Wireless Sensing of Device-Free Objects Using Multipath TDOA
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Solution Overview
Problem
Existing wireless communication systems struggle to accurately locate device-free objects, such as people or vehicles, due to the complexity of multipath propagation and interference in 5G networks, which affects the precision of positioning methods.
Innovation Solution
A method utilizing wireless communication signals to detect and locate device-free objects by analyzing RF channel impulse responses and time difference of arrival (TDOA) measurements, employing multiple base stations to reflect signals off these objects and triangulate their position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional positioning methods are used in 5G networks, then basic location detection is possible, but measurement precision deteriorates due to multipath propagation and interference
Solution Approach 1:
The patent converts the harmful multipath propagation into a beneficial effect by using reflected signals from device-free objects (people, vehicles) as additional positioning information. Instead of treating multipath interference as noise to be eliminated, the system exploits these reflections to detect and locate objects that do not have dedicated positioning devices, thereby transforming a harmful factor into a useful resource for enhanced positioning accuracy
Solution Approach 2:
The patent introduces wireless communication signals as an intermediary medium to indirectly detect device-free objects. By analyzing how these signals interact with objects (reflection, scattering, absorption), the system can infer object presence and location without requiring the objects themselves to transmit or process signals, thus mediating between the base station and the passive objects
2Measurement precision
If multiple base stations are deployed to improve positioning accuracy, then measurement precision improves, but device complexity increases
Solution Approach 1:
The patent makes existing base stations perform multiple functions: their primary communication function remains intact, and they simultaneously serve positioning and object detection functions by analyzing wireless signals. This multi-functionality allows the system to achieve enhanced positioning accuracy without adding dedicated positioning infrastructure, as the same base stations handle both communication and sensing tasks
Solution Approach 2:
The system enables base stations to self-serve the additional function of device-free object detection by processing their own transmitted signals and the signals received from user equipment. The base stations analyze channel state information and signal characteristics to automatically detect and locate objects in their coverage areas without requiring external assistance or additional processing infrastructure
3Measurement precision
If signal analysis methods are enhanced to mitigate multipath effects, then measurement precision improves, but loss of information increases due to complex signal processing
Solution Approach 1:
The patent performs preliminary calibration by having user equipment transmit reference signals before actual positioning measurements. This preliminary action establishes a baseline channel characterization that accounts for existing multipath conditions, allowing the system to later distinguish between normal multipath propagation and signals reflected from device-free objects, thereby reducing information loss during subsequent measurements
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 the accuracy of locating device-free objects by mitigating multipath effects, allowing for precise positioning in complex 5G environments.
Implementation Method 1
a signal transmitted through a multi-path propagation channel
Implementation Method 2
propagation of echoes of the transmitted signal from a moving target
Implementation Method 3
time difference of arrival (TDOA) measurements
Data Source
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AI summary
Disclosed are techniques for wireless sensing. In an aspect, a user equipment measures at least a line-of-sight path and a non-line-of-sight path of a first downlink positioning reference signal (DL-PRS) from a first transmission-reception point, measures at least an LOS path and an NLOS path of a second DL-PRS from a second TRP, measures at least an LOS path and an NLOS path of a third DL-PRS from a third TRP, and enables a location of a non-participating target object to be determined based, at least in part, on reference signal time difference (RSTD) measurements between a time of arrival of the LOS path of the first DL-PRS and the ToAs of the NLOS paths of the first, second, and third DL-PRS. In an aspect, the non-participating target object does not participate in determining its own location.