Various methods and apparatuses for impulse noise detection

• US 20070183526A1
• Filed: 02/06/2006
• Published: 08/09/2007
• Est. Priority Date: 02/06/2006
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: 2Wire, Inc. (CommScope Holding Company, Inc.)
• Inventors: Desjardins, Philip, Behrin, Mike, Norrell, Andy, Lery, Scott
• Granted Patent: US 7,813,439 B2
• Time in Patent Office: Days
• US Class Current: 375/265
• CPC Class Codes: H04L 1/004 by using forward error control H04L1/0618 takes precedence; coding, decoding or code conversion, for error detection or correction H03M13/00
• CPC Class Codes: H04L 25/03159 operating in the frequency domain H04L25/03165, H04L25/03178 take precedence
• CPC Class Codes: H04L 25/061 providing hard decisions only; arrangements for tracking or suppressing unwanted low frequency components, e.g. removal of dc offset removal of dc offset in coupling arrangements H04L25/029, H04L25/0296
• CPC Class Codes: H04L 25/067 providing soft decisions, i.e. decisions together with an estimate of reliability H04L25/068 and H04L25/069 take precedence; sequence estimation techniques H04L25/03178
• CPC Class Codes: H04L 27/2078 in which the phase change per symbol period is constrained coset coding H04L27/186
• CPC Class Codes: H04L 27/2647 Arrangements specific to the receiver only equalisation H04L27/01

Abstract

Methods and apparatuses for reducing effects of impulse noise in a DSL transmitter receiver device are described. According to certain embodiment, the method includes comparing a hard decision output of a decoder with a soft decision output for a convolution coded modulation symbol received at a digital subscriber line (DSL) receiver. The presence of impulse noise is detected based on a lack of agreement between the hard decision output and the soft decision output.

Claims

1. A method for impulse noise detection, comprising:

comparing a hard decision output of a decoder with a soft decision output for a convolution coded modulation symbol received at a digital subscriber line (DSL) receiver; and

detecting a presence of impulse noise based on a lack of agreement between the hard decision output and the soft decision output.

2. The method recited in claim 1, wherein the convolution coded modulation is a trellis coded modulation.

3. The method recited in claim 1, further comprising:

selecting the hard decision output from a set of hard decision outputs of the decoder based upon a distance between the hard decision outputs and a point received at the decoder.

4. The method recited in claim 1, further comprising:

selecting the soft decision output from a set of soft decision outputs of the decoder based upon a match between the set of soft decision outputs and a received sequence.

5. The method recited in claim 1, further comprising:

setting an indicator to indicate a lack of agreement between the hard decision output and the soft decision output; and

comparing the indicator with a threshold to determine presence of impulse noise.

6. The method recited in claim 1, further comprising:

reducing an amount of data transmitted with data frames in which the presence of impulse noise is detected as compared to data frames with no impulse noise.

7. The method recited in claim 5, further comprising:

utilizing the indicator in an erasure indicator for DSL systems employing erasure decoding.

8. A digital subscriber line (DSL) modem, having a receiver comprising:

a comparator to compare soft decision data and hard decision data of a decoder at the receiver for a convolution coded modulation symbol received at the receiver; and

an impulse noise predictor to predict when data frames are affected by impulse noise based upon an output of the comparator.

9. The DSL modem recited in claim 8, wherein the data frames are decoded into P-dimensional constellations having 2^N sub-constellations.

10. The DSL modem recited in claim 8, wherein the comparator selects the hard decision data from a set of hard decision outputs of the decoder based upon a distance between the hard decision outputs and a point received at the decoder.

11. The DSL modem recited in claim 10, wherein the distance between the selected hard decision output and the received point is shorter than the distance between the remaining hard decision outputs in the set of hard decision outputs and the received point.

12. The DSL modem recited in claim 9, further comprising:

a trellis decoder to decode which sub-constellations are received at the DSL modem.

13. The DSL modem recited in claim 8, wherein the comparator selects the soft decision data from a set of soft decision outputs of the decoder based upon a match between the set of soft decision outputs and a received sequence.

14. The DSL modem recited in claim 9, further comprising:

a table for setting an indicator to indicate a lack of agreement between the hard decision data and the soft decision data.

15. A DSL system comprising:

a first transmitter-receiver device having a receiver, the receiver having an impulse noise predictor to determine if data frames are affected by impulse noise based on a comparison of soft decision data and hard decision data of a decoder at the receiver; and

a second transmitter-receiver device having a transmitter.

16. The DSL system recited in claim 15, the first transmitter-receiver device further comprising:

an impulse noise predictor to predict if data frames are affected by impulse noise based upon an output of the comparator.

17. The DSL system recited in claim 15, the first transmitter-receiver device to transmit parameters of the impulse noise to the second transmitter-receiver device.

18. The DSL system recited in claim 17, the second transmitter-receiver device to reduce payload data in frames upon receiving the control parameters from the first transmitter-receiver device.