Efficient use of fading correlations in MIMO systems

We investigate the effects of both fading correlations and transmitter channel knowledge in multiple element antenna (MEA) communication systems. While for independent and identically distributed, fades between receive and transmit antennas, pioneering work showed that a huge increase in capacity is possible for MEAs compared to a single antenna system, recent contributions warn that fading correlations destroy most of this advantage. While this is true for zero transmitter channel knowledge, we will show however, that long-term average channel state information enables the transmitter to efficiently use the fading correlations to its advantage and offers the potential to even increase capacity beyond the one possible for independent fading. A conceived transmit technique is presented that efficientlymakes use of fading correlations, and also provides optimum choice of digital modulation schemes that carry the information.