Parallel feedback processing
Embodiments of a parallel feedback processor are disclosed. The parallel feedback processor includes a plurality of parallel coupled feedback filters. Each feedback filter includes a non-linear operator. At least one of feedback filter includes a plurality of sub-filters. Each sub-filter computes a one of possible non-linear operator filter outputs of the at least one feedback filter. One sub-filter output is selected as an output of the at least one feedback filter.
1 . A parallel feedback processor, comprising:
a plurality of parallel coupled feedback filters, each feedback filter comprising a non-linear operator;
at least one feedback filter comprising a plurality of sub-filters, each sub-filter computing one of possible non-linear operator filter outputs of the at least one feedback filter;
wherein one sub-filter output is selected as an output of the at least one feedback filter.
2 . The parallel feedback processor of claim 1 , wherein each of the feedback filters receives a subset of input samples of a transmitter signal stream.
3 . The parallel feedback processor of claim 2 , wherein each filter receives 1/N of the input samples, where N equals the number of feedback filters.
4 . The parallel feedback processor of claim 1 , wherein the non-linear operator is a modulo operator.
5 . The parallel feedback processor of claim 1 , wherein the non-linear operator is a constellation slicer.
6 . The parallel feedback processor of claim 1 , wherein the preprocessor comprises a Tomlinson-Harashima processor.
7 . The parallel feedback processor of claim 1 , wherein feedback of the processor comprises at least one FIR filter.
8 . The parallel feedback processor of claim 1 , wherein feedback of the processor comprises at least one IIR filter.
9 . The parallel feedback processor of claim 1 , wherein the sub-filter output is selected by an output of the non-linear operator of at least one other of the feedback filters.
10 . The parallel feedback processor of claim 9 , wherein the sub-filter output is selected by an output of the non-linear operator of a sub-filter of at least one other of the feedback filters.
11 . The parallel feedback processor of claim 4 , wherein a number of sub-filters is equal to a number of possible modulo shifts of the modulo operator.
12 . The parallel feedback processor of claim 4 , wherein a plurality of feedback filters comprises sub-filters, and a number of sub-filters of each feedback filter is equal to a product of a number of possible modulo shifts of a subset of the feedback filters.
13 . The parallel feedback processor of claim 11 , wherein the number of possible modulo shifts is determined by feedback coefficients of the feedback filters.
14 . The parallel feedback processor of claim 13 , wherein the number of possible modulo shifts is determined by summing absolute values of the feedback coefficients of the feedback filters.
15 . The parallel feedback processor of claim 11 , wherein the number of possible modulo shifts is determined by a range of amplitude values of input signals to the modulo operator.
16 . The parallel feedback processor of claim 1 , wherein a number of sub-filters is determined by selecting a desired signal distortion, and selecting the number of sub-filters required to ensure that the signal distortion is less than the desired signal distortion.
17 . The parallel feedback processor of claim 1 , wherein only sub-filters most likely to be selected are included within the parallel feedback processor.
18 . The parallel feedback processor of claim 4 , wherein a number of sub-filters is less than a number of possible modulo shifts of the modulo operator.
19 . The parallel feedback processor of claim 18 , wherein modulo shifts of the sub-filters are dynamically selected.
20 . The parallel feedback processor of claim 19 , wherein the dynamic selections are based upon partial values of previously occurring coefficients.
21 . The parallel feedback processor of claim 19 , wherein the dynamic selections are based upon lower resolution values of feedback coefficients.
22 . The parallel feedback processor of claim 1 , wherein outputs of the sub-filters are selected by a sub-filter MUX, an output of the sub-filter MUX generating the at least one feedback filter output.
23 . The parallel feedback processor of claim 1 , wherein a signal processor pre-processes a digital signal stream for transmission.
24 . The parallel feedback processor of claim 1 , wherein a signal processor post-processes a received digital signal stream.
25 . The parallel feedback processor of claim 23 , wherein a receiver reverses a transmit modulo operation.
26 . The parallel feedback processor of claim 1 , wherein at least one of the non-linear operators receive input estimates that are lower precision than other processing of the feedback filters.
27 . The parallel feedback processor of claim 1 , wherein a plurality of the sub-filters share filter coefficients.
28 . The parallel feedback processor of claim 1 , wherein select operations within the feedback filters are implemented with look up tables (LUT)s.
29 . A method of parallel feedback processing, comprising:
receiving a digital stream of samples;
a first feedback filter processing a subset of the samples;
a second feedback filter simultaneously receiving and processing a different subset of the samples, the simultaneous processing comprising;
multiple sub-filters receiving the different subset of samples;
each sub-filter processing a different one of a number of possible non-linear operator ouputs; and
the first feedback filter selecting one of the sub-filter processed outputs as a second feedback filter chain output.
30 . The method of parallel feedback processing of claim 29 , wherein each sub-filter processing a different one of a number of possible non-linear operator ouputs comprises each sub-filter processing a different one of a number of possible modulo shifts.
31 . The method of parallel feedback processing of claim 30 , wherein a number of sub-filters is equal to the number of possible modulo shifts of a modulo operator of the first feedback filter.
32 . The method of parallel feedback processing of claim 30 , wherein the number of possible modulo shifts is determined by coefficients of the feedback filters.
33 . The method of parallel feedback processing of claim 30 , wherein the number of possible modulo shifts is determined by summing absolute values of the feedback coefficients of the feedback filters.
34 . The method of parallel feedback processing of claim 30 , wherein the number of possible modulo shifts is determined by a range of amplitude values of input signals to the modulo unit.
35 . The method of parallel feedback processing of claim 29 , wherein a number of sub-filters is determined by selecting a desired signal distortion, and selecting the number of sub-filters required to ensure that the signal distortion is less than the desired received signal distortion.
36 . The method of parallel feedback processing of claim 29 , wherein only sub-filters most likely to be selected are included within a parallel feedback processor.
37 . The method of parallel feedback processing of claim 30 , wherein a number of sub-filters is less than a number of possible modulo shifts of a modulo operator.
38 . The method of parallel feedback processing of claim 30 , wherein modulo shifts of the sub-filters are dynamically selected.
39 . The method of parallel feedback processing of claim 29 , wherein the non-linear operator is a slicer, and slicer output values of the sub-filters are dynamically selected.
40 . The method of parallel feedback processing of claim 38 , wherein the dynamic selections are based upon partial values of previously occurring coefficients.
41 . The method of parallel feedback processing of claim 38 , wherein the dynamic selections are based upon reduced resolution feedback values of coefficients.
42 . A network line card, the network line card comprising a bi-directional transceiver, the bi-directional transceiver comprising a parallel feedback processor, the parallel feedback processor comprising:
a plurality of parallel coupled feedback filters, each feedback filter comprising a non-linear operator;
at least one of feedback filter comprising a plurality of sub-filters, each sub-filter computing one of possible non-linear operator filter outputs of the at least one feedback filter;
wherein one sub-filter output is selected as an output of the at least one feedback filter.
43 . A server comprising a bi-directional transceiver, the bi-directional transceiver comprising a parallel feedback processor, the parallel feedback processor comprising:
a plurality of parallel coupled feedback filters, each feedback filter comprising a non-linear operator;
at least one of feedback filter comprising a plurality of sub-filters, each sub-filter computing one of possible non-linear operator filter outputs of the at least one feedback filter;
wherein one sub-filter output is selected as an output of the at least one feedback filter.
44 . A storage unit comprising a bi-directional transceiver, the bi-directional transceiver comprising a parallel feedback processor, the parallel feedback processor comprising:
a plurality of parallel coupled feedback filters, each feedback filter comprising a non-linear operator;
at least one of feedback filter comprising a plurality of sub-filters, each sub-filter computing one of possible non-linear operator filter outputs of the at least one feedback filter;
wherein one sub-filter output is selected as an output of the at least one feedback filter.
45 . A switch comprising a bi-directional transceiver, the bi-directional transceiver comprising a parallel feedback processor, the parallel feedback processor comprising:
a plurality of parallel coupled feedback filters, each feedback filter comprising a non-linear operator;
at least one of feedback filter comprising a plurality of sub-filters, each sub-filter computing one of possible non-linear operator filter outputs of the at least one feedback filter;
wherein one sub-filter output is selected as an output of the at least one feedback filter.