A novel power allocation approach for coordinate interleaved spatial multiplexing

MIMO systems promise significant capacity gains. When perfect CSI is available at the transmitter, precoding can further improve the performance. However, the performance is limited by the eigen layer having the least SNR. Coordinate Interleaved Spatial Multiplexing has been proposed recently, in which the performance of weaker eigen layers is improved at the expense of a degraded performance in the stronger layers. It has been showed that interleaving improves the overall performance of the system when the eigen layers have different diversities. Previous work on CISM assumes equal power to all the eigen layers. In this paper, we propose a power allocation approach to improve the performance of the scheme. We derive expressions for power allocation to the interleaved streams based on an optimality criterion, which tries to minimize the error probability. Simulations confirm our analytical results and show the improvement in performance.