Dual-stage echo cancellation in a wireless repeater using an inserted pilot

• US 8,737,911 B2
• Filed: 10/30/2009
• Issued: 05/27/2014
• Est. Priority Date: 05/11/2009
• Status: Active Grant

• Current Assignee: Qualcomm, Inc.
• Original Assignee: Qualcomm, Inc.
• Inventors: Black, Peter John, Gore, Dhananjay Ashok, Barriac, Gwendolyn Denise
• Primary Examiner(s): Ferguson, Keith
• Application Number:
  US12/609,698
• Publication Number:
  US 20100285734A1
• Time in Patent Office: 1,670 Days
• Field of Search: 455/11.1, 455/7, 455/24, 455/13.3, 455/15, 455/17, 455/1, 455/20, 455/22, 455/23, 455/422.1, 455/403, 455/500, 455/67.11, 455423-425, 455/509, 455/515, 455/550.18, 370/310, 370/315, 370/316, 370/317, 370/318, 375/211, 375/213
• US Class Current: 455/7
• 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

In one embodiment, a method for providing echo cancellation in a wireless repeater includes: adding the pilot signal to a transmit signal; receiving a receive signal being the sum of a remote signal, a feedback pilot signal and a feedback transmit signal; cancelling the feedback transmit signal from the receive signal using a currently available feedback channel estimate and generating a first echo cancelled signal; generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal; cancelling the feedback transmit signal and the feedback pilot signal from the receive signal using the updated feedback channel estimate and generating a second echo cancelled signal; and amplifying the second echo cancelled signal as the transmit signal. In another embodiment, the feedback pilot signal is cancelled from the first echo cancelled signal using the updated feedback channel estimate to generate the second echo cancelled signal.

Claims

1. A wireless repeater having a first antenna and a second antenna, the repeater comprising:

a pilot insertion unit configured to generate a pilot signal, the pilot signal to be added to a transmit signal for transmission as a composite transmit signal;

a first echo canceller to receive a receive signal and the transmit signal and generate a first echo cancelled signal using a currently available feedback channel estimate, the receive signal being the sum of a remote signal to be amplified, a feedback pilot signal and a feedback transmit signal, the feedback pilot signal and the feedback transmit signal being feedback signals fed back on a feedback channel between the first antenna and the second antenna, the first echo canceller configured to use the currently available feedback channel estimate to remove the feedback transmit signal from the receive signal;

a channel estimation block to receive the first echo cancelled signal and also to receive the pilot signal as a reference signal, the channel estimation block configured to generate an updated feedback channel estimate based on the first echo cancelled signal and the reference signal;

a second echo canceller to receive the receive signal, the pilot signal and the transmit signal and to generate a second echo cancelled signal using the updated feedback channel estimate, the second echo canceller configured to use the updated feedback channel estimate to remove the feedback transmit signal and the feedback pilot signal from the receive signal, and to thereby generate a second echo cancelled signal indicative of the remote signal; and

an amplifier to amplify the second echo cancelled signal as the transmit signal, wherein the repeater is configured to add the pilot signal to the transmit signal to be transmitted as the composite transmit signal.

2. The wireless repeater of claim 1, wherein the channel estimation block is configured to generate feedback channel estimates on a substantially continuous basis based on incoming receive signals, the first echo canceller configured to use the updated feedback channel estimate of a previous incoming receive signal as the currently available feedback channel estimate.

3. The wireless repeater of claim 1, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal is uncorrelated with the remote signal.

4. The wireless repeater of claim 1, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is lower than a power level of the transmit signal.

5. The wireless repeater of claim 4, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is at least 20 dB lower than the power level of the transmit signal.

6. The wireless repeater of claim 4, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is lower than and a function of a power level of the transmit signal.

7. The wireless repeater of claim 4, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is lower than and a function of a power level of the transmit signal and a gain of the repeater.

8. A wireless repeater having a first antenna and a second antenna, the repeater comprising:

means for generating a pilot signal, the pilot signal being added to a transmit signal for transmission as a composite transmit signal;

first means for receiving a receive signal and the transmit signal and generating a first echo cancelled signal using a currently available feedback channel estimate, the receive signal being the sum of a remote signal to be amplified, a feedback pilot signal and a feedback transmit signal, the feedback pilot signal and the feedback transmit signal being feedback signals fed back on a feedback channel between the first antenna and the second antenna, the first means using the currently available feedback channel estimate to remove the feedback transmit signal from the receive signal;

means for receiving the first echo cancelled signal and also receiving the pilot signal as a reference signal, and generating an updated feedback channel estimate based on the first echo cancelled signal and the reference signal;

second means for receiving the receive signal, the transmit signal and the pilot signal and generating a second echo cancelled signal using the updated feedback channel estimate, the second means using the updated feedback channel estimate to remove the feedback transmit signal and the feedback pilot signal from the receive signal, thereby generating the second echo cancelled signal indicative of the remote signal; and

means for amplifying the second echo cancelled signal as the transmit signal, the pilot signal being added to the transmit signal to be transmitted as the composite transmit signal.

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

generating a pilot signal and adding the pilot signal to a transmit signal for transmission as a composite transmit signal;

receiving a receive signal at a first antenna of the repeater, the receive signal being the sum of a remote signal to be amplified, a feedback pilot signal and a feedback transmit signal, the feedback pilot signal and the feedback transmit signal being feedback signals fed back to the first antenna on a feedback channel between second antenna and the first antenna;

cancelling the feedback transmit signal from the receive signal using a currently available feedback channel estimate and generating a first echo cancelled signal;

generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal;

cancelling the feedback transmit signal and the feedback pilot signal from the receive signal using the updated feedback channel estimate and generating a second echo cancelled signal;

amplifying the second echo cancelled signal as the transmit signal; and

transmitting the transmit signal and the pilot signal on the second antenna as the composite transmit signal.

10. The method of claim 9, wherein generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal comprises:

generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal on a substantially continuous basis based on incoming receive signals.

11. The method of claim 10, wherein cancelling the feedback transmit signal from the receive signal using a currently available feedback channel estimate comprises:

cancelling the feedback transmit signal from the receive signal using the updated feedback channel estimate of a previous incoming receive signal as the currently available feedback channel estimate.

12. The method of claim 9, wherein the pilot signal is uncorrelated with the remote signal.

13. The method of claim 9, wherein the pilot signal has a power level that is lower than the power level of the transmit signal.

14. The method of claim 13, wherein the pilot signal has a power level that is at least 20 dB lower than the power level of the transmit signal.

15. The method of claim 13, wherein the pilot signal has a power level that is a lower than and a function of a power level of the transmit signal.

16. The method of claim 13, wherein the pilot signal has a power level that is lower than and a function of a power level of the transmit signal and a gain of the repeater.

17. A wireless repeater having a first antenna and a second antenna, the repeater comprising:

a pilot insertion unit to generate a pilot signal, the pilot signal being added to a transmit signal for transmission as a composite transmit signal;

a first echo canceller to receive a receive signal and the transmit signal and generating a first echo cancelled signal using a currently available feedback channel estimate, the receive signal being the sum of a remote signal to be amplified, a feedback pilot signal and a feedback transmit signal, the feedback pilot signal and the feedback transmit signal being feedback signals fed back on a feedback channel between the first antenna and the second antenna, the first echo canceller using the currently available feedback channel estimate to remove the feedback transmit signal from the receive signal;

a channel estimation block to receive the first echo cancelled signal and also to receive the pilot signal as a reference signal, the channel estimation block configured to generate an updated feedback channel estimate based on the first echo cancelled signal and the reference signal;

a second echo canceller to receive the first echo cancelled signal and the pilot signal and configured to generate a second echo cancelled signal using the updated feedback channel estimate, the second echo canceller configured to use the updated feedback channel estimate to remove the feedback pilot signal from the first echo cancelled signal, thereby generating the second echo cancelled signal indicative of the remote signal; and

an amplifier to amplify the second echo cancelled signal as the transmit signal, the pilot signal being added to the transmit signal to be transmitted as the composite transmit signal.

18. The wireless repeater of claim 17, wherein the channel estimation block is configured to generate feedback channel estimates on a substantially continuous basis based on incoming receive signals, the first echo canceller to use the updated feedback channel estimate of a previous incoming receive signal as the currently available feedback channel estimate.

19. The wireless repeater of claim 17, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal is uncorrelated with the remote signal.

20. The wireless repeater of claim 17, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is lower than the power level of the transmit signal.

21. The wireless repeater of claim 20, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is at least 20 dB lower than the power level of the transmit signal.

22. The wireless repeater of claim 20, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is lower than and a function of a power level of the transmit signal.

23. The wireless repeater of claim 20, wherein the pilot insertion unit is configured to generate the pilot signal so the pilot signal has a power level that is lower than and a function of a power level of the transmit signal and a gain of the repeater.

24. A wireless repeater having a first antenna and a second antenna, the repeater comprising:

means for generating a pilot signal, the pilot signal being added to a transmit signal for transmission as a composite transmit signal;

first means for receiving a receive signal and the transmit signal and generating a first echo cancelled signal using a currently available feedback channel estimate, the receive signal being the sum of a remote signal to be amplified, a feedback pilot signal and a feedback transmit signal, the feedback pilot signal and the feedback transmit signal being feedback signals fed back on a feedback channel between the first antenna and the second antenna, the first means using the currently available feedback channel estimate to remove the feedback transmit signal from the receive signal;

means for receiving the first echo cancelled signal and also receiving the pilot signal as a reference signal, and generating an updated feedback channel estimate based on the first echo cancelled signal and the reference signal;

second means for receiving the first echo cancelled signal and the pilot signal and generating a second echo cancelled signal using the updated feedback channel estimate, the second means using the updated feedback channel estimate to remove the feedback pilot signal from the first echo cancelled signal, thereby generating the second echo cancelled signal indicative of the remote signal; and

means for amplifying the second echo cancelled signal as the transmit signal, the pilot signal being added to the transmit signal to be transmitted as the composite transmit signal.

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

generating a pilot signal and adding the pilot signal to a transmit signal for transmission on a first antenna as a composite transmit signal;

receiving a receive signal at a second antenna of the repeater, the receive signal being the sum of a remote signal to be amplified, a feedback pilot signal and a feedback transmit signal, the feedback pilot signal and the feedback transmit signal being feedback signals fed back to the receiving antenna on a feedback channel between the first antenna and the second antenna;

cancelling the feedback transmit signal from the receive signal using a currently available feedback channel estimate and generating a first echo cancelled signal;

generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal;

cancelling the feedback pilot signal from the first echo cancelled signal using the updated feedback channel estimate and generating a second echo cancelled signal;

amplifying the second echo cancelled signal as the transmit signal; and

transmitting the transmit signal and the pilot signal on the first antenna as the composite transmit signal.

26. The method of claim 25, wherein generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal comprises:

generating an updated feedback channel estimate using the first echo cancelled signal and the pilot signal as a reference signal on a substantially continuous basis based on incoming receive signals.

27. The method of claim 26, wherein cancelling the feedback transmit signal from the receive signal using a currently available feedback channel estimate comprises:

cancelling the feedback transmit signal from the receive signal using the updated feedback channel estimate of a previous incoming receive signal as the currently available feedback channel estimate.

28. The method of claim 25, wherein the pilot signal is uncorrelated with the remote signal.

29. The method of claim 25, wherein the pilot signal has a power level that is lower than the power level of the transmit signal.

30. The method of claim 29, wherein the pilot signal has a power level that is at least 20 dB lower than the power level of the transmit signal.

31. The method of claim 29, wherein the pilot signal has a power level that is a lower than and a function of a power level of the transmit signal.

32. The method of claim 29, wherein the pilot signal has a power level that is lower than and a function of a power level of the transmit signal and a gain of the repeater.