Extended orthogonal space time block codes in wireless relay networks

In this paper we propose complex extended orthogonal space-time block codes (EO-STBCs) with feedback for wireless relay networks with the assumption of quasi-static flat fading channels. Full rate in each stage and full cooperative diversity for distributed EO-STBCs (D-EO-STBCs) are achieved by providing channel state information (CSI) at certain relay nodes. Two closed-loop schemes are proposed which make use of limited feedback from the destination node to a particular number of relay nodes, not exceeding half of the total number of such relay nodes. In our simulations, we use four relay nodes. Simulation results show that these two closed-loop D-EOSTBCs achieve full cooperative diversity in addition to array gain with linear processing. In particular, the proposed D-EO-STBCs designs preserve low decoding complexity and save both transmission power and total transmit time between source and destination.