An Adaptive Transmit Diversity with Orthogonal Space-Time Block Coding

Abstract – Design of space-time codes is based on the statistical analysis of the propagation channel. As knowledge of the channel characteristics is not available at the transmitter, the improvement introduced by antenna diversity is primarily relying on the channel having uncorrelated signal paths. We introduce a combination of eigenbeamforming with orthogonal space-time block codes at the transmitter. This combines the benefits of decorrelation through eigen-analysis and achieving system diversity gain. The system has been simulated using four transmit antennas in both uncorrelated and correlated channels. Results showed that this scheme provides a significant improvement in the performance of spatially correlated channels.