METHOD IN A WIRELESS REPEATER EMPLOYING AN ANTENNA ARRAY INCLUDING VERTICAL AND HORIZONTAL FEEDS FOR INTERFERENCE REDUCTION

• US 20120015603A1
• Filed: 06/07/2011
• Published: 01/19/2012
• Est. Priority Date: 07/14/2010
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Proctor, James Arthur Jr., Gainey, Kenneth M., Howard, Steven J., Inanoglu, Hakan
• Granted Patent: US 8,787,248 B2
• Time in Patent Office: Days
• US Class Current: 455/9
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H04B 7/0691 using subgroups of transmit antennas
• CPC Class Codes: H04B 7/0874 using subgroups of receive antennas
• CPC Class Codes: H04B 7/15571 by signal isolation, e.g. isolation by frequency or by antenna pattern, or by polarization
• CPC Class Codes: H04W 24/10 Scheduling measurement reports ; Arrangements for measurement reports
• CPC Class Codes: H04W 84/047 using dedicated repeater stations

Abstract

An echo cancellation wireless repeater with first and second antenna arrays having vertical and horizontal feed antenna elements selects a combination of antenna elements for reception and transmission to reduce interference and improve the quality of signal reception. In one embodiment, the antenna elements are switchably connected to transceiver circuits and a combination of antenna elements is selected based on the best desired performance result. In another embodiment, the antenna elements are each connected to its own transceiver circuit and the echo cancellation repeater performs beamforming in baseband to select a combination of antenna elements.

Claims

1. A method to reduce interference in an echo cancellation repeater for a wireless communication network, the repeater employing a first antenna array and a second antenna array, each antenna array including a first set of antenna elements for vertical feed mode and a second set of antenna elements for horizontal feed mode, the method comprising:

(a) selecting a combination of antenna elements from the first and second antenna arrays;

(b) receiving incoming receive signals on receiver circuits associated with the selected antenna elements;

(c) generating correlation energy measurements indicative of correlation of the receive signals and one or more reference signals;

(d) selecting a desired receive signal being a receive signal with the largest correlated energy level, excluding receive signals that are feedback signals of the repeater;

(e) calculating antenna weights for the selected antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm;

(f) determining a performance result associated with the selected combination of antenna elements;

(g) storing calculated antenna weights and the performance result associated with the selected combination of antenna elements;

(h) repeating steps (a) to (g) for one or more combinations of antenna elements from the first and second antenna arrays; and

(i) selecting a combination of antenna elements from the first and second antenna arrays based on the stored performance results.

2. The method of claim 1, wherein generating correlation energy measurements indicative of the correlation of the receive signals and one or more reference signals comprises:

generating correlation energy measurements indicative of correlation of the receive signals and one or more pilot code phases of a CDMA-based communication system.

3. The method of claim 1, wherein generating correlation energy measurements indicative of the correlation of the receive signals and one or more reference signals comprises:

generating correlation energy measurements indicative of correlation of the receive signals and one or more scrambling codes of a WCDMA-based communication system.

4. The method of claim 1, wherein generating correlation energy measurements indicative of the correlation of the receive signals and one or more reference signals comprises:

generating correlation energy measurements indicative of correlation of the receive signals and one or more pilot tones of an OFDM symbol or an OFDM preamble.

5. The method of claim 1, wherein the receive signals include the feedback signals of the repeater and selecting a desired receive signal being a receive signal with the largest correlated energy level comprises:

selecting a desired receive signal being a receive signal with the largest correlated energy level a given delay prior to the receive signal with the overall largest correlated power level, the receive signal with the overall largest correlated power being a feedback signal and the given delay being a delay through the repeater.

6. The method of claim 1, wherein calculating antenna weights for the selected antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm comprises:

calculating antenna weights in closed form using an error minimizing algorithm to minimize an error between the desired receive signal and the reference signal.

7. The method of claim 6, wherein calculating antenna weights in closed form using an error minimizing algorithm comprises:

calculating antenna weights in closed form using a minimum mean square error (MMSE) algorithm to minimize a mean square error between the desired receive signal and the reference signal.

8. The method of claim 1, wherein calculating antenna weights for the selected antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm comprises:

calculating antenna weights adaptively for the antenna elements to maximize a signal-to-noise ratio (SNR) of the desired receive signal.

9. The method of claim 8, wherein calculating antenna weights adaptively for the antenna elements to maximize a signal-to-noise ratio (SNR) of the desired receive signal comprises:

calculating antenna weights recursively using a metric and an adaptive metric optimization algorithm to optimize the metric, the metric being indicative of the SNR of the desired receive signal.

10. The method of claim 9, wherein calculating antenna weights recursively using a metric and an adaptive metric optimization algorithm comprises:

calculating a metric being a ratio of the correlated power measurement of the desired receive signal to the sum of the correlated power measurements of some or all of the other receive signals.

11. The method of claim 10, wherein calculating a metric being a ratio of the correlated power measurement of the desired receive signal to the sum of the correlated power measurements of some or all of the other receive signals comprises:

calculating a metric being a ratio of the correlated power measurement of the desired receive signal to the sum of the correlated power measurements of dominant non-desired receive signals, the dominant non-desired receive signals being the receive signals other than the desired receive signal having a correlated power level above a predetermined threshold.

12. The method of claim 9, wherein calculating antenna weights recursively using a metric and an adaptive metric optimization algorithm comprises:

applying a steepest descent adaptive algorithm to modify the antenna weights of the antenna elements to optimize the metric.

13. The method of claim 1, wherein after receiving incoming receive signals on receiver circuits associated with the selected antenna elements and before generating correlation energy measurements, the method further comprises cancelling estimated feedback signals from the receive signals.

14. The method of claim 13, further comprising:

applying the calculated antenna weights to the receive signals;

combining the weighted receive signals; and

amplifying and transmitting the combined signals as output signals on one of the first and second antenna arrays.

15. The method of claim 1, further comprising:

applying the calculated antenna weights to the receive signals;

combining the weighted receive signals;

cancelling estimated feedback signals from the combined signals; and

amplifying and transmitting the echo cancelled signals as output signals on the antenna array of the repeater.

16. The method of claim 1, wherein selecting a combination of antenna elements from the first and second antenna arrays comprises:

selecting at least one antenna element of the vertical feed mode and one antenna element of the horizontal feed mode.

17. The method of claim 1, wherein determining a performance result associated with the selected combination of antenna elements comprises:

determining the performance result based on one or more performance factors, the one or more performance factors including one of an amount of feedback signal, a quality of a channel and a signal-to-noise ratio (SNR) of the receive signal.

18. The method of claim 17, wherein selecting a combination of antenna elements from the first and second antenna arrays based on the stored performance results to optimize a desired performance result comprises:

selecting a combination of antenna elements from the first and second antenna arrays to optimize the desired performance result based on a combination of antenna elements having the lowest feedback signal, or a combination of antenna elements providing a channel with a high degree of ease of feedback cancellation, or a combination of antenna elements providing a highest signal-to-noise ratio (SNR) of the receive signal.

19. The method of claim 17, wherein determining the performance result based on one or more performance factors comprises determining the performance result based on a weighted sum of one or more performance factors.

20. A repeater for a wireless communication network, the repeater employing echo cancellation and employing a first antenna array and a second antenna array, each antenna array including a first set of antenna elements for vertical feed mode and a second set of antenna elements for horizontal feed mode, the repeater comprising:

one or more switches, each switch being coupled to two or more antenna elements in each of the first and second antenna arrays, the one or more switches being configured to select one of the two or more antenna elements coupled thereto;

receiver circuits coupled to the one or more switches to receive incoming receive signals associated with the selected antenna elements;

an antenna element selection module and an antenna weight computation module configured to select one or more combinations of antenna elements, to perform calculations of antenna weights for each selected combination of antenna elements, to determine a performance result associated with each selected combination of antenna elements, and to select a combination of antenna elements from the first and second antenna arrays based on the performance results; and

an antenna weight application module configured to apply the calculated antenna weight to condition the receive signals.

21. The repeater of claim 20, wherein the antenna weight computation module is further configured to generate for each of the selected antenna elements correlation energy measurements indicative of correlation of the receive signals and one or more reference signals, and to select a desired receive signal being a receive signal with the largest correlated energy level, excluding receive signals that are feedback signals of the repeater, and to calculate antenna weights for the antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm.

22. The repeater of claim 21, wherein the one or more reference signals comprise one or more pilot code phases of a CDMA-based communication system.

23. The repeater of claim 21, wherein the one or more reference signals comprise one or more scrambling codes of a WCDMA-based communication system.

24. The repeater of claim 21, wherein the one or more reference signals comprise one or more pilot tones of an OFDM symbol or an OFDM preamble.

25. The repeater of claim 21, wherein the receive signals include the feedback signals of the repeater and the antenna weight computation module is configured to select a desired receive signal being a receive signal with the largest correlated energy level a given delay prior to the receive signal with the overall largest correlated power level, the receive signal with the overall largest correlated power being a feedback signal and the given delay being a delay through the repeater.

26. The repeater of claim 21, wherein the antenna weight computation module is configured to calculate antenna weights in closed form using error minimizing algorithm to minimize an error between the desired receive signal and the reference signal.

27. The repeater of claim 21, wherein the antenna weight computation module is configured to calculate antenna weights in closed form using a minimum mean square error (MMSE) algorithm to minimize a mean square error between the desired receive signal and the reference signal.

28. The repeater of claim 21, wherein the antenna weight computation module is configured to calculate antenna weights adaptively for the selected antenna elements to maximize a signal-to-noise ratio (SNR) of the desired receive signal.

29. The repeater of claim 28, wherein the antenna weight computation module is configured to calculate antenna weights recursively using a metric and an adaptive metric optimization algorithm to optimize the metric, the metric being indicative of the SNR of the desired receive signal.

30. The repeater of claim 29, wherein the metric comprises a ratio of the correlated power measurement of the desired receive signal to the sum of the correlated power measurements of some or all of the other receive signals.

31. The repeater of claim 30, wherein the metric comprises a ratio of the correlated power measurement of the desired receive signal to the sum of the correlated power measurements of dominant non-desired receive signals, the dominant non-desired receive signals being the receive signals other than the desired receive signal having a correlated power level above a predetermined threshold.

32. The repeater of claim 29, wherein the adaptive metric optimization algorithm comprises a steepest descent adaptive algorithm applied to modify the antenna weights of M antenna elements to optimize the metric.

33. The repeater of claim 20, further comprising an echo canceller configured to cancel estimated feedback signals from the receive signals.

34. The repeater of claim 33, wherein the antenna weight computation module is further configured to combine the weighted receive signals and amplify and transmit the combined signals as output signals on the antenna array of the repeater.

35. The repeater of claim 20, wherein the antenna weight computation module is further configured to combine the weighted receive signals, cancel estimated feedback signals from the combined signals, and amplify and transmit the echo cancelled signals as output signals on the antenna array of the repeater.

36. The repeater of claim 20, wherein the antenna element selection module is configured to select at least one antenna element of the vertical feed mode and one antenna element of the horizontal feed mode for each combination of antenna elements.

37. The repeater of claim 20, wherein the antenna element selection module is configured to determine a performance result associated with each selected combination of antenna elements based on one or more performance factors, the one or more performance factors including one of an amount of feedback signal, a channel quality and a signal-to-noise ratio (SNR) of the receive signal.

38. The repeater of claim 37, wherein the antenna element selection module is configured to select a combination of antenna elements from the first and second antenna arrays to optimize a desired performance result based on a combination of antenna elements having a lowest feedback signal, or a combination of antenna elements providing a channel with a high degree of ease of feedback cancellation, or a combination of antenna elements providing a highest signal-to-noise ratio (SNR) of the receive signal.

39. The repeater of claim 37, wherein the antenna element selection module is configured to determine a performance result associated with each selected combination of antenna elements based on a weighted sum of one or more performance factors.

40. A computer readable medium having stored thereon computer executable instructions for performing at least the following acts:

(a) selecting a combination of antenna elements from first and second antenna arrays of an echo cancellation repeater, each antenna array including a first set of antenna elements for vertical feed mode and a second set of antenna elements for horizontal feed mode;

(b) receiving incoming receive signals on receiver circuits associated with the selected antenna elements;

(c) generating correlation energy measurements indicative of correlation of the receive signals and one or more reference signals;

(d) selecting a desired receive signal being a receive signal with the largest correlated energy level, excluding receive signals that are feedback signals;

(e) calculating antenna weights for the selected antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm;

(f) determining a performance result associated with the selected combination of antenna elements;

(g) storing calculated antenna weights and the performance result associated with the selected combination of antenna elements;

(h) repeating steps (a) to (g) for one or more combinations of antenna elements from the first and second antenna arrays; and

(i) selecting a combination of antenna elements from the first and second antenna arrays based on the stored performance results.

41. A repeater for a wireless communication network, the repeater employing echo cancellation and employing a first antenna array and a second antenna array, each antenna array including a first set of antenna elements for vertical feed mode and a second set of antenna elements for horizontal feed mode, the repeater comprising:

means coupled to each set of two or more antenna elements in each of the first and second antenna arrays, the means for selecting one of the two or more antenna elements coupled thereto;

means for receiving incoming receive signals associated with the selected antenna elements;

means for selecting one or more combinations of antenna elements, performing calculations of antenna weights for each selected combination of antenna elements, determining a performance result associated with each selected combination of antenna elements, and selecting a combination of antenna elements from the first and second antenna arrays based on the performance results; and

means for applying the calculated antenna weight to condition the receive signals.

42. A method to reduce interference in an echo cancellation repeater for a wireless communication network, the repeater employing a first antenna array and a second antenna array, each antenna array including a first set of antenna elements for vertical feed mode and a second set of antenna elements for horizontal feed mode, the method comprising:

(a) receiving incoming receive signals on receiver circuits associated with the antenna elements;

(b) generating correlation energy measurements indicative of correlation of the receive signals and one or more reference signals;

(c) selecting a desired receive signal being a receive signal with the largest correlated energy level, excluding receive signals that are feedback signals of the repeater;

(d) calculating antenna weights for the antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm;

(e) determining a performance result associated with the antenna elements;

(f) performing beamforming in baseband to adjust the calculated antenna weights, the adjusted antenna weights selecting a combination of antenna elements from the first and second antenna arrays for receiving and transmitting signals; and

(g) performing echo cancellation on the receive signal or on a weighted combined receive signal using the calculated antenna weights.

43. The method of claim 42, wherein determining a performance result associated with the antenna elements comprises:

determining the performance result based on one or more performance factors, the one or more performance factors including one of an amount of feedback signal, a channel quality and a signal-to-noise ratio (SNR) of the receive signal.

44. The method of claim 43, wherein performing beamforming in baseband to adjust the calculated antenna weights to optimize a desired performance result comprises:

performing beamforming in baseband to adjust the calculated antenna weights to optimize a desired performance result based on a combination of antenna elements having the lowest feedback signal, or a combination of antenna elements providing a channel with a high degree of ease of feedback cancellation, or a combination of antenna elements providing a highest signal-to-noise ratio (SNR) of the receive signal.

45. The method of claim 43, wherein determining the performance result based on one or more performance factors comprises determining the performance result based on a weighted sum of one or more performance factors.

46. A repeater for a wireless communication network, the repeater employing echo cancellation and employing a first antenna array and a second antenna array, each antenna array including a first set of antenna elements for vertical feed mode and a second set of antenna elements for horizontal feed mode, the repeater comprising:

receiver circuits coupled to receive incoming receive signals associated with the antenna elements;

an antenna element selection module and an antenna weight computation module configured to perform calculations of antenna weights for the antenna elements, to determine a performance result associated with the antenna elements, and to select a combination of antenna elements from the first and second antenna arrays based on the performance results;

an antenna weight application module configured to apply the calculated antenna weight to condition the receive signals; and

an echo canceller configured to cancel estimated feedback signals from the receive signals or from a weighted combined receive signal using the calculated antenna weights.

47. The repeater of claim 46, wherein the antenna element selection module is configured to determine a performance result associated with the antenna elements based on one or more performance factors, the one or more performance factors including one of an amount of feedback signal, a channel quality and a signal-to-noise ratio (SNR) of the receive signal.

48. The repeater of claim 47, wherein the antenna element selection module is configured to select a combination of antenna elements from the first and second antenna arrays based on a combination of antenna elements having the lowest feedback signal, or a combination of antenna elements providing a channel with a high degree of ease of feedback cancellation, or a combination of antenna elements providing a highest signal-to-noise ratio (SNR) of the receive signal.

49. The repeater of claim 47, wherein the antenna element selection module is configured to determine a performance result associated with each selected combination of antenna elements based on a weighted sum of one or more performance factors.