Determining the position of a mobile device using the characteristics of received signals and a reference database

• US 8,314,736 B2
• Filed: 08/06/2010
• Issued: 11/20/2012
• Est. Priority Date: 03/31/2008
• Status: Expired due to Fees

• Current Assignee: Golba LLC
• Original Assignee: Golba LLC
• Inventors: Moshfeghi, Mehran
• Primary Examiner(s): Phan, Dao
• Application Number:
  US12/852,443
• Publication Number:
  US 20100309051A1
• Time in Patent Office: 837 Days
• Field of Search: 342/453, 342/457, 342463-465, 455/65, 455/456.1, 455/456.2
• US Class Current: 342/465
• CPC Class Codes: G01S 5/0236 Assistance data, e.g. base station almanac
• CPC Class Codes: G01S 5/02521 using a radio-map
• CPC Class Codes: G01S 5/0273 using multipath or indirect path propagation signals in position determination
• CPC Class Codes: H04W 4/027 using movement velocity, acceleration information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 64/006 with additional information processing, e.g. for direction or speed determination

Abstract

Some embodiments use scanning devices to characterize radio signals received at a number of locations within a geographical area of interest. The signal characteristics along with the location information associated with the characteristics are stored in a centralized reference database. A mobile device characterizes signals it receives at a certain location and compares the characteristics with the signal characteristics stored in the reference database to obtain accurate location information of the certain location.

Claims

1. A method of determining a location of a mobile device, the method comprising:

receiving a first plurality of signals with a known transmission pattern at the mobile device from a set of transmitters, the first plurality of signals comprising at least one multipath signal;

computing a first set of parameters from the first plurality of signals using the known transmission pattern;

retrieving, from a database, a second set of parameters computed from a second plurality of signals, the second plurality of signals comprising at least one multipath signal, each parameter in the second set of parameters associated with a location where a corresponding signal from the second plurality of signals was received, wherein each location associated with a parameter in the second set of parameters is identified by a set of coordinate values;

for each particular location associated with a parameter in the second set of parameters;

multiplying each parameter in the first set of parameters with each parameter in the second set of parameters that is associated with the particular location; and

summing a result of each multiplication to determine a correlation coefficient corresponding to the particular location;

normalizing each correlation coefficient; and

determining the location of the mobile device by computing a set of coordinate values for the location of the mobile device, each coordinate value for the location of the mobile device computed as a weighted average of each normalized correlation coefficient multiplied by a coordinate value in the set of coordinate values corresponding to the second set of parameters.

2. The method of claim 1, wherein a plurality of transmitters in the set of transmitters transmit over a particular transmission channel, wherein the first and second sets of parameters comprise a plurality of parameters characterizing the particular transmission channel, wherein the first and second sets of parameters comprise at least one of a channel multipath profile and channel fast Fourier transform (FFT) coefficients.

3. The method of claim 1, wherein the mobile device is moving, the method further comprising:

calculating a velocity of the mobile device; and

revising the determined location of the mobile device based on the velocity of the mobile device and a plurality of previously determined locations of the mobile device.

4. The method of claim 3, wherein the parameters in the first and second sets of parameters comprise a Doppler shift, wherein determining the location of the mobile device comprises utilizing the Doppler shift.

5. The method of claim 1, wherein the first and second sets of parameters comprise time of arrival delay extracted using received signal strength indicator (RSSI) transition, time of arrival delay extracted using signal preamble correlation, time difference of arrival, transmitter signal strength, angel of arrival, and equalizer filter coefficients.

6. The method of claim 1, wherein at least one signal comprises a set of pilot tones, wherein the first and second sets of parameters comprise phase and amplitude of each pilot tone.

7. The method of claim 1 further comprising:

determining an estimated location of the mobile device prior to determining the mobile device location; and

limiting the second set of parameters to parameters associated with locations in a vicinity of the estimated location of the mobile device.

8. The method of claim 7, wherein determining the estimated location of the mobile device comprises using a set of previously determined locations of the mobile device.

9. The method of claim 7, wherein each transmitter transmits an identification, wherein each parameter in the database is associated with an identification of a transmitter, wherein retrieving the second set of parameters comprises retrieving parameters associated with identifications of the transmitters transmitting the first plurality of signals.

10. The method of claim 1, wherein determining the location of the mobile device does not comprise using a location of a transmitter.

11. The method of claim 1, wherein determining the location of the mobile device does not comprise determining a distance from the mobile device to a transmitter.

12. The method of claim 1, wherein each signal has a set of preambles, wherein computing the first set of parameters using the known transmission pattern comprises determining a peak time of arrival for each signal based on the set of signal preambles.

14. The method of claim 1, wherein the first set of parameters comprises a plurality of different parameter types, the method further comprising:

calculating a location of the mobile device based on each parameter type; and

determining the location of the mobile device as a weighted average of the calculated locations.

15. The method of claim 14, wherein the transmitters transmit signals for a plurality of radio types, each radio type using a different standard, wherein the set of parameters comprises a plurality of parameters computed from signals of one or more of the radio types, the method further comprising:

determining the location of the mobile device for each particular radio type as a weighted average of the calculated locations based on parameters computed from signals of the particular radio type; and

determining the location of the mobile device as a weighted average of the locations determined for each radio type.

16. The method of claim 1, wherein the transmitters transmit signals for a plurality of radio types, each radio type using a different standard, the method further comprising:

calculating a location of the mobile device based on parameters computed from signals of each radio type; and

determining the location of the mobile device as a weighted average of the calculated locations.

34. The method of claim 1, wherein the parameters in the first and second sets of parameters comprise amplitudes of profiles of multipath signals.

35. The method of claim 1, wherein the parameters in the first and second sets of parameters comprise amplitudes and phases of profiles of multipath signals.

36. The method of claim 1, wherein multiplying each parameter in the first set of parameters with each parameter in the second set of parameters further comprises using a Gaussian multiplier centered on a set of extracted peaks of the second plurality of signals, the Gaussian multiplier having a standard deviation depending on a sampling distance and a sampling frequency of the second plurality of signals.

37. The method of claim 1, wherein the location associated with each parameter in the second set of parameters corresponds to a grid point in a set of grid points, wherein multiplying each parameter in the first set of parameters with each parameter in the second set of parameters comprises:

grouping the second set of parameters into a plurality of groups of parameters based on a proximity of the corresponding grid points; and

for each group of parameters, multiplying each parameter in the first set of parameters with each parameter in the group of parameters.

38. The method of claim 37, wherein summing the result of each multiplication to determine a correlation coefficient corresponding to the particular location comprises:

summing a result of each multiplication for each group of parameters;

determining a group of parameters resulting in a highest summation result; and

determining a correlation coefficient corresponding to the particular location using the highest summation result.

13. A method of determining a location of a mobile device, the method comprising:

receiving a first plurality of signals having a known transmission pattern at the mobile device from a set of transmitters, the first plurality of signals comprising at least one multipath signal, each signal having a set of preambles, each signal having a set of peaks, wherein the mobile device and each transmitter operate using a clock, wherein the mobile device clock is not synchronized with the transmitters clocks, wherein the transmitters clocks are not synchronized with each other;

determining a time of arrival of a first peak for each signal based on the set of signal preambles;

normalizing the time of arrival of the peaks of each signal to make the time of arrival of the first peak of a first signal received at the mobile device to occur at a time equal to zero;

computing a first set of parameters from the first plurality of signals using the known transmission pattern and the normalized time of arrival of the peaks of each signal;

retrieving, from a database, a second set of parameters computed from a second plurality of signals, wherein a time of arrival of a first peak of each signal in the second plurality of signals is normalized to occur at a time equal to zero, the second plurality of signals comprising at least one multipath signal, each parameter in the second set of parameters associated with a location where a corresponding signal from the second plurality of signals was received;

comparing the first set of parameters with the second set of parameters; and

determining the location of the mobile device based on the comparison.

39. The method of claim 13, wherein a plurality of transmitters in the set of transmitters transmit over a particular transmission channel, wherein the first and second sets of parameters comprise a plurality of parameters characterizing the particular transmission channel, wherein the first and second sets of parameters comprise at least one of a channel multipath profile and channel fast Fourier transform (FFT) coefficients.

17. A method of determining a location of a mobile device, the method comprising:

at a set of scanning devices, receiving a plurality of signals from a plurality of signal sources, the plurality of signal sources comprising a set of signal sources that move with known periods, the plurality of signals comprising at least one multipath signal;

determining a location where each signal is received by a scanning device;

determining a time when each signal from a signal source in the set of signal sources is received by a scanning device at each location;

computing a set of parameters from the received signals;

storing the set of computed parameters and the locations where each signal is received in a reference database, one or more parameters in the set of computed parameters having timestamps, each timestamp identifying a time when a corresponding signal source in the set of signal sources is at a particular location;

receiving a request for parameters to determine the location of the mobile device, the request comprising a time when the mobile device received a signal from a particular signal source in the set of signal sources; and

retrieving a set of parameters from the reference database, the retrieved set of parameters comprising a set of parameters (i) computed from signals received from the particular signal source and (ii) having timestamps that are within a threshold of a time when the particular signal source was at a same location as the location the particular signal source was when the mobile device received the signal from the particular signal source, the retrieved set of parameters for comparing with a set of parameters computed from the set of signals received by the mobile device to determine the location of the mobile device.

18. The method of claim 17, wherein the set of scanning devices comprises one or more moving devices, each moving device comprising a set of antennas for receiving signals.

19. The method of claim 18, wherein one or more of the scanning devices in the set of scanning devices are position enabled, wherein a scanning device is position enabled when the scanning device comprises a set of equipment for determining the scanning device'"'"'s location.

20. The method of claim 17, wherein one or more of the scanning devices in the set of scanning devices are position enabled portable wireless devices, wherein a wireless device is position enabled when the wireless device comprises a set of equipment for determining the wireless device'"'"'s location.

21. The method of claim 17, wherein one or more scanning devices are fixed RF radios with known locations.

22. The method of claim 17, wherein one or more scanning devices comprise more than one antenna for receiving signals, wherein determining the location where each signal is received by a scanning device comprises determining a location where each signal is received by each antenna of a scanning device.

23. The method of claim 17, wherein one or more signal sources in the plurality of signal sources comprise a plurality of antennas for transmitting signals.

24. The method of claim 17 further comprising, updating the set of parameters in the reference database based on the parameters computed from the signals received by the wireless mobile device.

25. A method of determining a location of a mobile device, the method comprising:

receiving a first plurality of signals having a known transmission pattern at the mobile device from a transmitting device over a set of transmission channels, the transmitting device comprising a plurality of antennas, each signal in the plurality of signals received from one of the antennas of the transmitting device, the mobile device and the transmitting device each operating by using a clock, wherein the mobile device clock is not synchronized with the transmitting device clock;

characterizing the set of transmission channels to compute a first plurality of parameters associated with the first plurality of signals, characterizing the set of transmission channels comprising (i) characterizing a profile of the received signals to determine a time of arrival of a first peak for each signal received at the mobile device and (ii) normalizing the time of arrival of the peaks of each signal to make the time of arrival of the first peak of a first signal received at the mobile device to occur at a time equal to zero;

computing a first plurality of parameters from the first plurality of signals using the known transmission pattern and the normalized time of arrival of the peaks of each signal;

retrieving, from a database, a second plurality of parameters computed from a second plurality of signals, wherein a time of arrival of a first peak of each signal in the second plurality of signals is normalized to occur at a time equal to zero, the second plurality of signals comprising at least one multipath signal, each parameter in the second plurality of parameters associated with a location where a corresponding signal from the second plurality of signals was received;

correlating the first plurality of parameters with the second plurality of parameters; and

determining the location of the mobile device based on the correlation.

26. The method of claim 25, wherein the first and second pluralities of parameters comprise a plurality of parameters characterizing the set of transmission channels, wherein the first and second pluralities of parameters comprise multichannel profiles and channel fast Fourier transform (FFT) coefficients.

27. The method of claim 25 further comprising receiving one or more multipath signals related to the first plurality of signals, wherein characterizing the profile of the received signals comprises computing a set of parameters for the multipath signals.

28. The method of claim 25, wherein the transmitting device transmits signals of different standards comprising at least two of Wireless Local Area Network (WLAN) 802.11, Bluetooth, WiMax, HD Radio, Ultra-wideband (UWB), GPS, cellular, and 60 GHz standards.

29. The method of claim 25 further comprising receiving signals from a plurality of transmitting devices, wherein the transmitting devices transmit signals of different standards comprising at least two of Wireless Local Area Network (WLAN) 802.11, Bluetooth, WiMax, HD Radio, Ultra-wideband (UWB), GPS, cellular, and 60 GHz standards.

30. The method of claim 25, wherein the mobile device comprises a plurality of antennas for receiving signals, wherein determining the location of the mobile device comprises:

determining a location of each of the plurality of mobile device antennas; and

determining the location of the mobile device based on the locations of the plurality of mobile device antennas.

31. The method of claim 25, wherein each of the plurality of transmitter antennas transmit with an associated preset time delay in relation to other antennas, wherein the mobile device receives signals from each particular transmitter antenna at a particular delay in relation to the signals received from the other transmitter antennas, each particular delay proportional to (i) a distance between the particular antenna and (ii) the preset time delay associated with the antenna.

32. The method of claim 31, wherein the set of transmission channels comprises a plurality of channels, each channel associated with one or more transmitter antenna.

33. The method of claim 25, wherein the plurality of antennas transmit together, wherein the set of transmission channels comprise one transmission channel for all antennas in the plurality of transmitter antennas.