RTT PROCESSING BASED ON A CHARACTERISTIC OF ACCESS POINTS

摘要

Systems, apparatus and methods for estimating a location of a mobile device are presented. Before computing a location estimate, the mobile device groups a plurality of access points into two or more categories (for example, a first list of access points having a first characteristic and a second list of access points having a second characteristic). Round-trip time (RTT) measurements are computed for access points in the first list. A Short Interframe Space (SIFS) value may be determined for each access point in the first list or generally SIFT representing the first list as a whole. The RTT measurements are compensated with the appropriate SIFS value. The mobile device then computes its location or position fix estimate using the compensated RTT values while excluding less accurate RTT values from other access points. As a result, the location estimate eliminates adverse influent from some access points.

主权项

1. A method in a mobile device for estimating a location of the mobile device, the method comprising:
receiving signals from a plurality of access points; forming a first list of access points from only some of the plurality of access points based on a characteristic; measuring round-trip times (RTTs) for access points in the first list; estimating a first turnaround calibration function (TCF) representing the first list of access points; and computing a position fix of the mobile device based on the RTTs for access points in the first list and the first TCF.