Wireless Slave Wake-Up Using Preamble Extension for Low Power Links
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Solution Overview
Problem
Existing low power wireless communication protocols, such as IEEE 802.15.4, require slave devices to frequently wake up and enter higher power modes to detect beacon frames, even when no data is being transmitted, leading to unnecessary power consumption and inefficient battery life.
Innovation Solution
Introduce a frame structure with a common preamble and a preamble extension for frames of a second type, allowing slave devices to remain in a low power mode until detecting the preamble extension, and only transition to a higher power mode when necessary for data reception or transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If slave devices frequently wake up to detect beacon frames, then synchronization and communication reliability are maintained, but power consumption increases and battery life decreases
Solution Approach 1:
The master device transmits a preamble extension signal before the actual beacon frame to preliminarily indicate whether data communication is imminent. Slave devices wake up early to detect this extension signal, allowing them to determine in advance whether they need to fully activate for data reception or transmission, thus avoiding unnecessary full wake-ups and reducing power consumption while maintaining communication reliability
Solution Approach 2:
The beacon frame structure is segmented into two parts: a preamble extension signal and the main beacon frame. The preamble extension contains a flag indicating whether data communication is imminent, allowing slave devices to make differential power management decisions. This segmentation enables selective activation based on actual communication needs, resolving the contradiction between maintaining reliability and reducing power consumption
2Duration of action of moving object
If slave devices remain in low power mode, then battery life is extended, but detection of incoming data frames is delayed
Solution Approach 1:
The system performs preliminary action by transmitting and detecting the preamble extension signal before the main beacon frame. Slave devices wake up in low power mode just long enough to detect this extension signal, which preliminarily indicates whether data communication is imminent. This allows them to extend their active period only when necessary, extending battery life while maintaining fast detection speed for actual data frames
Solution Approach 2:
The slave device's power mode is dynamically adjusted based on the detection result of the preamble extension signal. When the flag indicates data communication is imminent, the slave device transitions to high power mode for fast detection; when no data is expected, it remains in low power mode. This dynamic adaptation resolves the contradiction between battery life and detection speed
Data Source
AI summary
Frames of a first and second type with a common preamble that are periodically transmitted by a master device (200) are received at a slave device (100) that is maintained in a low powered mode, and periodically set in a higher-powered mode to receive and process the received frames based on a slave clock (130) in a period prior to an expected transmission of the common preamble of each frame from the master device (200) to detect a preamble extension of a frame of the second type in the period. The slave device (100) returns to a low powered mode when no preamble extension is detected in the period. Information is received from and/or transmitted to the master device (200) by the slave device (100) when a preamble extension is detected. The slave device (100) is returned to the low powered mode after the information has been received and/or transmitted.