Time- and frequency-domain equalization for quasi-orthogonal STBC over frequency-selective channels

We investigate time- and frequency-domain equalization techniques for quasi-orthogonal space-time block codes. The proposed schemes extend the original symbol-level scheme developed for flat-fading channels to a block-level implementation either in the time or frequency domain. Receiver structures which exploit the embedded quasi-orthogonality, therefore keeping the equalizer complexity at a manageable level, are presented. The considered schemes are applied to the EDGE TDMA system and their performances are compared under both perfect and estimated channel conditions.