{"id":{"repo_id":"mit","oai_identifier":"oai:dspace.mit.edu:1721.1/139240"},"canonical_url":"https://search.dev.ndltd.org/etd/mit/oai:dspace.mit.edu:1721.1/139240","repository":{"repo_id":"mit","name":"MIT","base_url":"https://dspace.mit.edu/oai/request"},"display":{"title":"Analysis of the Position-Dependent Error in FTM RTT Indoor Navigation","abstract":"Fine time measurement (FTM) of the round-trip time (RTT) of a signal between an initiator (smartphone) and a responder (Wi-Fi access point) provides a promising method for indoor positioning. Accurate indoor positioning is a requirement for a wide range of applications, such as asset tracking, indoor navigation, and contact tracing. Unfortunately, the error of reported FTM RTT distance measurements has been shown to have a standard deviation that ranges from 1-2 meters in ideal setups. A major FTM RTT error source was discovered and coined as the “position-dependent error”. This error is heavily depend on the position of an initiator relative to a responder, with the reported measurement fluctuating by meters from an initiator position change of millimeters. Using an Android app and a CNC machine for 2D and 3D positioning, these unusual error properties are explored in depth through experimentation. This experimentation includes evaluating the position-dependent error in both the spatial and frequency domains when varying the test setup, using different smartphones and Wi-Fi access points, and changing the bandwidth and central frequency of the Wi-Fi access points. Possible causes of the position-dependent error are analyzed, such as inaccurate time of arrival or super-resolution algorithms, a dependence on received signal strength, and clock instability. In the end, recommendations for error amelioration are made, and the future of FTM RTT is discussed.","abstract_html":"Fine time measurement (FTM) of the round-trip time (RTT) of a signal between an initiator (smartphone) and a responder (Wi-Fi access point) provides a promising method for indoor positioning. Accurate indoor positioning is a requirement for a wide range of applications, such as asset tracking, indoor navigation, and contact tracing. Unfortunately, the error of reported FTM RTT distance measurements has been shown to have a standard deviation that ranges from 1-2 meters in ideal setups. A major FTM RTT error source was discovered and coined as the “position-dependent error”. This error is heavily depend on the position of an initiator relative to a responder, with the reported measurement fluctuating by meters from an initiator position change of millimeters. Using an Android app and a CNC machine for 2D and 3D positioning, these unusual error properties are explored in depth through experimentation. This experimentation includes evaluating the position-dependent error in both the spatial and frequency domains when varying the test setup, using different smartphones and Wi-Fi access points, and changing the bandwidth and central frequency of the Wi-Fi access points. Possible causes of the position-dependent error are analyzed, such as inaccurate time of arrival or super-resolution algorithms, a dependence on received signal strength, and clock instability. In the end, recommendations for error amelioration are made, and the future of FTM RTT is discussed.","abstract_has_math":false,"creators":["Houle, David E."],"institution":"Massachusetts Institute of Technology","degree_name":"Master","degree_level":null,"degree_discipline":null,"degree_department":"Massachusetts Institute of Technology. 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Accurate indoor positioning is a requirement for a wide range of applications, such as asset tracking, indoor navigation, and contact tracing. Unfortunately, the error of reported FTM RTT distance measurements has been shown to have a standard deviation that ranges from 1-2 meters in ideal setups. A major FTM RTT error source was discovered and coined as the “position-dependent error”. This error is heavily depend on the position of an initiator relative to a responder, with the reported measurement fluctuating by meters from an initiator position change of millimeters. Using an Android app and a CNC machine for 2D and 3D positioning, these unusual error properties are explored in depth through experimentation. This experimentation includes evaluating the position-dependent error in both the spatial and frequency domains when varying the test setup, using different smartphones and Wi-Fi access points, and changing the bandwidth and central frequency of the Wi-Fi access points. Possible causes of the position-dependent error are analyzed, such as inaccurate time of arrival or super-resolution algorithms, a dependence on received signal strength, and clock instability. In the end, recommendations for error amelioration are made, and the future of FTM RTT is discussed."]},{"key":"dc:description.degree","label":"Dc Description Degree","values":["M.Eng."]},{"key":"dc:title","label":"Title","values":["Analysis of the Position-Dependent Error in FTM RTT Indoor Navigation"]}]}],"canonical_facts":{"dc:contributor.advisor":["Horn, Berthold Klaus Paul"],"dc:contributor.department":["Massachusetts Institute of Technology. Department of Electrical Engineering and Computer Science"],"dc:creator":["Houle, David E."],"dc:date.accessioned":["2022-01-14T14:58:48Z"],"dc:date.available":["2022-01-14T14:58:48Z"],"dc:date.issued":["2021-06"],"dc:description.abstract":["Fine time measurement (FTM) of the round-trip time (RTT) of a signal between an initiator (smartphone) and a responder (Wi-Fi access point) provides a promising method for indoor positioning. Accurate indoor positioning is a requirement for a wide range of applications, such as asset tracking, indoor navigation, and contact tracing. Unfortunately, the error of reported FTM RTT distance measurements has been shown to have a standard deviation that ranges from 1-2 meters in ideal setups. A major FTM RTT error source was discovered and coined as the “position-dependent error”. This error is heavily depend on the position of an initiator relative to a responder, with the reported measurement fluctuating by meters from an initiator position change of millimeters. Using an Android app and a CNC machine for 2D and 3D positioning, these unusual error properties are explored in depth through experimentation. This experimentation includes evaluating the position-dependent error in both the spatial and frequency domains when varying the test setup, using different smartphones and Wi-Fi access points, and changing the bandwidth and central frequency of the Wi-Fi access points. Possible causes of the position-dependent error are analyzed, such as inaccurate time of arrival or super-resolution algorithms, a dependence on received signal strength, and clock instability. 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