Rate-maximized switching between spatial transmission modes

We evaluate the performance of the common idea to switch between spatial multiplexing and diversity transmission based on the actual channel state, aiming at maximizing the achievable data rate. For different spatial transmission schemes the achievable data rate is evaluated based on the signal to interference and noise ratio (SINR) seen after the equalizer in front of the detector. This process is carried out at the receiver; the decision on the favoured scheme is then signalled to the transmitter via a low-rate feedback link. We provide performance results in terms of spectral efficiency for a 2 x 2 and a 4 x 2 single-user MIMO link as well as for a multi-user system where base station and terminals are equipped with two antennas each.