Equal gain transmission in multiple-input multiple-output wireless systems

Wireless systems with multiple-transmit and multiple-receive antennas (MIMO systems) are of interest due to their ability to provide substantial gains in capacity and quality. In this paper we propose equal gain transmission (EGT) as a technique to provide diversity advantage in MIMO systems. Using bounds on the error rate we show that EGT obtains a diversity gain on the order of the product of the number of transmit and receive antennas. Since in practice full channel knowledge at the transmitter is difficult to realize, we propose a technique using quantized phase information at the transmitter that achieves a full diversity advantage given enough bits of feedback. Monte Carlo simulation comparisons with other systems show the performance as a function of quantization.