Method for improved line-of-sight signal detection using RF model parameters

• US 6,259,894 B1
• Filed: 12/04/1997
• Issued: 07/10/2001
• Est. Priority Date: 12/04/1997
• Status: Expired due to Term

• Current Assignee: Nokia of America Corporation (Nokia Corporation)
• Original Assignee: Lucent Technologies, Inc. (Nokia Corporation)
• Inventors: Tekinay, Sirin
• Primary Examiner(s): Urban, Edward F.
• Assistant Examiner(s): Jackson, Blane J.
• Application Number:
  US08/984,780
• Time in Patent Office: 1,314 Days
• Field of Search: 342/357, 342/457, 342/465, 342/451, 342/463, 342/453, 342/458, 455/506, 455/132, 455/278, 455/446, 455/422, 455/65, 455/67.1, 455/226.1, 455/296, 455/67.6, 455/456, 375/200, 375/347, 375/343, 375/346
• US Class Current: 455/65
• CPC Class Codes: G01S 3/46 using antennas spaced apart and measuring phase or time difference between signals therefrom, i.e. path-difference systems
• CPC Class Codes: H04B 17/391 Modelling the propagation channel
• CPC Class Codes: H04W 56/0085 detecting a given structure in the signal

Abstract

The invention provides a method for “adjusting” an identified or measured time-of-arrival of the first-arriving component of an incoming to more accurately reflect the time-of-arrival of the line-of-sight component of the incoming signal by reducing the so-called time-shift due to multipathing. In accordance with the principles of the present invention, the adjustment to the identified time-of-arrival of the first-arriving component is based on at least one parameter of an RF model that characterizes the scattering hostility of the RF environment in which the incoming signal traveled. The resultant adjusted time-of-arrival reflects the time at which the line-of-sight component of the incoming signal would have arrived if the RF environment were scatter-free.

Claims

1. A method comprising the step of:

adjusting an identified time-of-arrival of a first-arriving multipath component of an incoming signal by an amount based on at least one parameter of an RF model that characterizes the scattering hostility of the RF environment in which said incoming signal traveled;

said adjustment thereby reducing a time-shift of said identified time of arrival due to a blocked line-of-sight path in said RF environment in which said incoming signal traveled.

2. The method of claim 1 wherein each said at least one parameter is a measure of the number of multipaths a signal incurs as a result of traveling in a region of the RF environment.

3. The method of claim 2 wherein each said at least one parameter is a fractal dimension.

4. The method of claim 3 wherein said step of adjusting comprises the steps of:

obtaining a basis parameter that characterizes the scattering hostility of a given region of the RF environment, said basis parameter having an associated basis time-shift that is a measure of the time between the time-of-arrival of the first-arriving component of a given incoming signal and an expected time-of-arrival of the line-of-sight component of the given signal, if the given region in which the given signal traveled was scatter-free; and

adjusting the basis time-shift by an amount based on the difference between the value of said basis parameter and said at least one parameter to obtain said time-shift of the first-arriving component of said incoming signal.

5. A method, comprising:

receiving an incoming signal from a region of an RF environment;

identifying a time-of-arrival of a first-arriving multipath component of the incoming signal;

obtaining a parameter that characterizes a scattering hostility of the region of the RF environment; and

adjusting the identified time-of-arrival of the first-arriving multipath component by an amount based on the parameter.

6. The method of claim 5, wherein the adjustment reduces a time-shift of the identified time-of-arrival due to a blocked line-of-sight in the region of the RF environment.

7. The method of claim 5, wherein the parameter is a measure of a number of multipaths a signal incurs while traveling in the region of the RF environment.

8. The method of claim 5, wherein the parameter is a fractal dimension.

9. The method of claim 6, further comprising:

obtaining a basis parameter for the region of the RF environment, the basis parameter having a known basis time-shift;

calculating a difference between the parameter and the basis parameter; and

obtaining a time-shift of the first-arriving component from the difference and the known basis time-shift.

10. The method of claim 9, wherein the step of adjusting includes adjusting the identified time-of-arrival of the first-arriving component based on the obtained time-shift of the first-arriving component.

11. An apparatus to adjust an identified time-of-arrival of a first-arriving component of an incoming signal from a region of an RF environment, comprising:

a processor having first and second inputs and an output, the first input being connected to a signal indicating the identified time-of-arrival of the first-arriving component of the incoming signal; and

a device connected to the second input and including a set of parameters characterizing a scattering hostility of different regions of the RF environment wherein the processor adjusts the identified time-of-arrival of the first-arriving multipath component by an amount based on at least one of the set of parameters.

12. The apparatus of claim 11, wherein the processor adjusts the identified time-of-arrival of the first-arriving component, and outputs the adjusted time-of-arrival, based on a parameter from the device, the parameter being associated with the region of the RF environment from which the incoming signal was received.