In this paper, we have proposed a link adaptation scheme based on adaptive switching of the number of active RF modules such that MIMO channel capacity is maximized at low computational cost. We have proposed an approximated analytical solution for the selection of the MIMO order (MOS) depending on the full channel matrix and the signal-to-noise ratio. Following the results of MOS, we then form antenna groups based on the spatial correlation properties of antenna elements. These antenna groups transmit different data streams by dominant eigen mode transmission.We found out that our proposed scheme results in increased channel capacity particularly in low SNR and high correlation scenarios.