Novel frequency-domain DFE equalizer with oblique projection for CP-free space-time block coded MIMO-OFDM systems

This paper presents a new receiver framework for the cyclic-prefix free (CP-free) MIMO-OFDM system, equipped with the space-time block codes (ST-BC), over time varying multipath channels. Usually, without CP in the OFDM system the inter-carrier interference (ICI) could not be removed, effectively, at the receiver, when the inter-symbol-interference (ISI) has to be taken into account. In this paper, by exploiting the spatial and frequency resources, we propose a novel frequency-domain decision-feedback equalizer, associated with the oblique projection (OB), to combat the effects of ISI and ICI, simultaneously. The OB is a non-orthogonal projection and is very useful to deal with the structure noise (e.g., the ISI term). From computer simulations, we observe that the propose scheme can perform very close to the conventional CP-based MMO-OFDM with the ST-BC.