High spectral efficiency and high transmission data rate are the challenging requirements of wireless broadband communications. The MIMO technology has rapidly gained in popularity due to its powerful performance-enhancing capabilities. Spatial diversity can be obtained by using multiple antennas and space-time codes. For future wireless broadband systems, OFDM is discussed as access scheme. OFDM provides an essentially flat fading channel for each subcarrier by insertion of a cyclic guard interval at each antenna. Therefore, space-time block codes are well suited to be applied in OFDM. We...