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International Conference on Cognitive Radio Oriented Wireless Networks and Communications

作者： Fakhreddine Gaaloul Hong-Chuan Yang Redha M. Radaydeh Mohamed-Slim Alouini Division of Physical Sciences and Engineering King Abdullah University for Science and Technology Thuwal Makkah Saudi Arabia Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

This paper investigates the performance of a cognitive radio transceiver that can monitor multiple channels and opportunistically use any one of them should it be available. In our work, we propose and compare two different opportunistic channel access schemes. The first scheme applies when the secondary user (SU) has access to only one channel. The second scheme applies when the SU has access to multiple channels but can at a given time monitor and access only one channel. Two switching strategies, namely the switch and examine and the switch and stay strategies, are proposed. For these proposed access schemes, we investigate their performance by deriving the analytical expression of the novel metric of the average access duration and the average waiting time and based on these two metrics a time average SU throughput formula is proposed to predict the performance of the secondary cognitive system.

关键词： Switches Measurement Sensors Cognitive radio Random variables Throughput Transmitters

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On the performance of multiuser scheduling with post-examining under non-identical fading

On the performance of multiuser scheduling with post-examini...

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IEEE Conference on Wireless Communications and Networking

作者： Fakhreddine Gaaloul Redha M. Radaydeh Mohamed-Slim Alouini Hong-Chuan Yang Division of Physical Sciences and Engineering King Abdullah University for Science and Technology Thuwal Makkah Saudi Arabia Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

We investigate the performance of a multiuser downlink access scheme based on a post-selection switch and examine algorithm. The studied scheme sequentially switches over the users that experience independent and non-identically distributed fading conditions, and selects a single user with an acceptable channel quality as compared to a pre-selected signal-to-noise ratio (SNR) threshold. If no one of the users can satisfy the target channel quality, the base station (BS) takes the advantage of the knowledge of all users channels and serves the user with the best channel quality among all users. This scheme reduces considerably the feedback load but offers a lower average spectral efficiency (ASE) as compared to that of the full feedback system with instantaneous best user selection. On the other hand, it improves the system performances, such as outage probability and average bit error rate (BER), as compared to a system that is based on a standard switching scheme without post-selection. Numerical results for the ASE average BER, and average feed back load, are presented for the cases of outdated and non-outdated rate-adaptive modulation scheme operating over independent and non-identically distributed users.

关键词： Signal to noise ratio Bit error rate Manganese Channel estimation Fading Switches Modulation

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ncRNA-class Web Tool: Non-coding RNA feature extraction and pre-miRNA classification web tool

ncRNA-class Web Tool: Non-coding RNA feature extraction and ...

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8th International Workshop on Artificial Intelligence Applications and Innovations, AIAI 2012: AIAB, AIeIA, CISE, COPA, IIVC, ISQL, MHDW, and WADTMB

作者： Kleftogiannis, Dimitrios Theofilatos, Konstantinos Papadimitriou, Stergios Tsakalidis, Athanasios Likothanassis, Spiros Mavroudi, Seferina Math. and Computer Sciences and Engineering King Abdullah Univ. of Science and Technology Saudi Arabia Department of Computer Engineering and Informatics University of Patras Greece Department of Social Work School of Sciences of Health and Care Technological Educational Institute of Patras Greece Department of Information Management Technological Institute of Kavala Greece

ISBN: (纸本)9783642334115

Until recently, it was commonly accepted that most genetic information is transacted by proteins. Recent evidence suggests that the majority of the genomes of mammals and other complex organisms are in fact transcribed into non-coding RNAs (ncRNAs), many of which are alternatively spliced and/or processed into smaller products. Non coding RNA genes analysis requires the calculation of several sequential, thermodynamical and structural features. Many independent tools have already been developed for the efficient calculation of such features but to the best of our knowledge there does not exist any integrative approach for this task. The most significant amount of existing work is related to the miRNA class of non-coding RNAs. MicroRNAs (miRNAs) are small non-coding RNAs that play a significant role in gene regulation and their prediction is a challenging bioinformatics problem. Non-coding RNA feature extraction and pre-miRNA classification Web Tool (ncRNA-class Web Tool) is a publicly available web tool ( http://150.140.142.24:82/*** ) which provides a user friendly and efficient environment for the effective calculation of a set of 58 sequential, thermodynamical and structural features of non-coding RNAs, plus a tool for the accurate prediction of miRNAs. © 2012 IFIP International Federation for Information Processing.

关键词： Forecasting

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On hybrid cooperation in underlay cognitive radio networks

On hybrid cooperation in underlay cognitive radio networks

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Asilomar Conference on Signals, Systems & computers

作者： Nurul H. Mahmood Ferkan Yilmaz Geir E. Øien Mohamed-Slim Alouini Department of Electronics & Telecommunications Norwegian University of Science and Technology (NTNU) Trondheim Norway Computer Electrical and Mathematical Science & Engineering (CEMSE) Division King Abdullah University of Science and Technology (KAUST) Thuwal Makkah Province Saudi Arabia

In wireless systems where transmitters are subject to a strict received power constraint, such as in underlay cognitive radio networks, cooperative communication is a promising strategy to enhance network performance, as it helps to improve the coverage area and outage performance of a network. However, this comes at the expense of increased resource utilization. To balance the performance gain against the possible over-utilization of resources, we propose a hybrid-cooperation technique for underlay cognitive radio networks, where secondary users cooperate only when required. Various performance measures of the proposed hybrid-cooperation technique are analyzed in this paper, and are also further validated numerically.

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Per-energy capacity and handoff strategies in macro-femto cells environment

Per-energy capacity and handoff strategies in macro-femto ce...

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IEEE Wireless Communications and Networking Conference Workshops (WCNCW)

作者： Jaime Peña León Faouzi Bader Mohamed-Slim Alouini Electrical Engineering Program King Abdullah University for Science and Technology Thuwal Makkah Saudi Arabia Centre Tecnológic de Telecomunicacions de Catalunya-(CTTC) Castelldefels Barcelona Spain

The effect of smaller cells being placed in a heterogeneous network can improve the way energy is spent in a system. Handoff strategies, bandwidth allocation and path loss calculations in different scenarios show how this is possible as the size of the cell is decreased. As a result, users can experience the same or better capacities while maximising the capacity per unit energy spent. The per-energy capacity metric is introduced as a suitable handoff strategy that considers the energy spent as an important criterion.

关键词： Macrocell networks Interference Bandwidth Channel allocation Measurement Base stations

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Low Complexity Receiver Design for MIMO-Radar

Low Complexity Receiver Design for MIMO-Radar

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Institute of electrical and Electronics Engineers Globecom Workshops

作者： Sajid Ahmed Mohamed-Slim Alouini Electrical Engineering Program King Abdullah University of Science and Technology (KAUST)

ISBN: (纸本)9781467349420

In this work, an algorithm for the multiple-input multiple-output (MIMO) radar is proposed. It has low computational complexity compared to the available schemes, and relatively low side-lobe-levels in the receive beampattem compared to the phased-array and MIMO-radar. In the proposed algorithm, the received signal vector of MIMO-radar is divided into sub-vectors, and each sub-vector is multiplied with the corresponding weight vector. The number of sub-vectors and weight vectors are optimally found to maximise the received signal power from the target of interest direction. The proposed scheme can be effectively applied in passive radars to minimise the side-lobe levels and place deep nulls for interferers in the receive beampattem. Simulation results show that the proposed scheme has relatively lower side lobe levels and better detection capabilities compared to MIMO-radar and phased-array.

关键词： Colocated antennas MIMO-radar partitioning

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Outage performance of two-way DF relaying systems with a new relay selection metric

Outage performance of two-way DF relaying systems with a new...

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IEEE Conference on Wireless Communications and Networking

作者： Amal Hyadi Mustapha Benjillali Mohamed-Slim Alouini Electrical Engineering Program King Abdullah University for Science and Technology Thuwal Makkah Saudi Arabia Institut National des Postes et Télécommunications (INPT) Rabat Morocco

This paper investigates a new constrained relay selection scheme for two-way relaying systems where two end terminals communicate simultaneously via a relay. The introduced technique is based on the maximization of the weighted sum rate of both users. To evaluate the performance of the proposed system, the outage probability is derived in a general case (where an arbitrary channel is considered), and then over independently but not necessarily identically distributed (i.n.i.d.) Rayleigh fading channels. The analytical results are verified through simulations.

关键词： Relays Signal to noise ratio Fading Probability density function Protocols Measurement Context

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Generating correlated QPSK waveforms by exploiting real gaussian random variables

Generating correlated QPSK waveforms by exploiting real gaus...

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Asilomar Conference on Signals, Systems & computers

作者： Seifallah Jardak Sajid Ahmed Mohamed-Slim Alouini Signals and Systems Department Ecole Polytechnique de Tunisie (EPT)-University of Carthage Tunis Tunisia Electrical Engineering Program King Abdullah University for Science and Technology Thuwal Makkah Saudi Arabia

ISBN: (纸本)9781467350501

The design of waveforms with specified auto- and cross-correlation properties has a number of applications in multiple-input multiple-output (MIMO) radar, one of them is the desired transmit beampattern design. In this work, an algorithm is proposed to generate quadrature phase shift-keying (QPSK) waveforms with required cross-correlation properties using real Gaussian random-variables (RV's). This work can be considered as the extension of what was presented in [1] to generate BPSK waveforms. This work will be extended for the generation of correlated higher-order phase shift-keying (PSK) and quadrature amplitude modulation (QAM) modulation schemes that can better approximate the desired beampattern.

关键词： Colocated antennas constant-envelope waveforms Hermite polynomials multiple-input multiple-output (MIMO) radar Hermite polynomials waveforms Quadrature phase shift keying Cross correlation Phase shift Quadrature amplitude modulation Gauss Random variable

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Lumped model for rotational modes in phononic crystals

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Physical Review B 2012年第13期86卷 134304-134304页

作者： Pai Peng Jun Mei Ying Wu Division of Mathematical and Computer Sciences and Engineering King Abdullah University of Science and Technology (KAUST) Thuwal 23955-6900 Saudi Arabia Department of Physics South China University of Technology Guangzhou 510641 China

We present a lumped model for the rotational modes induced by the rotational motion of individual scatterers in two-dimensional phononic crystals comprised of square arrays of solid cylindrical scatterers in solid hosts. The model provides a physical interpretation of the origin of the rotational modes, reveals the important role played by the rotational motion in determining the band structure, and reproduces the dispersion relations in a certain range. The model increases the possibilities of manipulating wave propagation in phononic crystals. In particular, expressions derived from the model for eigenfrequencies at high symmetry points unambiguously predict the presence of a new type of Dirac-like cone at the Brillouin center, which is found to be the result of accidental degeneracy of the rotational and dipolar modes.

关键词： LUMPED elements (Electronics) PHONONIC crystals ROTATIONAL motion SCATTERING (Physics) ELECTRONIC band structure THEORY of wave motion SYMMETRY (Physics)

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Solar Cells: Re‐evaluating the Role of Sterics and Electronic Coupling in Determining the Open‐Circuit Voltage of Organic Solar Cells (Adv. Mater. 42/2013)

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Advanced Materials 2013年第42期25卷

作者： Kenneth R. Graham Patrick Erwin Dennis Nordlund Koen Vandewal Ruipeng Li Guy O. Ngongang Ndjawa Eric T. Hoke Alberto Salleo Mark E. Thompson Michael D. McGehee Aram Amassian Materials Science and Engineering Program Physical Sciences and Engineering Division King Abdullah University of Science and Technology (KAUST) Thuwal Saudi Arabia 23955–6900 Department of Materials Science and Engineering Stanford University Stanford California 94305 USA Department of Chemistry University of Southern California Los Angeles California 90089 USA Stanford Synchrotron Radiation Lightsource SLAC National Accelerator Laboratory Menlo Park California 94025 USA

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