From Spectrum Pooling to Space Pooling: Opportunistic Interference Alignment in MIMO Cognitive Networks - Computer Science > Information TheoryReport as inadecuate




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Abstract: We describe a non-cooperative interference alignment IA technique whichallows an opportunistic multiple input multiple output MIMO link secondaryto harmlessly coexist with another MIMO link primary in the same frequencyband. Assuming perfect channel knowledge at the primary receiver andtransmitter, capacity is achieved by transmiting along the spatial directionsSD associated with the singular values of its channel matrix using awater-filling power allocation PA scheme. Often, power limitations lead theprimary transmitter to leave some of its SD unused. Here, it is shown that theopportunistic link can transmit its own data if it is possible to align theinterference produced on the primary link with such unused SDs. We provide botha processing scheme to perform IA and a PA scheme which maximizes thetransmission rate of the opportunistic link. The asymptotes of the achievabletransmission rates of the opportunistic link are obtained in the regime oflarge numbers of antennas. Using this result, it is shown that depending on thesignal-to-noise ratio and the number of transmit and receive antennas of theprimary and opportunistic links, both systems can achieve transmission rates ofthe same order.



Author: S.M. Perlaza, N. Fawaz, S. Lasaulce, M. Debbah

Source: https://arxiv.org/







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