Patent ID: 9143971
Filing Date: 2015-09-22
Classification: G01S,H04W

Abstract:
1. A method of estimating a location of a mobile station in a wireless LAN (local area network), the method comprising: matching a time synchronization with a AP (access point) based on a beacon frame, including time stamp information, received from the AP; obtaining time offset information between the AP and two neighbor APs located nearby the AP based on beacon frames received from each of the two neighbor APs; transmitting a position request signal including departure time information of the position request signal and an identifier of the mobile station to the AP by synchronizing with the AP; receiving, from the AP in response to the position request signal, a position response signal including a first location of the mobile station and a first distance between the mobile station and the AP and departure time information of the position response signal; calculating a ToA (time of arrival) of a signal between the mobile station and the AP based on a received time point of the position response signal and the received departure time information of the position response signal, wherein the ToA represents a time period; calculating each of a second distance between the mobile station and the AP and a second location of the mobile station using the calculated ToA; and determining a final location of the mobile station by compensating the first distance and the first location with the second distance and the second location, wherein the second distance is calculated by multiplexing the calculated ToA with a propagation velocity of the signal between the mobile station and the AP, the propagation velocity being a value known to the mobile station, and wherein the second location is calculated by using three ToAs including the calculated ToA and ToAs of each of the two neighbor APs.