Methods and apparatuses for detecting and reducing non-linear echo in a multi-carrier communication system

• US 20060062379A1
• Filed: 09/22/2004
• Published: 03/23/2006
• Est. Priority Date: 09/22/2004
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: 2Wire, Inc. (CommScope Holding Company, Inc.)
• Inventors: Sedarat, Hossein, Fisher, Kevin Dean
• Granted Patent: US 7,177,419 B2
• Time in Patent Office: Days
• US Class Current: 379/406.10
• CPC Class Codes: H04B 3/23 using a replica of transmitted signal in the time domain, e.g. echo cancellers

Abstract

Apparatuses, systems, and methods for a multi-carrier communication system that detects and reduces an echo from a non-linear element present on the transmission medium. In an embodiment, a training period is established between a first transmitter-receiver device and a second transmitter-receiver device in the discrete multiple tone system that separates communication signals into two or more seperste frequency bands. Noise caused by an echo generated by a non-linear element present on the transmission medium is detected during the training period. The significance of the non-linear echo contribution to the overall ambient noise level present in the system may be determined.

Claims

1. A method, comprising:

establishing a training period between a first transmitter-receiver device and a second transmitter-receiver device in a discrete multiple tone system that separates communication signals into two or more distinct frequency bands; and

detecting for an echo generated by a non-linear element present on a transmission medium during the training period.

2. The method of claim 1, further comprising:

eliminating the echo generated by the non-linear element by reducing transmit power of the transmitter-receiver device that is generating the echo.

3. The method of claim 1, further comprising:

eliminating the echo generated by the non-linear element by placing an isolating filter in between the non-linear element and the transmission medium.

4. The method of claim 1, further comprising:

comparing a significance of noise contribution from the echo to ambient noise present on the transmission medium.

5. The method of claim 4, wherein when the noise contribution from the echo to the ambient noise present on the transmission medium is significant indicated by a threshold amount, then compensate for the presence of the echo generated by the non-linear element.

6. The method of claim 1, further comprising:

detecting for the echo generated by the non-linear elements present on the transmission medium during the training period when communication signals are expected in at least a first and a second frequency band.

7. The method of claim 1, further comprising:

learning a power level of ambient noise and a periodic training signal present in a first frequency band when the periodic training signal is being transmitted to this location; and

measuring the power level of ambient noise and the periodic training signal present on the transmission medium in a first frequency band while maintaining a local transmit communication signal utilizing a second frequency band silent.

8. The method of claim 7, wherein the measuring the power level of ambient noise and the periodic training signal present on the transmission medium is averaged over two or more frames and based upon a Fast Fourier Transform algorithm.

9. The method of claim 7, further comprising:

determining a power level of the echo generated by the non-linear element on the transmission medium when the training protocol directs that a communication signal should be present in both frequency bands.

10. A machine readable medium storing instructions to cause the machine to perform the following operations, comprising:

establishing a training period between a first transmitter-receiver device and a second transmitter-receiver device in a discrete multiple tone system that separates communication signals into two or more distinct frequency bands; and

detecting for noise caused by an echo generated by a non-linear element present on a transmission medium during the training period.

11. The article of manufacture of claim 10 containing further instructions to cause the further operations, comprising:

comparing a significance of noise contribution from the echo to the ambient noise level present on the transmission medium, wherein if significant, the echo is eliminated by placing an isolating filter in between the non-linear element and the transmission medium.

12. The article of manufacture of claim 10 containing further instructions to cause the further operations, comprising:

comparing a significance of noise contribution from the non-linear element to the ambient noise level present on the transmission medium, wherein if significant, the echo is eliminated by reducing transmit power of the transmitter-receiver device that is generating the echo.

13. The article of manufacture of claim 10 containing further instructions to cause the further operations, comprising:

detecting for a presence of the echo in one of the frequency bands when a training protocol directs that no signal should be present in that frequency band at that point in the training period.

14. The article of manufacture of claim 10 containing further instructions to cause the further operations, comprising:

learning a power level of ambient noise present on the transmission medium while maintaining a local transmit communication signal utilizing a first frequency band silent; and

measuring the power level of any signals present in a second frequency band while transmitting in the first frequency band and maintaining the second frequency band silent.

15. The article of manufacture of claim 14 containing further instructions to cause the further operations, comprising:

determining a power level of the echo generated by the non-linear element on the transmission medium when the training protocol directs that no signal should be present in the second frequency band at that point in the training period.

16. The article of manufacture of claim 10 containing further instructions to cause the further operations, comprising:

setting a maximum transmit power level based on results from the training period.

17. An apparatus, comprising:

means for establishing a training period between a first transmitter-receiver device and a second transmitter-receiver device in a discrete multiple tone system that separates communication signals into two or more distinct frequency bands; and

means for detecting for noise caused by an echo generated by a non-linear noise source present on a transmission medium during the training period.

18. The apparatus of claim 17, further comprising:

means for comparing a significance of noise contribution from the non-linear noise source to ambient noise present on the transmission medium.

19. The apparatus of claim 17, further comprising:

means for detecting for echo on the transmission medium during the training period when communication signals are expected in at least a first frequency band and a second frequency band.

20. The apparatus of claim 17, further comprising:

means for detecting for a presence of a first signal in one of the frequency bands when a training protocol directs that no signal should be present in that frequency band at that point in the training period.

21. An apparatus, comprising:

a transmitter-receiver device, wherein the receiver portion contains a frequency filter and a non-linear echo detector to detect for the presence of an echo generated by a non-linear element.

22. The apparatus of claim 21, wherein the transmitter portion contains a transmit power level controller and the non-linear echo detector supplies a signal to the transmit power level controller to eliminate the echo by reducing transmit power of the transmitter-receiver device.

23. The apparatus of claim 21, wherein the non linear echo detector measures a power level of ambient noise and a periodic training signal present on a transmission medium based on an algorithm employing a Fast Fourier Transform and averages the measurements over two or more frames data.