Wakeup Receiver Using 2D Signal Patterns for Low-Latency IoT

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Solution Overview

Problem

Existing wireless sensor nodes in IoT applications face challenges with high power consumption and latency due to continuous monitoring requirements, and conventional wakeup receivers suffer from large latency when using standard compliant radios like BLE, which are not compatible with low-power energy-detection based architectures.

Innovation Solution

A fully-integrated wakeup receiver using a 2-dimensional wakeup pattern that down-converts input signals to DC, applies automatic gain control, and compares RSSI and packet length with a two-dimensional template to generate a wakeup signal, allowing for low-power operation and reduced latency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If continuous monitoring is performed by the main radio to meet latency requirements, then response time is improved, but power consumption increases

Engineering Contradiction:

Improveresponse timeVSAvoidpower consumption

Core Design Contradiction:

Loss of timeVSUse of energy by moving object

Solution Approach 1:

The system segments the monitoring function by introducing a separate wakeup receiver (WuRx) that continuously monitors the channel while the main radio remains in low-power sleep mode. This segmentation allows continuous monitoring without requiring the power-hungry main radio to be always on, thus resolving the contradiction between fast response time and low power consumption.

Inventive Principle:

Principle #1Segmentation

2Use of energy by moving object

If simple OOK modulation is used in the wakeup receiver to minimize power consumption, then power usage is improved, but compatibility with standard compliant radios deteriorates

Engineering Contradiction:

Improvepower consumptionVSAvoidcompatibility with standard radios

Core Design Contradiction:

Use of energy by moving objectVSAdaptability or versatility

Solution Approach 1:

The patent changes the modulation parameter from simple OOK to constant envelope modulations (GFSK, HS-OQPSK) that are compatible with standard Bluetooth Low Energy (BLE) and IEEE 802.15.4 radios. This parameter change maintains low power consumption while improving compatibility with standard compliant radios, as these modulations can be implemented with simple envelope detection in the wakeup receiver.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If conventional wakeup receivers operate with BLE advertising packets directly, then compatibility with standard radios is improved, but latency increases

Engineering Contradiction:

Improvecompatibility with BLE radiosVSAvoidlatency

Core Design Contradiction:

Adaptability or versatilityVSLoss of time

Solution Approach 1:

The patent extracts the essential wakeup detection functionality from the complete packet processing chain. The wakeup receiver only extracts and detects the preamble and initial synchronization symbols needed to generate a wakeup interrupt, rather than processing entire BLE advertising packets. This extraction reduces processing time and latency while maintaining compatibility with BLE radios.

Inventive Principle:

Principle #2Taking out (Extraction)

4Adaptability or versatility

If complex modulations like FSK or PSK are used in the wakeup receiver, then communication capability is improved, but power consumption and hardware complexity increase

Engineering Contradiction:

Improvecommunication capabilityVSAvoidpower consumption

Core Design Contradiction:

Adaptability or versatilityVSUse of energy by moving object

Solution Approach 1:

The patent employs a simplified wakeup receiver with envelope detection that uses minimal hardware resources and consumes very low power. Instead of implementing complex FSK or PSK demodulation circuits, the system uses a disposable-like approach where the wakeup receiver performs only essential detection functions and hands off to the main radio for full communication processing, thus achieving adequate communication capability at minimal power cost.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

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 solution enables efficient power management and significantly reduces latency, making it suitable for latency-critical IoT applications by allowing the receiver to detect valid wakeup signals with high accuracy and low false alarms, while being compatible with standard compliant radios like BLE.

Implementation Method 1

The wakeup receiver is further configured to down-convert the input signal to a DC signal

Methodology Applied

Scientific EffectDown-conversion: Homodyne Detection

Data Source

PatentUS10652823B2Wakeup receiver

Publication Date: 2020.05.12 STICHTING IMEC NEDERLAND

AI summary

Systems and methods providing a wakeup receiver for latency-critical applications are described herein. An example system includes a wakeup receiver communicatively coupled to a communication channel. The wakeup receiver is configured to monitor an input signal of the communication channel and down-convert the input signal to a DC signal. The system also includes an analog to digital converter (ADC) configured to digitize the DC signal and provide an ADC output. The system further includes a digital baseband (DBB) module configured to determine a received signal strength indication (RSSI) from the signal. The DBB is also configured to, for each packet, determine a respective packet length and compare the RSSI and respective packet length with a two-dimensional template. The DBB is additionally configured to, based on the comparison, determine an interrupt condition and, based on determining the interrupt condition, generate a wakeup signal.