System and method for un-interrupted operation of communications during interference

• US 8,842,767 B2
• Filed: 04/30/2010
• Issued: 09/23/2014
• Est. Priority Date: 11/04/2009
• Status: Expired due to Fees

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Powell, Scott, Tu, Chung Ming, Dinc, Kadir, Feyh, German, Esmailian, Tooraj, Han, KuoRuey
• Primary Examiner(s): Bayard, Emmanuel
• Application Number:
  US12/771,722
• Publication Number:
  US 20110103459A1
• Time in Patent Office: 1,607 Days
• Field of Search: 375229-234, 375284-285, 375/296
• US Class Current: 375/285
• CPC Class Codes: H04L 25/03057 with a recursive structure H04L25/03031 takes precedence
• CPC Class Codes: H04L 25/03146 with a recursive structure H04L25/03127 takes precedence

Abstract

Methods and systems to substantially eliminate effects of EMI burst noise in an Ethernet system are provided herein. The method includes the step of computing and storing filter coefficients configured to adapt to a range of EMI frequencies. The method further comprises the step of receiving a signal and detecting EMI and frequency of the EMI in the received signal. The method further comprises selecting filter coefficients corresponding to the determined frequency of the detected EMI and adjusting a frequency response of one or more filters using the selected filter coefficients so as to substantially eliminate effects of the EMI in the received signal. The method further includes the step of sending filter coefficients to a link partner corresponding to the frequency of the detected EMI.

Claims

1. A method for reducing effects of Electromagnetic Interference (EMI) in an Ethernet system, comprising:

computing and storing filter coefficients corresponding to a range of EMI frequencies;

receiving a signal;

detecting the EMI in the received signal;

determining a frequency of the EMI;

selecting a subset of the stored filter coefficients for a Feed Forward Equalizer (FFE) and a Decision Feedback Equalizer (DFE) corresponding to the determined frequency of the EMI; and

adjusting a frequency response of the FFE and the DFE using the selected subset of the stored filter coefficients so as to reduce effects of the EMI in the received signal.

2. The method of claim 1, further comprising signaling a presence of the EMI to a link partner.

3. The method of claim 2, wherein signaling comprises:

sending a predetermined sequence of bits in a plurality of consecutive frames to indicate the presence of the EMI to the link partner.

4. The method of claim 3, further comprising sending the predetermined sequence of bits using auxiliary bits.

5. The method of claim 1, further comprising transmitting a sine wave approximately equal in frequency to that of the EMI to signal a presence of the EMI to a link partner.

6. The method of claim 1, further comprising transmitting a sine wave based on a frequency of the EMI to signal a presence of the EMI to a link partner.

7. The method of claim 1, further comprising sending one or more of the selected subset of the stored filter coefficients to the DFE corresponding to the frequency of the EMI to a link partner.

8. The method of claim 1, further comprising sending one or more of the selected subset of the stored filter coefficients to the DFE by encoding the one or more of the selected subset of the stored filter coefficients in a High-level Data Link Control (HDLC) packet.

9. The method of claim 1, further comprising encoding a frequency in a High-level Data Link Control (HDLC) packet to send the frequency of the EMI to a link partner.

10. The method of claim 1, wherein detecting comprises:

using a Power Spectral Density (PSD) of the received signal to distinguish the EMI from the received signal.

11. The method of claim 1, wherein detecting comprises:

detecting the EMI based on an output of an analog-to-digital converter.

12. The method of claim 1, wherein detecting comprises:

detecting the EMI based on an input to the FFE.

13. The method of claim 1, wherein detecting comprises:

detecting the EMI based on a difference between an output of a slicer and an input of the slicer.

14. The method of claim 1, wherein determining comprises:

determining the frequency of the EMI based on an output of an analog-to-digital converter, an input to the FFE or an output of a slicer.

15. The method of claim 1, further comprising performing the detecting, determining, selecting and adjusting steps in less than a pre-determined amount of time.

16. The method of claim 15, wherein the pre-determined amount of time is approximately 10 ms.

17. The method of claim 1, wherein the filter coefficients are for a notch filter.

18. The method of claim 1, wherein computing and storing comprises:

computing the filter coefficients for the FFE and the DFE using a Least-mean-square (LMS) module.

19. The method of claim 1, wherein computing and storing comprises:

storing the filter coefficients prior to detecting the EMI in the received signal.

20. The method of claim 1, wherein detecting, selecting, and adjusting are performed in a digital domain.

21. A system to reduce effects of Electromagnetic Interference (EMI) in an Ethernet system, comprising:

a processor configured to store filter coefficients corresponding to a range of pre-determined EMI frequencies;

a Feed Forward Equalizer (FFE) configured to adapt its frequency response using FFE filter coefficients selected from the stored filter coefficients corresponding to a frequency of the EMI so as to reduce effects of the EMI in a received signal; and

a Decision Feedback Equalizer (DFE) configured to adapt its frequency response using DFE filter coefficients selected from the stored filter coefficients corresponding to the frequency of the EMI so as to reduce the effects of the EMI in the received signal.

22. The system of claim 21, wherein the processor is further configured to send a predetermined sequence of auxiliary bits in a plurality of low-density-parity-check (LDPC) blocks to signal a presence of the EMI to a link partner.

23. The system of claim 21, further comprising a Direct Digital Frequency Synthesizer (DDFS) configured to send a sine wave approximately equal in magnitude and frequency to that of the EMI to signal a presence of the EMI to a link partner.

24. The system of claim 21, wherein the processor is further configured to encode the DFE filter coefficients in a High-level Data Link Control (HDLC) packet to transmit the DFE filter coefficients to a link partner.

25. The system of claim 21, wherein the processor is further configured to encode the frequency of the EMI in a High-level Data Link Control (HDLC) packet to transmit the frequency of the EMI to a link partner.

26. The system of claim 21, further comprising a tone detector configured to detect the EMI and the frequency of the EMI based on an output of an analog-to-digital converter.

27. The system of claim 21, further comprising a tone detector configured to detect the EMI and the frequency of the EMI based on an input to the FFE.

28. The system of claim 21, further comprising a tone detector configured to detect the EMI and the frequency of the EMI based on an output of a slicer.

29. The system of claim 21, wherein the FFE comprises:

a configurable notch filter configured to remove the EMI.

30. The system of claim 21, wherein the processor is further configured to select the FFE filter coefficients or the DFE filter coefficients corresponding to the determined frequency of the EMI.

31. A method to reduce effects of Electromagnetic Interference (EMI) in an Ethernet system, comprising:

receiving a signal from a link partner indicating a presence of the EMI;

receiving filter coefficients for a programmable pre-coder from the link partner corresponding to the EMI; and

adjusting a frequency response of the pre-coder using the received filter coefficients so as to reduce effects of the EMI on the received signal.

32. The method of claim 31, wherein the programmable pre-coder is a Tomlinson-Harashima pre-coder.

33. A non-transitory computer readable medium having stored thereon computer executable instructions that, when executed by a computing device, cause the computing device to perform a method comprising:

computing and storing filter coefficients corresponding to a range of Electromagnetic Interference (EMI) frequencies;

receiving a signal indicating a presence of EMI and a frequency of the EMI;

selecting a subset of the stored filter coefficients for a Feed Forward Equalizer (FFE) and a Decision Feedback Equalizer (DFE) corresponding to the frequency of the EMI; and

adjusting a frequency response of the FFE and the DFE using the selected subset of the stored filter coefficients so as to reduce effects of the EMI in the received signal.