Artykuły w czasopismach: „Level-crossing rate (LCR)”

1

Chau, Yawgeng A., i Karl Y. T. Huang. "On the Second-Order Statistics of Correlated Cascaded Rayleigh Fading Channels". International Journal of Antennas and Propagation 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/108534.

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The second-order statistics of two correlated cascaded (double) Rayleigh fading channels are analyzed, where different relevant second-order cross-correlation functions of in-phase and quadrature components of the cascaded Rayleigh channels are derived. The level crossing rate (LCR) and average fade duration (AFD) of the cascaded channels are evaluated, and a single-integral form of the LCR is derived. Numerical results of the LCR and AFD are presented, and the effect of the correlation is illustrated.

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Milosavljević, Srđan, Dejan Milić, Slaviša Trajković, Petar Spalević i Bojana Milosavljević. "LEVEL CROSSING RATE OF MACRODIVERSITY OUTPUT PROCESS IN THE PRESENCE OF η-μ SHORT TERM FADING AND GAMMA LONG TERM FADING". Facta Universitatis, Series: Automatic Control and Robotics 16, nr 2 (24.10.2017): 157. http://dx.doi.org/10.22190/fuacr1702157m.

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In this paper macrodiversity reception with macrodiversity selection combining (SC) receiver and two microdiversity MRC receivers operating over shadowed multipath fading channel is studied. Received signal experiences short term fading and correlated Gamma long term fading resulting in system performance degradation. Level crossing rate (LCR) of η-μ random process and level crossing rate of signals at outputs of microdiversity MRC receivers are efficiently calculated. By using these derived formulas, level crossing rate of macrodiversity SC receiver output signal process is calculated. By using this result, average fade duration (AFD) of the proposed wireless communication system can be calculated. The influence of η-μ short term fading severity parameter, Gamma long term fading severity parameter and Gamma long term correlation coefficient on level crossing rate is analysed and studied.

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Suljovic, Suad, Dejan Milic i Stefan Panic. "LCR of SC receiver output signal over α-κ-μ multipath fading channels". Facta universitatis - series: Electronics and Energetics 29, nr 2 (2016): 261–68. http://dx.doi.org/10.2298/fuee1602261s.

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Wireless mobile communication system with selection combining (SC) diversity receiver is investigated in this paper. Received signal envelope experiences ?-?-? short term fading resulting in system performance degradation. Level crossing rate (LCR) and average fade duration (AFD) of SC receiver output signal envelope are obtained as rapidly converging infinite series expressions. Numerically evaluated results are presented graphically, in order to discuss the effects of transmission parameters: multipath fading severity, dominant component power and nonlinearity propagation parameter on observed LCR performance of dual SC.

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4

Li, Lei, i Xiao Dong Wang. "Fade Statistic Analysis of SC in Distributed Antenna System". Applied Mechanics and Materials 336-338 (lipiec 2013): 1708–12. http://dx.doi.org/10.4028/www.scientific.net/amm.336-338.1708.

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Exact and closed form expressions for the average level crossing rate (LCR) and average fade duration (AFD) of the output signal envelope of selection diversity system are derived, assuming each branch is subject to independent but nonidentical composite fading in distributed antenna systems (DAS). Numerical results validate the derived expressions. It shows that DAS promise significant diversity gains over collocated multiple antenna system.

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5

Krstic, Dragana, Petar Nikolic, Danijela Aleksic, Sinisa Minic, Dragan Vuckovic i Mihajlo Stefanovic. "Product of Three Random Variables and its Application in Relay Telecommunication Systems in the Presence of Multipath Fading". Journal of Telecommunications and Information Technology 1 (29.03.2019): 83–92. http://dx.doi.org/10.26636/jtit.2019.130018.

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In this paper, the product of three random variables (RVs) will be considered. Distribution of the product of independent random variables is very important in many applied problems, including wireless relay telecommunication systems. A few of such products of three random variables are observed in this work: the level crossing rate (LCR) of the product of a Nakagami-m random variable, a Rician random variable and a Rayleigh random variable, and of the products of two Rician RVs and one Nakagami-m RV is calculated in closed forms and presented graphically. The LCR formula may be later used for derivation of average fade duration (AFD) of a wireless relay communication radio system with three sections, working in the multipath fading channel. The impact of fading parameters and multipath fading power on the LCR is analyzed based on the graphs presented.

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6

Jaksic, Dejan, Risto Bojovic, Petar Spalevic, Dusan Stefanovic i Slavisa Trajkovic. "Performance Analysis of 5G Transmission over Fading Channels with Random IG Distributed LOS Components". International Journal of Antennas and Propagation 2017 (2017): 1–4. http://dx.doi.org/10.1155/2017/4287586.

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Mathematical modelling of the behavior of the radio propagation at mmWave bands is crucial to the development of transmission and reception algorithms of new 5G systems. In this study we will model 5G propagation in nondeterministic line-of-sight (LOS) conditions, when the random nature of LOS component ratio will be observed as Inverse Gamma (IG) distributed process. Closed-form expressions will be presented for the probability density function (PDF) and cumulative distribution function (CDF) of such random process. Further, closed-form expressions will be provided for important performance measures such as level crossing rate (LCR) and average fade duration (AFD). Capitalizing on proposed expressions, LCR and AFD will be discussed in the function of transmission parameters.

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7

Yang, Xiao Xue, Chun Yang Zhang i You Zheng Wang. "Statistical Properties Analysis of Relay Channel". Applied Mechanics and Materials 610 (sierpień 2014): 854–61. http://dx.doi.org/10.4028/www.scientific.net/amm.610.854.

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The statistical properties of relay channel are quite different from the direct transmission channel for including two phases channel of source to relay and relay to destination. In this paper, we study the relay channel from three viewpoints of probability density function (PDF), level crossing rate (LCR) and Doppler spectrum for Rayleigh, Rice and Nakagami fading models. The closed form expressions are deduced, and simulation evaluation is done to verify the results.

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Akram, Muhammad Imran, i Asrar U. H. Sheikh. "On the Statistical Properties of Nakagami-Hoyt Vehicle-to-Vehicle Fading Channel under Nonisotropic Scattering". International Journal of Antennas and Propagation 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/179378.

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This paper presents the statistical properties of the vehicle-to-vehicle Nakagami-Hoyt (Nakagami-q) channel model under non-isotropic condition. The spatial time correlation function (STCF), the power spectral density (PSD), squared time autocorrelation function (SQCF), level crossing rate (LCR), and the average duration of Fade (ADF) of the Nakagami-Hoyt channel have been derived under the assumption that both the transmitter and receiver are nonstationary having nonomnidirectional antennas. A simulator that uses the inverse-fast-fourier-transform- (IFFT-) based computation method is designed for this model. The simulator and analytical results are compared.

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9

Kuo, Po Yu, i Gan Zhi Fan. "Analysis and Implementation of Rayleigh Fading Channel Using MATLAB". Applied Mechanics and Materials 764-765 (maj 2015): 476–80. http://dx.doi.org/10.4028/www.scientific.net/amm.764-765.476.

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Mobile wireless communication is the fastest growing segment of the communication industry. However, it is faced with the challenge of providing reliable high-speed communications due to channel impediments which change over time in unpredictable ways. To analyze the reliability and performance of real communication system, the Rayleigh fading channel is generally applied to simulate the real wireless communication. In this paper, we analyze and implement a flat Rayleigh fading channel based on the inverse discrete Fourier transform (IDFT). The simulation results of level crossing rate (LCR) and average fade duration (AFD) are shown in this paper.

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10

Lin, Jia-Chin, i Chun-Lin Lin. "Second-Order Statistics of MRC Reception With a Transparent Amplify-and-Forward Relay". International Journal of Interdisciplinary Telecommunications and Networking 12, nr 1 (styczeń 2020): 1–14. http://dx.doi.org/10.4018/ijitn.2020010101.

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Achievable spatial diversity supported by a single transparent amplify-and-forward (AF) relay relies on disintegrated channel state information (CSI) that can be acquired at the destination. This paper studies the impact of the quantization of the source-relay (SR) CSI in terms of the first- and second-order statistics of maximal-ratio combining (MRC) reception with the incomplete SR CSI at the destination. Probability density functions (PDFs) of the upper and lower bounds of the signal-to-noise ratio (SNR) achieved at the destination are derived. Corresponding level-crossing rate (LCR) and average fade-duration (AFD), which are undoubtedly required to choose parameters of forward error correcting (FEC) mechanisms across the transparent AF relay network, are evaluated via Monte Carlo simulations. The simulations show that the SNR PDF, LCR and AFD highly depends not only on the accuracy of SR CSI at the destination but also on the location of the AF relay.

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11

Stefanovic, Nenad, Marija Blagojevic, Ivan Pokrajac, Marian Greconici, Yigang Cen i Vladimir Mladenovic. "A Symbolic Encapsulation Point as Tool for 5G Wideband Channel Cross-Layer Modeling". Entropy 22, nr 10 (14.10.2020): 1151. http://dx.doi.org/10.3390/e22101151.

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Considering that networks based on New Radio (NR) technology are oriented to provide services of desired quality (QoS), it becomes questionable how to model and predict targeted QoS values, especially if the physical channel is dynamically changing. In order to overcome mobility issues, we aim to support the evaluation of second-order statistics of signal, namely level-crossing rate (LCR) and average fade duration (AFD) that is missing in general channel 5G models. Presenting results from our symbolic encapsulation point 5G (SEP5G) additional tool, we fill this gap and motivate further extensions on current general channel 5G. As a matter of contribution, we clearly propose: (i) anadditional tool for encapsulating different mobile 5G modeling approaches; (ii) extended, wideband, LCR, and AFD evaluation for optimal radio resource allocation modeling; and (iii) lower computational complexity and simulation time regarding analytical expression simulations in related scenario-specific 5G channel models. Using our deterministic channel model for selected scenarios and comparing it with stochastic models, we show steps towards higherlevel finite state Markov chain (FSMC) modeling, where mentioned QoS parameters become more feasible, placing symbolic encapsulation at the center of cross-layer design. Furthermore, we generate values within a specified 5G passband, indicating how it can be used for provisioningoptimal radio resource allocation.

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12

Suljovic, Suad, Dejan Milic, Zorica Nikolic, Stefan Panic, Mihajlo Stefanovic i Djoko Bandjur. "Performance of macro diversity wireless communication system operating in Weibull multipath fading environment". Facta universitatis - series: Electronics and Energetics 30, nr 4 (2017): 599–609. http://dx.doi.org/10.2298/fuee1704599s.

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In this paper, we consider wireless mobile radio communication system with macro diversity reception. Signal is subject to Weibull small scale fading and Gamma large scale fading resulting in system performance degradation. Receiver uses macro diversity selection combining (SC) technique in order to reduce the impact of long term fading effects, and two micro diversity SC branches are used to mitigate Weibull short term fading effects on system performance. Probability density function (PDF), and cumulative distribution function (CDF), as well as level crossing rate (LCR) and average fade duration (AFD) of the SC receiver output signal envelope are evaluated. The obtained expressions converge rapidly for all considered values of Weibull fading parameter and Gamma shadowing severity parameter. Mathematical results are studied in order to analyze the influence of Weibull fading parameter and Gamma shadowing severity parameter on statistical properties of the SC receiver output signal.

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13

Vela-Garcia, L., J. Vázquez Castillo, R. Parra-Michel i Matthias Pätzold. "An Accurate Hardware Sum-of-Cisoids Fading Channel Simulator for Isotropic and Non-Isotropic Mobile Radio Environments". Modelling and Simulation in Engineering 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/542198.

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The rapid technological development in the field of wireless communications calls for devices capable of reproducing and simulating the behavior of the channel under realistic propagation conditions. This paper presents a hardware fading channel simulator that is able to generate stochastic processes characterized by symmetrical and asymmetrical Doppler power spectral densities (PSDs) depending on the assumption of isotropic or non-isotropic scattering. The concept of the proposed hardware simulator is based on an implementation of the sum-of-cisoids (SOC) method. The hardware simulator is capable of handling any configuration of the cisoid's amplitudes, frequencies, and phases. Each of the cisoids that constitutes the SOC model is implemented using a piecewise polynomial approximation technique. The investigation of the higher-order statistics of the generated fading processes, like the level-crossing rate (LCR) and the average duration of fades (ADF), shows that our design is able to reproduce accurately the key features of realistic channel models that are considered as candidates for the latest wireless communication standards.

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14

Khan, Mohammad Monirujjaman, Qammer H. Abbasi, Akram Alomainy i Yang Hao. "Performance of Ultrawideband Wireless Tags for On-Body Radio Channel Characterisation". International Journal of Antennas and Propagation 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/232564.

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Experimental characterisation of on-body radio channel for ultrawideband (UWB) wireless active tags is reported in this paper. The aim of this study is to investigate the performance of the commercially available wireless tags on the UWB on-body radio channel characterisation. Measurement campaigns are performed in the chamber and in an indoor environment. Statistical path loss parameters of nine different on-body radio channels for static and dynamic cases are shown and analyzed. Results demonstrated that lognormal distribution provides the best fits for on-body propagation channels path loss model. The path loss was modeled as a function of distance for 34 different receiver locations for propagation along the front part of the body. A reduction of 11.46% path loss exponent is noticed in case of indoor environment as compared to anechoic chamber. In addition, path loss exponent is also extracted for different body parts (trunk, arms, and legs). Second-order channel parameters as fade probability (FP), level crossing rate (LCR), and average fade duration (AFD) are also investigated.

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15

Beuerman, Steven L., i Edward J. Coyle. "State space expansions and the limiting behavior of quasi-birth-and-death processes". Advances in Applied Probability 21, nr 02 (czerwiec 1989): 284–314. http://dx.doi.org/10.1017/s0001867800018553.

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The notion of complete level crossing information, or LCI-completeness, is introduced for quasi-birth-death (QBD) processes. It is shown that state space expansions allow any QBD-process to be modified so that it is LCI-complete. For any LCI-complete, QBD-process, there exists a matrix W such that , where is the vector of limiting probabilities for all states on level n of the process. When W cannot be found in closed form, it can be found via an algorithm requiring fewer than m steps, where m is the number of states on each level of the process. The result of this algorithm is always a linear matrix equation for which W is the solution. In essentially all cases considered in this paper, the matrix W is a solution of the matrix quadratic X 2 A 2 + XA 1 + A 0 = 0. Despite this fact, W is never equal to Neuts' rate matrix R , although the non-zero eigenvalues and the corresponding left eigenvectors of R are a subset of the eigenvalues and left eigenvectors of W . This fact leads to two methods for determining R from W . If the transition rates of the QBD-process are level-dependent, then it is also shown that matrices W(n) exist such that .

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16

Beuerman, Steven L., i Edward J. Coyle. "State space expansions and the limiting behavior of quasi-birth-and-death processes". Advances in Applied Probability 21, nr 2 (czerwiec 1989): 284–314. http://dx.doi.org/10.2307/1427161.

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The notion of complete level crossing information, or LCI-completeness, is introduced for quasi-birth-death (QBD) processes. It is shown that state space expansions allow any QBD-process to be modified so that it is LCI-complete.For any LCI-complete, QBD-process, there exists a matrix W such that , where is the vector of limiting probabilities for all states on level n of the process. When W cannot be found in closed form, it can be found via an algorithm requiring fewer than m steps, where m is the number of states on each level of the process. The result of this algorithm is always a linear matrix equation for which W is the solution.In essentially all cases considered in this paper, the matrix W is a solution of the matrix quadraticX2A2 + XA1 + A0 = 0.Despite this fact, W is never equal to Neuts' rate matrix R, although the non-zero eigenvalues and the corresponding left eigenvectors of R are a subset of the eigenvalues and left eigenvectors of W. This fact leads to two methods for determining R from W.If the transition rates of the QBD-process are level-dependent, then it is also shown that matrices W(n) exist such that .

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17

STEFANOVIĆ, ČASLAV. "APPLICATION OF LAPLACE APPROXIMATION FORMULA IN PERFORMANCE ANALYSIS OF WIRELESS RELAY COMMUNICATION SYSTEM IN MULTIPATH FADING ENVIRONMENT". Safety Engineering 7, nr 1 (15.06.2017). http://dx.doi.org/10.7562/se2017.7.01.03.

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In this paper, Laplace approximation formula is efficiently used to calculate infinite-series expression for average level crossing rate (LCR) of the product of Nakagami-m and kappa-mu random processes. The results can be used in performance analysis of dual-hop relay wireless mobile communication system in specific multipath fading environment when the first section is under the influence of NLOS multipath environment while the second section is under the influence of LOS multipath fading environment. The influences of multipath fading parameters on the LCR of the proposed model are examined, graphically presented and discussed. Moreover, analytical approach of applying Laplace approximation formula in multi-hop systems is further considered by obtaining closed form expressions for the LCR of the product of three and four Nakagami-m processes, respectively. Key words: average level crossing rate, kappa-mu multipath fading, Laplace approximation formula, Nakagami-m distribution, relay communications system.

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18

Pätzold, Matthias, Nurilla Avazov i Van Duc Nguyen. "Design and Simulation of Measurement-Based Correlation Models for Shadow Fading". REV Journal on Electronics and Communications 1, nr 2 (1.09.2011). http://dx.doi.org/10.21553/rev-jec.14.

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This paper deals with the design of measurement-based correlation models for shadow fading. Based on the correlation model, we design a simulation model using the sum-of-sinusoids (SOS) method to enable the simulation of spatial lognormal processes characterizing real-world shadow fading scenarios. The model parameters of the simulation model are computed by applying the Lp-norm method (LPNM). This method facilitates an excellent fitting of the simulation model’s autocorrelation function (ACF) to that of measured channels. Our study includes an evaluation of all important statistical quantities of the proposed measurement-based simulation model, such as the probability density function (PDF), spatial ACF, decorrelation and coherence distance, as well as the level-crossing rate (LCR) and the average duration of fades (ADF). A comparison with the Gudmundson correlation model shows that the developed measurement-based correlation model outperforms the former one by far in terms of the goodness of fit to the measured data. The proposed measurement-based simulation model allows to study the effects of long-term fading on the performance of mobile communication systems under real-world shadow fading conditions.

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Artykuły w czasopismach na temat „Level-crossing rate (LCR)”

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