Systems and Methods for Providing Geolocation Using Wireless Signals

• US 20110129022A1
• Filed: 12/01/2009
• Published: 06/02/2011
• Est. Priority Date: 12/01/2009
• Status: Active Grant

• Current Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Original Assignee: AT&T Intellectual Property I LP (AT&T, Inc.)
• Inventors: Henry, Paul, Rice, Christopher, Kim, Byoung-Jo
• Granted Patent: US 8,416,134 B2
• Time in Patent Office: Days
• US Class Current: 375/260
• CPC Class Codes: G01S 5/02528 Simulating radio frequency fingerprints
• CPC Class Codes: G01S 5/06 Position of source determined by co-ordinating a plurality of position lines defined by path-difference measurements G01S5/12 takes precedence
• CPC Class Codes: H04W 4/02 Services making use of location information
• CPC Class Codes: H04W 4/029 Location-based management or tracking services

Abstract

A system for determining a location of a receiver is disclosed. The system includes at least one transmitter transmitting one or more radio signals, respectively. The system also includes a receiver comprising a clock, a memory, and a processor configured to execute computer-executable instructions stored in the memory. The instructions makes the receiver operable to receive the radio signals, capture the radio signals as one or more received signal waveform, respectively, and store the received signal waveforms in the memory. The instructions also make the receiver operable to calculate one or more virtual transmitted waveforms based upon the received signal waveforms, respectively and determine, based upon the received signal waveforms and the virtual transmitted waveforms, a position of the receiver relative to the transmitters.

Claims

1. A system for determining a location of a receiver, the system comprising:

one or more transmitters configured to transmit one or more radio signals, respectively;

a receiver communicatively linked to the transmitters, the receiver comprising a clock, a memory, and a processor, wherein the processor is configured to execute computer-executable instructions stored in the memory, the execution of which make the receiver operable to;

receive the radio signals;

capture the radio signals as one or more received signal waveform, respectively;

store the received signal waveforms in the memory;

calculate one or more virtual transmitted waveforms based upon the received signal waveforms, respectively; and

determine, based upon the received signal waveforms and the virtual transmitted waveforms, a position of the receiver relative to the transmitters.

2. The system of claim 1, wherein the computer-executable instructions is configured to make the receiver operable to determine the position of the receiver relative to the transmitters based on said waveforms and transmission timing information regarding the transmitters.

3. The system of claim 2, wherein:

the one or more transmitters include a first transmitter configured to transmit a first radio signal of said one or more radio signals, a second transmitter configured to transmit a second radio signal of said one or more radio signals, and a third transmitter configured to transmit a third signal of said one or more radio signals;

the computer-readable instructions, executable by the processor make the receiver operable to receive the first radio signal, the second radio signal, and the third radio signal;

the receiver is configured to execute the instructions to perform the receiving, capturing, storing, and calculating steps with respect to each of the first radio signal, the second radio signal and the third radio signal; and

in determining the position of the receiver relative to the transmitters, the receiver is configured to determine the position of the receiver relative to the first transmitter, the second transmitter, and the third transmitter.

4. The system of claim 2, wherein:

the receiver comprises a virtual transmitter module configured to calculate the virtual transmitted waveforms, including generating one or more virtual transmitted data streams, respectively; and

the virtual transmitted data streams are substantially identical to transmitted data streams associated with the radio signals transmitted by the transmitters.

5. The system of claim 4, wherein the virtual transmitter module is further configured to virtually transmit the virtual transmitted data streams to obtain the respective virtual transmitted signal waveforms.

6. The system of claim 5, wherein the receiver further comprises a time shift determiner configured to compare the virtual transmitted signal waveforms to the respective received signal waveforms to determine time shifts required to align the virtual transmitted signal waveforms to the respective received signal waveforms.

7. The system of claim 6, wherein the computer-readable instructions further comprise instructions, executable by the processor to make the receiver operable to determine the position of the receiver relative to the transmitters based on the time shifts.

8. The system of claim 7, wherein the computer-readable instructions further comprise instructions, executable by the processor to make the receiver operable to:

obtain transmitter location data for each of the transmitters; and

determine the location of the receiver based upon the transmitter location data for the transmitters and the position of the receiver relative to the transmitters.

9. The system of claim 4, wherein the virtual transmitter module comprises a data stream determination application, wherein:

the data stream determination application applies a fast Fourier transform (FFT) algorithm to the received signal waveforms to create corresponding data output; and

the data stream determination application transmits the data output to an orthogonal frequency-division multiplexing (OFDM) demodulator to generate corresponding virtual transmitted data streams.

10. The system of claim 9, wherein the virtual transmitter module comprises a virtual transmitter application, wherein:

the virtual transmitter application receives the virtual transmitted data streams;

the virtual transmitter application transmits the virtual transmitted data streams to an OFDM modulator to generate corresponding modulated data streams; and

the virtual transmitter application applies an inverse fast Fourier transform (IFFT) algorithm to the modulated data streams to generate corresponding virtual transmitted signal waveforms.

11. The system of claim 10, wherein the computer-readable instructions further comprise instructions, executable by the processor to make the receiver operable to store the virtual transmitted signal waveforms at the memory.

12. A method for determining location of a receiver using radio signals, the method comprising:

transmitting from one or more transmitters, one or more radio signals, respectively;

receiving the radio signals at the receiver in communication with the transmitters;

capturing the radio signals, at the receiver, as one or more received signal waveforms, respectively;

storing, at a memory device associated with the receiver, the received signal waveforms;

calculating, at the receiver, one or more virtual transmitted signal waveforms, respectively, wherein the virtual transmitted signal waveforms are calculated based upon the radio signals; and

determining, at the receiver, a position of the receiver relative to the transmitters based upon the received signal waveforms and the virtual transmitted signal waveforms.

13. The method of claim 12, wherein determining the position of the receiver relative to the transmitters is based on said waveforms and transmission timing information regarding the transmitters.

14. The method of claim 13, wherein calculating the virtual transmitted signal waveforms includes, for each virtual transmitted waveform:

generating a data stream at a virtual transmitter module of the receiver, the data stream being substantially identical to a transmitted data stream, including the respective radio signal transmitted by the transmitter; and

virtually transmitting the data stream to obtain the virtual transmitted signal waveform.

15. The method of claim 14, further comprising:

determining a time difference with respect to the respective signal corresponding to each transmitter of said transmitters including;

comparing, at a time shift determiner associated with the receiver, the respective virtual transmitted signal waveform to the respective received signal waveform; and

determining, at the time shift determiner, time shifts required to align the virtual transmitted signal waveforms to the respective received signal waveforms;

obtaining transmitter location data for each of the transmitters; and

determining the location of the receiver based upon the transmitter location data for the transmitters and the position of the receiver relative to the transmitters.

16. The method of claim 15, further comprising, for each of the received radio signals:

applying a fast Fourier transform (FFT) algorithm to the corresponding received signal waveform to create a data output;

transmitting the data output to an orthogonal frequency-division multiplexing (OFDM) demodulator to generate a virtual transmitted data stream;

transmitting the virtual transmitted data stream to an OFDM modulator to generate a modulated data stream;

applying an inverse fast Fourier transform (IFFT) algorithm to the modulated data stream to generate the virtual transmitted signal waveform; and

storing the virtual transmitted signal waveform at the memory.

17. A computer readable medium comprising computer readable instructions that, when executed, cause a receiver to perform steps comprising:

receiving radio signals, the radio signals being transmitted by one or more transmitters in communication with the receiver;

capturing the received radio signals as one or more received signal waveform, respectively;

storing the received signal waveforms at a memory device associated with the receiver;

obtaining one or more virtual transmitted waveforms, respectively, based, at least partially, upon the radio signals received from the transmitters; and

determining a position of the receiver relative to the transmitters based upon the received signal waveforms and the virtual transmitted waveforms.

18. The computer readable medium of claim 17, further comprising computer readable instructions that, when executed, cause the receiver to perform steps comprising:

generating one or more data streams at a virtual transmitter module associated with the receiver, the data streams being substantially identical to one or more transmitted data stream transmitted by the one or more transmitters, respectively;

virtually transmitting each of the data streams at the virtual transmitter module associated with the receiver to obtain the respective virtual transmitted signal waveforms;

obtaining transmitter location data for each of the transmitters; and

determining the location of the receiver based upon the transmitter location data for the transmitters and the position of the receiver relative to the transmitters.

19. The computer readable medium of claim 18, further comprising computer readable instructions that, when executed, cause the receiver to perform steps comprising:

applying, at the virtual transmitter module, a fast Fourier transform (FFT) algorithm to each received signal waveform to create respective data output;

transmitting the data output to an orthogonal frequency-division multiplexing (OFDM) demodulator to generate respective virtual transmitted data streams;

transmitting each virtual transmitted data stream to an OFDM modulator to generate respective modulated data streams;

applying an inverse fast Fourier transform (IFFT) algorithm to each modulated data stream to generate the respective virtual transmitted signal waveforms;

storing the virtual transmitted signal waveforms at the memory;

retrieving, at a time shift determiner associated with the receiver, the transmitted signal waveforms;

comparing, at the time shift determiner, each virtual transmitted signal waveforms to the respective received signal waveform;

determining, at the time shift determiner, time shifts required to align the virtual transmitted signal waveforms to the respective received signal waveforms.

20. The computer readable medium of claim 19, further comprising computer readable instructions that, when executed, cause the receiver to perform steps comprising:

outputting the time shifts;

determining, at the receiver, the position of the receiver relative to the transmitters based on the time shifts;

obtaining, at the receiver, transmitter location data associated with each transmitter; and

determining, at the receiver, the location of the receiver based upon the transmitter location data for the transmitters and the position of the receiver relative to the transmitters.