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This paper presents exact, novel formulations for the probability density function and cumulative distribution function for the product of two independent and non-identically distributed $\alpha $ - $\mu $ , $\kappa $ - $\mu $ , and $\eta $ - $\mu $ variates. The expressions are given in terms of both 1) generalized Fox H-function and 2) easily computable series expansions. The formulations derived can be directly used to explore the performance of a number of wireless communication processes, including multihop systems, cascaded channels, radar communications, multiple-input multiple-output links, and others. Due to the high flexibility of the above-mentioned distributions, the results presented here comprise a substantial number of useful product distributions. As application examples, performance metrics for the cascaded fading channel are derived. The validity of the expressions is confirmed via Monte Carlo simulation. It is noteworthy that, because any composite multipath-shadowing fading model is obtained as a particular case of the product of two fading variables, the results given here provide a plethora of composite multipath-shadowing fading scenarios. [ABSTRACT FROM PUBLISHER]

A fading model—the $\alpha $ - $\eta $ - $\kappa $ - $\mu $ model—is proposed that accounts for virtually all relevant short-term propagation phenomena described in the literature. These phenomena include nonlinearity of the medium, power of the scattered waves, power of the dominant components, and number of multipath clusters. They are mapped onto physical parameters, and apart from the first one, which is assumed to influence only the resulting signal envelope, the others affect independently its in-phase and quadrature components. Imbalance parameters are then introduced so as to better assess the impact of these phenomena on the entire process. The signal is described by means of its envelope and phase probability density functions (pdfs). To this end, complex-based and envelope-based models are proposed and explored. An exact joint envelope-phase pdf is found in the closed form. The marginal statistics in these cases remain in the integral forms. Interestingly, the envelope density function obtained through the envelope-based model is found to compute more efficiently than that obtained through the complex model. In addition, capitalizing on the results in the literature, exact series-expansion formulations are found for the envelope pdf as well as for the envelope cumulative distribution function. To the best of the author’s knowledge, this is probably the most general and unifying, physically based, complex fading model proposed in the literature. Because of its comprehensiveness, a number of issues remain open and constitute a fertile field for investigation. [ABSTRACT FROM PUBLISHER]

Blocking probability is widely used as a performance measure for dimensioning a variety of networks, including wireless communication systems. However, the performance of the system may be affected by factors other than traffic and resources, i.e., the primary ingredients in blocking. Such factors include interference, energy consumption, service delay restriction, and others. In this case, blocking by itself does not fully convey the extent of the system quality of service (QoS). Those other phenomena may lead the system to experience an outage, in which case resources, even if available, cannot be used because of the performance degradation that this may incur. In this paper, we propose a performance measure, i.e., BlockOut probability, that combines blocking and outage in one parameter. Exact, closed-form, and recursive forms of this parameter are presented, and a simple example of application is shown. The BlockOut probability encompasses the well-known Erlang-B formula as a special case. Although the application example focuses on wireless systems, BlockOut may find use in a variety of other networks. [ABSTRACT FROM PUBLISHER]

Correlation among channels is a physical phenomenon that affects the performance of a wireless communication system and that cannot be neglected in a myriad of realistic fading scenarios. Providing computable mathematical means to better characterize the corresponding statistics is certainly of interest to any design engineer. In this context, this paper further extends the statistical correlation investigations of the \alpha–\mu fading model, presenting a new, exact, and easily computable series-type formulation for the multivariate \alpha–\mu joint cumulative distribution function (JCDF). Along with this general result and capitalizing on practical assumptions, an alternative, simpler formulation for the \alpha–\mu multivariate joint density function and its corresponding distribution function are also provided. These formulations are still general and yet compact, assuming arbitrary fading parameters and correlations among the marginal variates. An important feature of the series-type distribution is that any truncation version of it is a valid distribution. As an application example, the truncated series-based outage probability of the selection combining scheme is computed and compared with that obtained by means of numerical methods and simulations. The results show that a small number of terms of the series are sufficient to provide excellent agreement between approximate and exact results. [ABSTRACT FROM PUBLISHER]

The aim of this paper is to propose an improvement on the Nakagami-mcomplex signal model presented elsewhere in the literature. By introducing what here is named a phase parameter, a more general and realistic framework is obtained. However, with an additional parameter, the formulations are still found in simple and closed-form expressions. With another physically based consideration, which, incidentally, further simplifies the formulations, the phase parameter is written as a function of the fading parameter, and the expressions are found in an even more compact manner. With the proposed fading model, higher order statistics are then derived, particularly those related to the phase crossing rate. [ABSTRACT FROM AUTHOR]

This paper derives an exact closed-form expression for the phase-envelope joint distribution of the κ-μ fading environment, a general fading model that includes the Rice and the Nakagami-m models as special cases. The derived joint statistics are obtained so that compatibility with both Rice as well as Nakagami-m cases are kept. Monte Carlo simulation plots are presented that are in accordance with the formulations developed here. As a consequence of the derivation of the required PDF, an interesting solution to a very general probability problem is proposed, namely, given the PDF of the modulus of a variate, find the PDF of the variate. Additionally, several new integral relations of the modified Bessel function are given. [ABSTRACT FROM AUTHOR]

We derive important second-order statistics-joint distribution of the envelope and its time derivative, second-order distribution, autocorrelation, level crossing rate, and average fade duration-of an existing Nakagami fading simulator, and show that these statistics but the autocorrelation differ considerably from the well-established statistics of the classical simulator. [ABSTRACT FROM AUTHOR]

The aim of this Letter is twofold: to propose a simulator for both the phase and the envelope of Nakagami fading channels with arbitrary parameters and to derive precise closed-form approximations to the correlation functions of the Nakagami envelope, phase, and quadrature components. [ABSTRACT FROM AUTHOR]

Abstract-We propose a novel method for generating random sequences matching both a target non-Gaussian distribution and a target autocorrelation. In the proposed scheme, samples matching the target distribution are drawn independently and then suitably rearranged to match the target autocorrelation. Our method overcomes the difficulties of the standard method in generating sequences with unknown inverse distribution. Many examples are included. [ABSTRACT FROM AUTHOR]

In this paper, exact expressions for the level crossing rate (LCR) and average fade duration (AFD) for two-branch selection, equal-gain and maximal-ratio combining systems in a Hoyt fading environment are presented. The expressions apply to unbalanced, non-identical, correlated diversity channels and have been validated by specializing the general results to some particular cases whose solutions are known. In passing, the joint bidimensional envelope-phase Hoyt distribution with arbitrary fading parameters is obtained. [ABSTRACT FROM AUTHOR]

This paper derives general exact expressions for the level crossing rate (ICR) and the average fade duration (AFD) of dual-branch selection, equal-gain, and maximal-ratio combiners operating over non- identical correlated Weibull fading channels. Sample numerical results are discussed by specializing the general expressions to a space-diversity system using horizontally spaced antennas at a mobile station. It is verified that as the antenna spacing becomes larger, the LCR decreases, becoming oscillatory and convergent. In addition, when the direction of the mobile is perpendicular to the axis of the antenna, the AFD is loosely dependent on the antenna spacing. Some simulation results are presented to verify the correctness of the analytical formulation. [ABSTRACT FROM AUTHOR]

In this paper, an extensive and detailed investigation of the joint statistics of two narrowband signals with space-frequency separation in a Ricean fading channel is carried out. All the analysis and its results include nonstationary environments, where the parameters of the bivariate Ricean model differ from one signal to the other. A general treatment of the angles of arrival of the multipath propagation waves is also performed. A comprehensive expression for the space-frequency correlation coefficient of arbitrary orders of the envelopes is provided. Some insightful plots of this coefficient are presented and examined. The coherence distance (or time) and the coherence bandwidth are obtained and analyzed. [ABSTRACT FROM AUTHOR]

This paper introduces a fading model, which explores the nonlinearity of the propagation medium. It derives the corresponding fading distribution—the α-μ distribution-which is in fact a rewritten form of the Stacy (generalized Gamma) distribution. This distribution includes several others such as Gamma (and its discrete versions Erlang and central Chi-squared), Nakagami-m (and its discrete version Chi), exponential, Weibull, one-sided Gaussian, and Rayleigh. Based on the fading model proposed here, higher order statistics are obtained in closed-form formulas. More specifically, level-crossing rate, average fade duration, and joint statistics (joint probability density function, general joint moments, and general correlation coefficient) of correlated α-μ variates are obtained, and they are directly related to the physical fading parameters. [ABSTRACT FROM AUTHOR]

This paper specializes and parameterizes the general result presented elsewhere in the literature in order to introduce, fully characterize, and investigate the Symmetrical n - k Distribution, a general distribution used to describe the statistical variation of the envelope in a fast fading environment. It proposes estimators for the involved parameters and uses field measurements to validate the distribution. In spite of its specialization, the Symmetrical n - k. Distribution still includes, as special cases, important distributions such as Rayleigh, Rice, Hoyt, Nakagami-q, and One-Sided Gaussian. The fact that the Symmetrical n - k Distribution has one more parameter than the well-known distributions renders it more flexible. Of course, in situations in which those distributions included in it give good results a better fitting is given by the Symmetrical n - k Distribution. In addition, in many other situations in which these distributions give poor results a good fitting may be found through the Symmetrical n - k. Distribution. More specifically, its nonmonomodal feature finds applications in several circumstances, examples of which are given in this paper. [ABSTRACT FROM AUTHOR]

The article focuses on the wireless communication services in Brazil. It was 1990 when the wireless experience in the country started. Cellular services were first deployed in Rio de Janeiro and Brasília. The national regulator of telecommunications services in the country is the agency, called the National Telecommunications Agency. Also noted is the official document of the Brazilian Ministry of Communications describing the Upgrading and Expansion Program for the Postal and Telecommunications System (PASTE), published in 1995.

This paper develops an exact and general formulation in order to investigate the performance of equal gain, selection/equal gain, and selection/maximal ratio combining techniques. The performance is examined in terms of both the reliability and mean signal-to-noise ratio at the combiner output. Although the solution presented here considers the Nakagami fading environment, the formulation is general and can be easily applied to any other fading channel [ABSTRACT FROM PUBLISHER]

Presents exact and closed-form expressions for the level crossing rate and average fade duration for the M branch pure selection combining, equal gain combining and maximal ratio combining techniques in a Nakagami environment. Level crossing rate; Average fade duration; Results and discussion.

A number of new results aiming at facilitating the use of the $\alpha $ - $\eta $ - $\kappa $ - $\mu $ fading model are presented. These results include: 1) fast convergent, with no recursions, series representations for the envelope probability density function (PDF) and cumulative distribution function (CDF); 2) higher order moments of the envelope; 3) moment generating function (MGF) of the envelope; 4) asymptotic behavior of the envelope PDF and also of the envelope CDF; 5) a procedure for parameter estimation; 6) new closed-form expressions for particular cases of the envelope distribution; 7) new mathematical identity for the generalized Laguerre polynomial and the generalized hypergeometric function; and 8) approximate, but tight, series representation for the phase PDF. As application examples, the following are given: 1) outage probability; 2) outage capacity; 3) amount of fading; and 4) bit error rate, for which the asymptotic behavior is also presented. [ABSTRACT FROM AUTHOR]

Describes the popularity of wireless communications in Brazil as of May 2002. History of the wireless communications in the country; Factor which led to the provision of personal communication services by telecommunication operators; Ideal number of frequency bands for Brazil; Statistics on cellular users in the country.

Deals with the privatization and deregulation of telephony in Brazil. Causes of the deregulation of emerging economies; Issue on the privatization of telephony; Principles of the telecommunications policy in Brazil.

New, exact expressions for the probability density and distribution functions of a bivariate Hoyt (Nakagami-q) process with arbitrary correlation pattern in a nonstationary environment are derived, a solution to a longstanding unsolved problem. More specifically, the following are obtained: joint probability density function, joint cumulative distribution function, power and envelope correlation coefficients, and some statistics related to the signal-to-noise ratio at the output of the selection combiner, namely, outage probability and probability density function. The exact expressions are given in infinite series form, but are mathematically tractable, easy to evaluate, and flexible enough to accommodate a myriad of correlation scenarios, useful in the analysis of a more general fading environment. The power correlation coefficient is found in an exact, simple, closed-form formula, whereas the envelope one, also exact, is more mathematically elaborate. Approximate, simple closed-form expressions for the joint distribution are also obtained that yield (i) excellent results for small to medium correlation coefficients and (ii) reasonable ones for high correlation coefficient. [ABSTRACT FROM AUTHOR]

A number of realistic wireless applications can be found for which the propagated signal may experience extreme fading conditions. In particular, a recent work has reported on an experiment conducted within an enclosed environment where it has been shown that the fading conditions are indeed harsh, drastically departing from those predicted by traditional fading models. This paper investigates the κ-μ Extreme fading distribution, a member of the κ-μ fading model and obtained from it when its parameters reach their extreme values (κ → ∞ and μ ∞ 0) for a fixed amount of fading. Field data reported elsewhere and collected in enclosed environment, along with other fading data collected by the authors' team, are used to compare the curve fit performance of the κ-μ Extreme model and the recently proposed Two-Ray distribution. The results show that the κ-μ Extreme distribution is flexible and suitable to model these scenarios. The performance of this new model is then explored in the three basic combining techniques, namely selection, maximum ratio, and equal gain, and a number of exact, closed-form formulas are obtained. Interestingly, it is shown that in extreme fading conditions, the selection combiner may outperform the equal gain combiner. [ABSTRACT FROM AUTHOR]

The performance of dual-hop amplify-and-forward (AF) two-way relaying systems with multiple cochannel interferers at the AF relay and two noisy end-sources is investigated. Assuming a Nakagami- m fading environment, closed-form approximate expressions for the outage probability, average error probability, and achievable sum rate are derived, yielding results which, in practice, are indistinguishable from the exact analysis. In addition, the derived approximate expressions are evaluated instantaneously, regardless of the number of interferers, highly contrasting with the intricacy and computational inefficiency inherent to the exact formulations, which requires the evaluation of nested multiple integrals, i.e., a problem that becomes computationally intractable as the number of interferers increases. Our analysis allows for general operating scenarios with distinct integer-value Nakagami-m fading parameters and unequal average fading power values between the hops. Monte Carlo simulation results are presented to corroborate the tightness of the proposed approximations. [ABSTRACT FROM PUBLISHER]

This correspondence focuses on the analysis of average symbol error rate (ASER) of $M$ -ary phase-shift keying (MPSK) over $\boldsymbol {\kappa }$ - $\boldsymbol {\mu }$ , $ \boldsymbol {\eta }$ - $ \boldsymbol {\mu }$ , and $\boldsymbol {\alpha }$ - $\boldsymbol {\mu }$ fading channels subject to imperfect carrier phase recovery. The random phase noise is considered to be Tikhonov (or von Mises) distributed. Specifically, exact expressions for the ASER i) under non-fading scenario, ii) under $\boldsymbol {\kappa }$ - $\boldsymbol {\mu }$ , iii) $ \boldsymbol {\eta }$ - $ \boldsymbol {\mu }$ , and iv) $\boldsymbol {\alpha }$ - $\boldsymbol {\mu }$ fading channels, as well as v) their corresponding asymptotic behavior for high signal-to-noise ratio, (SNR) values are analytically obtained and evaluated. The derived expressions support arbitrary values of the fading parameters, namely $\boldsymbol {\alpha }$ , $ \boldsymbol {\kappa }$ , $\boldsymbol {\eta }$ and $ \boldsymbol {\mu }$ , and they are validated by reducing them to particular cases, for which results are available in the literature, and by means of simulations. Several important conclusions concerning the system performance as a function of the channel parameters and loop SNR are drawn. [ABSTRACT FROM AUTHOR]

A thorough millimeter-wave measurement campaign is carried out in an indoor environment with an aim at characterizing the short-term fading channel behavior. The measurements are conducted in a variety of scenarios, with frequencies ranging from 55 GHz to 65 GHz, in line-of-sight and non-line-of-sight conditions, and combinations of horizontal and vertical polarizations at both transmitter and receiver. A number of fading models are tested, namely Rayleigh, Rice, Nakagami- ${m}$ , ${\alpha }$ - ${\mu }$ , ${\kappa }$ - ${\mu }$ , ${\eta }$ - ${\mu }$ , and ${\alpha }$ - ${\eta }$ - ${\kappa }$ - ${\mu }$. The statistics under analysis are those characterizing the fading amplitude and the frequency selectivity. In particular, the probability density and cumulative distribution functions for the former and level crossing rate per bandwidth unit for the latter are the respective first- and second-order statistics used. To this end, from the experimental data, the parameters of the models are estimated and the corresponding theoretical curves are plotted and compared with the empirical ones. Whereas the required theoretical formulations of the first-order statistics of these models are already well known, those of the second-order statistics as well as these fitting process in such a band shown here are unprecedented in the literature. [ABSTRACT FROM AUTHOR]

The Internet of Things has dramatically expanded its scope of applications in the last few years, reaching all areas of human activities, from biology to technology to social sciences. In the same way, IoT applications are becoming a driving force in the economy, playing a central role in many businesses. This scenario presents challenges in the teaching and designing of IoT applications due to its inherent multidisciplinary nature, with areas of knowledge ranging from electrical and computing engineering to those related to the target application to the business itself. In this article, we present a teaching methodology that relies on the project-based learning approach and makes use of a six-layer IoT Open Reference Model that covers all aspects of an IoT solution, from sensors to the end-user interface. The proposed methodology focuses on a complete understanding of the business behind the application and on the end-user needs. Following a top-down approach, from the business to the devices required to collect the necessary information, the approach allows students to have a complete view of all components involved in any IoT application. The proposed methodology has been applied in graduate and extension courses at the University of Campinas and has proven extremely useful. [ABSTRACT FROM AUTHOR]

The aim of this paper is twofold: 1) to show that the newly proposed ${\alpha } - {\eta } - {\kappa } - {\mu }$ complex fading model provides the best fit for the envelope of a signal propagated in a millimeter wave in a given scenario and 2) to further improve the knowledge of this fading model through the derivation of some of its higher order statistics. The fitting process is carried out based on some field measurements campaigns conducted by independent research groups at the 28 GHz band as well as at the 60 GHz band available elsewhere in the literature. The higher order statistics concern the time derivative of the whole ${\alpha } - {\eta } - {\kappa } - {\mu }$ process with a view at obtaining important metrics, such as level crossing rate, average fade duration, and phase crossing rate. An extensive number of exact formulations for the corresponding statistics are derived. Through a small sample of plots, the flexibility provided by the physically based model becomes evident, showing its potential to be used in a variety of propagation scenarios. [ABSTRACT FROM AUTHOR]

We here introduce an extension and natural generalization of both the $\kappa$-$\mu$ shadowed and the classical Beckmann fading models: the Fluctuating Beckmann (FB) fading model. This new model considers the clustering of multipath waves on which the line-of-sight (LoS) components randomly fluctuate, together with the effect of in-phase/quadrature power imbalance in the LoS and non-LoS components. Thus, it unifies a variety of important fading distributions as the one-sided Gaussian, Rayleigh, Nakagami- $m$, Rician, $\kappa$ -$\mu$, $\eta$- $\mu$, $\eta$ -$\kappa$, Beckmann, Rician shadowed, and the $\kappa$- $\mu$ shadowed distribution. The chief probability functions of the FB fading model, namely probability density function, cumulative distribution function, and moment generating function are derived. The second-order statistics such as the level crossing rate and the average fade duration are also analyzed. These results can be used to derive some performance metrics of interest of wireless communication systems operating over FB fading channels [ABSTRACT FROM PUBLISHER]

In this paper, a bivariate \kappa- \mu model is presented. Exact expressions for the 1) joint probability density function, the 2) joint cumulative distribution function, 3) joint arbitrary moments, and the 4) normalized envelope correlation coefficient are derived. The joint statistics are given in terms of their respective parameters (\kappa1,\mu1) and (\kappa2,\mu2), with \mu1=\mu2=\mu>\mbox{0} and arbitrary \kappa1>\mbox{0} and \kappa2>\mbox{0}. The parameter describing the correlation between $\kappa$- $\mu$ fading channels is then written in terms of the physical instances known to affect it in a wireless medium, namely, Doppler shift, the separation distance between two reception points, frequency, and delay spread. As an application example, the outage probability of a dual-branch selection-combining scheme is presented. The effect of correlation in the various aspects of system performance is then investigated. The validity of the analytical results is supported by reducing them to particular cases, for which results are available in the literature, and by means of simulation for the general cases. [ABSTRACT FROM AUTHOR]

This paper derives a general analytical expression for the correlation coefficient of signals received by two identical spaced antennas in a radar system used to detect meteorological phenomena such as rain and clouds. Such a correlation coefficient is found as a function of the relevant physical parameters, namely, distance between antennas (baseline distance), signal bandwidth, and antenna directivity. One of the antennas transmits the signal and receives its echoes from the scatterers, characterizing a monostatic radar, whereas the other antenna only receives these echoes, characterizing a bistatic radar. Our approach can be easily extended to nonidentical antennas. [ABSTRACT FROM PUBLISHER]