METHOD AND APPARATUS FOR UPDATING EQUALIZATION COEFFICIENTS OF ADAPTIVE PRE-EQUALIZERS

• US 20130051442A1
• Filed: 08/30/2011
• Published: 02/28/2013
• Est. Priority Date: 08/30/2011
• Status: Active Grant

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: General Instrument Corporation (CommScope Holding Company, Inc.)
• Inventors: Cooper, Michael J., Moore, Charles S., Moran, John L., Morrissette, Marc L., Thompson, Robert J.
• Granted Patent: US 8,937,992 B2
• Time in Patent Office: Days
• US Class Current: 375/222
• CPC Class Codes: H04L 25/03006 Arrangements for removing intersymbol interference
• CPC Class Codes: H04L 25/03885 adaptive

Abstract

A method and apparatus for updating equalization coefficients of an adaptive pre-equalizer of a network element are provided. The method includes monitoring a communications channel to measure distortion of a communications signal received from the network element and detecting whether a transient impairment is present in the communication signal. When a transient impairment is not detected to be present, a pre-equalization coefficient update is transmitted to the network element. However, when a transient impairment is detected to be present, at least selected ones of the pre-equalization coefficients are scaled before the update is transmitted to the network element or the update is withheld from being transmitted to the network element. An apparatus is also disclosed.

Claims

1. A method of updating equalization coefficients of an adaptive pre-equalizer of a network element, comprising the steps of:

monitoring a communications channel to measure distortion of a communications signal received from the network element;

detecting, during said monitoring step, whether a transient impairment is present in the communication signal;

determining, after said monitoring step, pre-equalization coefficients based on the distortion measured during said monitoring step;

when a transient impairment is not detected during said detecting step, transmitting, to the network element, a pre-equalization coefficient update with the pre-equalization coefficients determined during said determining step; and

when a transient impairment is detected during said detecting step, modifying the pre-equalization coefficients determined during said determining step before transmitting a pre-equalization coefficient update with the pre-equalization coefficients, as modified, to the network element;

wherein said steps of monitoring, detecting, determining, transmitting, and modifying and transmitting are performed by an electronic communications device having an equalizer unit.

2. A method according to claim 1, wherein said step of modifying the pre-equalization coefficients includes scaling at least some of the pre-equalizations determined during said determining step.

3. A method according to claim 2, wherein during said scaling step, at least some of the pre-equalization coefficients determined by said determining step are reduced by a scaling factor of less than 1.

4. A method according to claim 3, wherein a magnitude of the scaling factor is determined based on a magnitude of the transient impairment detected during said detecting step, and wherein the magnitude of the transient impairment detected during said detecting step is determined based on at least one of a strength of impulse power of the transient impairment, a duration of impulse of the transient impairment, and a repetition of successive impulses of the transient impairment.

5. A method according to claim 1, wherein said detecting step uses at least one of equalizer stress, non-main tap to total energy ratio (NMTER), Reed-Solomon Forward Error Correction (RS FEC) statistics, and burst Modulation Error Rate (MER) to determine whether a transient impairment is present in the communication signal.

6. A method according to claim 1, wherein after said monitoring, detecting, determining, and transmitting or modifying and transmitting steps are completed, the steps are repeated during a next time interval.

7. A method according to claim 1, wherein the transient impairment is at least one of impulse noise and narrowband interference.

8. A method according to claim 1, wherein the electronic communications device is a cable modem termination system (CMTS) and the network element is a cable modem.

9. A method of updating equalization coefficients of an adaptive pre-equalizer of a network element, comprising the steps of:

monitoring a communications channel to measure distortion of a communication signal received from the network element;

detecting, during said monitoring step, whether a transient impairment is present in the communication signal;

when a transient impairment is not detected during said detecting step, transmitting a pre-equalization coefficient update to the network element; and

when a transient impairment is detected during said detecting step, withholding transmission of the pre-equalization coefficient update;

wherein said steps of monitoring, detecting, transmitting, and withholding are performed by an electronic communications device having an equalizer unit.

10. A method according to claim 9, further comprising the step of determining a set of pre-equalization coefficients based on the distortion measured during said monitoring step.

11. A method according to claim 9, wherein said detecting step uses at least one of equalizer stress, non-main tap to total energy ratio (NMTER), Reed-Solomon Forward Error Correction (RS FEC) statistics, and burst Modulation Error Rate (MER) to determine whether a transient impairment is present in the communication signal.

12. A method according to claim 9, wherein after said monitoring, detecting, transmitting, and withholding steps are completed, the steps are repeated during a next time interval.

13. A method according to claim 9, wherein the transient impairment is at least one of impulse noise and narrowband interference.

14. A method according to claim 9, wherein the electronic communications device is a cable modem termination system (CMTS) and the network element is a cable modem.

15. Apparatus for communicating with a network element and for transmitting a pre-equalization coefficient update to the network element, comprising:

an equalizer module configured to determine a pre-equalization coefficients for the network element from measurements of distortion taken by the apparatus from a communications signal received from the network element;

the apparatus being configured to detect whether a transient impairment is present in the communication signal;

the apparatus being configured to transmit a pre-equalization coefficient update to the network element in a normal state of operation when a transient impairment is not present; and

the apparatus being configured to modify the pre-equalization coefficients with a scaling factor of less than one before transmitting a pre-equalization coefficient update to the network element or withhold from transmitting the pre-equalization coefficient update to the network element in an impaired state of operation when a transient impairment is detected to be present.

16. Apparatus according to claim 15, further comprising a transmitter and receiver unit configured to transmit signals to the network element and to receive signals from the network element via at least one communications channel.

17. Apparatus according to claim 16, further comprising a processor unit having a microprocessor for controlling operation of said transmitter and receiver unit and said equalizer module, and wherein said equalizer module is configured to detect whether a transient impairment is present in the communication signal and to modify the pre-equalization coefficients with a scaling factor.

18. Apparatus according to claim 15, wherein, during said impaired state of operation, the apparatus is configured to alter a magnitude of said scaling factor based on a magnitude of the transient impairment detected, and wherein said magnitude of the transient impairment detected is based on at least one of a strength of impulse power of the transient impairment, a duration of impulse of the transient impairment, and a repetition of successive impulses of the transient impairment.

19. Apparatus according to claim 15, wherein the apparatus is configured to detect whether a transient impairment is present in the communication signal by monitoring at least one of equalizer stress, non-main tap to total energy ratio (NMTER), Reed-Solomon Forward Error Correction (RS FEC) statistics, and burst Modulation Error Rate (MER).

20. Apparatus according to claim 15, wherein the apparatus is a cable modem termination system (CMTS).