A novel APP-based soft-output adaptive equalizer. Exploiting non-linear MMSE fixed-lag smoothed estimates of the transmitted symbols

Author

Galli, Stefano

Author_Institution

Telcordia Technol. Inc., Morristown, NJ, USA

Volume

4

fYear

2001

fDate

2001

Firstpage

1084

Abstract

Non-linear minimum mean square error (NL-MMSE) estimators have seldom been used in practice because of the intrinsic analytic difficulties that arise in their development. However, it has been shown by Galli (2000) that the a posteriori probabilities (APPs) of the states of the ISI channel can be efficiently used to generate NL-MMSE filtered and fixed-lag smoothed estimates of the transmitted symbols. On the basis of this new result, a novel soft-output adaptive receiver is presented for TDMA-based cellular land-mobile radio communications. The proposed receiver uses NL-MMSE fixed-lag smoothed estimates of the transmitted symbols for channel estimation and tracking and exploits the APPs for the computation of the branch metrics of the Viterbi algorithm (VA). Simulations have shown that, in some situations, gains of at least 14 dB over the conventional hard-decision driven receivers are obtainable

Keywords

adaptive equalisers; cellular radio; intersymbol interference; least mean squares methods; maximum likelihood estimation; nonlinear estimation; radio receivers; radiofrequency interference; time division multiple access; APP-based soft-output adaptive equalizer; ISI channel; NL-MMSE filtered estimates; TDMA-based cellular land-mobile radio communications; Viterbi algorithm; a posteriori probabilities; channel estimation; fixed-lag smoothed estimates; nonlinear MMSE fixed-lag smoothed estimates; nonlinear minimum mean square error estimators; soft-output adaptive receiver; tracking; transmitted symbols; Adaptive equalizers; Channel estimation; Computational modeling; Delay estimation; Land mobile radio; Mean square error methods; Multilevel systems; Receivers; State estimation; Viterbi algorithm;

fLanguage

English

Publisher

ieee

Conference_Titel

Communications, 2001. ICC 2001. IEEE International Conference on

Conference_Location

Helsinki

Print_ISBN

0-7803-7097-1

Type

conf

DOI

10.1109/ICC.2001.936818

Filename

936818