Wireless Node Localization via Wideband Spectrum Sensing
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Solution Overview
Problem
Accurate localization of wireless nodes is challenging due to limitations in traditional techniques such as RSSI, ToF, and phase-based ranging, which are affected by multipath and non-Line of Sight constraints, and existing standards like Bluetooth Low Energy have bandwidth limitations, leading to inaccurate location resolution.
Innovation Solution
A system utilizing wideband spectrum-sensing units synchronized with a master transceiver, which samples transmissions with an ADC bandwidth greater than the receive bandwidth, correlates samples with historical data using methods like convolution or Matrix Pencil to determine power delay profiles, and applies Time Difference Of Arrival to accurately locate wireless nodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional RSSI, ToF or phase-based ranging techniques are used, then localization can be performed, but accuracy is limited by transceiver bandwidth and multipath interference
Solution Approach 1:
The system performs preliminary actions by capturing and storing wideband samples of transmitted signals in advance. These pre-captured samples are then correlated with received signals to extract multipath components and determine channel impulse responses, enabling accurate localization without requiring complex real-time processing during the measurement phase.
Solution Approach 2:
The patent transitions from narrowband frequency domain analysis to wideband time domain analysis by capturing signals across a broad frequency spectrum and transforming them into time-domain channel impulse responses. This dimensional change from frequency to time domain enables separation of multipath components based on their arrival times, significantly improving localization accuracy.
2Measurement precision
If additional wireless receivers and repetitive measurements are used to mitigate limitations, then localization accuracy may improve, but power dissipation and complexity increase
Solution Approach 1:
The master transceiver performs multiple functions: it transmits test signals, captures its own transmitted signal through wideband sampling, receives reflected signals from the wireless device, and processes all this information to determine channel impulse responses and device location. This multi-functionality eliminates the need for additional dedicated receivers and reduces overall system complexity and power consumption.
Solution Approach 2:
The system uses the master transceiver's own transmitted signal as the reference for correlation. By self-generating the test signal and using it to correlate with received signals, the system eliminates the need for separate reference signal sources and reduces the number of required components, thereby reducing power dissipation and complexity.
3Device complexity
If narrowband transceivers are used, then device complexity is reduced, but location resolution accuracy deteriorates
Solution Approach 1:
The wideband frequency spectrum is segmented into multiple frequency sub-bands that are processed individually. The channel impulse response is determined by combining results from multiple frequency sweeps, each operating at manageable bandwidth levels. This segmentation allows accurate wideband processing while keeping individual processing stages relatively simple.
Solution Approach 2:
The system performs periodic frequency sweeps across the wideband spectrum, capturing channel characteristics at different frequencies sequentially. By periodically sweeping through the frequency range and combining the results, the system achieves accurate wideband channel impulse response measurement without requiring simultaneous processing of the entire wideband signal, thus reducing instantaneous processing complexity.
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
This approach enables precise localization of wireless nodes by overcoming multipath and bandwidth limitations, allowing for accurate determination of direct and indirect paths and environmental mapping, while also detecting potential spoofing attempts.
Implementation Method 1
each of the wideband spectrum-sensing units may comprise an Analog to Digital Converter (ADC) configured to sample the transmission to generate the plurality of wideband samples, wherein the ADC has an ADC bandwidth greater than a receive bandwidth of the master transceiver
Implementation Method 2
the wideband samples from the respective second memory are correlated with a corresponding plurality of reconstructed samples stored in the first memory, to determine a respective power delay profile of the transmission
Implementation Method 3
the slave location of the slave transceiver is determined relative to the respective sensing locations of the wideband spectrum-sensing units by applying a Time Difference Of Arrival method to the respective power delay profiles
Implementation Method 4
a respective time reference of each of the wideband spectrum-sensing units and the master transceiver synchronized to a reference clock
Data Source
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AI summary
A method for localizing a wireless node includes synchronizing a respective time reference of a plurality of wideband spectrum-sensing units (20a, 20b, 20c, 20d, generally 20) and a master transceiver (14). A sensing location of each wideband spectrum-sensing unit (20) is stored in a first memory. Each wideband spectrum-sensing unit stores in a second memory a plurality of time-limited samples of a transmission received from a slave transceiver (16). The time limit of the transmission is determined by the master transceiver (14), receiving the transmission. The samples from the second memory are correlated with a corresponding plurality of reconstructed samples stored in the first memory to form a respective power delay profile for each of the of the wideband spectrum-sensing units (20). A slave location of the slave transceiver is determined by applying a Time Difference Of Arrival method to the respective power delay profiles.