Indoor Positioning via Transponder Grouping and RTT Delay Estimation
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Solution Overview
Problem
In indoor environments, satellite signals from GPS and other satellite positioning systems are unreliable, leading to inaccuracies in round-trip time (RTT) measurements due to the difficulty in estimating the turnaround calibration factor (TCF) and cyclic shift diversity (CSD) delays, which affects the accuracy of position fixes by mobile devices.
Innovation Solution
Mobile devices group wireless transponders with similar attributes to estimate and apply a consistent delay in RTT measurements, reducing computation and power consumption while improving positioning accuracy by accounting for TCF and CSD delays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If satellite positioning systems are used for indoor navigation, then outdoor positioning accuracy is improved, but indoor signal reliability deteriorates
Solution Approach 1:
The patent introduces wireless transponders as intermediary devices to relay positioning signals between satellites and mobile devices in indoor environments. These transponders receive satellite signals and retransmit them locally, enabling indirect signal propagation through the building structure where direct satellite reception is blocked, thus resolving the contradiction between outdoor GPS accuracy and indoor signal reliability
2Measurement precision
If individual TCF and CSD delays are estimated for each transponder, then measurement precision is improved, but device complexity and power consumption increase
Solution Approach 1:
The patent merges the estimation of TCF and CSD delays by grouping transponders with similar signal characteristics into clusters. Instead of estimating delays individually for each transponder, the system estimates a common delay parameter for each group, significantly reducing computational complexity while maintaining acceptable measurement precision through the averaging effect of grouping similar transponders
3Measurement precision
If more transponders are measured individually for RTT, then positioning accuracy is improved, but power consumption increases
Solution Approach 1:
The patent applies grouping to reduce the number of individual RTT measurements required. By clustering transponders with similar attributes, the system performs RTT measurements on representative transponders from each group and applies the estimated delays to all transponders in that group, thereby achieving comparable positioning accuracy with fewer measurements and reduced power consumption
4Device complexity
If TCF and CSD delays are not accounted for, then computation is simplified, but measurement precision deteriorates
Solution Approach 1:
The patent performs preliminary estimation of TCF and CSD delays by grouping transponders and computing representative delay values before actual RTT measurements. This preliminary action establishes baseline correction parameters that are then applied during positioning calculations, maintaining measurement precision while simplifying the real-time computation process during actual navigation operations
Data Source
AI summary
Disclosed are methods, systems and devices for providing location based services in a venue. To estimate its location, in a particular implementation, a mobile device may obtain a measurement of a range to a transponder device positioned at a known location based on measurements of a signal round-trip time (RTT) in a message exchange with the transponder device. Positioning assistance data from a server may enable the mobile device to measure a delay at the transponder device in providing a response to a probe message to thereby more accurately measure the signal RTT.