legacy devices without requiring them to understand or implement rTWT protocols, enabling coordination while preserving legacy device simplicity.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If all devices continuously monitor the channel, then transmission opportunities are not missed, but energy consumption increases

Engineering Contradiction:

Improvetransmission opportunity detectionVSAvoidenergy consumption

Core Design Contradiction:

ReliabilityVSUse of energy by moving object

Solution Approach 1:

Instead of continuous monitoring, devices wake up at predetermined Target Wake Times to transmit or receive data, then return to sleep mode. This periodic operation ensures transmission opportunities are not missed while dramatically reducing energy consumption compared to continuous monitoring.

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

Devices are scheduled in advance with specific wake times and transmission opportunities communicated through TWT negotiation. This preliminary scheduling allows devices to sleep confidently knowing when to wake up, eliminating the need for continuous channel monitoring while maintaining reliable transmission opportunity detection.

Inventive Principle:

Principle #10Preliminary action

3Loss of time

If rTWT scheduled transmissions are protected from legacy devices, then latency is reduced, but network complexity increases

Engineering Contradiction:

ImprovelatencyVSAvoidnetwork protocol complexity

Core Design Contradiction:

Loss of timeVSDevice complexity

Solution Approach 1:

The wireless medium is segmented into different time periods: unprotected periods where legacy devices can transmit freely, and protected rTWT periods where legacy devices are prevented from transmitting. This temporal segmentation ensures low latency for rTWT traffic during protected periods while maintaining simple legacy device operation during unprotected periods.

Inventive Principle:

Principle #1Segmentation

Data Source

PatentEP4679927A1Restricted target wake time with unavailability indication on the access point side

Publication Date: 2026.01.14 INTEL CORP

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AI summary

This disclosure describes systems, methods, and devices related to restricted target wake time (rTWT) Protection. A device may receive an initial Control frame (ICF) sent by an associated Ultra-High Reliability Station (UHR STA) to initiate a Transmission Opportunity (TxOP). The device may transmit an Information Control Response (ICR) frame to the UHR STA, incorporating an Unavailability Target Start Time field, marking the start of unavailability, and an Unavailability Duration, indicating the length of unavailability.