Microwave Mobile Communications
Microwave Mobile Communications
A new approach to power adjustment for spatial covariance based downlink beamforming
ICASSP '01 Proceedings of the Acoustics, Speech, and Signal Processing, 2001. on IEEE International Conference - Volume 05
Space-time transmit precoding with imperfect feedback
IEEE Transactions on Information Theory
Efficient use of side information in multiple-antenna data transmission over fading channels
IEEE Journal on Selected Areas in Communications
Majorization and matrix-monotone functions in wireless communications
Foundations and Trends in Communications and Information Theory
Optimality of beamforming in fading MIMO multiple access channels
IEEE Transactions on Communications
Robust cognitive beamforming with partial channel state information
IEEE Transactions on Wireless Communications
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We study the optimal transmission strategy of a multiple-inputsingle-output wireless communication link. The receiver has perfectchannel state information while the transmitter hasonly long-term channel state information in terms of the channelcovariance matrix. It was recently shown that the optimal eigenvectors of the transmitcovariance matrix correspond with the eigenvalues of the channelcovariance matrix. However, the optimal eigenvalues are difficult tocompute. We study the properties of these optimal capacity achieving eigenvalues, and present a necessary and sufficient condition for theoptimal eigenvalues of the transmit covariance matrix. Furthermore, we develop a necessary and sufficient condition forachieving capacity when transmitting in all directions. We compare thecapacity gain of an optimal diversity system with a system which works with beamforming, and we derive an upperbound. We answer the main questions regarding the system design using the developed results. Additionally, we show inwhich way the multiplexing gain can be computed in case the channel covariancematrix is given. We compute the maximum number of required paralleldata streams, and we define a multiplexing function inorder to obtain a measure for the available multiplexinggain. Furthermore, we show that the capacity gain is small considering theadditional complexity at the receiver. We illustrate allresults by numerical simulations.