Phase Shift TOA Passive Location Ranging
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Solution Overview
Problem
Current Wi-Fi positioning systems face challenges in accurately determining location using phase shift based time of arrival (PS-TOA) measurements, particularly in passive location ranging protocols, where the complexity of TOA calculations and latency in measurement reporting hinder efficient location estimation.
Innovation Solution
The system employs a responder station (RSTA) and an initiator station (ISTA) to measure and report PS-TOAs, with the RSTA broadcasting time stamps to enable the passive station (PSTA) to calculate differential distances between the RSTA-ISTA pair, simplifying the calculation process and reducing latency by using phase shift based TOAs instead of traditional TOAs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional TOA measurements are used in passive location ranging, then location estimation can be performed, but calculation complexity increases and latency in measurement reporting occurs
Solution Approach 1:
The patent changes the measurement parameter from traditional time of arrival (TOA) to phase shift based time of arrival (PS-TOA). This parameter transformation simplifies the calculation process while maintaining location estimation accuracy, as phase shift measurements can be directly converted to distance information without complex time synchronization requirements
Solution Approach 2:
The patent extracts and reports only the essential phase shift measurement data from client Wi-Fi modems, separating the measurement function from the calculation function. The access points collect these extracted PS-TOA measurements and perform the location calculations, reducing the computational burden on client devices while maintaining measurement precision
2Measurement precision
If traditional TOA measurements are used in passive location ranging, then location estimation can be performed, but latency in measurement reporting occurs
Solution Approach 1:
The patent performs phase shift measurements continuously and maintains a ready state for immediate reporting. By preparing measurements in advance and having the measurement data readily available, the system can report PS-TOA measurements immediately when needed, eliminating the latency associated with traditional TOA measurement and reporting processes
Solution Approach 2:
The transformation to PS-TOA measurements enables immediate feedback because phase shift can be measured and reported more quickly than traditional TOA methods. The phase shift information is derived from ongoing wireless communications without requiring additional measurement time, thus reducing reporting latency while maintaining location accuracy
3Productivity
If phase shift based TOA measurements are implemented, then calculation complexity is reduced and immediate feedback is enabled, but measurement precision may be affected
Solution Approach 1:
The patent implements a feedback mechanism where access points receive PS-TOA measurements from multiple client modems and use these measurements to calculate and determine the location of passive stations. The system aggregates feedback from multiple sources and uses collaborative location estimation to maintain precision while benefiting from the simplified PS-TOA measurement approach
Solution Approach 2:
The patent combines PS-TOA measurements from multiple access points and client modems to perform collaborative location estimation. By merging multiple measurement perspectives, the system maintains high measurement precision even though individual PS-TOA measurements are simpler than traditional TOA measurements, achieving both calculation efficiency and accuracy
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 reduces calculation complexity for client Wi-Fi modems, allows immediate feedback of phase shift measurements, and enables location estimation within a single ranging opportunity, improving the accuracy and efficiency of passive location ranging.
Implementation Method 1
measuring, by a responder station (RSTA), a first phase shift time of arrival (PS-TOA)
Data Source
AI summary
A method and system for phase shift based time of arrival (TOA) reporting in passive location ranging is herein provided. According to one embodiment, a method includes measuring, by a responder station (RSTA), a first phase shift time of arrival (PS-TOA); measuring, by an initiator station (ISTA), a second PS-TOA; reporting, by the RSTA, the first PS-TOA, reporting, by the ISTA, the second PS-TOA; broadcasting, by the RSTA, time stamps; and determining, by a passive station (PSTA), a differential distance between the PSTA and a pair of the RSTA and ISTA based on the first PS-TOA, the second PS-TOA, and the broadcast time stamps.