BLE Tag Localization Using Channel State Information

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Solution Overview

Problem

Conventional Bluetooth Low Energy (BLE) localization methods rely on signal strength measurements, which are inaccurate and prone to multipath and dynamic environment issues, leading to low accuracy and robustness in tracking BLE tags.

Innovation Solution

A computer-implemented method using channel state information (CSI) to determine the location of BLE tags by measuring signal strength and phase across multiple frequency bands, combining data from multiple communication devices to isolate direct paths and mitigate multipath effects, thereby achieving sub-meter localization accuracy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If signal strength measurements are used for BLE localization, then the system is simple to implement, but localization accuracy deteriorates due to multipath and dynamic environment effects

Engineering Contradiction:

Improveease of implementationVSAvoidlocalization accuracy

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent changes the measurement parameter from signal strength (RSSI) to channel state information (CSI), which includes phase and amplitude information across multiple frequency subcarriers. This parameter transformation enables multipath component separation and significantly improves localization accuracy while maintaining implementation feasibility through existing BLE hardware capabilities

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent segments the frequency band into multiple subcarriers and separates direct path signals from multipath components by analyzing phase and amplitude variations across these segments. This segmentation allows the system to identify and utilize only the direct path information for accurate localization, filtering out the harmful multipath effects

Inventive Principle:

Principle #1Segmentation

2Device complexity

If conventional RSSI-based methods are used, then device complexity is low, but localization accuracy is poor in multipath-rich environments

Engineering Contradiction:

Improvesystem complexityVSAvoidlocalization accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The patent makes the existing BLE communication protocol multi-functional by utilizing it for both data transmission and channel state information measurement. The same physical layer components are used to extract CSI for localization purposes, eliminating the need for separate dedicated localization hardware and maintaining low device complexity

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent introduces channel state information as an intermediary that bridges the gap between raw signal measurements and accurate localization. CSI serves as a mediator that contains rich spatial information about signal paths, enabling accurate localization without requiring complex additional sensing hardware

Inventive Principle:

Principle #24Intermediary (Mediator)

3Difficulty of detecting and measuring

If signal strength alone is measured, then the measurement process is simple, but robustness against multipath effects deteriorates

Engineering Contradiction:

Improvemeasurement simplicityVSAvoidrobustness to multipath

Core Design Contradiction:

Difficulty of detecting and measuringVSReliability

Solution Approach 1:

The patent adds the frequency dimension by measuring channel state information across multiple frequency subcarriers instead of single-frequency signal strength measurement. This dimensional expansion provides additional degrees of freedom to distinguish direct path signals from multipath components through their characteristic frequency-dependent phase and amplitude patterns

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 CSI-based method enhances localization accuracy to sub-meter levels in multipath-rich environments, improving upon conventional systems by a factor of 2, from 2.42 meters to 86 cm, and addresses bandwidth limitations and phase measurement challenges in BLE systems.

Implementation Method 1

determining at least one of a channel state information and a signal strength associated with the detected transmission on the one or more communication channels for each frequency band in a plurality of frequency bands

Methodology Applied

Scientific EffectChannel state information measurement:

Implementation Method 2

The phase and/or amplitude may be determined based on an angle of arrival of a signal (e.g., θ), corresponding to the detected transmission, at the communication devices

Methodology Applied

Scientific EffectAngle of arrival measurement:

Data Source

PatentUS11140651B2Location determination of wireless communications devices

Publication Date: 2021.10.05 RGT UNIV OF CALIFORNIA

AI summary

A method, a system, and a computer program product for determining a location of a communication device. Data corresponding to a detected transmission of a data packet between a tag device and one or more communication devices is received on one or more communication channels. At least one of a channel state information and a signal strength associated with the detected transmission for each frequency band in a plurality of frequency bands are determined. Based on the determined channel state information, one or more lengths of signal paths corresponding to the detected transmission of the data packet are determined. A shortest length in across one or more communication devices is selected to determine a location of the tag device.