Group Layered Space-time Research Articles

Multiple-input multiple-output underwater acoustic communications by using a quasi-orthogonal group space-time architecture

A Quasi-orthogonal Group Space-Time (QoGST) architecture is presented in this paper for better diversity and multiplexing tradeoff gains in Multiple-Input Multiple-Output (MIMO) underwater acoustic (UWA) communications. Both QoGST and Group Layered Space-Time (GLST) are the combination of space-time block coding (STBC) and layered space-time coding. For GLST, the STBC is taken just in each group. For QoGST, however, all groups are encoded together via inter-group STBC, which can effectively suppress the interference between groups with the orthogonal STBC. At the receivers, the STBC decoding is performed and thus we have the higher diversity gains for the group detection. A statistical model of UWA channel which is presented by Milica Stojanovic and contains variations caused by small- and large-scale effects is considered. Simulation results show that the frame error rate (FER) of QoGST is much lower than that of GLST, which means the QoGST has the higher diversity gains. Furthermore, the lower bound diversity and multiplexing tradeoff of QoGST is coincides with that of GLST and the upper bound diversity and multiplexing tradeoff of QoGST is closer to the optimal values.

A Proposition of 600 Mbps WLAN-Like System with Low-Complexity MIMO Decoder for FPGA Implementation

This paper deals with our works on developing a high-throughput wireless LAN using a group layered space-time (GLST) system with low-complexity MIMO decoder. It achieves the throughput of 600 Mbps for 30 meter propagation distance by utilizing 80 MHz bandwidth in the 5 GHz frequency band. Run test under channel model B of IEEE802.11TGn demonstrates its excellent performance. The register transfer level results show that the developed system is synthesized successfully and the prototyping in the target FPGA chips of Stratix II EP2S180F1508C4 gives the expected results.

A quasi-orthogonal group space-time architecture to achieve a better diversity-multiplexing tradeoff

Most existing MIMO (multiput-input multiput-output) schemes optimize only either the diversity gain or the multiplexing gain. To obtain a good tradeoff between these two, the quasi-orthogonal group space-time (QoGST) architecture is proposed, wherein the transmit stream is subgrouped but encoded via an inter-group space-time block encoder, with group interference suppression at the receiver. This paper also considers another combined space-time coding and layered space-time architecture, which we refer to as group layered space-time (GLST), where space-time block coding is employed within each group. Under the assumption of Rayleigh fading and a prior perfect channel state information at the receiver, a performance analysis will demonstrate that both QoGST and GLST can achieve a good diversity-multiplexing tradeoff. QoGST is even superior to GLST. Simulation results will validate our analysis and further show that compared to the existent layered space-time block code (LSTBC) scheme, both QoGST and GLST can achieve a significant performance gain.