Estimating the location of a footprint of a building and using the footprint to estimate the location of a wireless terminal
A location engine uses the empirical measurements made by a scouting wireless terminal (i) to discover the existence of a reference radio within a geographic region; (ii) to generate an estimate of the location of the newly-discovered reference radio, and (iii) to generate an estimate of the transmission power of the downlink control channel radio signal transmitted by the newly-discovered reference radio. The location engine then uses: (i) the estimate of the location of the newly-discovered reference radio, and (ii) the estimate of the transmission power of the downlink control channel radio signal transmitted by the newly-discovered reference radio, and (iii) measurements, made by a user wireless terminal, of the power of each of the downlink control channel radio signals transmitted by each of the reference radios to generate an estimate of the location of the user wireless terminal.
1. A method comprising:
receiving:
(i) a first measurement value MV(1) of the locally-averaged signal strength of a first radio signal as received at a first measurement location ML(1), wherein the first measurement location ML(1) is outside of a building, wherein the first radio signal is characterized by a wavelength λ, and
(ii) a second measurement value MV(2) of the locally-averaged signal strength of the first radio signal as received at a second measurement location ML(2), wherein the second measurement location ML(2) is outside of the building, and wherein the first measurement location is not equal to the second measurement location;
generating:
(i) a first candidate location CL(1) of a radio transmitter of the first radio signal inside of the building, and
(ii) a second candidate location CL(2) of the radio transmitter of the first radio signal inside of the building, wherein the first candidate location is not equal to the second candidate location;
generating:
(i) a first candidate prediction of the total path loss A(1,1) for a hypothetical radio signal from the first candidate location CL(1) to the first measurement location ML(1), wherein the hypothetical radio signal is characterized by the wavelength λ, and
(ii) a second candidate prediction of the total path loss A(1,2) for the hypothetical radio signal from the first candidate location CL(1) to the second measurement location ML(2), and
(iii) a third candidate prediction of the total path loss A(2,1) for the hypothetical radio signal from the second candidate location CL(2) to the first measurement location ML(1), and
(iv) a fourth candidate prediction of the total path loss A(2,2) for the hypothetical radio signal from the second candidate location CL(2) to the second measurement location ML(2);
generating an estimate of the location of a footprint of the building based on which of:
(1) the first candidate location CL(1), and
(2) the second candidate location CL(2) is more consistent with the first measurement value MV(1), the second measurement value MV(2), the first candidate prediction of the total path loss A(1,1), the second candidate prediction of the total path loss A(1,2), the third candidate prediction of the total path loss A(2,1), and the fourth candidate prediction of the total path loss A(2,2).
2. The method of claim 1 further comprising:
receiving a third measurement value that is evidence of the locally-averaged signal strength of the first radio signal at a wireless terminal; and
generating an estimate of the location of the wireless terminal based on:
(i) the third measurement value, and
(ii) the estimate of the location of the footprint of the building.
3. The method of claim 2 further comprising:
transmitting the estimate of the location of the wireless terminal to the wireless terminal for use in a location-based application.
4. The method of claim 2 further comprising:
transmitting the estimate of the location of the wireless terminal to a remote data processing system for use in a location-based application.
5. The method of claim 2 further comprising:
using the estimate of the location of the wireless terminal in a location-based application.
6. The method of claim 1 further comprising:
generating an estimate of the transmission power of the radio transmitter of the first radio signal based on which of:
(1) the first candidate location CL(1), and
(2) the second candidate location CL(2) is more consistent with the first measurement value MV(1), the second measurement value MV(2), the first candidate prediction of the total path loss A(1,1), the second candidate prediction of the total path loss A(1,2), the third candidate prediction of the total path loss A(2,1), and the fourth candidate prediction of the total path loss A(2,2).
7. The method of claim 6 further comprising:
receiving a third measurement value that is evidence of the locally-averaged signal strength of the first radio signal at a wireless terminal; and
generating an estimate of the location of the wireless terminal based on:
(i) the third measurement value, and
(ii) the estimate of the location of the footprint of the building, and
(iii) the estimate of the transmission power of the radio transmitter of the first radio signal.
8. The method of claim 1 further comprising:
generating an estimate of the location of an architectural feature of the building based on which of:
(1) the first candidate location CL(1), and
(2) the second candidate location CL(2) is more consistent with the first measurement value MV(1), the second measurement value MV(2), the first candidate prediction of the total path loss A(1,1), the second candidate prediction of the total path loss A(1,2), the third candidate prediction of the total path loss A(2,1), and the fourth candidate prediction of the total path loss A(2,2).
9. The method of claim 8 further comprising:
receiving a third measurement value that is evidence of the locally-averaged signal strength of the first radio signal at a wireless terminal; and
generating an estimate of the location of the wireless terminal based on:
(i) the third measurement value, and
(ii) the estimate of the location of the footprint of the building, and
(iii) the estimate of the location of an architectural feature of the building.
10. A method comprising:
receiving:
(i) a first measurement value MV(1,1) of the power of a first radio signal as received at a first measurement location ML(1), wherein the first radio signal is transmitted by a radio transmitter and is characterized by a first wavelength λ1, and
(ii) a second measurement value MV(2,2) of the power of a second radio signal as received at a second measurement location ML(2), wherein the second radio signal is transmitted by the radio transmitter and is characterized by a second wavelength λ2;
generating:
(i) a first candidate location CL(1) of the radio transmitter, and
(ii) a second candidate location CL(2) of the radio transmitter, wherein the first candidate location is not equal to the second candidate location;
generating:
(i) a first candidate prediction of the total path loss A(1,1,1) for a first hypothetical radio signal from the first candidate location CL(1) to the first measurement location ML(1), wherein the first hypothetical radio signal is characterized by the wavelength λ1, and
(ii) a second candidate prediction of the total path loss A(2,2,2) for a second hypothetical radio signal from the second candidate location CL(2) to the second measurement location ML(2), wherein the second hypothetical radio signal is characterized by the wavelength λ2, and
generating an estimate of a location of a footprint of a building based on which of:
(1) the first candidate location CL(1), and
(2) the second candidate location CL(2) is more consistent with the first measurement value MV(1,1), the second measurement value MV(2,2), the first candidate prediction of the total path loss A(1,1,1), and the second candidate prediction of the total path loss A(2,2,2).
11. The method of claim 10 further comprising:
receiving a third measurement value that is evidence of the power of the first radio signal at a wireless terminal; and
generating an estimate of the location of the wireless terminal based on:
(i) the third measurement value, and
(ii) the estimate of the location of the footprint of the building.
12. The method of claim 11 further comprising:
transmitting the estimate of the location of the wireless terminal to the wireless terminal for use in a location-based application.
13. The method of claim 11 further comprising:
transmitting the estimate of the location of the wireless terminal to a remote data processing system for use in a location-based application.
14. The method of claim 11 further comprising:
using the estimate of the location of the wireless terminal in a location-based application.
15. The method of claim 11 further comprising:
generating an estimate of the location of an architectural feature of a building based on which of:
(1) the first candidate location CL(1), and
(2) the second candidate location CL(2) is more consistent with the first measurement value MV(1,1), the second measurement value MV(2,2), the first candidate prediction of the total path loss A(1,1,1), and the second candidate prediction of the total path loss A(2,2,2).
16. The method of claim 15 further comprising:
receiving a third measurement value that is evidence of the locally-averaged signal strength of the first radio signal at a wireless terminal; and
generating an estimate of the location of the wireless terminal based on:
(i) the third measurement value, and
(ii) the estimate of the location of the footprint of the building, and
(iii) the estimate of the location of the architectural feature of the building.
17. The method of claim 11 further comprising:
generating an estimate of the transmission power of the radio transmitter of the first radio signal based on which of:
(1) the first candidate location CL(1), and
(2) the second candidate location CL(2) is more consistent with the first measurement value MV(1,1), the second measurement value MV(2,2), the first candidate prediction of the total path loss A(1,1,1), and the second candidate prediction of the total path loss A(2,2,2).
18. The method of claim 17 further comprising:
receiving a third measurement value that is evidence of the locally-averaged signal strength of the first radio signal at a wireless terminal; and
generating an estimate of the location of the wireless terminal based on:
(i) the third measurement value, and
(ii) the estimate of the location of the footprint of the building, and
(iii) the estimate of the transmission power of the radio transmitter of the first radio signal.