sions for improved + ftw. Forschungszentrum f. Telekommunikation Wien, Donau-City Str. 1/3, A-1220 Vienna, Austria, http://www.ftw.at/, This work was partly funded by Kplus, Infineon Technologies and the Austrian Research Centers Seibersdorf (ARCS) through ftw. Project C3. # Institut f. Nachrichtentechnik und Hochfrequenztechnik, Technische Universitat Wien, Gusshausstr. 27-29/E389, A-1040 Vienna, Austria, http://www.nt.tuwien.ac.at/ First published in "Smart Antennas - State of the Art in Europe", EURASIP, to appear 2004, published by "Hindawi Publishing Corporation". estimation was presented in [30]. We show that such multiuser MIMO communication systems achieve low bit error rates at moderate complexity. Section 1.4.4 treats equalization of time-variant MIMO multipath channels. We propose a multiuser MIMO equalizer for OFDM using a basis expansion [21,22] with prolate spheroidal sequences to represent the time-variant mobile radio channel. The resulting block-wise estimator-e