Time of Arrival Measurement Using Segmented Narrowband Signals
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Solution Overview
Problem
Current device localization and tracking technologies using time of arrival (TOA) measurements face challenges in indoor and multipath environments due to limited accuracy and the need for expensive, power-hungry wideband transmitters and receivers, as well as computationally intensive methods that are not effective in dense multipath conditions.
Innovation Solution
The method involves generating and transmitting multiple narrowband signal portions, which are then combined to form a wideband impulse response, allowing for accurate TOA measurement using relatively inexpensive radios and overcoming regulatory power limitations, while phase and amplitude corrections are applied to ensure high-resolution channel impulse responses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wideband signals are used for TOA measurement, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent segments the wideband signal into multiple narrowband signal portions transmitted at different frequencies. Each narrowband portion is processed separately to extract channel response information, which is then combined to reconstruct the wideband channel impulse response. This segmentation allows achieving wideband TOA measurement accuracy using simpler narrowband radio hardware.
Solution Approach 2:
The patent transitions from time-domain wideband signal processing to frequency-domain narrowband signal processing by transmitting signals at multiple discrete frequencies. The channel response at each frequency is measured and then transformed back to obtain the wideband channel impulse response, effectively using frequency dimensionality to achieve time-resolution equivalent to wideband signals.
2Measurement precision
If UWB technology is used for accurate TOA measurement, then measurement precision is improved, but use of energy increases
Solution Approach 1:
The system segments the UWB frequency spectrum into multiple narrower frequency bands, transmitting narrowband signal portions at each frequency rather than continuous wideband signals. This reduces the instantaneous power requirement while maintaining the ability to reconstruct the wideband channel response for accurate TOA measurement.
Solution Approach 2:
The patent employs periodic transmission of narrowband signal portions across different frequencies rather than continuous wideband transmission. Each narrowband signal is transmitted sequentially at different frequency points, allowing the system to accumulate channel response information over time with lower instantaneous power consumption.
3Measurement precision
If super-resolution schemes based on eigenvalue analysis are used, then measurement precision is improved, but productivity decreases
Solution Approach 1:
The patent extracts only the essential information needed for TOA measurement from the channel frequency response, specifically focusing on identifying the first significant peak in the reconstructed channel impulse response. This avoids the computationally intensive eigenvalue and eigenvector calculations of full super-resolution schemes while maintaining adequate measurement accuracy for practical applications.
Solution Approach 2:
The patent employs simpler, computationally less intensive signal processing methods that are easier and faster to implement, sacrificing the marginal accuracy improvements of complex super-resolution algorithms. The approach uses straightforward peak detection and channel response reconstruction that can be executed efficiently in real-time systems.
4Measurement precision
If UWB signals are used for TOA measurement, then measurement precision is improved, but quantity of base stations required increases
Solution Approach 1:
The patent changes the transmission parameters by using narrowband signal portions at multiple discrete frequencies instead of continuous wideband signals. This allows the system to achieve sufficient channel response information with fewer base stations, as each base station can effectively contribute to multiple frequency measurements, reducing the total number of base stations needed for comprehensive coverage.
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 more accurate localization and tracking over longer distances with fewer base stations, using less expensive hardware, and improves time synchronization between devices by enhancing the accuracy of TOA measurements in challenging environments.
Implementation Method 1
a transmitter generates a plurality of signal portions and transmits the signal portions separately
Implementation Method 2
An estimate of the channel impulse response can be determined by correlating the received signal against the transmitted signal
Implementation Method 3
Greater accuracy is achieved by measuring the time of arrival (TOA) (or in some cases the phase) of a radio signal
Data Source
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AI summary
Disclosed is a method of measuring time of arrival of a signal transmitted from a transmitter (120) to a receiver (110-n). The method comprises: modulating a plurality of narrowband signal portions onto different carrier frequencies; transmitting, by the transmitter, each modulated signal portion to the receiver; receiving, by the receiver, the transmitted signal portions; estimating the channel impulse response by combining (610) the received signal portions; and measuring (620) the time of arrival using the estimated channel impulse response. Further disclosed is a method of measuring a time of arrival of a signal transmitted from a transmitter to a receiver. The method comprises: estimating a noise level (1310) in an impulse response of a channel between the transmitter and the receiver; finding a first peak (1330) in the channel impulse response that is not noise or a side lobe of a subsequent peak, using the estimated noise level; and measuring the time of arrival (1220) using the first peak.