Space-time Code Selection for Transmit Antenna Diversity Systems

In this paper a space-time code selection approach for transmit antenna diversity systems is proposed. The receiver compares the equivalent SISO channel envelopes with a set of predetermined threshold levels, decides on the antennas to be used and sends this information to the transmitter, which adjusts the space-time code to the number of selected antennas using four bits for feedback information. Threshold levels are found off-line based on the Doppler frequency, in such a way that CSI outdate at the transmitter is taken into account. Simulation results show that the system performs well for a range of Doppler frequencies for correlated and uncorrelated channels, outperforming transmit antenna selection techniques and adaptive transmit antenna diversity systems.