Dana Ciochina

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We address the problem of robust multiuser downlink beamforming under the assumption that the transmitter has partial covariance-based channel state information (CSI). In our approach, the uncertainty on the channel covariance matrices is assumed to be confined in an ellipsoid of given size and shape, where prior knowledge about the statistical distribution(More)
We consider optimal beamforming and user admission in cellular secondary networks where radio access to the licensed spectrum is granted under the premise that the interference level created in the primary network falls below a predefined threshold and Quality of Service (QoS) demands of the secondary users (SUs) need to be fulfilled. In scenarios where the(More)
We address the problem of multi-user downlink beamforming and power allocation in a cognitive radio (CR) secondary network (SN) with constraints on the total interference in the primary network (PN). We derive the Lagrange dual of the problem and show that both problems are equivalent. Two algorithms are proposed to solve the problem. The first is based on(More)
In this paper we take a new perspective on the worst case robust multiuser downlink beamforming problem with imperfect second order channel state information at the transmitter. Recognizing that all channel covariance matrices form a Riemannian manifold, we propose to use a measure properly defined along this manifold in order to model the set of mismatched(More)
We examine the robust downlink beamforming design from the point of outage probability constraint. We further reason that since the estimated downlink channel correlation (DCC) matrices form a manifold in the signal space, the estimation error should be measured in terms of Riemannian distance (RD) instead of the commonly used Euclidean distance (ED).(More)
This paper introduces a low complexity method for antenna sector selection in mmWave Hybrid MIMO communication systems like the IEEE 802.11ay amendment for Wireless LANs. The method is backwards compatible to the methods already defined for the released mmWave standard IEEE 802.11ad. We introduce an extension of the 802.11ad channel model to support common(More)
UNLABELLED In time, well water, as a source of drinking and coking water, with physical-chemical, bacteriological, and biological indicators suggestive of alteration in water potability, determines complex, sometimes irreversible, metabolic disorders. MATERIAL AND METHODS Sixty individuals residing in a rural community were divided into 2 groups: study(More)
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