Estimation of speed and direction of travel in a WLAN positioning system
A method for estimating the speed and bearing of a Wi-Fi enabled device using WLAN radio signals in a WLAN based location service is provided. A method used to estimate a speed of travel of a Wi-Fi enabled device comprises the Wi-Fi enabled device receiving signals transmitted by Wi-Fi access points in range of the Wi-Fi enabled device, and using the signals to estimate the speed of and/or direction of travel of the Wi-Fi enabled device.
1. A method of inferring whether a Wi-Fi enabled device is substantially stationary, comprising:
receiving information from signals transmitted by at least one Wi-Fi access point and received by the Wi-Fi enabled device, the receiving occurring over time;
measuring, during at least one amount of time, a first duration of time during which the Wi-Fi enabled device detects signals transmitted by the at least one Wi-Fi access point;
inferring whether the Wi-Fi enabled device is substantially stationary based on the first duration of time during which signals from the at least one Wi-Fi access point were detected; and
calculating a quality of estimation for the inference of whether the Wi-Fi enabled device is substantially stationary based on a number of Wi-Fi access points from which signals are received during the at least one amount of time.
2. The method of claim 1 , comprising:
measuring, during the at least one amount of time, a second duration of time during which the Wi-Fi enabled device detects signals transmitted by a second Wi-Fi access point; and
averaging the first duration of time and the second duration of time to calculate an average total duration of time;
wherein the inferring comprises inferring that the Wi-Fi enabled device is substantially stationary based on the average total duration of time.
3. The method of claim 2 , comprising:
determining that the average total duration of time is above a threshold;
wherein the inferring comprises inferring that the Wi-Fi enabled device is substantially stationary based on the determination that the average total duration of time is above the threshold.
4. The method of claim 2 , comprising:
determining that the average total duration of time is below a threshold; and
wherein the inferring comprises inferring that the Wi-Fi enabled device is not substantially stationary based on the determination that the average total duration of time is below the threshold.
5. The method of claim 2 , further comprising:
determining an estimate of coverage area of at least one of the first Wi-Fi access point and the second Wi-Fi access point; and
wherein the averaging further comprises weighting at least one of the first duration of time and the second duration of time based on the coverage area of the respective Wi-Fi access point.
6. The method of claim 2 , further comprising:
determining a nominal coverage area for Wi-Fi access points; and
wherein the averaging further comprises weighting at least one of the first duration of time and the second duration of time based on the nominal coverage area.
7. The method of claim 2 , wherein the number of Wi-Fi access points from which signals are received during the at least one amount of time is equal to a number of Wi-Fi access points whose respective durations of time are averaged to calculate the average total duration of time.
8. The method of claim 1 , wherein the inferring comprises inferring that the Wi-Fi enabled device is substantially stationary without requiring position estimates of the Wi-Fi enabled device.
9. A system for inferring whether a Wi-Fi enabled device is substantially stationary, comprising:
at least one non-transitory computer-readable media comprising instructions that when executed cause a computer system to:
receive information from signals transmitted by at least one Wi-Fi access point and received by the Wi-Fi enabled device, the receiving occurring over time;
measure, during at least one amount of time, a first duration of time during which the Wi-Fi enabled device detects signals transmitted by the at least one Wi-Fi access point;
infer whether the Wi-Fi enabled device is substantially stationary based on the first duration of time during which signals from the at least one Wi-Fi access points were detected; and
calculate a quality of estimation for the inference of whether the Wi-Fi enabled device is substantially stationary based on a number of Wi-Fi access points from which signals are received during the at least one amount of time.
10. A non-transitory computer readable medium having software stored thereon for inferring whether a Wi-Fi enabled device is substantially stationary, the software when executed operable to:
process signals transmitted by a plurality of Wi-Fi access points and received by the Wi-Fi enabled device over at least one amount of time;
measure, during the at least one amount of time, a duration of time during which the Wi-Fi enabled device detects signals transmitted by each of the plurality of Wi-Fi access points;
average the durations of time during which the Wi-Fi enabled device detects signals transmitted by each of the plurality of Wi-Fi access points to produce an average total duration of time;
infer whether the Wi-Fi enabled device is substantially stationary based on the average total duration of time; and
use the inference whether the Wi-Fi enabled device is substantially stationary in a location based service provided to a user on the Wi-Fi enabled device.
11. The non-transitory computer readable medium of claim 10 , wherein the software when executed is further operable to:
calculate a quality of estimation for the inference of whether the Wi-Fi enabled device is substantially stationary based on a number of Wi-Fi access points in the plurality of Wi-Fi access points.
12. The non-transitory computer readable medium of claim 10 , wherein the software when executed is further operable to:
determine that the average total duration of time is above a threshold;
wherein the inference is that the Wi-Fi enabled device is substantially stationary when the average total duration of time is above the threshold.
13. The non-transitory computer readable medium of claim 10 , wherein the software when executed is further operable to:
determine that the average total duration of time below a threshold;
wherein the inference is that the Wi-Fi enabled device is not substantially stationary when the average total duration of time is below the threshold.
14. The non-transitory computer readable medium of claim 10 , wherein the software that when executed infers whether the Wi-Fi enabled device is substantially stationary performs the inference absent estimation of a specific position of the Wi-Fi enabled device.
15. The non-transitory computer readable medium of claim 10 , wherein the software when executed is further operable to:
determine an estimate of coverage area of at least one of the plurality of Wi-Fi access points; and
weight the duration of time for the at least one of the plurality of Wi-Fi access points based on the estimate of coverage area.
16. The non-transitory computer readable medium of claim 10 , wherein the software when executed is further operable to:
determine a nominal coverage area for Wi-Fi access points; and
weight the duration of time for at least one of the plurality of Wi-Fi access points based on the nominal coverage area.