802.11ah Control Frame Next TWT Field Optimization

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Solution Overview

Problem

Wireless communication devices without a target wake time (TWT) schedule incur overhead when using control frames that include a Next TWT field, which is unnecessary for synchronization with an access point (AP) without receiving a beacon.

Innovation Solution

A method using one bit in the frame control field of a control frame to optionally indicate the presence of a Next TWT field, allowing devices without a TWT schedule to access control frames without the overhead of the Next TWT field, thereby synchronizing with the AP's time synchronization function.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If control frames include a Next TWT field for all devices, then devices with TWT schedule can synchronize efficiently, but devices without TWT schedule incur unnecessary overhead

Engineering Contradiction:

Improvesynchronization efficiencyVSAvoidcontrol frame size

Core Design Contradiction:

ProductivityVSQuantity of substance

Solution Approach 1:

The control frame structure is made dynamic by conditionally including or excluding the Next TWT field based on the receiving device's TWT schedule status. The frame control field contains a indication bit that signals whether the Next TWT field is present, allowing the frame format to adapt to different device types and reduce unnecessary overhead for devices without TWT schedules.

Inventive Principle:

Principle #15Dynamics

2Reliability

If control frames always include Next TWT field, then TWT-scheduled devices receive synchronization information, but frame complexity increases for all devices

Engineering Contradiction:

Improvesynchronization reliabilityVSAvoidframe structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Different parts of the control frame structure are optimized for different device types. Devices with TWT schedules receive the complete frame with Next TWT field for reliable synchronization, while devices without TWT schedules receive simplified frames without this field, reducing their processing complexity. The indication bit in the frame control field enables receiving devices to selectively process only the relevant portions of the frame.

Inventive Principle:

Principle #3Local quality

3Loss of time

If Next TWT field is included in all control frames, then time synchronization is maintained for TWT devices, but communication overhead increases

Engineering Contradiction:

Improvesynchronization timeVSAvoidcommunication overhead

Core Design Contradiction:

Loss of timeVSLoss of energy

Solution Approach 1:

The Next TWT field is extracted from the universal control frame structure and made optional. Only devices with active TWT schedules require and process this field, while devices without TWT schedules can operate with simplified control frames that exclude this field entirely. This extraction eliminates unnecessary data transmission and processing overhead for devices that do not need time synchronization information.

Inventive Principle:

Principle #2Taking out (Extraction)

Data Source

PatentEP2982082B1Method of efficiency improvement for control frames in 802.11ah

Publication Date: 2021.04.28 INTEL CORP

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Figure 3A~3B

AI summary

Systems and methods are presented that a STA that has not set up a target wake time (TWT) schedule with an AP to use a control frame without incurring the overhead of the Next TWT field in order to determine AP changes or to sync with the AP's time synchronization function without receiving a beacon. In an embodiment, the configuration may include using one bit in a frame control (FC) field of a control frame to indicate a presence of a Next TWT field, such that the Next TWT field is optionally present in the control frame and contains the next target wake time value for an intended recipient of the control frame.