Bluetooth Spatial-Temporal Localization via ToF and AoA
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Indoor positioning systems using Bluetooth Low Energy (BLE) face challenges in accurately determining the location of a Bluetooth-enabled transmitter due to multipath noise and limited antenna accuracy, which affects angle of arrival (AoA) estimation and introduces computational overhead.
Innovation Solution
A method and device that utilize time-of-flight (ToF) and AoA estimation by sampling radio signal phases with an array of antennas, employing a Constant Tone Extension (CTE) signal to improve AoA accuracy, and a two-stage signal model to determine ToF and AoA jointly, with initial ToF estimation followed by AoA refinement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If multiple BLE beacons are used to determine distance via RSSI, then distance measurement accuracy is improved, but computational overhead increases due to coordination requirements
Solution Approach 1:
The patent extracts the distance measurement function from multi-beacon RSSI coordination and implements it through two-way ToF measurement between the Bluetooth-enabled device and transmitter. This eliminates the need for complex multi-beacon coordination while maintaining accurate distance measurement through direct peer-to-peer timing measurements.
Solution Approach 2:
The patent introduces ToF measurement as an intermediary mechanism to replace direct RSSI-based distance estimation. By using precise timing measurements of radio wave propagation time, the system achieves accurate distance measurement without requiring multiple beacons or complex coordination protocols.
2Measurement precision
If the number of antennas is increased to improve AoA estimation accuracy, then measurement precision is improved, but device size and computational constraints are violated
Solution Approach 1:
The patent performs preliminary ToF measurement and phase difference calculation before AoA estimation. By pre-processing the signal phase information and compensating for frequency hopping effects in advance, the system achieves accurate AoA estimation with fewer antennas, as the preliminary processing extracts maximum information from limited antenna samples.
Solution Approach 2:
The patent changes the measurement parameter from direct signal strength (RSSI) to time-of-flight and phase difference. This parameter transformation enables accurate positioning with fewer antennas by utilizing the temporal and phase characteristics of the signal, which contain more directional information than amplitude-based methods.
3Measurement precision
If traditional AoA estimation is used in multipath environments, then orientation measurement is obtained, but measurement precision deteriorates due to phase distortion and amplitude distortion
Solution Approach 1:
The patent converts the harmful multipath phase distortions into useful information by measuring the phase difference between transmitted and received signals. By using two-way ToF measurement and phase comparison, the system can distinguish between direct path and reflected paths, effectively utilizing the phase information that would otherwise be corrupted by multipath effects.
Solution Approach 2:
The patent implements feedback through two-way communication where the Bluetooth-enabled transmitter also measures the signal from the Bluetooth-enabled device. This mutual measurement provides feedback that helps distinguish direct paths from multipath components, improving orientation measurement accuracy in reflective environments.
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
Enhances location accuracy of a Bluetooth-enabled transmitter by mitigating multipath noise and improving AoA estimation, enabling precise indoor positioning with reduced computational overhead.
Implementation Method 1
Bluetooth is an accessible and widespread technology prevalent throughout indoor spaces and supported by many of today's devices. Like other communication protocols including Wi-Fi and UWB, BLE can be used to transmit data between devices using radio waves.
Implementation Method 2
the distance of the Bluetooth enabled device from the multiple BLE beacons is estimated at the Bluetooth enabled device based on Received Signal Strength Indicator (RSSI) of radio signals from the multiple BLE beacons, where the RSSI is a representation of the power of the radio signal
Implementation Method 3
The distance of the Bluetooth-enabled transmitter from the Bluetooth-enabled device can be determined based on a time-of-flight (ToF) of radio waves (for example, Bluetooth signal) from the Bluetooth-enabled transmitter to the Bluetooth-enabled device.
Implementation Method 4
the orientation or direction of the Bluetooth-enabled transmitter with respect to the Bluetooth-enabled device may be determined based on AoA of the radio signals at the Bluetooth-enabled device from the Bluetooth-enabled transmitter
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
A Bluetooth-enabled device (101) is provided, the Bluetooth-enabled device being configured to control a radio frequency (RF) chain during a first period to receive at a single antenna selected from a plurality of antennas, a constant tone extension (CTE) signal (105) of multiple frames transmitted by a Bluetooth-enabled transmitter (103) over multiple frequencies. Further the RF chain is controlled during a second period to switch among the plurality of antennas to receive the CTE signal at each of the plurality of antennas. An initial time-of-flight (ToF) data of the CTE signal is determined from first samples of the CTE signal received during the first period. Further, the Bluetooth-enabled transmitter is localized with respect to a location of the Bluetooth-enabled device using a signal model connecting samples of the CTE signal with an unknown angle-of-arrival of the CTE signal received at specific times, an unknown ToF conditioned on the initial ToF data.