Adaptive Transmission Using Channel Inversion for Multiple Antenna Systems

摘要

Adaptive modulation often achieves a significantly higher capacity than non-adaptive modulation in multiple-antenna communication systems, particularly when transmit antennas outnumber receive antennas. Adaptive modulation generally involves varying signal power, constellation and coding in response to changing channel conditions, which adds considerable system complexity. In this paper, we consider simpler adaptive transmission schemes based on channel inversion (CI) and multidimensional eigen-beamforming. We derive optimal CI schemes for multiple-antenna systems and show that these schemes suffer a small loss in capacity relative to optimal adaptive modulation, even for relatively small arrays.