Experimental Evaluation of Eigenvector Beamforming Method with 8X4 MIMO-OFDM Testbed

Multiple input multiple output (MIMO) systems increase the channel capacity within the limited frequency band. MIMO techniques can be combined with orthogonal frequency division multiplexing (OFDM), which is known to combat frequency selectivity in wireless channels. When channel state information (CSI) is available at the transmitter, the eigenvector beamforming method is well known to achieve the maximum channel capacity. However, the performance of eigenvector beamforming, which employs both modulation and forward error correction schemes, is not very well understood. In this paper, we evaluate the channel capacity and the frequency utilization of an eigenvector beamforming method in an actual indoor environment using an 8X4 MIMO-OFDM testbed that we developed. The experiment results indicate that the transmission bit rate increases offered by the eigenvector beamforming method in 4X4 MIMO and 8X4 MIMO channels are 3.83 fold and 4.90 fold larger than the performance of conventional transmission in SISO channel respectively and these ratios are larger than the increases in the channel capacity.