Abstract:

For a multiple input multiple output system, antenna selection reduces complexity at the expense of performance. In this paper, we propose two novel RF pre-processing architectures that significantly improve the performance of antenna selection, which marginally increasing the complexity. These architectures introduce a RF pre-processing matrix, M, that multiplies the vector of incoming signals prior to down-conversion. The elements of M use only the knowledge of the channel statistics. In the first architecture, M outputs a reduced number of streams - an explicit selection algorithm is therefore not required. In the second architecture, the number of output streams equals the number of input streams, and a selection switch that uses instantaneous channel state information achieves the reduction of the number of streams. We show that the optimal pre-processing receiver projects the received signal along the eigenvectors of the correlation matrix. In a correlated channel, both these architectures significantly outperform conventional antenna selection. We also develop a beam-pattern based intuition and compare the performance of our scheme to other RF pre-processing schemes previously proposed in the literature.