Method for calibrating an AOA location system for frequency hopping air interfaces

• US 20040252752A1
• Filed: 02/02/2004
• Published: 12/16/2004
• Est. Priority Date: 01/31/2003
• Status: Active Grant

• Current Assignee: CommScope Technologies, LLC (CommScope Holding Company, Inc.)
• Original Assignee: Andrew LLC (CommScope Holding Company, Inc.)
• Inventors: Gravely, Thomas B., Carlson, John P., Kennedy, Joseph P. Jr., Blackburn, Doug, Alles, Martin C.
• Granted Patent: US 7,405,696 B2
• Time in Patent Office: Days
• US Class Current: 375/132
• CPC Class Codes: G01S 19/03 Cooperating elements; Interaction or communication between different cooperating elements or between cooperating elements and receivers
• CPC Class Codes: G01S 5/021 Calibration, monitoring or correction G01S5/0252 takes precedence
• CPC Class Codes: H04B 1/713 using frequency hopping
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management

Abstract

A method for calibrating an antenna and signal processing system enabling angle or arrival (AOA) determination for a frequency hopping signal, in which a calibration coefficient is determined in response to one or more calibration signals injected into the system at one or more of the frequencies in the hopping sequence and proximate in time to reception of the communication signal. The calibration coefficients are reflective of a frequency and time dependent parameter of a path between the antenna and wireless location sensor. The AOA is determined as a function of the calibration coefficient and the radio frequency energy of the received communication signal. Several embodiment of the method are illustrated.

Claims

1. A method of calibrating an antenna array and signal processing system for receiving a frequency hopping communication signal comprising the steps of:

obtaining a frequency hopping sequence of the communication signal;

receiving the communication signal;

injecting a calibration signal at one frequency of the frequency hopping sequence of the communication signal in response to receipt of said communication signal;

determining a calibration coefficient C₁ for said one frequency; and

, applying C₁ to a received signal at each frequency of the received signal.

2. The method of claim 1 wherein the received signal is said communication signal.

3. The method of claim 1 wherein the received signal is a later received signal.

4. The method of claim 1 further comprising the step of determining the AOA of the communication signal based on said communication signal and C₁.

5. The method of claim 1 wherein said frequency hopping sequence is comprised of N frequencies f_i where i=1 to N and the calibration coefficient C₁ is associated with each f_i.

6. The method of claim 1 wherein the step of injecting the calibration signal is proximate in time to receiving the received signal.

7. The method of claim 1 wherein the one frequency is determined as a function of an average frequency of the hopping sequence.

8. The method of claim 1 wherein the one frequency is the first frequency in the frequency hopping sequence.

9. The method of claim 1 wherein the one frequency is arbitrarily chosen from the frequency hopping sequence.

10. The method of claim 1 wherein the one frequency is determined as a function of a first moment of the frequencies in the frequency hopping sequence.

11. A method of calibrating an antenna array and signal processing system for receiving a frequency hopping communication signal comprising the steps of:

obtaining a frequency hopping sequence of the communication signal

injecting a calibration signal at one frequency of the frequency hopping sequence of the communication signal in response to receipt of said communication signal;

determining a calibration coefficient C₁ for said one frequency;

storing said calibration coefficient C₁,

receiving the communication signal; and

,

applying the calibration coefficient C₁ to the communication signal for each frequency of the communication signal.

12. The method of claim 11 wherein the step of injecting a calibration signal is initiated periodically.

13. The method of claim 11 wherein the step of injecting is triggered in anticipation of receiving said communication signal.

14. The method of claim 11 further comprising the step of determining the AOA of the communication signal based on said communication signal and C₁.

15. The method of claim 11 wherein said frequency hopping sequence is comprised of N frequencies f_i where i=1 to N and the calibration coefficient C₁ is associated with each f_i.

16. The method of claim 11 wherein the one frequency is determined as a function of an average frequency of the hopping sequence.

17. The method of claim 11 wherein the one frequency is the first frequency in the frequency hopping sequence.

18. The method of claim 11 wherein the one frequency is arbitrarily chosen from the frequency hopping sequence.

19. The method of claim 11 wherein the one frequency is determined as a function of a first moment of the frequencies in the frequency hopping sequence.

20. In a network overlay geolocation system, a method for locating a mobile appliance including determining the AOA of an uplink signal from the mobile appliance at a base station from measurements, by a wireless location sensor, of an attribute of the uplink signal and a frequency specific calibration of a path between a multi element antenna array and the wireless location sensor, the improvement comprising the steps of:

(a) collecting segments of a frequency hopping signal associated with a specific hop;

(b) calibrating the path, at approximately the specific hop'"'"'s frequency, proximate in time to the collecting of the segment, over a plurality of hopping sequence cycles; and

,

(c) estimating the AOA of a frequency hopping signal from the collected segments associated with the specific hop and the path calibrations at approximately the specific hop'"'"'s frequency.

21. The method according to claim 20 wherein the step of calibrating includes generating a calibration signal.

22. The method according to claim 20 wherein the step of calibrating includes tuning the calibration source to the specific hop frequency.

23. The method according to claim 20 where the plurality of hopping sequence cycles is based on hop duration.

24. The method according to claim 20 wherein the network is a GSM system.