METHOD IN A WIRELESS REPEATER EMPLOYING AN ANTENNA ARRAY FOR INTERFERENCE REDUCTION

• US 20120015608A1
• Filed: 07/14/2010
• 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 8,477,665 B2
• Time in Patent Office: Days
• US Class Current: 455/63.1
• CPC Class Codes: H04B 7/15571 by signal isolation, e.g. isolation by frequency or by antenna pattern, or by polarization

Abstract

A wireless repeater with an antenna array determines the antenna weights to modify the spatial selectivity of the antenna array to reduce interference and improve the quality of signal reception. The antenna weights are determined using an error minimizing algorithm to minimize the error between a desired receive signal and a reference signal or an adaptive metric optimization algorithm to calculate adaptively antenna weights to minimize the signal-to-noise ratio of a desired receive signal.

Claims

1. A method to reduce interference in a repeater for a wireless communication network, the repeater employing an antenna array including M antenna elements, the method comprising:

receiving incoming signals on M receiver circuits associated with the M antenna elements;

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

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; and

calculating antenna weights for the M antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm.

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 the 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 the 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 the 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 wherein 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 comprises:

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

6. The method of claim 1, wherein calculating antenna weights for the M 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 reduce the 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 reduce the mean square error between the desired receive signal and the reference signal.

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

calculating antenna weights adaptively for the M 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 M 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 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 M antenna elements to optimize the metric.

13. The method of claim 1, wherein after receiving incoming signals on M receiver circuits associated with the M antenna elements and before generating correlation energy measurements, the method further comprises cancelling 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 the antenna array of the repeater.

15. The method of claim 1, further comprising:

applying the calculated antenna weights to the receive signals;

combining the weighted receive signals;

cancelling 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. A repeater for a wireless communication network, the repeater employing an antenna array including M antenna elements, the repeater comprising:

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

an antenna weight computation module configured to perform calculations of antenna weights for the M antenna elements, the antenna weight computation module operative to generate correlation energy measurements indicative of the correlation of the receive signals and one or more reference signals, 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 calculate antenna weights for the M antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm; and

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

17. The repeater of claim 16, wherein the one or more reference signals comprise one or more pilot code phases of a CDMA-based communication system.

18. The repeater of claim 16, wherein the one or more reference signals comprise one or more scrambling codes of a WCDMA-based communication system.

19. The repeater of claim 16, wherein the one or more reference signals comprise one or more pilot tones of an OFDM symbol or an OFDM preamble.

20. The repeater of claim 16, wherein the receive signals include the feedback signals of the repeater and wherein the antenna weight computation module is configured to select a receive signal with the largest correlated energy level a given delay prior to the receive signal with the overall largest correlated power level as the desired receive signal, wherein the given delay is the estimated delay through the repeater.

21. The repeater of claim 16, wherein the antenna weight computation module is configured to calculate antenna weights in closed form using an error minimizing algorithm to reduce the error between the desired receive signal and the reference signal.

22. The repeater of claim 16, 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 the mean square error between the desired receive signal and the reference signal.

23. The repeater of claim 16, wherein the antenna weight computation module is configured to calculate antenna weights adaptively for the M antenna elements to maximize a signal-to-noise ratio (SNR) of the desired receive signal.

24. The repeater of claim 23, 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.

25. The repeater of claim 24, 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.

26. The repeater of claim 25, 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 signals being the receive signals other than the desired receive signal having a correlated power level above a predetermined threshold.

27. The repeater of claim 24, wherein the adaptive metric optimization algorithm comprises a steepest descent adaptive algorithm applied to modify the antenna weights of the M antenna elements to optimize the metric.

28. The repeater of claim 16, further comprising an echo canceller configured to cancel feedback signals from the receive signals.

29. The repeater of claim 28, wherein the antenna weight application 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.

30. The repeater of claim 16, wherein the antenna weight application module is further configured to combine the weighted receive signals, cancel feedback signals from the combined signals, and amplify and transmit the echo cancelled signals as output signals on the antenna array of the repeater.

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

receiving input signals indicative of incoming signals received on M antenna elements of an antenna array of a repeater;

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

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; and

calculating antenna weights for the M antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm.

32. A repeater for a wireless communication network, the repeater employing an antenna array including M antenna elements, the repeater comprising:

means for receiving incoming signals associated with the M antenna elements;

means for performing calculations of antenna weights for the M antenna elements, the means for generating correlation energy measurements indicative of the correlation of the receive signals and one or more reference signals, 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, and calculating antenna weights for the M antenna elements using one of an error minimizing algorithm and an adaptive metric optimization algorithm; and

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