Adaptive adjustment of time and frequency domain equalizers in communications systems

Abstract

An update mechanism and approach are provided for configuring a communications receiver. According to the approach, a time domain equalizer and a frequency domain equalizer in a communications receiver are dynamically updated based upon performance data that indicates the performance of a communications channel from which the communications receiver receives data. This approach accounts for changes in the communications channel attributable to changes in the transmission medium or changes in interference sources.

1. A communications receiver comprising:
 a time domain equalizer; 
 a frequency domain equalizer; and 
 an update mechanism configured to update both the time domain equalizer and the frequency domain equalizer based upon performance of a communications channel from which the communications receiver receives data, wherein updating the time domain equalizer includes: 
 causing the time domain equalizer to operate with a first set of coefficients, 
 determining first performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the first set of coefficients, 
 changing the coefficients used by the time domain equalizer so that the time domain equalizer operates with a second set of coefficients, 
 determining second performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the second set of coefficients, 
 selecting for use by the time domain equalizer, based upon the first performance data and the secondperformance data, either the first set of coefficients or the second set of coefficients, 
 if the first set of coefficients is selected for use, then changing the coefficients used by the time domain equalizer so that the time domain equalizer operates with the first set of coefficients, and 
 if the second set of coefficients is selected for use, then causing the time domain equalizer to continue to operate with the second set of coefficients. 
 
 
     
     
       2. The communications receiver as recited in  claim 1 , wherein the update mechanism is further configured to determine the first and second performance data based upon synchronization symbols received by the communications receiver. 
     
     
       3. The communications receiver as recited in  claim 1 , wherein the communications receiver is a digital subscriber line communications receiver. 
     
     
       4. The communications receiver as recited in  claim 1 , wherein the communications receiver is part of a discrete multitone communications system. 
     
     
       5. The communications receiver as recited in  claim 1 , wherein:
 the first performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the first set of coefficients; and 
 the second performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the second set of coefficients. 
 
     
     
       6. The communications receiver as recited in  claim 1 , wherein:
 the communications receiver uses an initial bit allocation; and 
 the update mechanism is further configured to
 determine an updated bit allocation based upon the first and second performance data, and 
 cause the communications receiver to use the updated bit allocation. 
 
 
     
     
       7. The communications receiver as recited in  claim 1 , wherein the update mechanism is further configured to perform gain adjustments on tones based upon the first and second performance data. 
     
     
       8. An update mechanism configured to:
 update both a time domain equalizer and a frequency domain equalizer in a communications receiver based upon performance of a communications channel from which the communications receiver receives data, wherein updating the time domain equalizer includes: 
 causing the time domain equalizer to operate with a first set of coefficients, 
 determining first performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the first set of coefficients, 
 changing the coefficients used by the time domain equalizer so that the time domain equalizer operates with a second set of coefficients, 
 determining second performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the second set of coefficients, 
 selecting for use by the time domain equalizer, based upon the first performance data and the second performance data, either the first set of coefficients or the second set of coefficients, 
 if the first set of coefficients is selected for use, then changing the coefficients used by the time domain equalizer so that the time domain equalizer operates with the first set of coefficients, and 
 if the second set of coefficients is selected for use, then causing the time domain equalizer to continue to operate with the second set of coefficients. 
 
 
     
     
       9. The update mechanism as recited in  claim 8 , wherein the update mechanism is further configured to determine the first and second performance data based upon synchronization symbols received by the communications receiver. 
     
     
       10. The update mechanism as recited in  claim 8 , wherein the communications receiver is a digital subscriber line communications receiver. 
     
     
       11. The update mechanism as recited in  claim 8 , wherein the communications receiver is part of a discrete multitone communications system. 
     
     
       12. The update mechanism as recited in  claim 8 , wherein:
 the first performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the first set of coefficients; and 
 the second performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the second set of coefficients. 
 
     
     
       13. The update mechanism as recited in  claim 8 , wherein:
 the communications receiver uses an initial bit allocation; and 
 the update mechanism is further configured to
 determine an updated bit allocation based upon the first and second performance data, and 
 cause the communications receiver to use the updated bit allocation. 
 
 
     
     
       14. The update mechanism as recited in  claim 8 , wherein the update mechanism is further configured to perform gain adjustments on tones based upon the first and second performance data. 
     
     
       15. A method for configuring a communications receiver comprising:
 updating both a time domain equalizer and a frequency domain equalizer contained in the communications receiver based upon performance of a communications channel from which the communications receiver receives data, wherein updating the time domain equalizer includes: 
 causing the time domain equalizer to operate with a first set of coefficients, 
 determining first performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the first set of coefficients, 
 changing the coefficients used by the time domain equalizer so that the time domain equalizer operates with a second set of coefficients, 
 determining second performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the second set of coefficients, 
 selecting for use by the time domain equalizer, based upon the first performance data and the second performance data, either the first set of coefficients or the second set of coefficients, 
 if the first set of coefficients is selected for use, then changing the coefficients used by the time domain equalizer so that the time domain equalizer operates with the first set of coefficients, and 
 if the second set of coefficients is selected for use, then causing the time domain equalizer to continue to operate with the second set of coefficients. 
 
 
     
     
       16. The method as recited in  claim 15 , further comprising determining the first and second performance data based upon synchronization symbols received by the communications receiver. 
     
     
       17. The method as recited in  claim 15 , wherein the communications receiver is a digital subscriber line communications receiver. 
     
     
       18. The method as recited in  claim 15 , wherein the communications receiver is part of a discrete multitone communications system. 
     
     
       19. The method as recited in  claim 15 , wherein:
 the first performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the first set of coefficients; and 
 the second performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the second set of coefficients. 
 
     
     
       20. The method as recited in  claim 15 , wherein:
 the communications receiver uses an initial bit allocation; and 
 the method further comprises
 determining an updated bit allocation based upon the first and second performance data, and 
 causing the communications receiver to use the updated bit allocation. 
 
 
     
     
       21. The method as recited in  claim 15 , further comprising performing gain adjustments on tones based upon the first and second performance data. 
     
     
       22. A non-transitory computer-readable medium having computer-readable instructions for configuring a communications receiver stored thereon, wherein the instructions are configured to be executed by a processor of a computing device, and wherein the computer-readable medium carrying instructions which, when processed by one or more processors, cause comprise:
 updatinginstructions to update both a time domain equalizer and a frequency domain equalizer contained in the communications receiver based upon performance of a communications channel from which the communications receiver receives data, wherein updatinginstructions to update the time domain equalizer includescomprise: causinginstructions to cause the time domain equalizer to operate with a first set of coefficients,;    determininginstructions to determine first performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the first set of coefficients,;   changing theinstructions to change coefficients used by the time domain equalizer so that the time domain equalizer operates with a second set of coefficients.;   determininginstructions to determine second performance data that reflects performance of the time domain equalizer when the time domain equalizer is operating with the second set of coefficients,;   selectinginstructions to select for use by the time domain equalizer, based upon the first performance data and the second performance data, either the first set of coefficients or the second set of coefficients,;   if the first set of coefficients is selected for use, then changing instructions to change the coefficients used by the time domain equalizer so that the time domain equalizer operates with the first set of coefficients,; and   if the second set of coefficients is selected for use, then causing instructions to cause the time domain equalizer to continue to operate with the second set of coefficients.   
 
     
     
       23. The computer-readable medium as recited in  claim 22 , wherein the computer-readable instructions further comprising one or more additional comprise instructions which, when processed by the one or more processors, cause determining to determine the first and second performance data based upon synchronization symbols received by the communications receiver. 
     
     
       24. The computer-readable medium as recited in  claim 22 , wherein the communications receiver is a digital subscriber line communications receiver. 
     
     
       25. The computer-readable medium as recited in  claim 22 , wherein the communications receiver is part of a discrete multitone communications system. 
     
     
       26. The computer-readable medium as recited in  claim 22 , wherein:
 the first performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the first set of coefficients; and 
 the second performance data reflects one or more signal to noise ratios of data received by the communications receiver when the time domain equalizer is operating with the second set of coefficients. 
 
     
     
       27. The computer-readable medium as recited in  claim 22 , wherein:
 the communications receiver uses an initial bit allocation; and 
 the computer-readable medium further comprises one or more additional instructions which, when processed by the one or more processors, causes instructions further comprise:
 determininginstructions to determine an updated bit allocation based upon the first and second performance data, and 
 causinginstructions to cause the communications receiver to use the updated bit allocation. 
 
 
     
     
       28. The computer-readable medium as recited in  claim 22 , wherein the computer-readable instructions further comprises one or more additional comprise instructions which, when processed by the one or more processors, causes performing to perform gain adjustments on tones based upon the first and second performance data. 
     
     
       29. A communications receiver comprising:
 a time domain equalizer;   a frequency domain equalizer; and   an update mechanism configured to update both the time domain equalizer and the frequency domain equalizer based upon performance of a communications channel from which the communications receiver receives data, wherein the update mechanism is further configured to:
 cause the frequency domain equalizer to operate with synchronization symbols; 
 determine an average of the synchronization symbols; 
 determine an updated frequency domain equalizer based upon the average of the synchronization symbols; and 
 determine whether a new set of time domain equalizer coefficients are used for the determined updated frequency domain equalizer and, if so, update the frequency domain equalizer. 
   
     
     
       30. The communications receiver as recited in claim 29, wherein the update mechanism is further configured to perform gain adjustments on tones based upon the new set of time domain equalizer coefficients. 
     
     
       31. The communications receiver as recited in claim 29, wherein determining whether the new set of time domain equalizer coefficients are used comprises conducting a threshold test. 
     
     
       32. The communications receiver as recited in claim 31, wherein the threshold test is based on a normal approximation. 
     
     
       33. The communications receiver as recited in claim 31, wherein the threshold test is based on signal to noise ratio determinations. 
     
     
       34. The communications receiver as recited in claim 29, wherein updating the frequency domain equalizer further includes determining whether a current set of time domain equalizer coefficients are used and, if so, updating the frequency domain equalizer. 
     
     
       35. The communications receiver as recited in claim 29, wherein the communications receiver is a digital subscriber line communications receiver. 
     
     
       36. The communications receiver as recited in claim 29, wherein the communications receiver is part of a discrete multitone communications system. 
     
     
       37. A method for configuring a communications receiver comprising:
 updating both a time domain equalizer and a frequency domain equalizer contained in the communications receiver based upon performance of a communications channel from which the communications receiver receives data, wherein updating the frequency domain equalizer includes:
 causing the frequency domain equalizer to operate with synchronization symbols; 
 determining an average of the synchronization symbols; 
 determining an updated frequency domain equalizer based upon the average of the synchronization symbols; and 
 determining whether a new set of time domain equalizer coefficients are used for the determined updated frequency domain equalizer and, if so, updating the frequency domain equalizer. 
   
     
     
       38. The method as recited in claim 37, wherein updating the frequency domain equalizer further includes performing gain adjustments on tones based upon the new set of time domain equalizer coefficients. 
     
     
       39. The method as recited in claim 37, wherein determining whether the new set of time domain equalizer coefficients are used comprises conducting a threshold test. 
     
     
       40. The method as recited in claim 39, wherein the threshold test is based on a normal approximation. 
     
     
       41. The method as recited in claim 39, wherein the threshold test is based on signal to noise ratio determinations. 
     
     
       42. The method as recited in claim 37, wherein updating the frequency domain equalizer further includes determining whether a current set of time domain equalizer coefficients are used and, if so, updating the frequency domain equalizer. 
     
     
       43. A non-transitory computer-readable medium having computer-readable instructions for configuring a communications receiver stored thereon, wherein the instructions are configured to be executed by a processor of a computing device, and wherein the instructions comprise:
 instructions to update both a time domain equalizer and a frequency domain equalizer contained in the communications receiver based upon performance of a communications channel from which the communications receiver receives data, wherein instructions to update the frequency domain equalizer comprise:
 instructions to cause the frequency domain equalizer to operate with synchronization symbols; 
 instructions to determine an average of the synchronization symbols; 
 instructions to determine an updated frequency domain equalizer based upon the average of the synchronization symbols; and 
 instructions to determine whether a new set of time domain equalizer coefficients are used for the determined updated frequency domain equalizer and, if so, updating the frequency domain equalizer. 
   
     
     
       44. The computer-readable medium as recited in claim 43, wherein updating the frequency domain equalizer further comprises determining whether a current set of time domain equalizer coefficients are used and, if so, updating the frequency domain equalizer.