Modified Wi-Fi Signal Positioning for GNSS-Denied Environments
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Solution Overview
Problem
Existing radio navigation systems face challenges in determining accurate coordinates and motion parameters of movable objects, particularly in environments with limited GNSS signal reception, such as indoor locations, due to restricted line-of-sight visibility and the complexity and cost of deploying pseudolite and hybrid positioning systems, which result in low communication channel throughput and imprecise position determination.
Innovation Solution
A method and apparatus using modified Wi-Fi signals, based on the IEEE 802.11 protocol, involving a master base station and slave stations with known coordinates, to calculate position by measuring delay and phase differences, utilizing specially generated symbol sequences and service information in frame fields for precise positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pseudolite signals or hybrid positioning devices are used to improve position determination accuracy in GNSS-denied environments, then positioning accuracy is improved, but device complexity and deployment cost increase significantly
Solution Approach 1:
The patent uses existing Wi-Fi infrastructure (access points and stations) as copies of traditional positioning systems. Instead of deploying specialized pseudolite equipment, the invention repurposes commercially available Wi-Fi devices to transmit positioning signals, thereby achieving GNSS-like functionality using off-the-shelf components that are already widely deployed
Solution Approach 2:
The Wi-Fi access points and stations perform dual functions: their original data communication role plus a new positioning signal transmission role. The same Wi-Fi infrastructure that provides internet connectivity is also used to transmit modified signals containing positioning information, eliminating the need for separate dedicated positioning hardware
2Measurement precision
If hybrid positioning devices utilizing both GNSS signals and ground base station signals are deployed to achieve better coverage and improved position accuracy, then position accuracy is improved, but communication channel throughput decreases
Solution Approach 1:
The patent merges positioning signal transmission with existing Wi-Fi data communication channels. Instead of creating separate positioning channels that would compete for bandwidth, the invention embeds positioning information within the Wi-Fi protocol framework, allowing simultaneous data communication and positioning functions to share the same infrastructure without significant throughput degradation
3Adaptability or versatility
If Wi-Fi access points and fingerprinting positioning methods are used to enable both position determination and data transmission, then versatility is improved, but measurement precision of coordinate estimates decreases
Solution Approach 1:
The patent modifies the Wi-Fi signal parameters by incorporating specially generated symbol sequences and timing information into the standard Wi-Fi frame structure. These parameter changes enable the extraction of precise timing measurements (delay and phase differences) from ordinary Wi-Fi communications, achieving centimeter-level accuracy while maintaining data transmission functionality
4Ease of operation
If range-difference location methods using GNSS satellites are employed to determine position coordinates, then position determination capability is improved, but reliability decreases in environments with restricted line-of-sight visibility
Solution Approach 1:
The patent introduces ground-based Wi-Fi access points and stations as intermediary positioning sources that replace distant GNSS satellites. These local intermediaries provide positioning signals that can penetrate indoor environments and urban canyons where direct satellite visibility is blocked, ensuring continuous positioning capability in GNSS-denied 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
Enables accurate and efficient determination of coordinates and motion parameters of movable objects, even in environments with deficient GNSS signals, by leveraging modified Wi-Fi signals and synchronized base stations for enhanced positioning accuracy.
Implementation Method 1
measuring delay and phase differences being received from different pairs of the base stations at the mobile station
Implementation Method 2
measuring delay and phase differences being received from different pairs of the base stations at the mobile station
Data Source
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AI summary
Position determination for a mobile station is achieved through the modification of certain Wi-Fi access point and station signals, that are radiated by a certain master (i.e., guiding) base station, combined with slave (i.e., guided) stations having known coordinates, and processing the signals received from these base stations at the mobile station to determine the desired position.