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IEEE International Symposium on Personal, Indoor and Mobile Radio Communications

作者： Adel M. Elmahdy Sameh Sorour Karim G. Seddik Electrical Engineering Department Alexandria University Alexandria 21544 Egypt. Computer Electrical and Mathematical Sciences and Engineering (CEMSE) Division King Abdullah University of Science and Technology (KAUST) Thuwal Kingdom of Saudi Arabia. Electronics Engineering Department American University in Cairo AUC Avenue New Cairo 11835 Egypt.

ISBN: (纸本)9781467362337

In this paper, we investigate the problem of minimizing the frame completion delay for Instantly Decodable Network Coding (IDNC) in relay-assisted wireless multicast networks. We first propose a packet recovery algorithm in the single relay topology which employs generalized IDNC instead of strict IDNC previously proposed in the literature for the same relay-assisted topology. This use of generalized IDNC is supported by showing that it is a super-set of the strict IDNC scheme, and thus can generate coding combinations that are at least as efficient as strict IDNC in reducing the average completion delay. We then extend our study to the multiple relay topology and propose a joint generalized IDNC and relay selection algorithm. This proposed algorithm benefits from the reception diversity of the multiple relays to further reduce the average completion delay in the network. Simulation results show that our proposed solutions achieve much better performance compared to previous solutions in the literature.

关键词： Network Coding Relay Assisted Networks Wireless Multicast

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Application of PDSLin to the magnetic reconnection problem

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Computational science and Discovery 2013年第1期6卷 014002-014002页

作者： Yuan, Xuefei Li, Xiaoye S Yamazaki, Ichitaro Jardin, Stephen C Koniges, Alice E Keyes, David E Lawrence Berkeley National Laboratory Berkeley CA 94720 United States Innovative Computing Laboratory University of Tennessee Knoxville TN 37996 United States Theory and Computation Department Princeton Plasma Physics Laboratory Princeton NJ 08540 United States Department of Astrophysical Sciences Princeton University Princeton NJ 08544 United States Division of Computer Electrical and Mathematical Sciences and Engineering King Abdullah University of Science and Technology Thuwal 23955-6900 Saudi Arabia Department of Applied Physics and Applied Mathematics Columbia University New York NY 10027 United States

Magnetic reconnection is a fundamental process in a magnetized plasma at both low and high magnetic Lundquist numbers (the ratio of the resistive diffusion time to the Alfvén wave transit time), which occurs in a wide variety of laboratory and space plasmas, e.g. magnetic fusion experiments, the solar corona and the Earth's magnetotail. An implicit time advance for the two-fluid magnetic reconnection problem is known to be difficult because of the large condition number of the associated matrix. This is especially troublesome when the collisionless ion skin depth is large so that the Whistler waves, which cause the fast reconnection, dominate the physics (Yuan et al 2012 J. Comput. Phys. 231 5822-53). For small system sizes, a direct solver such as SuperLU can be employed to obtain an accurate solution as long as the condition number is bounded by the reciprocal of the floating-point machine precision. However, SuperLU scales effectively only to hundreds of processors or less. For larger system sizes, it has been shown that physics-based (Chacón and Knoll 2003 J. Comput. Phys. 188 573-92) or other preconditioners can be applied to provide adequate solver performance. In recent years, we have been developing a new algebraic hybrid linear solver, PDSLin (Parallel Domain decomposition Schur complement-based Linear solver) (Yamazaki and Li 2010 Proc. VECPAR pp 421-34 and Yamazaki et al 2011 Technical Report). In this work, we compare numerical results from a direct solver and the proposed hybrid solver for the magnetic reconnection problem and demonstrate that the new hybrid solver is scalable to thousands of processors while maintaining the same robustness as a direct solver. © 2013 IOP Publishing Ltd.

关键词： Magnetoplasma

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A Statistical Model for Uplink Intercell Interference with Power Adaptation and Greedy Scheduling

A Statistical Model for Uplink Intercell Interference with P...

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IEEE Vehicular technology Conference

作者： Hina Tabassum Ferkan Yilmaz Zaher Dawy Mohamed Slim Alouini Electrical Engineering Program King Abdullah University of Science and Technology (KAUST) Department of Electrical and Computer Engineering American University of Beirut (AUB)

ISBN: (纸本)9781467318808

This paper deals with the statistical modeling of uplink inter-cell interference (ICI) considering greedy scheduling with power adaptation based on channel conditions. The derived model is implicitly generalized for any kind of shadowing and fading environments. More precisely, we develop a generic model for the distribution of ICI based on the locations of the allocated users and their transmit powers. The derived model is utilized to evaluate important network performance metrics such as ergodic capacity, average fairness and average power preservation numerically. Monte-Carlo simulation details are included to support the analysis and show the accuracy of the derived expressions. In parallel to the literature, we show that greedy scheduling with power adaptation reduces the ICI, average power consumption of users, and enhances the average fairness among users, compared to the case without power adaptation.

关键词： statistical models (nuclear) inter-cell interference greedy method Consumers Power (Psychology) ICI up link Performance metrics Energy sources Shadowing (Histology) average power TRANSMITTING

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Cognitive Relaying and Power Allocation under Channel State Uncertainties

Cognitive Relaying and Power Allocation under Channel State ...

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IEEE Wireless Communications And Networking Conference

作者： P Ubaidullat Mohamed-Slim Alouini Sonia Aissa Computer Electrical and Mathematical Sciences and Engineering (CEMSE) Division King Abdullah University of Science and Technology (KAUST) Thuwal Makkah Province Saudi Arabia. Institut National de la Recherche Scientifique (INRS) University of Quebec Montreal QC Canada.

ISBN: (纸本)9781467359382

In this paper, we present robust joint relay precoder designs and transceiver power allocations for a cognitive radio network under imperfect channel state information (CSI). The secondary (or cognitive) network consists of a pair of single-antenna transceiver nodes and a non-regenerative two-way relay with multiple antennas which aids the communication process between the transceiver pair. The secondary nodes share the spectrum with a licensed primary user (PU) while guaranteeing that the interference to the PU receiver is maintained below a specified threshold. We consider two robust designs: the first is based on the minimization of the total transmit power of the secondary relay node required to provide the minimum quality of service, measured in terms of mean-square error (MSE) of the transceiver nodes, and the second is based on the minimization of the sum-MSE of the transceiver nodes. The robust designs are based on worst-case optimization and take into account known parameters of the error in the CSI to render the performance immune to the presence of errors in the CSI. Though the original problem is non-convex, we show that the proposed designs can be reformulated as tractable convex optimization problems that can be solved efficiently. We illustrate the performance of the proposed designs through some selected numerical simulations.

关键词： Power Allocation CSI presence

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An Inkjet-Printed UWB Antenna on Paper Substrate Utilizing a Novel Fractal Matching Network

An Inkjet-Printed UWB Antenna on Paper Substrate Utilizing a...

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IEEE International Symposium on Antennas and Propagation

作者： B. S. Cook A. Shamim Electrical Engineering Program King Abdullah University of Science and Technology Thuwal Saudi Arabia

ISBN: (纸本)9781467304610

In this work, the smallest reported inkjet-printed UWB antenna is proposed that utilizes a fractal matching network to increase the performance of a UWB microstrip monopole. The antenna is inkjet-printed on a paper substrate to demonstrate the ability to produce small and low-cost UWB antennas with inkjet-printing technology which can enable compact, low-cost, and environmentally friendly wireless sensor network.

关键词： Ultra wideband antennas matching network PRINTING technology Fractals Sensor networks Substrates ink jet printing

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On the Capacity of Rician Fading Channels With Full Channel State Information at Low SNR

On the Capacity of Rician Fading Channels With Full Channel ...

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IEEE International Conference on Communications

作者： Zouheir Rezki Mohamed-Slim Alouini Electrical Engineering Program Physical Science and Engineering (PSE) Division King Abdullah University of Science and Technology (KAUST)

ISBN: (纸本)9781457720529

The capacity of flat Rayleigh fading channels with full channel state information (CSI) at the transmitter and at the receiver at asymptotically low SNR has been recently shown to scale essentially as SNR log(1/SNR). In this paper, we investigate the Rician fading channel capacity with full CSI, and show that the capacity of this channel scales essentially as 1/1+K SNR log(1/SNR), where K is the Rician factor. This characterization includes perfect CSI at both the transmitter and the receiver or noisy CSI at the transmitter and perfect CSI at the receiver. We also show that one-bit CSI at the transmitter is enough to achieve this asymptotic capacity using an On-Off power control scheme. Our framework may be seen as a generalization of previous works as it captures the Rayleigh fading channel as a special case by letting K goes to zero.

关键词： Ergodic capacity Rician fading channel Imperfect channel estimation On-off signaling Channel state information low SNR Raleigh fading channels Transmitters Rician fading channels Receivers Rician fading Transmitter Channel capacity transmitter receivers signal to noise ratios Supernova remnants

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On the ergodic secret message capacity of the wiretap channel with finite-rate feedback

On the ergodic secret message capacity of the wiretap channe...

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IEEE International Symposium on Information Theory

作者： Zouheir Rezki Ashish Khisti Mohamed-Slim Alouini Electrical Engineering Program Physical Science and Engineering Division King Abdullah University of Science and Technology Thuwal Makkah Saudi Arabia Electrical and Computer Engineering Department University of Toronto Toronto ONT Canada Electrical Engineering Program Physical Science and Engineering (PSE) Division King Abdullah University of Science and Technology Thuwal Makkah Saudi Arabia

We study the secret message capacity of an ergodic block fading wiretap channel with partial channel state information at the transmitter and perfect channel state information at the receivers. We consider that in addition to the statistics of the main and the eavesdropper channel state information (CSI), the sender is provided by the legitimate receiver with a q-bit feedback, at the beginning of each coherence block, through an error-free feedback channel, with capacity q bits. We establish upper and lower bounds on the secrecy capacity. We show that a positive secrecy rate is achievable even when the feedback is at the end of each coherence block and q = 1. We also show that the lower and the upper bounds coincide asymptotically as q → ∞. Finally, asymptotic analysis at high Signal-to-Noise Ratio (SNR) are presented where it is found that the capacity is bounded at high-SNR and present a simple suboptimal scalar quantizer that is capacity achieving, without the need of any numerical optimization, as q → ∞. When applied to Rayleigh fading channels, we show that, at high-SNR, a 4-bit feedback achieves 90% of the secrecy capacity when perfect main CSI is available at the transmitter.

关键词： Coherence Upper bound Fading Automatic repeat request Signal to noise ratio Transmitters Receivers

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Formant-based analysis of vowels in Modern Standard ArabicPreliminary results

Formant-based analysis of vowels in Modern Standard ArabicPr...

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2012 11th International Conference on Information science, Signal Processing and their Applications, ISSPA 2012

作者： Seddiq, Yasser Mohammad Alotaibi, Yousef Ajami Computer Engineering Department King Saud University Saudi Arabia National Program of Electronics Communications and Photonics King Abdulaziz City for Science and Technology Saudi Arabia

ISBN: (纸本)9781467303828

Although of the importance of analyzing vowel phonemes in the Modern Standard Arabic (MSA), it has not been paid a considerable attention in the published literature yet. Consequently, a formant-based analysis for the six vowels of MSA in connected speech was carried out in this work. The values of the first three formant frequencies were captured. The present results were compared to some previously published results conducted on MSA and other Arabic dialects. The comparison was performed from geometric perspective using the Euclidean distance. The results of the geometric comparison were found to be consistent with the visual inspection of the vowel triangles. © 2012 IEEE.

关键词： Linguistics

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A Novel Ergodic Capacity Analysis of Diversity Combining and Multihop Transmission Systems over Generalized Composite Fading Channels

A Novel Ergodic Capacity Analysis of Diversity Combining and...

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IEEE International Conference on Communications

作者： Ferkan Yilmaz Mohamed-Slim Alouini Electrical Engineering Program Division of Physical Sciences and Engineering King Abdullah University of Science and Technology (KAUST)

ISBN: (纸本)9781457720529

Ergodic capacity is an important performance measure associated with reliable communication at the highest rate at which information can be sent over the channel with a negligible probability of error. In the shadow of this definition, diversity receivers (such as selection combining, equal-gain combining and maximal-ratio combining) and transmission techniques (such as cascaded fading channels, amplify-and-forward multihop transmission) are deployed in mitigating various performance impairing effects such as fading and shadowing in digital radio communication links. However, the exact analysis of ergodic capacity is in general not always possible for all of these forms of diversity receivers and transmission techniques over generalized composite fading environments due to it's mathematical intractability. In the literature, published papers concerning the exact analysis of ergodic capacity have been therefore scarce (i.e., only [1] and [2]) when compared to those concerning the exact analysis of average symbol error probability. In addition, they are essentially targeting to the ergodic capacity of the maximal ratio combining diversity receivers and are not readily applicable to the capacity analysis of the other diversity combiners/transmission techniques. In this paper, we propose a novel moment generating function-based approach for the exact ergodic capacity analysis of both diversity receivers and transmission techniques over generalized composite fading environments. As such, we demonstrate how to simultaneously treat the ergodic capacity analysis of all forms of both diversity receivers and multihop transmission techniques.

关键词： Ergodic capacity Moment generating function Diversity receivers Transmission techniques Composite fading channels Extended generalized-K fading Selection combining Equal-gain combining Maximal-ratio combining Cascaded fading channels

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Optimal power allocation of a single transmitter-multiple receivers channel in a cognitive sensor network

Optimal power allocation of a single transmitter-multiple re...

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International Conference on Wireless Communications in Unusual and Confined Areas (ICWCUCA)

作者： Jose Roberto Ayala Solares Zouheir Rezki Mohamed-Slim Alouini Mathematical and Computer Sciences and Engineering King Abdullah University of Science and Technology Physical Sciences and Engineering King Abdullah University of Science and Technology

The optimal transmit power of a wireless sensor network with one transmitter and multiple receivers in a cognitive radio environment while satisfying independent peak, independent average, sum of peak and sum of average transmission rate constraints is derived. A suboptimal scheme is proposed to overcome the frequency of outages for the independent peak transmission rate constraint. In all cases, numerical results are provided for Rayleigh fading channels.

关键词： Receivers Fading Wireless sensor networks Radio transmitters Cognitive radio Tin Resource management

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