Estimation of position using WLAN access point radio propagation characteristics in a WLAN positioning system

A method for estimating the position of a Wi-Fi enabled device using qualitative data related to one or more characteristics of a Wi-Fi access point's signal coverage area, the method comprising:

• receiving one or more signals transmitted by the Wi-Fi access points;
• identifying the Wi-Fi access points;
• retrieving previously calculated locations of the Wi-Fi access points and previously calculated weights assigned to the Wi-Fi access points from a reference database, where the weights correspond to characteristics of each Wi-Fi access point's coverage area, including a plurality of measured power values for each access point, wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point and
• using the calculated locations and the calculated weights to estimate the position of the Wi-Fi enabled device,
• wherein Wi-Fi access points having relatively small coverage areas are assigned a higher effective weight than Wi-Fi access points having relatively large coverage areas and the position estimate of the Wi-Fi enabled device will be biased to rely more heavily rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.

A method of characterizing Wi-Fi access points in order to increase the accuracy of position, velocity and bearing estimation techniques based on signals received from those access points by classifying the Wi-Fi access points based on coverage areas of the Wi-Fi signals emitted by the Wi-Fi access points, the method of characterizing comprising:

• measuring a series of Wi-Fi signals of each Wi-Fi access point;
• determining a coverage area of each Wi-Fi access point based on its corresponding series of signals;
• wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point;
• and
• assigning a weight to each Wi-Fi access point based on the coverage areas in which Wi-Fi access points having relatively small coverage areas are assigned a higher effective weight than Wi-Fi access points having relatively large coverage areas,
• wherein position, velocity, and bearing estimation techniques will bias their estimates of position, velocity, and bearing to more heavily rely on signals detected from the Wi-Fi access points with relatively smaller coverage areas, even if said signals are detected with relatively weaker power than signals detected from Wi-Fi access points with larger coverage areas and relatively higher power.

A method of characterizing Wi-Fi access points in order to increase the accuracy of position, velocity and bearing estimation techniques based on signals received from those access points by classifying the Wi-Fi access points based on coverage areas of the Wi-Fi signals emitted by the Wi-Fi access points, the method of characterizing comprising:

• measuring a series of power values of the Wi-Fi signal of the Wi-Fi access point at a plurality of distances from the Wi-Fi access point;
• determining a coverage area of the Wi-Fi access point based on the series of power values at the plurality of distances;
• and
• assigning a weight to the Wi-Fi access point based on the coverage area, wherein the coverage is divided according to at least two radials and at least one distance from the Wi-Fi access point,
• wherein the weight of the Wi-Fi access point is assigned using the differential of the power in dB and the distance in dB from the Wi-Fi access point, wherein a larger differential corresponds to a higher weight and a smaller differential corresponds to a smaller weight, so that position, velocity, and bearing estimation techniques will bias their estimates position, velocity, and bearing to move heavily rely on signals detected from the Wi-Fi access points with a relatively larger differential.