Method and apparatus for analyzing and mitigating noise in a digital subscriber line

Abstract

Data indicative of a level of stability of a DSL link is received. Based on the received data, it is determined whether the data indicates a level of stability of the DSL link that is above or below a minimum threshold. If the level of stability of the DSL link is below the minimum threshold, die noise associated with the DSL link before the time of failure is compared with the noise associated with the DSL link after the time of failure. If the difference between the noise before and after the time of failure exceeds a threshold, then the difference in noise is characterized as a stationary noise associated with the DSL link. However, if the difference between the noise before and after the time of failure is below the threshold, a determination is made whether the failure is associated with a loss of power to the DSL link or a severe impulse noise event—the difference in noise is characterized accordingly. Finally, the characterization of the noise associated with the DSL link is preserved for subsequent possible reconfiguration of the DSL link to improve link stability.

What is claimed is: 
     
         1 . A computer-implemented method of characterizing noise associated with a digital subscriber line (DSL) link, comprising:
 receiving at a controller data indicative of a level of stability of the DSL link;   determining at the controller whether the data indicates a level of stability of the DSL link that is above or below a minimum threshold;   if the level of stability of the DSL link is below the minimum threshold, the controller:
 comparing a noise level associated with the DSL link before a time of failure with a noise level associated with the DSL link after the time of failure; 
 if a difference between the noise level before and after the time of failure exceeds a threshold, then characterizing the noise as a stationary noise associated with the DSL link; 
 if the difference between the noise level before and after the time of failure is below the threshold, investigating whether the failure is associated with a loss of power to the DSL link or a severe impulse noise event and characterizing the noise accordingly; and 
 recording the characterization of the noise associated with the DSL link. 
   
     
     
         2 . The method of  claim 1 , further comprising the controller estimating a time of a failure of the DSL link based on the data, and wherein comparing the noise level associated with the DSL link before a time of failure with the noise level associated with the DSL link after the time of failure comprises
 comparing a noise level associated with the DSL link before the estimated time of failure with a noise level associated with the DSL link after the estimated time of failure.   
     
     
         3 . The method of  claim 1 , wherein comparing noise associated with the DSL link comprises comparing at a DSL receiver coupled to the associated DSL link the noise level before the time of failure with the noise level after the time of failure. 
     
     
         4 . The method of  claim 1 , further comprising the controller evaluating a distribution of the received data over time, and wherein determining at the controller whether the data indicates a level of stability of the DSL link that is above or below a minimum threshold comprises determining at the controller whether the distribution of data indicates a level of stability of the DSL link that is above or below a minimum threshold. 
     
     
         5 . The method of  claim 1 , wherein comparing the noise level associated with the DSL link before a time of failure with the noise level associated with the DSL link after the time of failure comprises comparing the noise level associated with the DSL link before a time of failure with the noise level associated with the DSL link after the DSL line is reinitialized and in a stable condition. 
     
     
         6 . The method of  claim 1 , wherein the noise level is measured according to at least one of mean-square-error of a decoder of a DSL receiver coupled to the DSL link, and signal to noise ratio (SNR) margin. 
     
     
         7 . The method of  claim 1 , wherein the difference between the noise level before and after the time of failure is calculated as a vector of values corresponding to a plurality of different frequencies, and whether the noise level exceeds or fails below the threshold comprises whether the noise level exceeds or falls below the threshold for a number of the plurality of different frequencies. 
     
     
         8 . An article of manufacture comprising a non-transitory computer readable medium containing instructions that when executed by a computing system, cause the computing system to perform the following steps:
 receiving data indicative of a level of stability of a Digital Subscriber Line (DSL) link;   determining whether the data indicates a level of stability of the DSL link that is above or below a minimum threshold;   if the level of stability of the DSL link is below the minimum threshold:
 comparing a noise level associated with the DSL link before a time of failure with a noise level associated with the DSL link after the time of failure; 
 if a difference between the noise level before and after the time of failure exceeds a threshold, then characterizing the difference in noise as a stationary noise associated with the DSL link; 
 if the difference between the noise level before and after the time of failure is below the threshold, investigating whether the failure is associated with a loss of power to the DSL link or a severe impulse noise event and characterizing the difference in noise accordingly; and 
 recording the characterization of the noise associated with the DSL link. 
   
     
     
         9 . The article of manufacture of  claim 8 , further comprising instructions that when executed by the computing system, cause the computing system to perform the step of estimating a time of a failure of the DSL link based on the data, and wherein the instruction for comparing the noise level associated with the DSL link before a time of failure with the noise level associated with the DSL link after the time of failure comprises an instruction for comparing the noise level associated with the DSL link before the estimated time of failure with the noise level associated with the DSL link after the estimated time of failure. 
     
     
         10 . The article of manufacture of  claim 8 , further comprising instructions that when executed by the computing system, cause the computing system to perform the step of evaluating a distribution of the received data over time, and wherein the determining whether the data indicates a level of stability of the DSL link that is above or below a minimum threshold comprises determining whether the distribution of data indicates a level of stability of the DSL link that is above or below a minimum threshold. 
     
     
         11 . The article of manufacture of  claim 8 , further comprising instructions that when executed by the computing system, cause the computing system to perform the step of reconfiguring the DSL link responsive to the recorded characterization of the noise associated with the DSL link. 
     
     
         12 . The article of manufacture of  claim 8 , further comprising instructions that when executed by the computing system, cause the computing system to perform the following steps:
 determining whether the distribution of performance monitoring data indicates a level of quality of the DSL link that is above or below a minimum threshold;   if the level of quality of the DSL link is below the minimum threshold:
 characterizing whether any impulse noise events associated with the DSL link are intermittent or persistent; 
 recording the characterization of the impulse noise events associated with the DSL link. 
   
     
     
         13 . The article of manufacture of  claim 12 , wherein the instructions for recording the characterization of the impulse noise events associated with the DSL link further comprises instructions for recording at least one of a date, time, duration, and affected frequency, associated with each of the impulse noise events. 
     
     
         14 . The article of manufacture of  claim 12 , further comprising instructions that when executed by the computing system, cause the computing system to perform the step of reconfiguring the DSL link responsive to the recorded characterization of impulse noise events. 
     
     
         15 . A apparatus to characterize noise associated with a digital subscriber line (DSL) link, comprising:
 collecting means for receiving data indicative of a level of stability of a DSL link;   analyzing means for:
 determining whether the data indicates a level of stability of the DSL link that is above or below a minimum threshold; 
 if the level of stability of the DSL link is below the minimum threshold: 
 comparing a noise level associated with the DSL link before a time of failure with a noise level associated with the DSL link after the time of failure;
 if a difference between the noise level before and after the time of failure exceeds a threshold, then characterizing the noise as a stationary noise associated with the DSL link; 
 if the difference between the noise level before and after the time of failure is below the threshold, investigating whether the failure is associated with a loss of power to the DSL link or a severe impulse noise event and characterizing the noise accordingly; and 
 recording the characterization of the noise associated with the DSL link. 
 
   
     
     
         16 . The apparatus of  claim 15 , wherein the analyzing means comprises further means for estimating a time of a failure of the DSL link based on the data, and wherein the analyzing means for comparing the noise level associated with the DSL link before a time of failure with the noise level associated with the DSL link after the time of failure comprises analyzing means for comparing a noise level associated with the DSL link before the estimated time of failure with a noise level associated with the DSL link after the estimated time of failure. 
     
     
         17 . The apparatus of  claim 15 , wherein the noise is measured according to at least one of mean-square-error of a decoder of a DSL receiver coupled to the DSL link, and signal to noise ratio (SNR) margin. 
     
     
         18 . The apparatus of  claim 15 , further comprising means for reconfiguring the DSL link responsive to the recorded characterization of the noise associated with the DSL link. 
     
     
         19 . The apparatus of  claim 15 , wherein:
 the collecting means further receiving a distribution of performance monitoring data indicative of a level of quality of the DSL link;   the analyzing means further determining:
 whether the distribution of performance monitoring data indicates a level of quality of the DSL link that is above or below a minimum threshold; 
 if the level of quality of the DSL link is below the minimum threshold:
 characterizing whether any impulse noise events associated with the DSL link are intermittent or persistent; 
 recording the characterization of the impulse noise events associated with the DSL link. 
 
   
     
     
         20 . The apparatus of  claim 19 , wherein the performance monitoring data comprises at least one of channel-, line-, or higher-layer performance monitoring data.