From theory to practice: MIMO real-time experiments of adaptive bit-loading with linear and non-linear transmission and detection schemes

In this paper we investigate the achievable practical throughput with channel aware bit-loading in experiments on a real-time MIMO test-bed. We compare three prominent MIMO transmission schemes, two of them are using only receive side detection namely linear MMSE or MMSE with successive interference cancellation while the third scheme is SVD-MIMO transmission or eigenspace-signalling, where the transmitter and the receiver both perform a joint signal processing. We show in measurements that a more complex scheme like V-BLAST can increase the link reliability significantly by either increasing the throughput al a fixed bit error rate or improving the bit error rate at a fixed rate. Furthermore we show that eigenspace-signalling outperforms LMMSE and V-BLAST in terms of achievable throughput especially in the low SNR region but requires accurate channel state information and signal processing at each side of the link.