Search results for "Computer Science::Performance"

showing 10 items of 25 documents

Quantum algorithms for formula evaluation

2010

We survey the recent sequence of algorithms for evaluating Boolean formulas consisting of NAND gates.

FOS: Computer and information sciencesQuantum PhysicsHardware_MEMORYSTRUCTURESFOS: Physical sciencesComputational Complexity (cs.CC)Computer Science::PerformanceComputer Science::Hardware ArchitectureComputer Science - Computational ComplexityComputer Science::Emerging TechnologiesComputer Science - Data Structures and AlgorithmsData Structures and Algorithms (cs.DS)Hardware_ARITHMETICANDLOGICSTRUCTURESQuantum Physics (quant-ph)Computer Science::Operating SystemsHardware_LOGICDESIGN
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Analysis of the IEEE 802.11e EDCA Under Statistical Traffic

2006

Many models have been proposed to analyze the performance of the IEEE 802.11 distributed coordination function (DCF) and the IEEE 802.11e enhanced distributed coordination function (EDCA) under saturation condition. To analyze DCF under statistical traffic, Foh and Zukerman introduce a model that uses Markovian Framework to compute the throughput and delay performance. In this paper, we analyze the protocol service time of EDCA mechanism and introduce a model to analyze EDCA under statistical traffic using Markovian Framework. Using this model, we analyze the throughput and delay performance of EDCA mechanism under statistical traffic.

IEEE 802Computer sciencebusiness.industryQuality of serviceComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSMarkov processWireless local area networks (WLAN)ThroughputDistributed coordination functionThroughputComputer Science::OtherComputer Science::Performancebackoff algorithmsymbols.namesakeWireless lanComputer Science::Networking and Internet ArchitecturesymbolsbusinessThroughput (business)Protocol (object-oriented programming)Computer network
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Bayesian prediction inM/M/1 queues

1994

Simple queues with Poisson input and exponential service times are considered to illustrate how well-suited Bayesian methods are used to handle the common inferential aims that appear when dealing with queue problems. The emphasis will mainly be placed on prediction; in particular, we study the predictive distribution of usual measures of effectiveness in anM/M/1 queue system, such as the number of customers in the queue and in the system, the waiting time in the queue and in the system, the length of an idle period and the length of a busy period.

Mathematical optimizationQueue management systemM/G/k queueM/D/1 queueM/M/1 queueM/D/c queueG/G/1 queueManagement Science and Operations ResearchComputer Science ApplicationsComputer Science::PerformanceComputational Theory and MathematicsStatisticsComputer Science::Networking and Internet ArchitectureM/G/1 queueM/M/c queueMathematicsQueueing Systems
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The UWB-OFDM Channel Analysis in Frequency

2009

In this paper, the ultra-wideband channel with orthogonal frequency division multiplexing (UWB-OFDM) is analyzed in the frequency domain. For UWB-OFDM channels with log-normal fading in the time domain, we show that the amplitude of each subcarrier can be approximated by a Nakagami-m random variable, where the fading parameter, the mean power and the correlation coefficient are expressed in terms of the following parameters: time arrival of the clusters, inter-arrival time of rays inside clusters, and power decay constants of rays and clusters.

PhysicsAutomatización y sistemas de controlOrthogonal frequency-division multiplexingTecnologíaNakagami distributionTopologyBanda anchaAutomation Command and control systemSubcarrierComputer Science::OtherSystems engineeringComputer Science::PerformanceIntersymbol interferenceAmplitudeFrequency domainComunicación inalámbricaElectronic engineeringComputer Science::Networking and Internet ArchitectureSistemas de comunicación inalámbricaFadingTime domainIngeniería de sistemas y comunicacionesComputer Science::Information Theory
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Anomalous Spreading of Power-Law Quantum Wave Packets

1999

We introduce power-law tail quantum wave packets. We show that they can be seen as eigenfunctions of a Hamiltonian with a physical potential. We prove that the free evolution of these packets presents an asymptotic decay of the maximum of the wave packets which is anomalous for an interval of the characterizing power-law exponent. We also prove that the number of finite moments of the wave packets is a conserved quantity during the evolution of the wave packet in the free space.

PhysicsQuantum PhysicsStatistical Mechanics (cond-mat.stat-mech)Network packetWave packetFOS: Physical sciencesGeneral Physics and AstronomyEigenfunctionPower lawConserved quantityComputer Science::Performancesymbols.namesakeQuantum mechanicsComputer Science::Networking and Internet ArchitecturesymbolsExponentQuantum Physics (quant-ph)Hamiltonian (quantum mechanics)QuantumCondensed Matter - Statistical MechanicsPhysical Review Letters
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Coherent quantum evolution via reservoir driven holonomies.

2006

We show that in the limit of a strongly interacting environment a system initially prepared in a decoherence-free subspace (DFS) coherently evolves in time, adiabatically following the changes of the DFS. If the reservoir cyclicly evolves in time, the DFS states acquire a holonomy.

PhysicsQuantum decoherenceHolonomyGeneral Physics and AstronomyComputer Science::Software EngineeringQuantum evolutionComputer Science::PerformanceQuantum mechanicsHolonomieLimit (mathematics)Decoherence-free subspace (DFS)Quantum evolutionComputer Science::Data Structures and AlgorithmsSubspace topologyPhysical review letters
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A simple equation for determining sea surface emissivity in the 3–15 µm region

2009

The high level of accuracy demanded for the sea surface temperature retrieval from infrared data requires an accurate determination of directional sea surface emissivity (SSE). Previous models have permitted calculating SSEs using a physical characterization of sea surface roughness and emission. However, these result in complex equations, and make an operational application difficult. This paper presents a simple SSE algorithm based on a parametrization of one of these models, which was selected as a reference since it reproduces SSE experimental data to a reasonable level of accuracy. The parametrization provides the SSE variation with observation angle and wind speed from a given nadir S…

Physics::Computational PhysicsPhysicsAATSRSurface finishWind speedComputer Science::PerformanceComputer Science::Mathematical SoftwareNadirEmissivitySurface roughnessGeneral Earth and Planetary SciencesRadiometryParametrizationRemote sensingInternational Journal of Remote Sensing
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A mini-slot-based cooperative MAC protocol for wireless mesh networks

2010

This paper proposes a TDMA-based medium access control protocol with cooperative communications enabled in wireless mesh networks. The proposed scheme is based on a multi-hop scenario which is extended from the conventional one-hop triangle cooperative transmission scenario. Benefiting from the elaborate mini-slot design, channel resources are fairly and efficiently allocated to each router so that no handshake is needed prior to every packet transmission. By giving priority for channel access to cooperative transmission performed by an optimal helper which is determined based on the received SNR, higher successful transmission rate can be achieved. Numerical results demonstrate that the pr…

Routing protocolRouterChannel allocation schemesWireless mesh networkbusiness.industryNetwork packetComputer scienceComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSTime division multiple accessThroughputData_CODINGANDINFORMATIONTHEORYComputer Science::PerformanceTransmission (telecommunications)Computer Science::Networking and Internet ArchitectureWirelessbusinessComputer networkCommunication channel2010 IEEE Globecom Workshops
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Throughput and energy efficiency comparison of one-hop, two-hop, virtual relay and cooperative retransmission schemes

2010

Two main types of approaches exist for implementing cooperative communications at the MAC layer: virtual-hop relay and cooperative retransmission. While the virtual-hop relay schemes employ relay nodes to forward packets when higher end-to-end throughput can be achieved compared with the direct transmission, the cooperative retransmission schemes use relays to retransmit data only after the direct transmission fails. However, the performance of the these different approaches has not been compared in the literature, especially when energy efficiency is considered. In order to find out the best transmission scheme, this paper evaluates and compares the performance of the one-hop direct transm…

Routing protocolbusiness.industryNetwork packetWireless networkComputer scienceRetransmissionDistributed computingComputerSystemsOrganization_COMPUTER-COMMUNICATIONNETWORKSThroughputData_CODINGANDINFORMATIONTHEORYlaw.inventionComputer Science::PerformanceRelaylawComputer Science::Networking and Internet ArchitectureFadingbusinessComputer Science::Information TheoryComputer networkEfficient energy use2010 European Wireless Conference (EW)
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Performance Analysis of M-DPSK Modulation over Fast-Hoyt Fading Channels under Non-Isotropic Scattering Conditions

2021

In this paper, we analyze the symbol error probability (SEP) performance of M-ary differential phase shift keying (M-DPSK) modulation schemes over frequency-flat fast-varying Hoyt multipath fading channels. Assuming general non-isotropic scattering conditions, we first derive a finite-range integral expression for the probability density function (PDF) of the phase difference between two non-isotropic Hoyt vectors perturbed by additive white Gaussian noise (AWGN). Based upon the theory of M-DPSK modulation and the obtained PDF formula, the SEP of M-DPSK and its corresponding asymptotic behavior in non-isotropic fast-Hoyt fading channels are derived. Specifically, a double semi-finite range …

ScatteringComputer scienceIsotropyMathematical analysisProbability density functionComputer Science::Performancesymbols.namesakeAdditive white Gaussian noiseModulation (music)Computer Science::Networking and Internet ArchitecturesymbolsFadingMultipath propagationComputer Science::Information TheoryRayleigh fading2021 IEEE 32nd Annual International Symposium on Personal, Indoor and Mobile Radio Communications (PIMRC)
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