Method of and apparatus for performing line characterization in a non-idle mode in a subscriber line communication system

• US 6,445,733 B1
• Filed: 02/23/1998
• Issued: 09/03/2002
• Est. Priority Date: 10/03/1997
• Status: Expired due to Term

• Current Assignee: Ikanos Communications Incorporated (Qualcomm, Inc.)
• Original Assignee: Conexant Systems Incorporated (Synaptics Incorporated)
• Inventors: Ko, Kenneth D., Zuranski, Edward S., Haque, Jamal, Patravali, Shrenik P., Rodriguez, Manuel I., Souders, Keith A., Tzouris, Anthony A.
• Primary Examiner(s): Vincent, David
• Assistant Examiner(s): Boakye, Alexander O.
• Application Number:
  US09/028,016
• Time in Patent Office: 1,653 Days
• Field of Search: 370/391, 370/437, 370/465, 370/466, 370/480, 370/469, 370/252, 370/241, 370/242, 370/493, 370/494, 370/495, 370/419, 370/463, 379/93.06, 379/93.31, 379/100, 375/222, 375/224, 375/231
• US Class Current: 375/231
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0057 Block codes H04L1/0061, H04L1/0064 take precedence
• CPC Class Codes: H04L 27/0002 analog front ends; means for connecting modulators, demodulators or transceivers to a transmission line duplex arrangements H04L5/143
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 7/048 using the properties of error detecting or error correcting codes, e.g. parity as synchronisation signal
• CPC Class Codes: H04L 7/10 Arrangements for initial synchronisation
• CPC Class Codes: H04M 11/062 using different frequency bands for speech and other data
• CPC Class Codes: Y02D 30/50 in wire-line communication networks, e.g. low power modes or reduced link rate

Abstract

A digital subscriber line communication system does not require the use of a plain old telephone service (POTS) splitter in the resident'"'"'s home. Digital signal processing techniques are utilized to adapt to varying subscriber line conditions due to POTS telephone equipment. The digital signal processing techniques eliminate the need for a splitter by reducing susceptibility to distortion due to varying subscriber line characteristics. The digital subscriber line modem characterizes the subscriber line under a variety of conditions when the modem is in a non-idle mode. The digital subscriber line modem includes a control circuit which performs rapid retrain operation utilizing line characterization information.

Claims

1. A method of characterizing a subscriber line in a communication system including a first modem and a second modem coupled via the subscriber line and communicating data on a communication channel, the method comprising:

providing a test signal on a control channel distinct from the communication channel from the first modem to the second modem across the subscriber line under a plurality of conditions;

receiving the test signal with the second modem under the conditions;

analyzing the test signal received by the second modem to generate a characterization signal for each of the conditions;

storing the characterization signal with respect to each of the conditions; and

wherein the test signal is provided in a different frequency range than the data.

2. The method of claim 1, wherein the test signal includes a plurality of tones at predetermined frequencies.

3. A method of characterizing a subscriber line in a communication system including a first modem and a second modem coupled via the subscriber line and communicating data on a communication channel, the method comprising:

providing a test signal on a control channel distinct from the communication channel from the first modem to the second modem across the subscriber line under a plurality of conditions;

receiving the test signal with the second modem under the conditions;

analyzing the test signal received by the second modem to generate a characterization signal for each of the conditions;

wherein the test signal is a chirp signal.

4. A method of characterizing a subscriber line in a communication system including a first modem and a second modem coupled via the subscriber line and communicating data on a communication channel, the method comprising:

providing a test signal on a control channel distinct from the communication channel from the first modem to the second modem across the subscriber line under a plurality of conditions;

receiving the test signal with the second modem under the conditions;

analyzing the test signal received by the second modem to generate a characterization signal for each of the conditions;

repeating the providing, receiving, analyzing, and storing steps at particular times of the day.

5. The method of claim 4, wherein the characterization signal is stored with reference to the particular times of the day.

6. The method of claim 4 further comprising:

providing instructions to a user to adjust the conditions of the subscriber line.

7. The method of claim 6, wherein the adjusting step includes placing at least one telephone coupled to the subscriber line off-hook.

8. A digital subscriber line modem, comprising:

a data line access coupled to a subscriber line;

an equalizer coupled to the data line access, the equalizer having a response in accordance with equalizer control signals;

a line characterization circuit coupled to the equalizer, the line characterization circuit receiving a subscriber line signal on the subscriber line while the modem is in a non-idle mode and the line characterization circuit analyzing the line signal to generate the equalizer control signals, the line characterization circuit storing the equalizer control signals, wherein the line characterization circuit receives the line signals when the subscriber line has a particular parameter, the equalizer control signals being stored with respect to the particular parameter; and

a retrain circuit, wherein the retrain circuit utilizes the equalizer control signals stored by the line characterization circuit to configure the digital subscriber line modem.

9. The digital subscriber line modem of claim 8, wherein the modem is an ADSL modem.

10. The digital subscriber line modem of claim 8, wherein the particular parameter is a time of day and a hook status.

11. The digital subscriber line modem of claim 8, wherein the equalizer control signals are tap coefficients and wherein the line signal is a low level test signal.

12. The digital subscriber line modem of claim 8, wherein the particular parameter is a time of day.

13. A method of characterizing a subscriber line in a communication system including a first modem communicating with a second modem across the subscriber line, the method comprising:

performing a non-destructive characterization task on the subscriber line under a plurality of conditions;

measuring parameters associated with the characterization tasks to obtain a result for each of the conditions; and

storing the result for each of the conditions, the result being related to characteristics of the subscriber line.

14. The method of claim 13 further comprising:

communication channel from the first modem to the second modem across the subscriber line under a plurality of conditions;

receiving the test signal with the second modem under the

providing instructions to a user to adjust the conditions of the subscriber line.

15. The method of claim 13 further comprising:

scheduling the performance of a series of the characterization task over a time period.

16. The method of claim 13, wherein one of the conditions involves placing at least one telephone coupled to the subscriber line off-hook.

17. The method of claim 13, wherein the characterization task includes passively receiving a line signal.

18. The method of claim 13, wherein the characterization task includes receiving a low level test signal.

19. The method of claim 18 further comprising:

performing statistical analysis on the parameters to determine a statistical result.

20. The method of claim 13, wherein the characterization tasks include receiving a test signal on a control channel.

21. A subscriber line modem, comprising:

a data line access coupled to the subscriber line;

a control circuit coupled to the subscriber line, the control circuit transmitting and receiving data on the subscriber line, the control circuit including a retrain circuit and a line characterization circuit, the retrain circuit configuring the control circuit for the subscriber line, the line characterization circuit characterizing the subscriber line and storing parameter signals associated with characteristics of the subscriber line, wherein the retrain circuit reads the parameter signals and configures the control circuit in response to the parameter signals wherein the parameter signals are stored in a data base, wherein the parameter signals are stored according to times of day.

22. The subscriber line modem of claim 21, wherein the line characterization circuit receives a subscriber line signal while the modem is in a non-idle mode.

23. The subscriber line modem of claim 21, wherein the parameter signals are stored in a solid state memory.

24. The subscriber line modem of claim 23, wherein the modem is an ADSL modem.

25. A digital subscriber line modem, comprising:

a data line access coupled to a subscriber line;

an equalizer coupled to the data line access, the equalizer having a response in accordance with equalizer control signals;

a line characterization circuit coupled to the equalizer, the line characterization circuit receiving a subscriber line signal on the subscriber line while the modem is in a non-idle mode and the line characterization circuit analyzing the line signal to generate the equalizer control signals, the line characterization circuit storing the equalizer control signals, wherein the line characterization circuit receives the line signals when the subscriber line has a particular parameter, the equalizer control signals being stored with respect to the particular parameter, wherein the particular parameter is a time of day; and

a retrain circuit, wherein the retrain circuit utilizes the equalizer control signals stored by the line characterization circuit to configure the digital subscriber line modem.

26. A subscriber line modem, comprising:

a data line access coupled to the subscriber line;

a control circuit coupled to the subscriber line, the control circuit transmitting and receiving data on the subscriber line, the control circuit including a retrain circuit and a line characterization circuit, the retrain circuit configuring the control circuit for the subscriber line, the line characterization circuit characterizing the subscriber line and storing parameter signals associated with characteristics of the subscriber line, wherein the retrain circuit reads the parameter signals and configures the control circuit in response to the parameter signals.