Position location using multiple carriers

1. A method of determining a distance estimate between a mobile device and a wireless transceiver communicating with the mobile device on at least one multi-carrier signal, the method comprising:

receiving at least one multi-carrier signal;

selecting at least two carrier signals from the at least one multi-carrier signal;

measuring a signal characteristic of each of the at least two carrier signals; and

determining the distance estimate between the mobile device and the wireless transceiver based at least partially upon the signal characteristic of each of the at least two carrier signals, wherein determining the distance estimate comprises:

determining a carrier timing estimate, based at least in part upon the first-arrival time, for each of a plurality of carrier signals from the at least one multi-carrier signal; and

combining the carrier timing estimates to form a multi-carrier timing estimate;

wherein the signal characteristic of the at least two carrier signals from the at least one multi-carrier signal is a first-arrival time.

2. The method of claim 1 , further comprising determining a position of the mobile device using the distance estimate determined between the mobile device and the wireless transceiver and distance estimates between the mobile device and other signal sources.

3. The method of claim 1 , wherein receiving the at least one multi-carrier signal comprises receiving a first multi-carrier signal from a first wireless communication network and a second multi-carrier signal from a second wireless communication network, the first wireless communication network differing from the second wireless communication network, and wherein selecting the at least two carrier signals comprises selecting a first carrier signal from the first multi-carrier signal and selecting a second carrier signal from the second multi-carrier signal.

4. The method of claim 1 , wherein the signal characteristic of the at least two carrier signals from the at least one multi-carrier signal is further related to signal strength.

5. The method of claim 1 , wherein determining the distance estimate comprises using the first-arrival time that minimizes the distance estimate.

6. The method of claim 1 , wherein determining the multi-carrier timing estimate comprises calculating a mean value of the carrier timing estimates.

7. The method of claim 1 , wherein determining the multi-carrier timing estimate comprises calculating a median value of the carrier timing estimates.

8. The method of claim 1 , wherein determining the multi-carrier timing estimate comprises identifying as an outlier at least one of the carrier timing estimates, with a corresponding carrier signal, based on comparing a carrier power of the corresponding carrier signal to carrier powers of other carrier signals from the at least one multi-carrier signal or based on comparing the carrier timing estimate to the carrier timing estimates of other carrier signals from the at least one multi-carrier signal.

9. The method of claim 8 , wherein the multi-carrier timing estimate is determined by excluding the outlier.

10. The method of claim 8 , wherein determining the multi-carrier timing estimate further comprises:

weighting the carrier timing estimates from the at least two carrier signals such that the outlier contribute less to the multi-carrier timing estimate than non-outlier carrier timing estimates; and

combining the weighted carrier timing estimates to form the multi-carrier timing estimate.

11. A method of determining a distance estimate between a mobile device and a wireless transceiver of a wireless communication system, the wireless transceiver communicating with the mobile device on a multi-carrier signal, the method comprising:

receiving the multi-carrier signal including a plurality of carrier signals generated using synchronized clocks;

selecting one of the plurality of carrier signals as a reference carrier signal and selecting a remainder of the plurality of carrier signals as at least one non-reference carrier signal; and

determining the distance estimate between the mobile device and the wireless transceiver using the reference carrier signal and the at least one non-reference carrier signal.

12. The method of claim 11 , further comprising determining a position of the mobile device using the distance estimate determined between the mobile device and the wireless transceiver and distance estimates between the mobile device and other signal sources.

13. The method of claim 11 , further comprising:

shifting a waveform of each of the at least one non-reference carrier signal according to a frequency difference relative to the reference carrier signal to form a shifted non-reference carrier signal waveform; and

combining a waveform of the reference carrier signal and the shifted non-reference carrier signal waveform to generate a composite signal;

wherein the distance estimate between the mobile device and the wireless transceiver is determined using the composite signal.

14. A method of determining a distance estimate between a mobile device and a wireless transceiver communicating with the mobile device on a plurality of carrier signals from at least one multi-carrier signal, the method comprising:

receiving the plurality of carrier signals from the at least one multi-carrier signal;

aligning the plurality of carrier signals based on respective known time offsets to form aligned carrier signals;

combining the aligned carrier signals to produce a composite signal; and

determining the distance estimate between the mobile device and the wireless transceiver using the composite signal.

15. An apparatus configured to determine a distance estimate between a mobile device and a wireless transceiver communicating with the mobile device on at least one multi-carrier signal, the apparatus comprising:

a transceiver configured to receive the at least one multi-carrier signal; and

a processor communicatively coupled to the transceiver and configured to:

receive the at least one multi-carrier signal;

select at least two carrier signals from the at least one multi-carrier signal;

measure a signal characteristic of each of the at least two carrier signals; and

determine the distance estimate between the mobile device and the wireless transceiver based at least partially upon the signal characteristic of each of the at least two carrier signals, wherein the processor configured to determine is configured to:

determine a carrier timing estimate, based at least in part upon the first-arrival time, for each of a plurality of carrier signals from the at least one multi-carrier signal; and

combine the carrier timing estimates to form a multi-carrier timing estimate;

wherein the signal characteristic of the at least two carrier signals from the at least one multi-carrier signal is a first-arrival time.

16. The apparatus of claim 15 , wherein the processor is further configured to:

determine a carrier timing estimate based the first-arrival time of each of the at least two carrier signals;

combine the carrier timing estimates to form a multi-carrier timing estimate.

17. The apparatus of claim 16 , wherein the processor is further configured to calculate a mean value of the carrier timing estimates.

18. A computer program product comprising:

a non-transitory processor-readable medium storing processor-readable instructions configured to cause a processor to:

receive at least one multi-carrier signal for communication between a wireless transceiver and a mobile device;

select at least two carrier signals from the at least one multi-carrier signal;

measure a signal characteristic of each of the at least two carrier signals; and

determine a distance estimate between the mobile device and the wireless transceiver based at least partially upon the signal characteristic of each of the at least two carrier signals, wherein the instructions configured to cause the processor to determine the distance estimate comprises instructions configured to cause the processor to:

determine a carrier timing estimate, based at least in part upon the first-arrival time, for each of a plurality of carrier signals from the at least one multi-carrier signal; and

combine the carrier timing estimates to form a multi-carrier timing estimate;

wherein the signal characteristic of the at least two carrier signals from the at least one multi-carrier signal is a first-arrival time.

19. The product of claim 18 , wherein the instructions are further configured to cause the processor to:

determine a carrier timing estimate, based at least in part upon the first-arrival time, for each of a plurality of carrier signals; and

combine the carrier timing estimates to form a multi-carrier timing estimate.

20. The product of claim 19 , wherein the instructions are further configured to cause the processor to calculate a mean value of the carrier timing estimates.

21. An apparatus configured to determine a distance estimate between a mobile device and a wireless transceiver communicating with the mobile device using at least one multi-carrier signal, the apparatus comprising:

means for receiving at least one multi-carrier signal;

means for selecting at least two carrier signals from the at least one multi-carrier signal;

means for measuring a signal characteristic of each of the at least two carrier signals; and

means for determining the distance estimate between the mobile device and the wireless transceiver based at least partially upon the signal characteristic of each of the at least two carrier signals, wherein the means for determining the distance estimate comprises:

means for determining a carrier timing estimate, based at least in part upon the first-arrival time, for each of a plurality of carrier signals from the at least one multi-carrier signal; and

means for combining the carrier timing estimates to form a multi-carrier timing estimate;

wherein the signal characteristic of the at least two carrier signals from the at least one multi-carrier signal is a first-arrival time.

22. The apparatus of claim 21 , wherein the means for determining the distance estimate comprise:

means for determining a carrier timing estimate, based at least in part upon the first-arrival time, for each of a plurality of carrier signals from the at least one multi-carrier signal; and

means for combining the carrier timing estimates to form a multi-carrier timing estimate.

23. The apparatus of claim 22 , wherein the means for determining the multi-carrier timing estimate comprise means for calculating a mean value of the carrier timing estimates.