Link adaptation in a multi-antenna system

We consider link adaptation for multi-antenna systems based on channel information also that at the transmitter. Using adaptive channel inversion (ACI), a step-wise trade-off between spatial multiplexing and diversity is realized. Due to pre- and post-processing, the channel is corrupted only by Gaussian noise in front of the detectors. By jointly optimizing the number of data streams and the common modulation, a nearly continuous adaptation of spectral efficiency is realized. Up to moderate powers, the channel capacity is approached in regular and singular MIMO channels, provided that scalar coding is applied.