Method and apparatus for calibrating antenna arrays

• US 5,546,090 A
• Filed: 04/28/1994
• Issued: 08/13/1996
• Est. Priority Date: 12/12/1991
• Status: Expired due to Term

• Current Assignee: Intel Corporation
• Original Assignee: ArrayComm LLC (Ygomi LLC)
• Inventors: Parish, David M., Barratt, Craig H., Yang, Chinping Q., Orchard, John T., Roy, III, Richard H.
• Primary Examiner(s): Sotomayor, John B.
• Application Number:
  US08/234,747
• Time in Patent Office: 838 Days
• Field of Search: 342/42, 342/44, 342/50, 342/51, 342/174
• US Class Current: 342/174
• CPC Class Codes: G01S 13/74 Systems using reradiation of radio waves, e.g. secondary radar systems; Analogous systems
• CPC Class Codes: G01S 2013/0245 Radar with phased array antenna
• CPC Class Codes: G01S 5/12 by co-ordinating position lines of different shape, e.g. hyperbolic, circular, elliptical or radial
• CPC Class Codes: G01S 7/4017 of HF systems
• CPC Class Codes: G01S 7/4052 by simulation of echoes
• CPC Class Codes: G01S 7/4095 the external reference signals being modulated, e.g. rotating a dihedral reflector or modulating a transponder for simulation of a Doppler echo
• CPC Class Codes: H01Q 1/246 specially adapted for base stations
• CPC Class Codes: H01Q 3/2605 Array of radiating elements provided with a feedback control over the element weights, e.g. adaptive arrays
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H04B 17/309 Measuring or estimating channel quality parameters
• CPC Class Codes: H04B 7/0408 using two or more beams, i.e. beam diversity
• CPC Class Codes: H04B 7/0491 using two or more sectors, i.e. sector diversity
• CPC Class Codes: H04B 7/0615 of weighted versions of same signal
• CPC Class Codes: H04B 7/0697 using spatial multiplexing
• CPC Class Codes: H04B 7/0842 Weighted combining
• CPC Class Codes: H04B 7/0845 per branch equalization, e.g. by an FIR-filter or RAKE receiver per antenna branch rake receivers as such H04B1/7115
• CPC Class Codes: H04W 16/28 using beam steering
• CPC Class Codes: H04W 64/00 Locating users or terminals or network equipment for network management purposes, e.g. mobility management
• CPC Class Codes: H04W 84/025 with acknowledge back capability

Abstract

A method and apparatus for calibrating antenna array systems comprising of a portable transponder (118) and a calibration processor (124). Calibration processor (124) generates calibration transmit signals which it transmits using transmit signal processor (104) and antenna array (111). Transponder (118) echoes these signals back and they are acquired by calibration processor (124) through antenna array (111) and receive signal processor (106). Calibration processor (124) processes the received signals to calculate antenna calibration vector (102).

Claims

1. A calibration system for an RF signal transceiving system including an antenna array comprising

an antenna array including a plurality of antennas for transmitting a first plurality of signals including individually identifiable signals and for receiving a second plurality of signals from a transponder signal,

signal processing means for generating said first plurality of signals and for processing said second plurality of signals,

means for applying said first plurality of signals to said antenna array,

transponder means for receiving said first plurality of signals and in response thereto retransmitting said transponder signal to said antenna array,

means for applying said second plurality of signals received from said antenna array to said signal processing means, said signal processing means comparing said second plurality of signals to determine receive calibration vectors,

said signal processing means determining transmit calibration vectors by comparing said first plurality of signals and said second plurality of signals.

2. The calibration system as defined by claim 1 wherein said first plurality of signals are individually identifiable by frequency.

3. The calibration system as defined by claim 1 wherein said first plurality of signals are individually identifiable by time.

4. The calibration system as defined by claim 1 wherein said first plurality of signals are individually identifiable by a plurality of spreading functions.

5. The calibration system as defined by claim 1 wherein said transponder means retransmits said transponder signal in frequencies differing from frequencies of said first plurality of signals.

6. The calibration system as defined by claim 1 in which transponder means retransmits said transponder signal in time periods differing from time periods of said transmitted first plurality of signals.

7. The calibration system as defined by claim 1 wherein said transponder means retransmits said transponder signal using a spreading function which is different from a spreading function for said first plurality of signals.

8. The calibration system as defined by claim 1 wherein said signal processing means generates a receive calibration vector by first forming a receive data matrix from said second plurality of signals as follows:

space="preserve" listing-type="equation">S.sub.rx =[S.sub.r1, S.sub.r2, . . . S.sub.rm ]

where S_rx is the receive data matrix and S_r1 through S_rm are each of said second plurality of signals,

forming a received data covariance matrix defined as the conjugate of the product of the received data covariance matrix with the conjugate transpose of said data covariance matrix as follows;

space="preserve" listing-type="equation">R.sub.rx = S.sub.rx.sup.H S.sub.rx

where M^H indicates conjugate transpose of matrix M and then performing an eigenvalue decomposition of R_rx to determine a receive calibration vector, v_rx in accordance with the following equation;

space="preserve" listing-type="equation">R.sub.rx v.sub.rx =λ

.sub.m v.sub.rx

where λ

_m is the largest eigenvalue of R_rx and v_rx is a corresponding eigenvector.

9. The calibration system as defined by claim 1 wherein said antenna array includes a plurality of antennas each of which transmits and receives signals.

10. The calibration system as defined by claim 1 wherein said antenna array includes a first plurality of antennas for transmitting said first plurality of signals and a second plurality of antennas for receiving said second plurality of signals.

11. The calibration system as defined by claim 1 wherein said transponder means is located in a handset and said RF signal transceiving system comprises a cellular telephone transceiving system.

12. A calibration system for determining transmit calibration vectors for an antenna array in an RF transceiving system comprising

an antenna array including a plurality of antennas for transmitting a first plurality of signals,

signal generator means for generating said first plurality of signals including individually identifiable signals,

means for applying said first plurality of signals to said antenna array,

transponder means for receiving said plurality of signals and in response thereto retransmitting a transponder signal,

antenna means for receiving said transponder signal, and

signal processing means for processing said transponder signal, said signal processing means determining a transmit calibration vector by comparing said first plurality of signals and said transponder signal.

13. The calibration system as defined by claim 12 wherein said first plurality of signals are individually identifiable by frequency.

14. The calibration system as defined by claim 12 wherein said first plurality of signals are individually identifiable by time.

15. The calibration system as defined by claim 12 wherein said first plurality of signals are individually identifiable by a plurality of spreading functions.

16. The calibration system as defined by claim 12 wherein said transponder means retransmits said transponder signal in frequencies differing from frequencies of said first plurality of signals.

17. The calibration system as defined by claim 12 in which transponder means retransmits said transponder signal in time periods differing from time periods of said first plurality of signals.

18. The calibration system as defined by claim 12 wherein said transponder means retransmits said transponder signal using a spreading function which is different from a spreading function for said first plurality of signals.

19. A calibration system for determining receive calibration vectors for an antenna array in an RF receiver system comprising

signal transmission means for generating and transmitting a transmission signal,

transponder means for receiving said transmission signal and in response thereto retransmitting a transponder signal,

an antenna array for receiving said transponder signal and producing a plurality of received signals, and

signal processing means for comparing said plurality of received signals and producing receive calibration vectors for said antenna array.

20. A method of calibrating an RF transceiver system including an antenna array comprising the steps of:

transmitting a first plurality of signals from said antenna array,

receiving said first plurality of signals with transponder means and retransmitting a transponder signal back to said antenna array,

generating a receive calibration vector using said transponder signal as received by individual antenna elements, and

generating transmit calibration vectors by comparing said first plurality of signals and said transponder signal as received by said individual antenna elements.

21. The method as defined by claim 20 wherein said step of transmitting includes individually identifying said first plurality of signals.

22. The method as defined by claim 21 wherein said step of transmitting includes individually identifying said first plurality of signals by frequency.

23. The method as defined by claim 21 wherein said step of transmitting includes individually identifying said first plurality of signals by time.

24. The method as defined by claim 21 wherein said step of transmitting includes individually identifying said first plurality of signals by means of a plurality of spreading functions.

25. The method as defined by claim 21 wherein said step of retransmitting said transponder signal includes frequency shifting the received first plurality of signals.

26. The method as defined by claim 21 wherein said step of retransmitting said transponder signal includes retransmitting the received first plurality of signals in a predetermined time slot.

27. The method as defined by claim 21 wherein said step of retransmitting said transponder signal includes changing spreading functions of the received plurality of signals.

28. A method of determining transmit calibration vectors for an antenna array in an RF transmission system comprising

transmitting a first plurality of signals from said antenna array, said first plurality of signals including individual identifiable signals transmitted from individual antenna elements in said antenna array,

receiving said first plurality of signals with transponder means and in response thereto retransmitting a transponder signal,

receiving said transponder signal, and

generating transmit calibration vectors by comparing said transponder signal and said first plurality of signals.

29. A method of determining receive calibration vectors for an antenna array in an RF receiver system comprising

transmitting a first RF signal,

receiving said first RF signal with transponder means and in response thereto retransmitting a transponder signal,

receiving said transponder signal with said antenna array and producing a plurality of received signals, and

comparing said plurality of received signals and producing receiver calibration vectors for said antenna array.