Kalman filter for indoor positioning

1. A position estimation method, comprising:

filtering, by a Kalman filter, an initial position estimate that includes a corresponding covariance and a previous initial position estimate that includes a corresponding covariance to generate an updated previous position estimate;

analyzing the updated previous position estimate to determine if the updated previous position estimate is outside of a range; and

constraining the updated previous position estimate based on the value being outside of the range.

2. The method of claim 1 , further comprising filtering the initial position estimate by another Kalman filter to generate an instantaneous initial position estimate that includes a corresponding covariance.

3. The method of claim 1 , wherein the initial position estimate is the instantaneous initial position estimate.

4. The method of claim 1 , further comprising providing a correction measurement with a corresponding small covariance to the Kalman filter to constrain the updated previous position estimate.

5. The method of claim 1 , wherein the corresponding covariance associated with the initial position estimate is computed using a Wi-Fi dilution of position (WDOP), which is the covariance associated with the initial position estimate.

6. The method of claim 5 , wherein the WDOP reflects a quality of the geometry of a plurality of wireless local area network access points.