Wake-up Preamble Generation for Wi-Fi Synchronization
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Solution Overview
Problem
In Wi-Fi networks, devices face high energy consumption and latency due to continuous listening during idle periods, and existing wake-up receivers struggle with synchronization due to complex modulation schemes, limiting their ability to quickly identify wake-up frames.
Innovation Solution
A wake-up preamble generation method that includes a regular sequence with bit reversal order and a synchronization field, such as a Barker sequence, to enable quick synchronization of the wake-up receiver without increasing power consumption, using a simple circuit structure with energy detection and RF modules for OOK modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the wake-up receiver uses a simple circuit structure with energy detection and RF modules only, then power consumption is reduced, but the receiver cannot perform demodulation for complex modulation schemes like OFDM, preventing synchronization
Solution Approach 1:
The patent segments the wake-up frame into two distinct parts: a first wake-up signal with simple OOK modulation that the low-power receiver can detect, and a second wake-up signal with complex OFDM modulation that requires the full transceiver. This segmentation allows the receiver to perform synchronization using only the simple first signal, avoiding the need for complex demodulation while maintaining reliable frame identification.
Solution Approach 2:
The patent introduces an intermediary mechanism where the simple first wake-up signal acts as a mediator to enable synchronization before the complex second OFDM signal is processed. The first signal with its distinctive pattern (two consecutive ones followed by two zeros) serves as a mediator that allows the receiver to align its timing and frequency without requiring full demodulation capability.
2Loss of time
If the STA continuously listens on the channel during idle periods, then communication latency is reduced, but energy consumption increases significantly
Solution Approach 1:
The patent extracts the essential synchronization function from the full transceiver operation and places it in a dedicated wake-up receiver with simplified circuitry. By taking out only the necessary energy detection and simple signal reception capabilities, the system enables low-power listening while maintaining the ability to quickly respond to wake-up frames without continuous full-transceiver operation.
Solution Approach 2:
The patent implements periodic wake-up listening where the STA transitions between deep sleep and wake-up listening states. Instead of continuous listening, the device periodically checks for wake-up frames during idle periods, reducing energy consumption while maintaining acceptable latency through timely wake-up responses when data becomes available.
3Device complexity
If the wake-up frame uses simple OOK modulation, then the receiver circuit structure can be simplified and power consumption reduced, but the receiver cannot perform demodulation for complex modulation schemes
Solution Approach 1:
The patent applies dynamics by having the modulation scheme change within the wake-up frame itself. The first wake-up signal uses simple OOK modulation adapted for low-power reception, while the second wake-up signal uses OFDM modulation for full communication. This dynamic modulation approach allows the receiver to handle different complexity levels as needed, adapting the modulation scheme to the operational phase.
Data Source
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AI summary
This disclosure relates to a wake-up preamble generation method, a synchronization method, and an apparatus. The wake-up preamble generation method includes: generating a wake-up frame, where the wake-up frame includes a wake-up preamble, the wake-up preamble includes a regular sequence including at least two regular subsequences, and a following regular subsequence is in bit reversal order of a current regular subsequence before the following regular subsequence; or the wake-up preamble includes at least one regular subsequence and a preset field, and the preset field is a synchronization field that has an auto-correlation property and a cross-correlation property or is a start-of-frame delimiter that has a unique sequence; and sending the wake-up frame, so that a receiver completes quick synchronization based on content of the wake-up preamble. In this application, a wake-up preamble is generated, and the wake-up preamble is used to synchronize a receiver, so that the receiver learns of an end bit of the preamble or a start bit of an information sequence, to implement quick synchronization.