Blind Differential Time-of-Arrival Estimation for Wireless Positioning
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Solution Overview
Problem
Conventional time-difference-of-arrival (TDOA) estimation techniques require high-data-rate connectivity, which is incompatible with most wireless communication networks due to the high-bandwidth demands for transmitting high-resolution digitized sample-streams, making them impractical for geographical position determination of transmitting devices over wireless networks.
Innovation Solution
A system and method for performing differential time-of-arrival (TOA) estimation that reduces the bandwidth and data transmission rate by transmitting lower-resolution, demodulated sequences and TOA estimates over wireless networks, enabling geographical position determination using a concentrator device and sensors that demodulate and correlate emitter signals to calculate differential TOA estimates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional TDOA estimation techniques are used to determine geographical position, then measurement precision is improved, but device complexity and data transmission requirements increase significantly
Solution Approach 1:
The patent segments the TDOA estimation process by having individual sensors perform local cross-correlation operations to generate TDOA estimates, which are then transmitted to a concentrator. This divides the computationally intensive processing from the data transmission function, allowing sensors to send only compact TDOA estimates rather than raw high-resolution sample streams, thereby reducing transmission complexity while maintaining position determination accuracy
Solution Approach 2:
The patent transitions from transmitting time-domain signal samples to transmitting frequency-domain representations (TDOA estimates in the spectral domain). This dimensional transformation from time-domain samples to frequency-domain correlation results dramatically reduces the data volume requiring transmission while preserving the information necessary for accurate geographical position determination
2Measurement precision
If high-resolution digitized sample-streams are transmitted over wireless networks, then measurement precision is improved, but the network bandwidth requirements are exceeded
Solution Approach 1:
The patent extracts only the essential information (TDOA estimates) from the complete signal data. Instead of transmitting entire high-resolution digitized sample streams, each sensor performs cross-correlation locally and extracts only the TDOA estimate parameters, which are then transmitted to the concentrator. This extraction process retains the measurement precision needed for accurate TOA estimation while reducing the transmitted data volume by more than an order of magnitude
Solution Approach 2:
The patent applies partial action by having sensors perform only the necessary cross-correlation operation to generate TDOA estimates, rather than transmitting complete signal waveforms. This partial processing approach at the sensor level provides sufficient information for concentration-level position determination while dramatically reducing the quantity of data that must be transmitted over the wireless network
Data Source
AI summary
A system for determining a geographical position of a transmitting device is disclosed. In embodiments, the system includes a concentrator device and a plurality of sensors. In embodiments, each sensor may be configured to: receive an emitter signal from a transmitting device; generate a demodulated sequence of the emitter signal; generate a time-of-arrival (TOA) estimate of the emitter signal; and transmit the demodulated sequence and the TOA estimate to the concentrator device. In embodiments, the concentrator may be configured to: receive a first demodulated sequence and a first TOA estimate (TOA1) from a first sensor; receive a second demodulated sequence and a second TOA estimate (TOA2), from a second sensor; determine a first arbitrary timing offset (ATO1) between the first demodulated sequence and the second demodulated sequence; and determine a first differential TOA estimate (TOADiff<sub2>1</sub2>) between the first sensor and the second sensor.