Adaptive equalizer system
One example includes an equalizer system. The system includes a filter system configured to receive digital sample blocks associated with an input signal and to provide equalized digital sample blocks associated with the respective digital sample blocks based on adaptive tap weights. Each of the digital sample blocks includes samples and each of the equalized digital sample blocks includes equalized samples. The system also includes a sample set selector to select a subset of equalized samples from each of the equalized digital sample blocks at the output of the filter and an error estimator configured to implement an error estimation algorithm on the subset of the equalized samples to determine a residual error associated with the equalized samples. The system further includes a tap weight generator configured to generate the adaptive tap weights in response to the residual error and to provide the adaptive tap weights to the filter.
1. An equalizer system comprising:
a filter system configured to receive digital sample blocks associated with an input signal and provide therefrom a plurality of equalized digital sample blocks based on tap weights, each of the digital sample blocks comprising a plurality of samples and each of the equalized digital sample blocks comprising a plurality of equalized samples;
a sample set selector configured to control selection of a proper subset of the equalized samples from each of the plurality of the equalized digital sample blocks based on a system signal;
an error estimator configured to determine a residual error using the proper subset of the equalized samples; and
a tap weight generator configured to generate the tap weights based on the residual error.
2. The system of claim 1 , further comprising an error estimator configured to implement an error estimation algorithm on the selected proper subset of the equalized samples selected by the sample set selector to determine the residual error.
3. The system of claim 2 , further comprising:
an error algorithm data store configured to store a plurality of error estimation algorithms; and
a selection controller configured to select the error estimation algorithm from the plurality of error estimation algorithms in the error algorithm data store.
4. The system of claim 3 , wherein the equalizer system is configured to support each of a plurality of modulation formats associated with digital sample blocks, wherein the selection controller is configured to receive a modulation format signal that is indicative of one of the plurality of modulation formats, wherein the error estimator is configured to implement one of the plurality of error estimation algorithms on the proper subset of the equalized samples selected by the sample set selector based on the modulation format signal.
5. The system of claim 1 , wherein the digital sample blocks are provided as a plurality of frames, the system further comprising a selection controller that is configured to generate a selection signal based on current system state of the equalizer system, wherein the sample set selector is configured to control the selection of the proper subset of the equalized samples in response to the selection signal.
6. The system of claim 5 , wherein the selection signal is provided from the selection controller based on a first system state of the equalizer system corresponding to frame boundaries for each of the plurality of frames being unknown, such that the sample set selector is configured to control selection of a subset of the equalized samples from each of the equalized digital sample blocks in the first system state, and
wherein the selection signal is provided from the selection controller based on a second system state of the equalizer system corresponding to frame boundaries for each of the plurality of frames being known, such that the sample set selector is configured to control selection of the proper subset of the equalized samples from each of the equalized digital sample blocks in the second system state, wherein the subset and the proper subset are different.
7. The system of claim 6 , wherein:
the equalized samples comprise a plurality of data samples and a plurality of support samples associated with each of the equalized digital sample blocks,
the subset of the samples includes all of the samples from each of the equalized sample blocks at the output of the filter, and
the proper subset of the equalized samples includes the plurality of support samples but not the plurality of data samples of each of the plurality of equalized digital sample blocks at the output of the filter.
8. The system of claim 1 , wherein:
the digital sample blocks are provided as a plurality of frames, each of the plurality of frames comprising a set of the plurality of digital sample blocks and further comprising a start-of-frame (SoF) pattern of samples configured to facilitate frame synchronization, and
the sample set selector is configured to select the proper subset of the equalized samples for error estimation from each of the equalized digital sample blocks based on a frame synchronization status signal.
9. The system of claim 8 , wherein:
when the frame synchronization status signal is in a first state, the sample set selector is configured to select a subset of the equalized samples from each of the equalized digital sample blocks at the output of the filter, and
when the frame synchronization signal is in a second state different than the first state, the sample set selector is configured to select the proper subset of the equalized samples from each of the equalized digital sample blocks at the output of the filter, the subset of the equalized samples being different from the proper subset of the equalized samples,
the first state of the frame synchronization status signal indicates that frame boundaries for the plurality of frames received at the filter are not known, and
the second state of the frame synchronization status signal indicates that the frame boundaries for the plurality of frames received at the filter are known.
10. The system of claim 9 , wherein:
the plurality of equalized samples comprises a plurality of data samples and a plurality of support samples associated with each of the plurality of equalized digital sample blocks,
the subset of the samples includes all of the samples from each of the plurality of equalized sample blocks at the output of the filter, and
the proper subset of the equalized samples includes the plurality of support samples but not the plurality of data samples of each of the plurality of equalized digital sample blocks at the output of the filter.
11. The system of claim 1 , wherein:
the plurality of equalized samples comprises a plurality of data samples and a plurality of support samples associated with each of the plurality of equalized digital sample blocks,
the sample set selector is configured to select the plurality of support samples from each of the plurality of equalized digital sample blocks at the output of the filter.
12. The system of claim 11 , wherein:
each of the plurality of data samples of each of the plurality of digital sample blocks is modulated based on a first modulation format,
each of the plurality of support samples of each of the plurality of digital sample blocks is modulated based on a second modulation format that is different from the first modulation format.
13. The system of claim 11 , wherein each of the plurality of data samples and each of the plurality of support samples of each of the plurality of digital sample blocks comprises modulated client data.
14. The system of claim 11 , wherein each of the plurality of data samples and each of the plurality of support samples of the plurality of digital sample blocks comprises an in-phase component and a quadrature-phase component.
15. The system of claim 11 , wherein the sample set selector is further configured to:
select the data samples of each equalized sample block at the output of the filter as a subset of the selected equalized samples, and
select the support samples of each equalized sample block at the output of the filter as a proper subset of the selected equalized samples.
16. The system of claim 15 , wherein the error estimator is configured to determine the residual error by:
implementing the error estimation algorithm on the subset of the selected equalized samples, and generating adjustable tap weights based on the error estimation results and the selected equalized samples, and
implementing the error estimation algorithm or a different error estimation algorithm on the proper subset of the selected equalized samples, and generating adjustable tap weights based on the error estimation results and the selected equalized samples, and
combining adjustable tap weights resulting from processing the subset and the proper subset of equalized samples to form final adjustable tap weights for use by the filter.
17. The system of claim 1 , wherein:
a set of the plurality of digital sample blocks forms a sample frame, where one or more digital sample blocks contain a pattern of samples identifying a start of frame (SoF),
the plurality of equalized samples comprises a plurality of data samples and a plurality of support samples associated with each of the plurality of equalized digital sample blocks.
18. The system of claim 17 , wherein:
the plurality of support modulation formats and the plurality of SoF modulation formats are of a lower modulation order than the plurality of data modulation formats.
19. A method for generating an equalized digital output signal from an equalizer system, the method comprising:
receiving digital sample blocks associated with an input signal at an input of a filter system, each of the digital sample blocks comprising a plurality of samples;
providing a plurality of equalized digital sample blocks from an output of the filter system based on tap weights, each of the equalized digital sample blocks comprising a plurality of equalized samples;
controlling selection of a proper subset of the equalized samples from each of the plurality of equalized digital sample blocks at the output of the filter system based on a system signal; and
estimating a residual error associated with the proper subset of the equalized samples; and
generating the tap weights based on the residual error.
20. The method of claim 19 , further comprising implementing the error estimation algorithm on the selected proper subset of the equalized samples to determine the residual error.
21. The method of claim 20 , further comprising:
storing a plurality of error estimation algorithms in an error algorithm data store; and
selecting the error estimation algorithm from the plurality of error estimation algorithms in the error algorithm data store.
22. The method of claim 21 , wherein the equalizer system is configured to support each of a plurality of modulation formats associated with digital sample blocks, the method further comprising receiving a modulation format signal that is indicative of one of the plurality of modulation formats, the method further comprising implementing one of the plurality of error estimation algorithms on the proper subset of the equalized samples based on the modulation format signal.
23. The method of claim 19 , wherein the digital sample blocks are provided as a plurality of frames, further comprising generating a selection signal based on current system state of the equalizer system, wherein controlling the selection of the proper subset comprises controlling the selection of the proper subset of the equalized samples in response to the selection signal.
24. The method of claim 23 , wherein the selection signal is provided based on a first system state of the equalizer system corresponding to frame boundaries for each of the plurality of frames being unknown, such that controlling the selection of the proper subset comprises controlling selection of a subset of the equalized samples from each of the equalized digital sample blocks in the first system state, and
wherein the selection signal is provided from the selection controller based on a second system state of the equalizer system corresponding to frame boundaries for each of the plurality of frames being known, such that controlling the selection of the proper subset comprises controlling selection of the proper subset of the equalized samples from each of the equalized digital sample blocks in the second system state, wherein the subset and the proper subset are different.
25. The method of claim 24 , wherein:
the equalized samples comprise a plurality of data samples and a plurality of support samples associated with each of the equalized digital sample blocks,
the subset of the samples includes all of the samples from each of the equalized sample blocks at the output of the filter, and
the proper subset of the equalized samples includes the plurality of support samples but not the plurality of data samples of each of the plurality of equalized digital sample blocks at the output of the filter.
26. The method of claim 19 , wherein:
the digital sample blocks are provided as a plurality of frames, each of the plurality of frames comprising a set of the plurality of digital sample blocks and further comprising a start-of-frame (SoF) pattern of samples configured to facilitate frame synchronization, and
controlling the selection of the proper subset comprises selecting the proper subset of the equalized samples for error estimation from each of the equalized digital sample blocks based on a frame synchronization status signal.
27. The method of claim 26 , wherein:
when the frame synchronization status signal is in a first state, controlling the selection of the proper subset comprises selecting a subset of the equalized samples from each of the equalized digital sample blocks at the output of the filter, and
when the frame synchronization signal is in a second state different than the first state, controlling the selection of the proper subset comprises selecting the proper subset of the equalized samples from each of the equalized digital sample blocks at the output of the filter, the subset of the equalized samples being different from the proper subset of the equalized samples,
the first state of the frame synchronization status signal indicates that frame boundaries for the plurality of frames received at the filter are not known, and
the second state of the frame synchronization status signal indicates that the frame boundaries for the plurality of frames received at the filter are known.
28. The method of claim 27 , wherein:
the plurality of equalized samples comprises a plurality of data samples and a plurality of support samples associated with each of the plurality of equalized digital sample blocks,
the subset of the samples includes all of the samples from each of the plurality of equalized sample blocks at the output of the filter, and
the proper subset of the equalized samples includes the plurality of support samples but not the plurality of data samples of each of the plurality of equalized digital sample blocks at the output of the filter.
29. The method of claim 19 , wherein:
the plurality of equalized samples comprises a plurality of data samples and a plurality of support samples associated with each of the plurality of equalized digital sample blocks,
controlling the selection of the proper subset comprises selecting the plurality of support samples from each of the plurality of equalized digital sample blocks.
30. The method of claim 29 , wherein:
each of the plurality of data samples of each of the plurality of digital sample blocks is modulated based on a first modulation format,
each of the plurality of support samples of each of the plurality of digital sample blocks is modulated based on a second modulation format that is different from the first modulation format.
31. The method of claim 29 , wherein each of the plurality of data samples and each of the plurality of support samples of each of the plurality of digital sample blocks comprises modulated client data.
32. The method of claim 29 , wherein each of the plurality of data samples and each of the plurality of support samples of the plurality of digital sample blocks comprises an in-phase component and a quadrature-phase component.
33. The method of claim 29 , wherein controlling the selection of the proper subset comprises:
selecting the data samples of each equalized sample block at the output of the filter as a subset of the selected equalized samples, and
selecting the support samples of each equalized sample block at the output of the filter as a proper subset of the selected equalized samples.
34. The method of claim 33 , further comprising:
implementing the error estimation algorithm on the subset of the selected equalized samples;
generating adjustable tap weights based on the error estimation results and the selected equalized samples;
implementing the error estimation algorithm or a different error estimation algorithm on the proper subset of the selected equalized samples, and generating adjustable tap weights based on the error estimation results and the selected equalized samples; and
combining adjustable tap weights resulting from processing the subset and the proper subset of equalized samples to form final adjustable tap weights for use by the filter.
35. The method of claim 19 , wherein:
a set of the plurality of digital sample blocks forms a sample frame, where one or more digital sample blocks contain a pattern of samples identifying a start of frame (SoF),
the plurality of equalized samples comprises a plurality of data samples and a plurality of support samples associated with each of the plurality of equalized digital sample blocks.
36. The method of claim 35 , wherein:
the plurality of support modulation formats and the plurality of SoF modulation formats are of a lower modulation order than the plurality of data modulation formats.