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

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

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

A method of characterizing WLAN 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 WLAN access points based on coverage areas of the WLAN signals emitted by the WLAN access points, the method of characterizing comprising:

• measuring a series of WLAN signals of each WLAN access point;
• determining a coverage area of each WLAN access point based on its corresponding series of signals;
• and
• assigning a weight to each WLAN access point based on the coverage areas in which WLAN access points having relatively small coverage areas are assigned a higher effective weight than WLAN access points having relatively large coverage areas, so that at least one of position, velocity, and bearing estimation techniques will bias their estimates of position, velocity, and bearing, respectively, to more heavily rely on signals detected from the WLAN access points with relatively smaller coverage areas.

A method of characterizing WLAN 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 WLAN access points based on coverage areas of the WLAN signals emitted by the WLAN access points, the method of characterizing comprising:

• measuring a series of power values of the WLAN signal of the WLAN access point at a plurality of distances from the WLAN access point;
• determining a coverage area of the WLAN access point based on the series of power values at the plurality of distances;
• and
• assigning a weight to the WLAN access point based on the coverage area,
• wherein the weight of the WLAN access point is assigned using the differential of the power in dB and the distance in dB from the WLAN 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 of position, velocity, and bearing to more heavily rely on signals detected from the WLAN access points with a relatively larger differential.

A method of characterizing WLAN 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 WLAN access points based on power-distance gradients of the WLAN signals emitted by the WLAN access points, the method of characterizing comprising:

• measuring a series of WLAN signals of each WLAN access point;
• determining a power-distance gradient of each WLAN access point based on its corresponding series of signals;
• and
• assigning a weight to each WLAN access point based on the power-distance gradients in which WLAN access points having relatively larger power-distance gradients are assigned a higher effective weight than WLAN access points having relatively smaller power-distance gradients, so that at least one of position, velocity, and bearing estimation techniques will bias their estimates of position, velocity, and bearing, respectively, to more heavily rely on signals detected from the WLAN access points with relatively larger power-distance gradients.