Feedback delay control in an echo cancellation repeater

• US 8,358,969 B2
• Filed: 10/30/2009
• Issued: 01/22/2013
• Est. Priority Date: 05/11/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Gore, Dhananjay Ashok, Barriac, Gwendolyn Denise, Howard, Steven J., Proctor, James Arthur Jr., Gainey, Kenneth M.
• Primary Examiner(s): Ferguson, Keith
• Application Number:
  US12/609,874
• Publication Number:
  US 20100285736A1
• Time in Patent Office: 1,180 Days
• Field of Search: 455/11.1, 455/7, 455/24, 455/13.3, 455/15, 455/17, 455/20, 455/22, 455/23, 455/422.1, 455/403, 455/500, 455/517, 455/67.11, 455423-425, 455/509, 455/515, 455/550.1, 370/310, 370/315, 370/316, 370/17, 370/318, 375/211, 375/213
• US Class Current: 455/11.1
• CPC Class Codes: H04B 7/15535 Control of relay amplifier gain amplifier gain control in general H03G3/00; gain control reducing self - or loop interference H04B7/15578
• CPC Class Codes: H04B 7/15585 by interference cancellation
• CPC Class Codes: H04L 27/2607 Cyclic extensions
• CPC Class Codes: H04L 27/2613 Structure of the reference signals

Abstract

A wireless repeater includes an echo canceller to cancel an estimated feedback amount from an input signal and a delay to delay the input signal. The delay may be selected to decorrelate a remote signal from a signal to be transmitted by the repeater.

Claims

1. A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

receive circuitry configured to receive the input signal from one of the first antenna and the second antenna and to generate a delayed echo cancelled signal using the input signal, the receive circuitry comprising;

an echo canceller configured to access a feedback signal estimate, and to cancel the feedback signal estimate from the input signal;

a variable delay element to introduce a first delay before or after the echo canceller, wherein the first delay is selected to decorrelate the amplified signal from the remote signal; and

an amplifier to amplify the delayed echo cancelled signal to generate an amplified signal to be transmitted.

2. The wireless repeater of claim 1, wherein the variable delay element is configured to introduce the first delay before the echo canceller.

3. The wireless repeater of claim 1, wherein the variable delay element is configured to introduce the first delay after the echo canceller.

4. The wireless repeater of claim 1, wherein the echo canceller is configured to generate a feedback channel estimate indicative of an estimated feedback for the channel between the first antenna and the second antenna, and further configured to generate the feedback signal estimate based on the feedback channel estimate, and wherein the echo canceller is configured to generate the echo cancelled signal by subtracting the feedback signal estimate from the input signal.

5. The wireless repeater of claim 1, wherein the first delay is selected based at least in part on a bandwidth of carriers.

6. The wireless repeater of claim 1, wherein the repeater is configured to adjust the first delay when the repeater is started up.

7. The wireless repeater of claim 1, wherein the value is further equal to or less than a maximum allowable delay of the repeater.

8. A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

receive circuitry configured to receive the input signal from one of the first antenna and the second antenna and to generate a delayed echo cancelled signal using the input signal, the receive circuitry comprising;

an echo canceller configured to access a feedback signal estimate, and to cancel the feedback signal estimate from the input signal;

a variable delay element to introduce a first delay before or after the echo canceller;

a channel estimation block to receive the input signal and the delayed echo cancelled signal and generate the feedback channel estimate using the delayed echo cancelled signal as a reference signal, the reference signal being indicative of the amplified signal which is delayed from the input signal by the first delay, the channel estimation block further to generate the feedback signal estimate based on the feedback channel estimate; and

a summer to receive the input signal and the feedback signal estimate, the summer configured to subtract the feedback signal estimate from the input signal to generate the echo cancelled signal; and

an amplifier to amplify the delayed echo cancelled signal to generate an amplified signal to be transmitted.

9. A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

receive circuitry configured to receive the input signal from one of the first antenna and the second antenna and to generate a delayed echo cancelled signal using the input signal, the receive circuitry comprising;

an echo canceller configured to access a feedback signal estimate, and to cancel the feedback signal estimate from the input signal;

a variable delay element to introduce a first delay before or after the echo canceller; and

an amplifier to amplify the delayed echo cancelled signal to generate an amplified signal to be transmitted,

wherein the first delay is selected based at least in part on a number of carriers in the input signal.

10. A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

receive circuitry configured to receive the input signal from one of the first antenna and the second antenna and to generate a delayed echo cancelled signal using the input signal, the receive circuitry comprising;

an echo canceller configured to access a feedback signal estimate, and to cancel the feedback signal estimate from the input signal;

a variable delay element to introduce a first delay before or after the echo canceller; and

an amplifier to amplify the delayed echo cancelled signal to generate an amplified signal to be transmitted,

wherein the repeater is configured to tune the first delay periodically during repeater operation.

11. A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

receive circuitry configured to receive the input signal from one of the first antenna and the second antenna and to generate a delayed echo cancelled signal using the input signal, the receive circuitry comprising;

an echo canceller configured to access a feedback signal estimate, and to cancel the feedback signal estimate from the input signal;

a variable delay element to introduce a first delay before or after the echo canceller; and

an amplifier to amplify the delayed echo cancelled signal to generate an amplified signal to be transmitted,

wherein the repeater is configured to determine a value of the first delay by computing a decorrelation value between the amplified signal and the remote signal.

12. A wireless repeater having a first antenna and a second antenna to receive an input signal and transmit an amplified signal, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and the second antenna, the repeater comprising:

means for receiving the input signal from one of the first and the second antenna and for generating a delayed echo cancelled signal using the input signal, where the means for receiving comprises;

means for cancelling a feedback signal estimate from the input signal;

means for introducing a first delay before or after the feedback signal is cancelled from the input signal, wherein the first delay is selected to decorrelate the amplified signal from the remote signal; and

means for amplifying the delayed echo cancelled signal.

13. A method for providing echo cancellation in a wireless repeater in a wireless communication system, comprising:

receiving an input signal at a first antenna of the repeater, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and a second antenna;

cancelling a feedback signal estimate from the input signal;

introducing a first delay to the signal before or after cancelling the feedback signal estimate, wherein the first delay is selected to decorrelate the amplified signal from the remote signal, and further wherein a delayed echo cancelled signal is generated based on the cancelling the feedback signal estimate from the input signal and the introducing the first delay;

amplifying the delayed echo cancelled signal; and

transmitting the amplified signal on the second antenna.

14. The method of claim 13, wherein introducing a first delay comprises introducing a first delay to the input signal before cancelling the feedback signal estimate from the input signal.

15. The method of claim 13, wherein introducing a first delay comprises introducing a first delay after cancelling a feedback signal estimate from the input signal.

16. The method of claim 13, wherein cancelling a feedback signal estimate from the input signal comprises:

estimating a feedback channel between the first antenna and the second antenna and providing a feedback channel estimate;

estimating the feedback signal estimate using the feedback channel estimate; and

subtracting the feedback signal estimate from the input signal.

17. The method of claim 13, wherein the first delay is selected based at least in part on a number of carriers in the input signal.

18. The method of claim 13, wherein the first delay is selected based at least in part on the bandwidth of carriers.

19. The method of claim 13, wherein the first delay is adjusted when the repeater is started up.

20. The method of claim 13, wherein the first delay is set to a value equal to or less than the maximum allowable delay of the repeater.

21. A method for providing echo cancellation in a wireless repeater in a wireless communication system, comprising:

receiving an input signal at a first antenna of the repeater, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and a second antenna;

cancelling a feedback signal estimate from the input signal;

introducing a first delay to the signal before or after cancelling the feedback signal estimate, wherein a delayed echo cancelled signal is generated based on the cancelling the feedback signal estimate from the input signal and the introducing the first delay;

amplifying the delayed echo cancelled signal; and

transmitting the amplified signal on the second antenna,

wherein cancelling a feedback signal estimate from the input signal comprises;

estimating a feedback channel between the first antenna and the second antenna and providing a feedback channel estimate;

estimating the feedback signal estimate using the feedback channel estimate; and

subtracting the feedback signal estimate from the input signal, and

further wherein estimating a feedback channel between the first antenna and the second antenna comprises estimating the feedback channel using the input signal and using the delayed echo cancelled signal as a reference signal, the reference signal being indicative of the amplified signal which is delayed from the input signal by the first delay.

22. A method for providing echo cancellation in a wireless repeater in a wireless communication system, comprising:

receiving an input signal at a first antenna of the repeater, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and a second antenna;

cancelling a feedback signal estimate from the input signal;

introducing a first delay to the signal before or after cancelling the feedback signal estimate, wherein a delayed echo cancelled signal is generated based on the cancelling the feedback signal estimate from the input signal and the introducing the first delay;

amplifying the delayed echo cancelled signal; and

transmitting the amplified signal on the second antenna,

wherein the first delay is tuned periodically during repeater operation.

23. A method for providing echo cancellation in a wireless repeater in a wireless communication system, comprising:

receiving an input signal at a first antenna of the repeater, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and a second antenna;

cancelling a feedback signal estimate from the input signal;

introducing a first delay to the signal before or after cancelling the feedback signal estimate, wherein a delayed echo cancelled signal is generated based on the cancelling the feedback signal estimate from the input signal and the introducing the first delay;

amplifying the delayed echo cancelled signal; and

transmitting the amplified signal on the second antenna,

wherein the value of the first delay is determined by computing a decorrelation value between the amplified signal and the remote signal.

24. A non-transitory machine-readable medium comprising instructions, which, when executed by a machine, cause the machine to perform operations for providing echo cancellation in a wireless repeater, the instructions comprising:

instructions to receive an input signal at a first antenna of the repeater, the input signal being a sum of a remote signal to be repeated and a feedback signal resulting from a feedback channel between the first antenna and a second antenna;

instructions to cancel a feedback signal estimate from the input signal;

instructions to introduce a first delay to the signal before or after cancelling the feedback signal estimate, wherein the first delay is selected to decorrelate the amplified signal from the remote signal, and further wherein a delayed echo cancelled signal is generated based on the cancelling the feedback signal estimate from the input signal and the introducing the first delay;

instructions to amplify the delayed echo cancelled signal; and

instructions to transmit the amplified signal on the second antenna.

25. The non-transitory machine-readable medium of claim 24, wherein the instructions to introduce a first delay further comprise instructions to introduce a first delay to the input signal before cancelling the feedback signal estimate from the input signal.

26. The non-transitory machine-readable medium of claim 24, wherein instructions to introduce a first delay further comprise instructions to introduce a first delay after cancelling a feedback signal estimate from the input signal.

27. The non-transitory machine-readable medium of claim 24, wherein the instructions to cancel a feedback signal estimate from the input signal further comprise:

instructions to estimate a feedback channel between the first antenna and the second antenna and providing a feedback channel estimate;

instructions to estimate the feedback signal estimate using the feedback channel estimate; and

instructions to subtract the feedback signal estimate from the input signal.