2.4 GHz CSI Sensing Engine Channel Diversity

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Solution Overview

Problem

CSI-based motion detection in the 2.4 GHz band faces challenges such as bandwidth limitations, interference, and congestion, which affect the performance of wireless devices that only support this frequency band for cost and power consumption reasons.

Innovation Solution

The implementation of a 2.4 GHz CSI sensing engine that enhances sampling rate, provides channel diversity through smart channel switching and time division, and employs interference mitigation using an ACI filter to rank channel subcarrier indexes, thereby improving detection accuracy despite congestion and interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by stationary object

If CSI-based motion detection is implemented in the 2.4 GHz band, then cost and power consumption are reduced, but bandwidth limitations, interference, and congestion affect detection performance

Engineering Contradiction:
Improvepower consumptionVSAvoiddetection performance
Core Design Contradiction:
Use of energy by stationary objectVSReliability

Solution Approach 1:

The patent segments the 2.4 GHz band into multiple subchannels and selectively activates only the subchannels with the best signal quality for CSI sampling. This segmentation allows the system to operate in the cost-effective 2.4 GHz band while mitigating interference by using only the cleanest frequency segments, thus maintaining detection performance despite the band's inherent congestion.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system dynamically switches between different 2.4 GHz subchannels based on real-time signal quality assessment. By continuously monitoring and adapting to changing channel conditions, the system maintains reliable detection performance despite interference and congestion, while still operating in the low-power 2.4 GHz band.

Inventive Principle:
Principle #15Dynamics

2Measurement precision

If the sampling rate is increased to improve detection accuracy, then detection precision improves, but bandwidth consumption increases

Engineering Contradiction:
Improvedetection accuracyVSAvoidbandwidth consumption
Core Design Contradiction:
Measurement precisionVSQuantity of substance

Solution Approach 1:

The patent applies local quality by focusing sampling efforts only on the highest-quality subchannels within the 2.4 GHz band. Instead of uniformly sampling all subchannels at high rates, the system identifies and concentrates sampling resources on the 1-3 subchannels with the best signal-to-noise ratio, achieving high detection accuracy while minimizing total bandwidth consumption.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The system performs partial sampling by selecting only the most critical subchannels for detailed CSI analysis rather than sampling the entire frequency band. This partial action on the most informative subchannels provides sufficient detection accuracy without the excessive bandwidth consumption that would result from full-band high-rate sampling.

Inventive Principle:
Principle #16Partial or excessive action

3Reliability

If channel diversity is provided through smart channel switching and time division, then detection reliability improves, but device complexity increases

Engineering Contradiction:
Improvedetection reliabilityVSAvoidchannel switching complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent implements periodic channel quality assessment and subchannel selection, where the system periodically evaluates all 2.4 GHz subchannels and switches to the best available subchannels for sampling. This periodic approach provides channel diversity and maintains detection reliability while using simple, repeatable switching logic that doesn't significantly increase device complexity.

Inventive Principle:
Principle #19Periodic action

Solution Approach 2:

The system introduces an intermediary channel quality assessment mechanism that mediates between the available subchannels and the sampling process. This intermediary layer evaluates signal quality and makes switching decisions, providing channel diversity for reliable detection while keeping the actual switching logic simple and manageable.

Inventive Principle:
Principle #24Intermediary (Mediator)

Data Source

PatentUS11894902B1Channel state information (CSI) sensing in the 2.4 GHz band
Publication Date: 2024.02.06 AMAZON TECH INC
  • US11894902B1 patent drawing
  • US11894902B1 patent drawing
  • US11894902B1 patent drawing

AI summary

Technologies directed to channel state information (CSI) sending in the 2.4 GHz band are described. A method includes receiving first CSI data representing channel properties of a first wireless channel used by first and wireless devices that operates in the 2.4 GHz band. The method receives second and third CSI data corresponding to second and third wireless channels. The method determines an inference probability of a motion or a non-motion condition in the geographical region based on an average probability of CSI samples from the first, second, and third CSI data.