A quasi-orthogonal group space-time architecture for higher diversity gains

Multiple-Input Multiple-Output (MIMO) systems can provide two kinds of gain: diversity gain and multiplexing gain. Most existing MIMO schemes, including space-time coding and layered space-time, aim at maximizing either of them. Therefore, it is desirable to design a scheme to get a better tradeoff between the multiplexing gain and diversity gain. In this paper, a novel Quasi-Orthogonal Group Space-Time (QoGST) architecture is proposed. In QoGST, the transmit stream is divided into several groups and all the groups are encoded via an inter-group space-time block encoder. Group interference suppression is adopted at the receiver. Performance is evaluated in terms of symmetric energy and it will be shown that compared to the Group Layered Space-Time (GLST) architecture, the proposed QoGST can achieve a higher symmetric energy and a better diversity-multiplexing tradeoff. Simulation results will validate our analysis and show that QoGST can achieve at least 3 dB gain over GLST at a FER of 10^-3, for instance. © 2004 IEEE.