Method and system for wireless LAN-based indoor position location
First Claim
1. A system for determining a location of a client in a local area network, the local area network including at least three access points in communication with the client, the system comprising:
- a ranging subsystem for determining estimated distances between the client and the at least three access points, each of the at least three access points having a known position; and
a positioning subsystem for determining the location of the client utilizing the estimated distances between the client and the at least three access points and the known positions of the at least three access points, the positioning subsystem including at least one virtual reference station, the at least one virtual reference station being used to determine the location of the client, the positioning subsystem using a trilateration process to determine the location of the client, the at least one virtual reference station being access points in the local area network and do not participate in the trilateration process.
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Accused Products
Abstract
A method and system for position location of clients in wireless local area networks. (WLANs). The position location technique utilizes time-of-flight (TOF) measurements of signals transmitted from a client to a number of wireless access points (APs) or vice versa to determine distances. Round-trip time (RTT) measurement protocols are used to estimate TOF and distances between the client at an unknown position and the WLAN APs. The method and system improves positioning accuracy by identifying and mitigating non-line-of sight (NLOS) errors such as multipaths. Trilateration algorithms are utilized in combination with median filtering of measurements to accurately estimate the position of the client.
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Citations
16 Claims
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1. A system for determining a location of a client in a local area network, the local area network including at least three access points in communication with the client, the system comprising:
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a ranging subsystem for determining estimated distances between the client and the at least three access points, each of the at least three access points having a known position; and a positioning subsystem for determining the location of the client utilizing the estimated distances between the client and the at least three access points and the known positions of the at least three access points, the positioning subsystem including at least one virtual reference station, the at least one virtual reference station being used to determine the location of the client, the positioning subsystem using a trilateration process to determine the location of the client, the at least one virtual reference station being access points in the local area network and do not participate in the trilateration process. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method of determining a location of a client in a local area network, the local area network including at least three access points in communication with the client, each of the one or more access points having a predetermined position, the method comprising:
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receiving, from the at least three access points, ranging protocol signals used to estimate distances from each access point to the client, at least one of the access points designated as a virtual reference station used to estimate the distances from each access point to the client; and calculating the location of the client based on the estimated distances from each access point to the client and the position of each access point using a trilateration process, the at least one of the access points designated as the virtual reference station being an access point in the local area network and not participating in the trilateration process. - View Dependent Claims (8, 9, 10, 11)
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12. A location management station for determining a location of a client in a local area network having at least three access points, each of the at least three access points having a predetermined position, the station comprising:
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an interface module adapted to receive, from the at least three access points, signals representing estimated distances from each access point to the client, at least one of the access points designated as a virtual reference station used to estimate the distances from each access point to the client; and a processor for calculating the location of the client based on the estimated distances from each access point to the client and the position of each access point using a trilateration process, the at least one of the access points designated as the virtual reference station being an access point in the local area network and not participating in the trilateration process. - View Dependent Claims (13)
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14. A system for determining a location of a client in a local area network, the local area network including at least three access points in communication with the client, the system comprising:
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a ranging subsystem for determining estimated distances between the client and the at least three access points, each of the at least three access points having a known position; and a positioning subsystem for determining the location of the client utilizing the estimated distances between the client and the at least three access points and the known positions of the at least three access points, the positioning subsystem including at least one virtual reference station, the at least one virtual reference station being used to determine the location of the client, the positioning subsystem computing a square-of-location-error (SLE) for each of the at least one virtual reference stations (VRS). - View Dependent Claims (15, 16)
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Specification