Low SNR capacity of double-scattering MIMO channels with transmitter channel knowledge
ICC'09 Proceedings of the 2009 IEEE international conference on Communications
IEEE Transactions on Signal Processing
Optimality of beamforming for MIMO multiple access channels via virtual representation
IEEE Transactions on Signal Processing
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We investigate the capacity of a general class of MIMO channels, known as double-scattering channels. Our results assume perfect channel state information (CSI) at the receiver and statistical CSI at the transmitter. We first derive the optimal capacity-achieving signaling directions, and show that they correspond to the eigenvectors of the transmit spatial correlation matrix. We then derive new simple closed-form power allocation policies which are shown to yield negligible capacity loss compared with the optimal power allocation policy, without requiring complicated numerical optimization methods to compute. Finally we derive a necessary and sufficient condition for which a beamforming approach (i.e. rank-1 transmission) achieves the ergodic capacity.