Multi-antenna cooperative systems with improved diversity multiplexing tradeoff

While Half-Duplex cooperative systems provide an alternative means to achieve diversity gain, they suffer from multiplexing gain loss due to the necessary two-phase transmission protocols that are employed. In this paper two new transmission techniques are presented for systems with multi-antenna relay nodes employing the Decode-and-Forward (DF) protocol which achieve improved multiplexing and diversity gains. The first technique extends to the multi-antenna relays case our previous work for single-antenna relay nodes [5]-[6] and is based on the channel´s matrix singular value decomposition (SVD). The second technique exploits the multiple-antenna relays so as to achieve Full-Duplex communication by permitting the latter ones to transmit and receive simultaneously. The transmissions´ orthogonality is achieved via a novel distributed interference nulling mechanism. The proposed schemes´ performance is theoretically studied and the results are verified through typical simulations.