文档介绍：Uppsala University
Signals and Systems
THE MULTIVARIABLE
DECISION FEEDBACK EQUALIZER
Multiuser Detection and Interference Rejection
Claes Tidestav
UPPSALA UNIVERSITY 1999
Dissertation for the degree of Doctor of Philosophy
in Signal Processing at Uppsala University, 1999
ABSTRACT
Tidestav, C., 1999. The Multivariable Decision Feedback Equalizer: Multiuser
Detection and Interference Rejection, 201 pp. Uppsala. ISBN 91-506-1371-5.
The multivariable decision feedback equalizer (DFE) is investigated as a tool for multiuser
detection and interference rejection. Three different DFE structures are introduced. The
first DFE has a non-causal feedforward filter and a causal feedback filter. We show how
its parameters can be tuned to give a minimum mean-square error. The second DFE is de-
rived under the constraint of realizability. The explicit structure and design equations for
an optimum realizable minimum mean-square error DFE are obtained. The zero-forcing
criterion is also considered, and conditions for the existence of a zero-forcing solution are
derived. We then consider a DFE where both feedforward and feedback filters are FIR
filters of predetermined degrees. We discuss the tuning procedure for obtaining the param-
eters of a minimum mean-square error DFE and present the conditions for the existence of
a zero-forcing solution. Two specific applications are considered next. In the first scenario,
an antenna array is used at the receiver in a cellular system to plish spatial division
multiple access. pare two DFEs, operating as multiuser detectors and interference
cancellers, respectively, and it is demonstrated that the difference in performance is small
when few users are active in the system. We also show that the parameter estimation prob-
lem is plicated for interference rejection. The second application is multiuser
detection in DS-CDMA. A family of minimum mean-square error detectors with different
amounts of decision feedback is desig