A new energy efficiency measure for quasi-static MIMO channels
Proceedings of the 2009 International Conference on Wireless Communications and Mobile Computing: Connecting the World Wirelessly
An information-theoretic look at MIMO energy-efficient communications
Proceedings of the Fourth International ICST Conference on Performance Evaluation Methodologies and Tools
Cooperative schemes for a source and an occasional nearby relay in wireless networks
IEEE Transactions on Information Theory
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We investigate the outage probability of a 2 times 1 multiple-input single-output (MISO) communication link subjected to quasi-static flat Rayleigh fading, under total and individual (per antenna) average power constraints and under a maximum correlation constraint. For a system with normalized fading and noise powers and a total power constraint P, it is shown that up to a rate of approximately log (1 + 1.2564 ldr P) it is best to divide the power equally between the two antennas, while for higher rates it is preferable to use all of the power in a single antenna. When individual power constraints are imposed on each antenna, and in addition, the correlation between the transmitted signals from each antenna can not be made larger than rhomax, it is shown that for rates smaller than log(1 + P) the optimal correlation is zero, while for rates higher than log(1 + gammaP), where gamma is a constant in [1,3/2], the best correlation is rhomax. For the remaining rates, the optimal correlation is either 0 or rhomax- Finally, we consider the outage performance of a two-user multiple access channel with a common message. The effect of the rate of the common message on the optimal correlation and on the optimum outage performance is examined.