Antenna array calibration for wireless communication systems

• US 20060240784A1
• Filed: 07/19/2005
• Published: 10/26/2006
• Est. Priority Date: 04/22/2005
• Status: Abandoned Application

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Naguib, Ayman Fawzy, Gorokhov, Alexei
• Application Number:
  US11/186,160
• Publication Number:
  US 20060240784A1
• Time in Patent Office: Days
• US Class Current: 455/73
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H04B 17/21 for calibration; for correcting measurements
• CPC Class Codes: H04B 17/26 using historical data, averaging values or statistics
• CPC Class Codes: H04B 17/318 Received signal strength
• CPC Class Codes: H04B 17/336 Signal-to-interference ratio [SIR] or carrier-to-interference ratio [CIR]

Abstract

Systems and methodologies are described that facilitate calibrating an antenna array in a wireless network by generating a copy of a transmitted signal or transmitted signal from a transmit chain of an antenna and providing it to a receive chain of one or more antennas in the array for comparison to obtain a gain mismatch measurement. Such comparisons can be performed for each antenna in the array to facilitate obtaining multiple measurements, upon which gain mismatch estimations can be generated. Additionally, the array and/or individual antennas therein can be calibrated based on the mismatch estimates

Claims

1. A method of calibrating an antenna array in a wireless network, comprising:

providing a copy of an output transmit signal from a transmit chain of a first antenna to a receive chain of the first antenna; and

comparing the copy of the output transmit signal to an output receive chain signal and determining a first overall gain mismatch measurement, A_n.

2. The method of claim 1, further comprising iterating comparisons for n antennas in the array to collect n measurements of A_n, where n is an integer.

3. The method of claim 2, further comprising:

providing the copy of the output transmit signal from the first antenna to a receive chain of a second antenna; and

comparing the copy of the output transmit signal to an output receive chain signal of the second antenna and determining a second overall gain mismatch measurement, B_n.

4. The method of claim 3, further comprising iterating for n-1 antennas in the array to collect n-1 measurements of B_n, where n is an integer.

5. The method of claim 4, further comprising determining receiver chain mismatch and transmit chain mismatch based at least in part on the n measurements of A_n and the n-1 measurements of B_n.

6. The method of claim 1, further comprising employing a time domain duplexing protocol to transmit and receive signals in the wireless network

7. The method of claim 6, further comprising providing the copy of the transmitted signal to the receive chain for comparison during a period in which the receive chain is dormant.

8. The method of claim 6, further comprising providing the copy of the transmitted signal to the receive chain for comparison during a period in which the first antenna is transmitting.

9. The method of claim 1, wherein providing a copy comprises providing copies of a plurality of signals and comparing the copy comprises comparing each of the copies and determining the first overall gain mismatch measurement to be an average of the mismatch measurements for the plurality of copies.

10. The method of 9, wherein the plurality of signals corresponds to signals transmitted at different time periods.

11. A method of calibrating an antenna array in a wireless network, comprising:

providing an output transmit signal from a transmit chain of a first antenna to receive chains of all antennas in the array; and

comparing the output transmit signal to an output receive chain signal at each antenna in the array and determining a first overall gain mismatch measurement, A_n.

12. The method of claim 11, further comprising iterating the method for each antenna in the array to collect n measurements of A_n, where n is an integer.

13. The method of claim 12, further comprising:

providing a copy of an output transmit signal from each antenna in the array to a receive chain of the first antenna; and

comparing the output transmit signals to an output receive chain signal of the first antenna and determining a second overall gain mismatch measurement, B_n.

14. The method of claim 13, further comprising iterating the method for each antenna in the array to collect n measurements of B_n, where n is an integer.

15. The method of claim 14, further comprising determining receive chain mismatch and transmit chain mismatch based at least in part on the n measurements of A_n and the n measurements of B_n.

16. The method of claim 11, further comprising employing a time domain duplexing protocol to transmit and receive signals in the wireless network

17. The method of claim 16, further comprising providing the transmitted signal to the receive chain for comparison during a period in which the receive chain is dormant.

18. The method of claim 16, further comprising providing the transmitted signal to the receive chain for comparison during a period in which the first antenna is transmitting.

19. The method of claim 11, wherein providing the transmitted signal comprises providing a plurality of transmitted signals from the first transmitter chain to receive chains of all antennas in the array and comparing comprises comparing each of the transmitted signals at the receive chains of all antennas in the array and determining the first overall gain mismatch measurement to be an average of the mismatch measurements for the plurality of transmitted signals.

20. The method of 19 wherein the plurality of transmitted signals corresponds to signals transmitted at different time periods.

21. An apparatus that facilitates calibrating an antenna array, comprising:

a calibration component that generates a receive chain output signal for each antenna in the array;

a sampling component that generates a copy of a transmit chain output signal for antennas in the array; and

a mismatch estimation component that determines gain mismatch attributable to transmit chains of antennas in the array and to receive chains of antennas in the array.

22. The apparatus of claim 21, the calibration component provides a copy of a first antenna transmit chain output to a receive chain of the first antenna.

23. The apparatus of claim 22, the calibration component compares the copy of the transmit chain output of the first antenna to the receive chain output signal for the first antenna to determine a mismatch measurement A_n.

24. The apparatus of claim 23, the calibration component performs an iteration of the comparison of a transmit chain output signal to a receive chain output signal for each antenna in the array to obtain n measurements of A_n, where n is the number of antennas in the array.

25. The apparatus of claim 24, the calibration component provides the copy of the first antenna transmit chain output signal to a receive chain of a next antenna in the array and performs a comparison to determine a mismatch measurement B_n.

26. The apparatus of claim 25, the calibration component performs an iteration of the comparison of the first antenna transmit chain output signal to the next antenna receive chain output signal for each antenna in the array to obtain n-1 measurements of B_n, where n is the number of antennas in the array.

27. The apparatus of claim 26, the mismatch estimation component estimates gain mismatch due to receive chains across the antenna array based at least in part on the n measurements of A_n and the n-1 measurements of B_n.

28. The apparatus of claim 27, the mismatch estimation component estimates gain mismatch due to transmit chains across the antenna array based at least in part on the n measurements of A_n and the n-1 measurements of B_n.

29. The apparatus of claim 28, the calibration component generates a multiplier by which the transmit chain output signals of one or more antennas in the array are pre-multiplied to compensate for gain mismatch due to at least one of the receiver chains and the transmit chains in the antenna array to calibrate the array.

30. The apparatus of claim 21, the calibration component, for each antenna, provides a copy of a given antenna transmit chain output signal generated by the sampling component to the receive chain of every antenna in the array and compares a receive chain output signal for every antenna in the array to the transmit chain output signal copy to obtain n gain mismatch measurements An, where n is the number of antennas in the array.

31. The apparatus of claim 30, the calibration component, for each antenna, provides a copy of a transmit chain output signal from every antenna in the array to the receive chain of the given antenna and compares the copies of the transmit chain output signals to a receive chain output signal of the given antenna to obtain n gain mismatch measurements B_n, where n is the number of antennas in the array.

32. The apparatus of claim 31, the mismatch estimation component estimates gain mismatch due to transmit chains across the antenna array based at least in part on the n measurements of A_n and the n measurements of B_n.

33. The apparatus of claim 32, the calibration component generates a multiplier by which the transmit chain output signals of one or more antennas in the array are pre-multiplied to compensate for gain mismatch due to at least one of the receiver chains and the transmit chains in the antenna array to calibrate the array.

34. The apparatus of claim 31, wherein the wireless network employs a time domain duplexed communication protocol.

35. The apparatus of claim 34, comparisons of transmit chain output signals and receive chain output signals are performed during a transmission period.

36. The apparatus of claim 21, wherein the mismatch estimation component determines gain mismatch by averaging a gain mismatch over a plurality of transmit chain output signals.

37. An apparatus that facilitates calibrating an antenna array and mitigating gain mismatch in a wireless network, comprising:

means for copying a transmit chain output signal transmitted from each antenna in the array; and

means for comparing the transmit chain output signal copy of each antenna to a receive chain output signal from every antenna in the array to obtain a plurality of gain mismatch measurements.

38. The apparatus of claim 37, further comprising means for estimating gain mismatch due to the transmit chains of antennas in the array and gain mismatch due to the receive chains in the array.

39. The apparatus of claim 38, further comprising means for compensating for gain mismatch to calibrate the array.

40. The apparatus of claim 39, the means for compensating generates a multiplier by which transmitted signals are pre-multiplied to offset estimated gain mismatch.

41. The apparatus of claim 37, the wireless network employs a time division duplexed channel transmission technique.

42. A computer-readable medium having stored thereon computer-executable instructions for:

generating a transmit chain output signal transmitted from antennas in an antenna array; and

comparing the transmit chain output signal of each antenna to a receive chain output signal from the antennas to obtain a plurality of gain mismatch measurements.

43. The computer-readable medium of claim 42, further comprising instructions for determining gain mismatch due to the receive chains of antennas in the array based at least in part on the plurality of gain mismatch measurements.

44. The computer-readable medium of claim 43, further comprising instructions for compensating for receive chain gain mismatch by generating a pre-multiplier by which a signal to be transmitted can be adjusted.

45. The computer-readable medium of claim 42, further comprising instructions for determining gain mismatch due to the transmit chains of antennas in the array based at least in part on the plurality of gain mismatch measurements.

46. The computer-readable medium of claim 45, further comprising instructions for compensating for transmit chain gain mismatch by generating a pre-multiplier by which a signal to be transmitted can be adjusted.

47. The computer-readable medium of claim 42, further comprising instructions for comparing transmit chain output signal to a receive chain output signal when the receive chain is not receiving an input signal.