Access Point Power Saving via Target Wake Time Synchronization
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Solution Overview
Problem
IEEE 802.11 standards do not allow access points to transition into a power-saving mode, leading to increased power consumption in both access points and associated electronic devices, which is not suitable for all applications or environments.
Innovation Solution
An access point selectively transitions to a power-saving mode by establishing target wakeup times (TWTs) with associated electronic devices, maintaining synchronization through TWT beacons or multi-user trigger frames, and transitioning to a higher-power mode only when necessary, thereby reducing power consumption without affecting communication performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the access point remains in active operating mode to ensure real-time availability for data traffic delivery and device association, then communication performance and reliability are improved, but power consumption increases
Solution Approach 1:
The access point implements periodic wake-up at predetermined target wakeup times (TWTs) instead of continuous operation. During sleep intervals, the access point transitions to a low-power state, and periodically wakes up to transmit beacons and handle data traffic. This periodic operation pattern reduces power consumption while maintaining necessary communication availability through scheduled wake-up cycles.
2Use of energy by moving object
If the access point transitions to power-saving mode to reduce power consumption, then energy efficiency is improved, but communication availability and synchronization with electronic devices deteriorate
Solution Approach 1:
The access point and electronic devices perform preliminary negotiation to establish target wakeup times (TWTs) before entering sleep mode. This advance scheduling ensures that both parties are synchronized on when the access point will wake up, eliminating uncertainty about communication availability. The preliminary TWT setup allows devices to know exactly when to expect the access point to be active, maintaining reliability without requiring continuous operation.
Solution Approach 2:
The access point transmits beacons containing synchronization information and TWT parameters to electronic devices. These beacons provide feedback to devices about the access point's wake-up schedule, current operational state, and any changes to TWT arrangements. This feedback mechanism allows devices to adjust their own operations accordingly, maintaining synchronized communication even when the access point is in power-saving mode.
3Measurement precision
If the access point frequently transmits beacons to maintain synchronization with electronic devices, then synchronization accuracy is improved, but power consumption and network overhead increase
Solution Approach 1:
The access point transmits beacons periodically at the established target wakeup times rather than continuously or at fixed high-frequency intervals. This periodic beacon transmission provides sufficient synchronization information to electronic devices at the moment of wake-up, maintaining synchronization accuracy while minimizing the number of transmissions. The periodic pattern aligns with the TWT schedule, ensuring devices receive necessary synchronization data without excessive beacon overhead.
Data Source
AI summary
An access point establishes target wakeup times (TWTs) with one or more associated electronic devices in a WLAN. The access point transitions to a power-saving mode outside of the one or more TWTs. The access point maintains synchronization with the one or more electronic devices, during at least a first TWT in the one or more TWTs, by transmitting, to the one or more electronic devices, a TWT beacon that includes, or in conjunction with, synchronization information. Alternatively or additionally, during at least the first TWT, the access point transmits a multi-user trigger frame that includes the synchronization information to the one or more electronic devices. In response to the multi-user trigger frame, the access point receives data frames from the one or more electronic devices, transmits one or more acknowledgments, and transitions into the power-saving mode during a remainder of at least the first TWT.