Wake-Up Receiver Frame Structure for Low-Latency IoT Radios
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Solution Overview
Problem
Existing IEEE 802.11 standards, including 802.11ah, do not adequately support ultra-low power consumption and low latency requirements for certain IoT applications, such as sensor networks, despite providing low power features.
Innovation Solution
Implementing a low-power wake-up receiver (WUR) that operates in the sub-1-GHz band, using simple modulation schemes like OOK with repetition, to wake up the main radio only when data is available, thereby reducing power consumption in IoT devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If the main radio operates continuously to ensure low latency response, then response time is reduced, but power consumption increases
Solution Approach 1:
The radio system is segmented into two functional parts: a low-power wake-up receiver that continuously monitors for wake-up signals, and a main radio that remains in sleep mode until activated. This segmentation allows the system to maintain responsiveness for critical wake-up events while keeping the power-intensive main radio dormant, thereby resolving the contradiction between continuous operation (low latency) and power saving.
Solution Approach 2:
The main radio operates in periodic cycles rather than continuously. It remains in sleep mode and is periodically awakened by wake-up signals received through the wake-up receiver. This periodic activation pattern reduces average power consumption while maintaining the capability to respond promptly when data needs to be transmitted or received.
2Use of energy by moving object
If the main radio is kept in sleep mode to reduce power consumption, then energy efficiency improves, but response time increases
Solution Approach 1:
The wake-up receiver serves as an intermediary component that bridges the gap between the sleep mode main radio and the external environment. It continuously monitors the channel for wake-up signals and activates the main radio when needed, enabling the system to maintain low power consumption while avoiding excessive latency by ensuring prompt activation when data arrives.
3Use of energy by moving object
If IEEE 802.11ah low power features are used, then power consumption is reduced, but they are inadequate for ultra-low power requirements
Solution Approach 1:
Instead of attempting to make the main radio ultra-low power capable, the system creates a simplified copy or alternative receiver specifically designed for wake-up functionality. The wake-up receiver uses a different, simpler modulation scheme (OOK with repetition) that is far more power-efficient than the main radio's modulation, thereby achieving ultra-low power consumption for the wake-up function while the main radio handles data transmission with its full capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The WUR significantly reduces power consumption by keeping the main radio in a low-power state until data is received, extending the network's operational lifetime while maintaining low latency.
Implementation Method 1
using simple modulation schemes like OOK with repetition
Implementation Method 2
operates in the sub-1-GHz band, using simple modulation schemes like OOK with repetition, to wake up the main radio
Data Source
AI summary
A method performed by a wireless device operating in a wireless network, wherein the wireless device includes a main radio and a wake-up receiver. The method includes detecting, by a first component of the wake-up receiver, a wake-up receiver preamble in a wireless transmission received by the wireless device and waking up a second component of the wake-up receiver in response to detecting the wake-up receiver preamble.