Matched-filter- and MMSE-based iterative equalization with soft feedback for QPSK transmission

Author

Rössler, Jurgen E. ; Gerstacker, Wolfgang H. ; Lampe, Alexander ; Huber, Johannes B.

Author_Institution

Lehrstuhl fur Nachrichtentech. II, Erlangen-Nurnberg Univ., Erlangen, Germany

fYear

2002

fDate

2002

Abstract

In this paper, two novel equalization algorithms applying soft-decision feedback, designed for quaternary phase-shift keying (QPSK) transmission are introduced. The first one uses a matched filter (MF) as a front end and is derived from Gerstacker et al. (2000) where it was originally developed for binary transmission. The second one is an improved version of the first, employing a minimum mean-squared error (MMSE) filter in each iteration in order to refine the data estimates. The rule for generating soft decisions is adapted continuously to the current state of the algorithm. In most cases, standard DFE methods are clearly outperformed. In contrast to the algorithm of Gerstacker, a performance close to that of maximum-likelihood sequence estimation can be obtained for the MMSE-based scheme for a broad class of channels

Keywords

equalisers; feedback; iterative decoding; least mean squares methods; matched filters; quadrature phase shift keying; sequential estimation; MMSE; QPSK transmission; data estimates; iterative equalization; iterative sequence estimation; matched filter; minimum mean-squared error filter; quaternary phase-shift keying; soft-decision feedback; Algorithm design and analysis; Decision feedback equalizers; Filtering algorithms; Intersymbol interference; Iterative algorithms; Iterative decoding; Matched filters; Maximum likelihood estimation; Phase shift keying; Quadrature phase shift keying;

fLanguage

English

Publisher

ieee

Conference_Titel

Broadband Communications, 2002. Access, Transmission, Networking. 2002 International Zurich Seminar on

Conference_Location

Zurich

Print_ISBN

0-7803-7257-3

Type

conf

DOI

10.1109/IZSBC.2002.991759

Filename

991759