USA As Represented by Secretary of the Navy

Sans R&d, LLC

John G Proakis

Nikola Alic

Fletcher A Blackmon

Masoud Salehi

Mohanadreza M Hagh

Ethem M Sozer

The present invention relates to a method of improving the performance in bandwidth constrained communication systems while reducing the complexity of the equalizer used for information retrieval, as well as to improving the capacity of communication systems. These properties are achieved by appropriate information encoding, prior to signal shaping before transmission, whereas the equalizer complexity is reduced by applying the intersymbol interference shortening filter prior to the information retrieving equalization. A proper combination of the recounted elements is capable of providing a qualitatively improved and previously unsuspected performance, as compared to its constituent elements.

Method and a system for a receiver design in bandwidth constrained communication systems

The present invention relates to a method of improving the performance in bandwidth constrained communication systems while reducing the complexity of the equalizer used for information retrieval, as well as to improving the capacity of communication systems. The said properties are achieved by appropriate information encoding, prior to signal shaping before transmission, whereas the equalizer complexity is reduced by applying the intersymbol interference shortening filter prior to the information retrieving equalization. A proper combination of the recounted elements is capable of providing a qualitatively improved and previously unsuspected performance, as compared to its constituent elements.

An iterative joint Minimum Mean Square Error (MMSE) decision feedback equalizer and turbo decoder includes a turbo decoder portion and a decision feedback equalizer (DFE) portion. The DFE receives input signals and processes these input signals to generate an estimated symbol sequence that is communicated to the turbo decoder portion. The estimated symbol sequence is also communicated to the feedback portion of the DFE. The feedback portion of the DFE includes a symbol-by-symbol detector and a feedback filter. The soft decoder output values generated by the turbo decoder portion are communicated to the feedback portion of the DFE and are combined with the coded output as log likelihood ratio values in a multipass, iterative fashion whereby the equalizer and decoder are linked via iterative feedback to provide communication performance enhancement.

Iterative joint minimum mean square error decision feedback equalizer and turbo decoder

The present invention provides a receiver for underwater acoustic telemetry which combines a decision feedback adaptive equalizer structure with a modified turbo-equalizer structure. The modified turbo-equalizer structure is of significantly reduced complexity because the decision feedback adaptive equalizer structure is operable to process a plurality of data channels to provide a single symbol data output stream for application to the input of the modified turbo-equalizer which uses a decision feedback equalized, interleaver, deinterleaver and a decoder. Either a hard viterbi decorder for single iteration processing or a soft in/soft out decorder such as a MAP decoder for multiple iteration can be used. The iteration provide improved performance compared to a normal DFE and lower complexity compared to the traditional turbo-equalizer.

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Winchester, MA, United States of America

John G Proakis