Joint adaptive optimization of soft decision device and feedback equalizer
The present invention uses a novel adaptive soft decision device in order to jointly optimize decision device and DFE operation. The soft decision device receives the input and output samples of the slicer and generates a feedback sample by non-linearly combining them with respect to a single decision reference parameter. Moreover, the soft decision device provides novel error terms used to adapt equalizer coefficients in order to jointly optimize decision device and equalizer coefficients.
1. A method for operating forward and feedback filters in a communications receiver having a decision feedback equalizer, said communications receiver having a decision feedback equalizer, said communications receiver responsive to a received signal to form slicer input samples and hard decision samples corresponding to said slicer output samples, said method comprising:
non-linearly combining said slicer input samples and said hard decision samples to form a soft decision samples in a soft decision device; and
the said soft decision device being adaptively adjusted to control contributions of said slicer input samples and said hard decision samples to form said soft decision samples; and
said soft decision device generating error signals to adjust said forward and feedback filters; and
operating said forward and feedback filters by coupling a composite decision samples to said feedback filter and by adapting said forward and feedback filters with said error signals.
2. The method of claim 1 , wherein said decision feedback equalizer operates in passband.
3. The method of claim 1 , wherein said feedback filter operates in baseband.