| 摘要 |
Determining the location of a wireless device to be located (DTL) by three or more locating devices (LDs). LDs operating at known locations estimate the distance to the DTL by sending wireless frames to the DTL and varying frame parameters such as transmit power and data rate, searching for the boundary at which the frame is or is not received and ACKd by the DTL. For a given set of frame parameters, the SNR required to be successfully received at the DTL is known. Given that the configuration of the LD is known, the EIRP of the DL is also known. Estimating the noise floor at the DTL, and using the SNR required to successfully receive the frame at the DTL and the EIRP at the LD transmitting the frame, the path loss can be calculated. From the path loss and operating frequency, a distance estimate is calculated. EIRP of the DTL is not and need not be known. Distance estimates from at least three LDs at known locations allow a location for the DTL to be calculated by a location engine (LE). Distance estimates from more than three LDs allow for an overdetermined solution. Distance estimates derived in this manner may be combined with distance estimates calculated using other approaches, such as measuring signal strengths, or TOA/TDOA measurements. The LE process may reside on a central controller supporting the LDs, on one of the LDs, or on any suitable device with network access.
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