Dissertation•
Queueing theory approach to rain fade analysis at microwave and millimeter bands in tropical Africa.
18 Nov 2015-
About: The article was published on 2015-11-18 and is currently open access. It has received 7 citations till now. The article focuses on the topics: Rain fade.
Citations
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01 May 1975
TL;DR: The Fundamentals of Queueing Theory, Fourth Edition as discussed by the authors provides a comprehensive overview of simple and more advanced queuing models, with a self-contained presentation of key concepts and formulae.
Abstract: Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.
2,562 citations
01 Jan 1997
61 citations
01 Aug 2016
TL;DR: In this paper, the characteristics of rainfall spikes are investigated as a randomly varying in four rainfall rate states in Jimma, Ethiopia using Markov chain model and queueing theory approach.
Abstract: Rainfall attenuation over radio wave propagation originates from the stochastic turbulence of rainfall intensity on wireless networks, especially at higher operating frequencies. Basically, three parameters characterize a stochastic process of rainfall: rainfall spike, rainfall rate regimes and the sojourn time of a rainfall spike in each rain rate regime. In this paper, the characteristics of rainfall spikes are investigated as a randomly varying in four rainfall rate states in Jimma, Ethiopia using Markov chain model and queueing theory approach. From the first model the spikes transition probability matrix among regimes is determined and found to be ergodic and, applying the second approach the sojourns time distribution of spike is modelled and the result shows Erlang-K probability distribution not the common exponential distribution for all regimes with very minimum fitting errors.
4 citations
Book Chapter•
01 Jan 2017
TL;DR: In this paper, the authors investigated the radio wave propagation modeling under clear air and precipitation environment over wireless communications in the horn of Africa, where they derived radio climatological parameters for different rain and clear air fade models.
Abstract: The congestion of lower operating frequency bands has led to the rapid growth of utilizing higher frequency spectrum for wireless communication systems. However, attenuation caused by precipitation is the main problem for systems operating at higher frequency bands. For this reason, for efficient operation of wireless networks, this problem should be properly addressed. This thesis has investigated the radio wave propagation modelling under clear air and precipitation environment over wireless communications in the horn of Africa. The research emphasises both precipitation and clear air effects over radio links in Ethiopia. Radio climatological parameters for different rain and clear air fade models are adequately derived. To this end, three years of atmospheric data of temperature, pressure and relative humidity obtained from National Meteorological Agency (NMA) of Ethiopia and clear air signal measurements over terrestrial Line-of-Sight (LOS) links measured with EthioTelecom for a period of one year are used for clear air fade modelling and analysis. On the other hand, based on experimental measurements of rainfall from a Davis Vantage weather station installed at Jimma University, Ethiopia, time series rainfall generation and characterization is also done. Clear air fading is modeled either from radio-climatological parameters or from extensive signal level measurements over wireless links. In terrestrial LOS links, prediction of the refractivity gradient uses ITU-R worldwide contour map. However, in this work, data from NMA is used for the determination of refractivity and refractivity gradient. Applying the ITU-R model, the geo-climatic factor is derived from atmospheric refractivity. Geo-climatic factor, in turn, is used for the estimation of fade depth, outage probability and multipath fading distribution over existing path lengths and operating frequencies for four different locations of Ethiopia. From clear air signal measurements, the distribution of signal level
2 citations
Cites background or methods from "Queueing theory approach to rain fa..."
...For instance, Alonge and Afullo propose queueing theory, with a special case of Markovian process to clarify the existence of queues in rainfall process and characterize the rainfall cycle in Durban and Butare, Rwanda [41, 42, 43, 44, 45, 46, 47, 48]....
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...Alonge and Afullo [42, 88, 89], in their studies at Durban (subtropical), South Africa and Butare (equatorial), Rwanda, proposed the required queue parameters describing rainfall process as service, inter-arrival and overlap times, using distrometer measurements....
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...In [88],Alonge and Afullo developed transition matrices for a four regimes of rainfall rate threshold using Markovian assumptions in Durban, South Africa....
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...In their work, they established that the service time of rain spikes is Erlang-distributed given by [42, 88, 89]:...
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...Recently, the queueing theory approach has become an interesting tool to express the fundamental time-domain characteristics of rainfall rate by analyzing rain spikes as a generating queueing process [42, 88, 89]....
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TL;DR: The proposed technique is based on three Markov models for widespread, shower, and thunderstorm rain events and predicts the attenuation experienced at different periods within the duration of a user’s connection and relies on an adaptive modulation and coding (AMC) scheme to dynamically mitigate rain attenuation.
Abstract: Signals transmitted via satellite networks at high frequency in the Ka, Q, and bands are susceptible to degradation due to rain attenuation. Adaptive transmission techniques are usually employed to mitigate the effect of rain and improve users’ quality of service (QoS) but the effectiveness of these techniques hinges on the accuracy with which rain attenuation on the link is known. Commonly, most techniques rely on predicted attenuation along the link for selection of optimal transmission parameters. This paper proposes an efficient approach to predict the rain attenuation experienced by sources of multimedia connections in rain-impacted satellite networks. The proposed technique is based on three Markov models for widespread, shower, and thunderstorm rain events and predicts the attenuation experienced at different periods within the duration of a user’s connection. It relies on an adaptive modulation and coding (AMC) scheme to dynamically mitigate rain attenuation and a call admission control (CAC) policy to guarantee the satisfaction of users’ QoS requirements.
2 citations
Cites background or methods from "Queueing theory approach to rain fa..."
...Note that the derived models feature different rain intensities for a particular terrain as obtained in [11, 28]....
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...Table 2: Steady-state and transition probability matrices [28]....
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...Note that the derived models adopted in this work feature different rain intensities for a particular terrain as obtained in [28, 29]....
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...*ese values of Pij and Wi were derived frommeasured rain data in [28], but values obtained from rain data for other areas are still applicable....
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...However, recent studies on measured rainfall data in Durban, South Africa, have shown that a rain event is usually a succession of rains of different intensities which occur as a result of succession of cloud arrivals [28, 29]....
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References
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10,184 citations
TL;DR: Light scattering by small particles as mentioned in this paper, Light scattering by Small Particle Scattering (LPS), Light scattering with small particles (LSC), Light Scattering by Small Parts (LSP),
Abstract: Light scattering by small particles , Light scattering by small particles , مرکز فناوری اطلاعات و اطلاع رسانی کشاورزی
9,737 citations
01 May 1975
TL;DR: The Fundamentals of Queueing Theory, Fourth Edition as discussed by the authors provides a comprehensive overview of simple and more advanced queuing models, with a self-contained presentation of key concepts and formulae.
Abstract: Praise for the Third Edition: "This is one of the best books available. Its excellent organizational structure allows quick reference to specific models and its clear presentation . . . solidifies the understanding of the concepts being presented."IIE Transactions on Operations EngineeringThoroughly revised and expanded to reflect the latest developments in the field, Fundamentals of Queueing Theory, Fourth Edition continues to present the basic statistical principles that are necessary to analyze the probabilistic nature of queues. Rather than presenting a narrow focus on the subject, this update illustrates the wide-reaching, fundamental concepts in queueing theory and its applications to diverse areas such as computer science, engineering, business, and operations research.This update takes a numerical approach to understanding and making probable estimations relating to queues, with a comprehensive outline of simple and more advanced queueing models. Newly featured topics of the Fourth Edition include:Retrial queuesApproximations for queueing networksNumerical inversion of transformsDetermining the appropriate number of servers to balance quality and cost of serviceEach chapter provides a self-contained presentation of key concepts and formulae, allowing readers to work with each section independently, while a summary table at the end of the book outlines the types of queues that have been discussed and their results. In addition, two new appendices have been added, discussing transforms and generating functions as well as the fundamentals of differential and difference equations. New examples are now included along with problems that incorporate QtsPlus software, which is freely available via the book's related Web site.With its accessible style and wealth of real-world examples, Fundamentals of Queueing Theory, Fourth Edition is an ideal book for courses on queueing theory at the upper-undergraduate and graduate levels. It is also a valuable resource for researchers and practitioners who analyze congestion in the fields of telecommunications, transportation, aviation, and management science.
2,562 citations
TL;DR: In this paper, a three-parameter gamma distribution was used for dual-measurement techniques to determine rainfall rate, and the relationship between pairs of integral rainfall parameters using a three parameter gamma drop size distribution was investigated.
Abstract: Empirical analyses are shown to imply variation in the shape or analytical form of the raindrop size distribution consistent with that observed experimentally and predicted theoretically. These natural variations in distribution shape are demonstrated by deriving relationships between pairs of integral rainfall parameters using a three parameter gamma drop size distribution and comparing the expressions with empirical. There comparisons produce values for the size distribution parameters which display a systematic dependence of one of the parameters on another between different rainfall types as well as from moment to moment within a given rainfall type. The implications of this finding are explored in terms of the use of a three-parameter gamma distribution in dual-measurement techniques to determine rainfall rate.
1,237 citations
"Queueing theory approach to rain fa..." refers methods in this paper
...This model is suitable for rainfall DSDS at both temperate and tropical areas [Ulbrich, 1983; Bhattacharya et al., 2000; Awang and Din, 2004]....
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TL;DR: In this paper, it was shown that the equilibrium distribution of a queue is a geometric series mixed with a concentration at 0, and that for a queue of size s = 1, 2 and 3, the equilibrium is a negative-exponential distribution mixed with concentration at n = 0.
Abstract: The stochastic processes which occur in the theory of queues are in general not Markovian and special methods are required for their analysis. In many cases the problem can be greatly simplified by restricting attention to an imbedded Markov chain. In this paper some recent work on single-server queues is first reviewed from this standpoint, and the method is then applied to the analysis of the following many-server queuing-system: Input: the inter-arrival times are independently and identically distributed in an arbitrary manner. Queue-discipline: "first come, first served." Service-mechanism: a general number, $s$, of servers; negative-exponential service-times. If $Q$ is the number of people waiting at an instant just preceding the arrival of a new customer, and if $w$ is the waiting time of an arbitrary customer, then it will be shown that the equilibrium distribution of $Q$ is a geometric series mixed with a concentration at $Q = 0$ and that the equilibrium distribution of $w$ is a negative-exponential distribution mixed with a concentration at $w = 0$. (In the particular case of a single server this property of the waiting-time distribution was first discovered by W. L. Smith.) The paper concludes with detailed formulae and numerical results for the following particular cases: Numbers of servers: s = 1, 2 and 3. Types of input: (i) Poissonian and (ii) regular.
988 citations
"Queueing theory approach to rain fa..." refers background in this paper
...This process can be completely understood by a suitable queue discipline aptly embedded in a Kendall notation [Kendall, 1953; Bolch et. al, 1998]....
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