초록 ▼

A system and method for accurately determining time of arrival using a mathematical model that mimics a correlation function. A correlation value is sampled at a predetermined periodic interval and a maximum correlation value, coinciding with a particular point in time, is determined. The mathematic

A system and method for accurately determining time of arrival using a mathematical model that mimics a correlation function. A correlation value is sampled at a predetermined periodic interval and a maximum correlation value, coinciding with a particular point in time, is determined. The mathematical model uses the maximum measured correlation value and correlation values at adjacent sample points to determine coefficients for the selected mathematical model. The coefficients may be calculated and used to determine the actual peak, which may fall in-between the sample points. The actual peak value is used to accurately determine the time of arrival of a signal. Time of arrival signals from a plurality of remote transmitters are used along with conventional triangulation techniques to accurately determine the location of the wireless unit.

대표청구항 ▼

What is claimed is: 1. A system to determine signal time of arrival in a wireless communication system, comprising: a searcher configured to analyze received signals to determine a correlation signal level at predetermined points in time, the searcher configured to determine a maximum signal level

What is claimed is: 1. A system to determine signal time of arrival in a wireless communication system, comprising: a searcher configured to analyze received signals to determine a correlation signal level at predetermined points in time, the searcher configured to determine a maximum signal level at a selected one of the predetermined points in time; and a modeling processor configured to generate a second order polynomial mathematical model of a predetermined response function using the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time, the modeling processor configured to determine a time associated with a peak correlation signal level based on the mathematical model, and further configured to determine a time of arrival of the received signals based on the time associated with the peak correlation signal level, an offset time encoded in the received signals, the mathematical model, and an iterative algorithm that avoids a division operation. 2. The system of claim 1 wherein the correlation signal levels are based on received signal strength of the received signals. 3. The system of claim 1, wherein the offset time encoded in the received signals identifies a source of the received signals. 4. The system of claim 1, further comprising a timer configured to provide system time used to measure the offset time. 5. The system of claim 1 wherein the mathematical model is a second-order mathematical function with three coefficients, and wherein the modeling processor is configured to determined the three coefficients in the mathematical model based on the maximum signal level at the selected one of the predetermined points in time and two correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time. 6. The system of claim 1 wherein the maximum signal level at the selected one of the predetermined points in time and the correlation signal levels from the predetermined points in time adjacent the selected one of the predetermined points in time are used to determine coefficients in the mathematical model. 7. The system of claim 6 wherein the coefficients in the mathematical model are used to determine the time associated with the peak correlation signal level based on the mathematical model. 8. The system of claim 1 wherein the mathematical model is a quadratic function having the form: y(x)=ax2 +bx+c. 9. The system of claim 8 wherein the modeling process is configured to determine coefficients in the mathematical model based on the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time. 10. The system of claim 9 wherein the modeling processor is configured to determine a time associated with the peak correlation signal based on the coefficients in the mathematical model. 11. A system to determine signal time of arrival in a wireless communication system, comprising: a searcher configured to analyze received signals to determine correlation signals level at predetermine points in time, the searcher configured to determine a maximum signal level at a selected one of the predetermined points in time; and a modeling processor configured to generate an nth order polynomial, n being greater than two, mathematical model of a predetermined response function based on the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time, the modeling processor configured to determine a time associated with a peak correlation signal level based on the mathematical model, and configured to determine coefficients in the mathematical model based on the maximum signal level and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time, and wherein the modeling processor is further configured to determine a time of arrival of the received signals based on at least the time associated with the peak correlation signal. 12. A system for determining signal time of arrival in a wireless communication system, comprising: analysis means for analyzing received signals to determine correlation signal levels at predetennined points in time and for determining a maximum signal level at a selected one of the predetermined points in time; and modeling means for generating a second-order mathematical model of a predetermined response function based on the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time, determining a time associated with a peak correlation signal level based on the mathematical model, and further for determining a time of arrival of the received signals based on the time associated with the peak correlation signal level, an offset time encoded in the received signals, the mathematical model and an iterative algorithm that avoids a division operation. 13. The system of claim 12 wherein the correlation signal levels are based on received signal strength of the received signals. 14. The system of claim 12 wherein the modeling means uses the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined paints in time adjacent the selected one of the predetermined points in time to determine coefficients in the mathematical model. 15. The system of claim 14 wherein the coefficients in the mathematical model are used to determine the time associated with the peak correlation signal level based on the mathematical mode. 16. A system for determining signal time of arrival in a wireless communication system, compnsing: analysis means for analyzing received signals to determine a correlation signal level at predetermined points in time and for determining a maximum signal level at a selected one of the predetermined points in time; and modeling means for generating an nth order mathematical model, n being greater than two, of a predetermined response function using the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time, the mathematical model configured to determine a time associated with a peak correlation signal level and further for determining a time of arrival of the received signals based on at least the time associated with the peak correlation signal. 17. A method for determining signal time of arrival in a wireless communication system, comprising: analyzing received signals to determine a correlation signal level at predetermined points in time; determining a maximum signal level at a selected one of the predetermined points in time; generating a second order mathematical model of a predetermined response function using the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time; determining a time associated with a peak correlation signal level based on the mathematical model; determining an offset time encoded within the received signals, the offset time identifying a source of the received signals; and determining a time of arrival of the received signals based on the time associated with the peak correlation signal level, the offset time, the mathematical model and an iterative algorithm that avoids a division operation. 18. The method of claim 17 wherein the correlation signal levels are based on received signal strength of the received signals. 19. The method of claim 17 wherein coefficients in the second-order mathematical function are used to determine the time associated with the peak correlation signal level based on the mathematical model. 20. The method of claim 17 wherein the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time are used to determine coefficients in the mathematical model. 21. The method of claim 20 wherein the coefficients in the mathematical model are used to determine the time associated with the peak correlation signal level based on the mathematical model. 22. A method for determining signal time of arrival in a wireless communication system, comprising: receiving wireless signals on an antenna; analyzing the received signals to determine a correlation signal levels at predetermined points in time; determining a maximum signal level at a selected one of the predetermined points in time; generating an nth order mathematical model, n being greater than two, of a predetermined response function using the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time; and determining a time associated with a peak correlation signal level based on the mathematical model, and determining coefficients of the mathematical model based on the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time, and determining a time of arrival of the received signals based at least on the time associated with the peak correlation signal level. 23. An article comprising a machine readable medium having stored thereon executable instructions, that, when executed cause one or more machines to perform operations comprising: receiving correlation signal levels at predetermined points in time; generating a maximum signal level at a selected one of the predetermined points in time; generating a second order mathematical model of a predetermined response function using the maximum signal level at the selected one of the predetermined points in time and correlation signal levels from predetermined points in time adjacent the selected one of the predetermined points in time; determining time information associated with a peak correlation signal level based on the mathematical model; determining offset time information encoded within the received signals, the offset time identifying a source of the received signals; and determining a time of arrival of the received signals based on the time information associated with the peak correlation signal level, the offset time information, the mathematical model and an iterative algorithm that avoids a division operation.