FTM Positioning Excluding Co-located BSSIDs
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Solution Overview
Problem
Fine Timing Measurement (FTM) positioning in wireless local area networks faces challenges in achieving low positioning error due to the need for strategically deployed access points, which is difficult to configure especially in public environments where access points are operated by different entities, and co-located basic service sets (BSSs) can interfere with accurate location determination.
Innovation Solution
The method involves an access point obtaining neighboring AP location information to determine a list of co-located BSSIDs and transmitting this list to a station, allowing the station to initiate FTM protocol with non-co-located BSSs for accurate positioning, using protocols like Access Network Query Protocol (ANQP) or FTM frame exchanges to avoid co-located BSSs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If FTM positioning is performed using multiple APs, then positioning accuracy is improved, but the complexity of AP deployment and configuration increases
Solution Approach 1:
The system performs preliminary identification of co-located BSSs by APs exchanging location information before the FTM positioning process. The initiating STA receives co-located BSSID lists from target APs in advance, allowing it to filter out co-located APs from the positioning calculation. This preliminary action eliminates the need for complex manual configuration during deployment while ensuring accurate positioning results.
2Measurement precision
If manual configuration of mBSSID or LocationID elements is performed in co-located BSSs, then co-located BSS identification is improved, but the ease of operation deteriorates
Solution Approach 1:
The system enables APs to automatically identify and exchange their own location information with neighboring APs without manual intervention. Each AP autonomously determines its location relative to others and includes this information in its beacon frames. The initiating STA then automatically receives and processes these location information elements, filtering out co-located BSSs based on the exchanged data. This self-service mechanism eliminates the need for administrators to manually configure mBSSID or LocationID elements.
3Productivity
If FTM frames are exchanged with co-located BSSs, then the quantity of measurements increases, but positioning reliability deteriorates
Solution Approach 1:
The system extracts and removes co-located BSSs from the set of available APs for FTM positioning. The initiating STA receives co-located BSSID lists from target APs, identifies which APs are co-located based on matching BSSIDs, and excludes these from the positioning calculation. This extraction ensures that only non-co-located, geometrically diverse APs are used for positioning, improving reliability while maintaining an adequate number of measurements.
Data Source
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AI summary
A method of indoor positioning using Fine Timing Measurement (FTM) avoiding co-located access point (AP) is proposed. In a wireless local area network, an AP obtains neighboring AP location information and determines a list of co-located BSSIDs. In a first option, an STA first selects an AP and query for AP location and co-located BSSID information using ANQP (Access Network Query Protocol). In a second option, the STA first selects an AP and initiates FTM protocol with the selected AP and thereby obtaining AP location and co-located BSSID information. Upon obtaining the AP location and the co-located BSSID list, the STA can initiates FTM protocol with additional non-co-located BSSs for determining an accurate STA location.