Wake-Up Receiver Downlink Indication for Low-Power Wi-Fi Stations
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Solution Overview
Problem
In wireless-fidelity (Wi-Fi) networks, stations equipped with wake-up receivers wake up frequently to receive beacon frames, leading to high power consumption, especially in stations with coin batteries where the percentage of downlink service data is small.
Innovation Solution
A method where a station controls its wake-up receiver to wake up within a preset listen interval to receive a wake-up beacon frame from the access point, and the main radio does not wake up to receive a beacon frame, allowing the station to determine if there is downlink service data based solely on the indication field in the wake-up beacon frame.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the main radio wakes up within a listen interval to receive beacon frames according to the 802.11 protocol, then the station can obtain downlink service data indication, but the main radio wakes up relatively frequently leading to high power consumption
Solution Approach 1:
The patent segments the beacon frame reception function by introducing a wake-up receiver that operates independently from the main radio. The wake-up receiver handles the initial beacon frame reception and downlink service data indication, allowing the main radio to remain in deep sleep state and wake up only when necessary, thus resolving the contradiction between reliable data indication and power consumption.
Solution Approach 2:
The wake-up receiver acts as an intermediary between the beacon frame transmission and the main radio. It receives and processes beacon frames containing downlink service data indications, then selectively wakes up the main radio only when downlink service data is available, eliminating the need for the main radio to wake up at every listen interval and significantly reducing power consumption while maintaining reliable data indication.
2Loss of energy
If the station enters deep sleep state to reduce energy consumption, then energy efficiency is improved, but transmission between AP and STA cannot be performed until STA wakes up resulting in latency
Solution Approach 1:
The wake-up receiver performs preliminary actions by continuously monitoring for beacon frames and downlink service data indications while the main radio remains in deep sleep. When downlink service data is detected in the beacon frame, the wake-up receiver proactively wakes up the main radio, ensuring immediate transmission capability and eliminating the latency that would otherwise occur while waiting for the main radio to wake up at its scheduled intervals.
3Loss of time
If the station follows a specific sleep policy to periodically wake up and check for downlink service data, then latency is reduced, but sleep efficiency is reduced
Solution Approach 1:
The wake-up receiver serves as an intermediary that eliminates the need for the main radio to periodically wake up and check for downlink service data. The wake-up receiver continuously monitors beacon frames and only triggers the main radio to wake up when actual downlink service data is available, achieving both low latency (immediate response to data availability) and high sleep efficiency (main radio remains in deep sleep during periods with no data).
Data Source
AI summary
One example method includes sending, by a first station (STA), a request frame to a wireless access point (AP). The request frame includes listen interval information, the listen interval information includes duration of a first listen interval, and the first STA is equipped with main radio and a wake-up receiver. The first STA receives a response frame sent by the AP, where the response frame carries an identity allocated by the AP to the first STA, and the identity of the first STA comprises an identity of the wake-up receiver of the first STA. The first STA controls the wake-up receiver to wake up within the first listen interval, and receives a wake-up beacon frame periodically sent by the AP.