A receiver ( 1 ) has an equalizer ( 2, 4, 5 ) which introduces inter symbol interferance (ISI) in a controlled manner and low pass filters to reduce noise. The ISI is introduced and the noise is reduced by a filter ( 4 ) in an adaptation path. A trellis decoder ( 3 ) of the receiver ( 1 ) removes the ISI to avoid propagation error. It does this in front end modules ( 20 ), outside of its critical path. There is a better decoder performance because noise is smaller.
1. A receiver for high bandwidth data communication of the type in which there is convolutional encoding in received signals, the receiver comprising:
an equalizer including means for introducing inter-symbol interference (ISI) in a controlled manner; and
a decoder including means for removing the ISI to avoid error propagation by using computation outside of the critical path of said decoder, said decoder having a plurality of front end blocks, each front end block computing a one-dimensional distance for each channel incoming from said equalizer, said decoder further being configured to select one of said distances.
2. A receiver as claimed in claim 1 , wherein the decoder includes means for removing the ISI in said front end blocks.
3. A receiver as claimed in claim 1 , wherein each front end block comprises:
a first block including means for computing a symbol estimate from an equalizer input;
a second block including means for deriving possible slices associated with the input received from said first block; and
a third block including means for computing said distances as associated with said slices.
4. A receiver as claimed in claim 3 , wherein, to introduce ISI, the equalizer includes means for adapting to an output response shape that is other than unity and is simple and bounded.
5. A receiver as claimed in claim 4 , wherein the equalizer includes a filter in an adaptation path.
6. A receiver as claimed in claim 1 , wherein said means for introducing ISI includes a filter and an adaptation engine arranged in an adaptation path separate from a data path connecting said equalizer and said decoder.
7. A receiver as claimed in claim 6 , wherein an output of said equalizer is connected to said decoder and to said filter, with an output of said filter being connected to said adaptation engine, and said adaptation engine updating coefficients of said equalizer.
8. A receiver as claimed in claim 1 , wherein each of said plurality of front end blocks comprises:
a first block configured to compute a symbol estimate from an equalizer input;
a second block for receiving an input from said first block, said second block configured to derive possible slices associated with said input; and
a third block for receiving an input from said second block, said third block being configured to compute the distances associated with said slices.
9. A receiver for high bandwidth data communication of the type in which there is convolutional encoding in received signals, the receiver comprising:
An equalizer having an output connected to a decoder in a data path and an output connected to a filter in an adaptation path an output opt said filter being connected to an adaptation engine in said adaptation path, said filter and said adaptation engine being configured to introduce inter-symbol interference (ISI) to said equalizer data path output in a controlled manner: and
said decoder configured to remove the inter-symbol interference (ISI) to avoid error propagation; and
wherein the decoder is configured to remove the ISI using computation outside the critical path of the decoder; and
wherein the decoder includes a plurality of front end blocks configured to remove the ISI; and
wherein each front end block is configured to compute a one-dimensional distance for each channel such that, with said plurality of front end block, several distances are computed said decoder having a block downstream of the front end block for selecting on of said distances.
10. A receiver as claimed in claim 9 , wherein each front end block comprises:
a first block configured to compute a symbol estimate from the equalizer output;
a second block configured to derive possible slices associated with the output of said first block; and
a third block configured to compute the distances associated with said slices.
11. A receiver as claimed in claim 10 , wherein said third block computes the distances using look-up tables.
12. A receiver as claimed in claim 10 , wherein, to introduce ISI, the equalizer is configured to adapt to an output response shape that is other than unity.