Line probe signal and method of use

• US 20020126803A1
• Filed: 01/16/2001
• Published: 09/12/2002
• Est. Priority Date: 01/16/2001
• Status: Active Grant

• Current Assignee: Chemtron Research LLC (Intellectual Ventures LLC)
• Original Assignee: Mindspeed Technologies Inc. (MACOM Technology Solutions Holdings, Inc.)
• Inventors: Patravali, Shrenik, Jones, William W., Jonsson, Ragnar H., Olafsson, Sverrir
• Granted Patent: US 6,693,992 B2
• Time in Patent Office: Days
• US Class Current: 379/22.02
• CPC Class Codes: H04L 1/0002 by adapting the transmission rate
• CPC Class Codes: H04L 5/023 Multiplexing of multicarrier modulation signals multicarrier modulation H04L27/2601
• CPC Class Codes: H04L 5/1446 of transmission speed
• CPC Class Codes: H04M 1/24 Arrangements for testing
• CPC Class Codes: H04M 3/305 testing of physical copper line parameters, e.g. capacitance or resistance locating faults in cables G01R31/08

Abstract

A system, method, and signal are disclosed for line probing. The invention provides an improved signal for line probing having desirable characteristics. In various embodiments the signal comprises a periodic sequence having good autocorrelation characteristics. The periodic sequence of the invention provides a faster and more accurate evaluation of the channel. Another embodiment of the invention comprises processing of the received sequence to determine a desired or maximum data rate for the line or channel. The invention also provides an evaluation and calculation of the noise on the line or channel.

Claims

1. A method for performing a line probe operation comprising:

generating a sequence signal;

transmitting the sequence signal over the line;

receiving the signal; and

processing the signal to evaluate line characteristics to determine a data transmission rate on the line.

2. The method of claim 1, wherein the sequence signal comprises a maximal length sequence, a Barker code type sequence, Kasami type sequence or a Gold code type sequence.

3. The method of claim 1, wherein the line comprises a twisted pair conductor.

4. The method of claim 1, wherein processing comprises performing cross correlation of the received signal and a reference signal to determine line characteristics.

5. The method of claim 1, wherein a scrambler in a digital subscriber line communication device generates the sequence signal.

6. A method for performing a line probe operation comprising:

generating a sequence signal, the sequence signal having correlation properties that approximate an impulse;

transmitting the sequence signal over a line to a remote location;

receiving data regarding the line from the remote location; and

establishing a transmit rate based on the data.

7. The method of claim 6, wherein the period of the sequences is 31.

8. The method of claim 6, wherein the period of the sequences is 63.

9. The method of claim 6, wherein the period of the sequences is 127.

10. The method of claim 6, wherein the period of the sequences is 255.

11. The method of claim 6, wherein generating a sequence signal occurs at a central office, transmitting the sequence signal occurs at the central office, receiving data occurs at a CPE, and establishing a data transmit rate occurs at the central office.

12. The method of claim 6, wherein generating a sequence signal occurs at a CPE, transmitting the sequence signal occurs at the CPE, receiving data occurs at a central office, and establishing a data transmit rate occurs at the central office.

13. The method of claim 6, wherein generating a sequence comprises generating a maximal length sequence having a period selected from the group of 31, 63, 127, and 255.

15. The method of claim 14, wherein the sequence signal comprises a maximal length sequence.

16. The method of claim 14, wherein the processing comprises determining a desired data transmission rate for the first device.

17. The method of claim 14, wherein the period of the sequence is selected from the group of periods consisting of 31, 63, 127, and 255.

19. The method of claim 18, wherein the maximal length sequence is selected from the set of maximal length sequences having periods consisting of 31, 63, 127, and 255.

20. The method of claim 18, wherein crosscorrelating comprises using sliding tap delay cross correlation.

21. The method of claim 18, wherein the line comprises a twisted pair.

22. The method of claim 18, further including calculating at the second location a maximum data rate supportable by the line, and sending information regarding the maximum data rate to the first location to control the rate of data transmission from the first location to the second location.

23. The method of claim 18, wherein the communication line connects to a digital subscriber line communication device.

25. The method of claim 24, wherein either of the first communication device or the second communication device comprises a digital subscriber line access multiplexer.

26. The method of claim 24, wherein the maximal length sequence, when crosscorrelated, generally resembles an impulse response of the communication channel.

27. The method of claim 24, wherein the communication channel comprises twisted pair conductors.

29. The system of claim 28, wherein the generator comprises a scrambler.

30. The system of claim 28, wherein the sequence signal comprises a maximal length type sequence.

31. The system of claim 28, wherein the sequence has a period of 31.

32. The system of claim 28, wherein the sequence has a period of 63.

33. The system of claim 28, wherein the sequence has a period of 127.

34. The system of claim 28, wherein the sequence has a period of 255.

36. The system of claim 35, wherein the crosscorrelator comprises:

a sequence generator configured to generate a second sequence signal, the second sequence signal being generally similar to the sequence signal that was transmitted to the system;

a multiplier configured to multiply the sequence generator output with the received signal; and

an accumulator configured to create a running summation of the output of the multiplier.

37. The system of claim 36, further including means for calculating a maximum data rate that the line will support;

and

a transmitter configured to transmit to a receiving device at a transmission rate less than the maximum data rate that the line will support.

38. The method of claim 35, further including a processor to perform Discrete Fourier Transform on the sequence signal.

40. The method of claim 39, wherein the generating is performed by a scrambler.

41. The method of claim 39, wherein the processing device is located in a digital subscriber line communication device.

42. The method of claim 39, wherein the signal comprises a sequence signal.

43. The method of claim 42, wherein the sequence signal comprises a maximal length sequence.

14. A method for performing a line probe operation comprising:

receiving a sequence signal from a first device, the sequence signal having autocorrelation properties that approximate an impulse;

processing the sequence signal to calculate data regarding at least one line characteristic; and

transmitting the data to the first device to control the rate of transmission from the first device.

18. A method for line probing a communication line comprising:

generating an maximal length sequence signal at a first location;

transmitting the sequence signal over the communication line to a second location;

receiving the sequence signal at the second location; and

crosscorrelating the received sequence signal with a reference signal at the second location.

24. A method for creating a line probe signal to evaluate the characteristics of a communication line used by a communication device operating under the digital subscriber line standard comprising:

generating a maximal length sequence at a first communication device, the first communication device configured to operate under the digital subscriber line standard,

transmitting the sequence from the first communication device to a second communication device over a communication channel, the second communication device configured to operate under the digital subscriber line standard;

receiving data transmission rate information at the first communication device from the second communication device; and

setting a data transmission rate for transmission from the first communication device to the second communication device based on the data transmission rate information.

28. A line probe system comprising:

a sequence generator configured to generate a sequence signal, the sequence signal used for line probing;

a signal mapper configured to map the sequence signal to a numerical value representative of the sequence signal values; and

a transmitter device configured to transmit the mapped signal onto the line to be probed.

35. A system for receiving a periodic sequence for use in line probing a line comprising:

a filter to isolate a desired portion of a received line probe sequence signal;

a correlator configured to processes the sequence signal to thereby obtain an approximation of the channel response to an impulse signal, wherein the impulse signal provides information regarding the characteristics of the line.

39. A method for transmitting information over a communication path to evaluate the frequency characteristics of the communication path comprising:

selecting a period for a signal wherein the period comprises a period selected from the group of 31, 63, 127, and 255;

generating the signal;

transmitting the signal to a processing device, the processing device configured to perform calculations on the received signal to determine the frequency characteristics of the communication path.

44. A method for channel probing a channel comprising:

generating a sequence signal defined by one of the following equations;

s(n)=s(n−

1)⊕

f(n) s(n)=s(n−

2)⊕

s(n−

5)⊕

f(n) s(n)=s(n−

1)⊕

s(n−

6)⊕

f(n) s(n)=s(n−

3)⊕

s(n−

7)⊕

f(n) s(n)=s(n−

2)⊕

s(n−

3)⊕

s(n−

4)⊕

s(n−

8)⊕

f(n) s(n)=s(n−

3)⊕

s(n−

5)⊕

f(n) s(n)=s(n−

5)⊕

s(n−

6)⊕

f(n) s(n)=s(n−

4)⊕

s(n−

7)⊕

f(n) s(n)=s(n−

4)⊕

s(n−

5)⊕

s(n−

6)⊕

s(n−

8)⊕

f(n)

transmitting the generated sequence signal to a device configured to analyze the signal.

45. The method of claim 44, further including receiving information regarding the channel in response the transmitting and selecting a data transmission rate based on the information regarding the channel.

46. The method of claim 44, wherein the channel is a channel intended to carry data transmitted under the digital subscriber line standard.

47. The method of claim 44, wherein f(n) is the logical ones input to the scrambler, s(n-k) is a tap point after a k-th delay element in a scrambler and ⊕

defines modulo-2 addition.

48. The method of claim 44, wherein the channel comprises a twisted pair of conductors connected to communication device operating under the G.shdls standard.

50. The method of claim 49, wherein the sequence has a period of 31, 63, 127, or 255.

51. The method of claim 49, wherein the sequence signal comprises a maximal length sequence.

49. A computer program product comprising a computer useable medium having computer program logic recorded thereon for generating a sequence signal comprising:

computer program code logic configured to obtain a polynomial for use in generating the sequence signal;

computer program code logic configured to generate a sequence signal using the polynomial; and

computer program code logic configured to process the sequence signal to prepare it for transmission over a line, the line to be probed by the sequence signal to evaluate the frequency response of the line.