Method for handling transmission errors on a telecommunications transmission line

• US 9,166,743 B2
• Filed: 12/29/2010
• Issued: 10/20/2015
• Est. Priority Date: 12/29/2010
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Eriksson, Per-Erik, Lu, Chenguang
• Primary Examiner(s): Javaid, Jamal
• Application Number:
  US13/976,665
• Publication Number:
  US 20130272110A1
• Time in Patent Office: 1,756 Days
• Field of Search: 370/216, 370/252, 370/222, 370/227, 370/235, 370/244
• US Class Current: 1/1
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1867 Arrangements specially adapted for the transmitter end
• CPC Class Codes: H04L 1/1874 Buffer management
• CPC Class Codes: H04L 1/20 using signal quality detector

Abstract

When data retransmission is used to handle errors caused by impulse noise, buffer memory requirements may be reduced and/or data rate increased by detecting impulse noise at the transmitting equipment and initiating retransmission in response to such detection rather than waiting for a retransmission indication from the receiving end. The decision to retransmit may be made dependent on the strength or other properties of the detected noise burst. The decision criterion may be made adaptive by correlating noise burst properties with received retransmission indications or the absence thereof.

Claims

1. A method, in a first communications equipment, for handling transmission errors on a telecommunications transmission line, the first communications equipment being adapted for connection to a first end of the telecommunications transmission line and for communication via the telecommunications transmission line with a second communications equipment connected to a second end of the telecommunications transmission line, the method comprising:

the first communications equipment buffering one or more data units which are to be transmitted so as to enable later retransmission;

the first communications equipment transmitting the one or more data units to the second communications equipment;

the first communications equipment detecting a first burst of impulse noise at the first end of the line;

the first communications equipment, in response to the detection;

selecting one or more of the buffered data units as selected data units;

retransmitting the selected data units to the second communications equipment;

wherein the selecting comprises selecting buffered data units such that at least one of the selected data units corresponds to a data unit previously transmitted at such a time that its reception by the second communications equipment coincides with a second burst of impulse noise at the second end of the line, the second burst of impulse noise originating from a same electrical event as the first burst of impulse noise.

2. The method of claim 1, wherein the selecting comprises selecting all buffered data units.

3. The method of claim 1, wherein the selecting comprises selecting a subset of the buffered data units.

4. The method of claim 3, wherein the selecting comprises selecting data units residing in predefined buffer positions.

5. The method of claim 1, further comprising determining whether to perform the retransmitting based on one or more properties of the first burst of impulse noise such that the retransmitting takes place only if a criterion depending on one or more properties of the first burst of impulse noise is fulfilled.

6. The method of claim 5, wherein the criterion is based on a measure of the strength of the first burst of impulse noise.

7. The method of claim 6, wherein the criterion is further based on an estimate of the attenuation of the transmission line.

8. The method of claim 5, wherein the criterion is based on a correlation between one or more properties of previous noise bursts detected at the first end of the line and corresponding retransmission indications from the second communications equipment.

9. The method of claim 1, wherein the first and second communications equipment are x Digital Subscriber Line (xDSL) equipment.

10. The method of claim 9, wherein the first communications equipment is an xDSL Digital Subscriber Line Access Multiplexer (xDSL DSLAM) and the second communications equipment is an xDSL Customer-Provided Equipment (xDSL CPE).

11. The method of claim 9, wherein the first communications equipment is an xDSL Customer-Provided Equipment (xDSL CPE) and the second communications equipment is an xDSL Digital Subscriber Line Access Multiplexer (xDSL DSLAM).

12. The method of claim 1, wherein the time is in a time interval during which a Discrete Multi-Tone (DMT) symbol was received by the first communications equipment and, during which reception, the first burst of impulse noise was present.

13. A first x Digital Subscriber Line (xDSL) Terminal Unit (XTU) adapted to be connected to a first end of a telecommunications transmission line and adapted to communicate via the telecommunications transmission line with a second XTU connected to a second end of the telecommunications transmission line, the first XTU comprising:

an impulse noise detector operative to initiate retransmission of one or more data units from the first XTU to the second XTU in response to detection of a first burst of impulse noise at the first end of the line;

a selector operationally coupled to the detector and configured to;

in response to the detector initiating retransmission, select one or more buffered data units as selected data units so that at least one of the selected data units corresponds to a data unit previously transmitted at such a time that its reception by the second XTU coincides with a second burst of impulse noise at the second end of the line, wherein the second burst of impulse noise originates from a same electrical event as the first burst of impulse noise;

a retransmission multiplexor operationally coupled to the detector and the selector and configured to;

buffer one or more data units which are to be transmitted so as to enable later retransmission; and

retransmit the selected data units to the second XTU.

14. The first XTU of claim 13, wherein the time is in a time interval during which a Discrete Multi-Tone (DMT) symbol was received by the first XTU and, during which reception, the first burst of impulse noise was present.

15. The first XTU of claim 13, wherein the detector is further configured to initiate retransmission responsive to determining that a certain criterion associated with a property of the first burst of impulse noise is fulfilled.

16. The first XTU of claim 15, wherein the certain criterion is based on a correlation between a property of a previous burst of impulse noise detected at the first end of the line by the first XTU and a corresponding retransmission indication received by the first XTU from the second XTU.