The Experts below are selected from a list of 99504 Experts worldwide ranked by ideXlab platform
P. Pouliguen - One of the best experts on this subject based on the ideXlab platform.
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Controlled Stratification Based on Kriging Surrogate Model: An Algorithm for Determining Extreme Quantiles in Electromagnetic Compatibility Risk Analysis
IEEE Access, 2020Co-Authors: T. Houret, Philippe Besnier, S. Vauchamp, P. PouliguenAbstract:An electromagnetic compatibility failure is a consequence of an applied Interference Level being in excess of the susceptibility Level of the electronic equipment under investigation. Both Interference and susceptibility Levels depend on various configurations of coupling paths described by sets of unknown or uncertain parameters. It is therefore convenient to describe the applied Interference and the susceptibility Levels as random variables. As extreme values may have a strong impact on the risk of failure, we focus in this article on the estimation of extreme values of Interference Level (relevant applied fields, currents or voltages) by means of a restricted set of numerical simulations. The controlled stratification method aims at reducing the variance of estimation of extreme quantile, based on a correlated simple model. We recently highlighted that a kriging surrogate model was a good candidate to provide this simple model. Combined with controlled stratification, we obtained better estimation performances than using a standalone kriging model with the same output sample size. In practice, this sample size is limited due to the excessive simulation time of electromagnetic solvers. In this paper, we propose an original algorithm, which aims at checking whether the sample size is adequate to perform an acceptable estimation or not. We first validate the algorithm using analytical models. Finally, we apply this method to estimate the 99% quantile of the total radiated power of a source located inside an open cavity with 16 uncertain inputs. In that case, the algorithm reduces the number of calls to the initial model to approximately 40% of the budget that is required using a standard Monte Carlo approach. Moreover, it provides almost 4 times more extreme outputs. More remarkably, our proposed algorithm provides guidance for assessing the performance of quantile estimation according to the initially sample size of the design of experiment.
Sae-Woong Bahk - One of the best experts on this subject based on the ideXlab platform.
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VTC Fall (2) - A novel multiple access scheme for uplink cellular systems
IEEE 60th Vehicular Technology Conference 2004. VTC2004-Fall. 2004, 2004Co-Authors: Hui Won Je, Oh-soon Shin, Sae-Woong BahkAbstract:A novel multiple access scheme for the uplink cellular systems, referred to as FH/SS-OFDMA, is proposed. The proposed scheme employs both frequency hopping and code multiplexing on the frequency domain to acquire frequency diversity and suppress intercell Interference. The performance of the proposed scheme is investigated and evaluated in cellular environments and compared with that of other multiple access schemes. It has been found that the proposed one outperforms other multiple access schemes. Simulation results for various parameters, such as system load, modulation scheme, spreading factor, and Interference Level are also presented.
E S Sousa - One of the best experts on this subject based on the ideXlab platform.
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reverse link capacity and Interference statistics of a fixed step power controlled ds cdma system under slow multipath fading
IEEE Transactions on Communications, 1999Co-Authors: B Hashem, E S SousaAbstract:Power control (PC) on the reverse link of a direct-sequence code-division multiple-access system is essential to increase system capacity. Perfect PC eliminates fluctuations in the received signal Level and hence reduces the required signal-to-Interference ratio. However, a perfect PC algorithm tracks multipath fading accurately, which results in increasing the intercell Interference Level. A fixed step PC algorithm becomes almost perfect when the power command rate is too fast compared to the Doppler rate, which is the case for low-mobility users. We investigate the statistics of the intercell Interference assuming users are moving slowly. These statistics are then used to find the system capacity. Three parameters that can affect the capacity are considered: the number of the fading process resolvable paths, the maximum transmitted power, and soft handoff.
Mari Carmen Aguayo-torres - One of the best experts on this subject based on the ideXlab platform.
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Overview of LTE for Vehicular Communications
Wireless Personal Communications, 2020Co-Authors: Antonio Cerezo Barranco, Mari Carmen Aguayo-torres, José Antonio Yébenes Gálvez, Jesús Aguilar Armijo, Juan Carlos Ruiz Sicilia, Gerardo GómezAbstract:This article provides an overview about vehicle-to-everything communications in relation to the latest Long Term Evolution (LTE) standards. We describe the main vehicular services and give a brief review of vehicular communication systems over LTE for both infrastructure-to-vehicle communications over the broadcast/multicast LTE service and vehicle-to-vehicle communications over the LTE sidelink. Next, we analyze the performance of vehicular systems using link simulations for different vehicular channel models implemented on a LTE simulator called WM-SIMA. Finally, we draw some conclusions about the impact of using different modulation and coding scheme as well as the Interference Level on the overall performance.
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Multi-user coverage probability of uplink cellular systems: A stochastic geometry approach
2014 IEEE Global Communications Conference GLOBECOM 2014, 2014Co-Authors: Francisco J. Martin-vega, F. Javier López-martínez, Gerardo Gómez, Mari Carmen Aguayo-torresAbstract:We analyze the coverage probability of multi-user uplink cellular networks with fractional power control. We use a stochastic geometry approach where the mobile users are distributed as a Poisson Point Process (PPP), whereas the serving base station (BS) is placed at the origin. Using conditional thinning, we are able to calculate the coverage probability of k users which are allocated a set of orthogonal resources in the cell of interest, obtaining analytical expressions for this probability considering their respective distances to the serving BS. These expressions give useful insights on the interplay between the power control policy, the Interference Level and the degree of fairness among different users in the system.
T. Houret - One of the best experts on this subject based on the ideXlab platform.
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Controlled Stratification Based on Kriging Surrogate Model: An Algorithm for Determining Extreme Quantiles in Electromagnetic Compatibility Risk Analysis
IEEE Access, 2020Co-Authors: T. Houret, Philippe Besnier, S. Vauchamp, P. PouliguenAbstract:An electromagnetic compatibility failure is a consequence of an applied Interference Level being in excess of the susceptibility Level of the electronic equipment under investigation. Both Interference and susceptibility Levels depend on various configurations of coupling paths described by sets of unknown or uncertain parameters. It is therefore convenient to describe the applied Interference and the susceptibility Levels as random variables. As extreme values may have a strong impact on the risk of failure, we focus in this article on the estimation of extreme values of Interference Level (relevant applied fields, currents or voltages) by means of a restricted set of numerical simulations. The controlled stratification method aims at reducing the variance of estimation of extreme quantile, based on a correlated simple model. We recently highlighted that a kriging surrogate model was a good candidate to provide this simple model. Combined with controlled stratification, we obtained better estimation performances than using a standalone kriging model with the same output sample size. In practice, this sample size is limited due to the excessive simulation time of electromagnetic solvers. In this paper, we propose an original algorithm, which aims at checking whether the sample size is adequate to perform an acceptable estimation or not. We first validate the algorithm using analytical models. Finally, we apply this method to estimate the 99% quantile of the total radiated power of a source located inside an open cavity with 16 uncertain inputs. In that case, the algorithm reduces the number of calls to the initial model to approximately 40% of the budget that is required using a standard Monte Carlo approach. Moreover, it provides almost 4 times more extreme outputs. More remarkably, our proposed algorithm provides guidance for assessing the performance of quantile estimation according to the initially sample size of the design of experiment.
