quantitative weights and aggregation based on the strong idempotency of aggregation operators quantitative weights are incorporated into the fusion process our general method is compared with some previous specific cases more details about weighted aggregation based on some penalty function is given further weighted integral based aggregation linked to quantifier based fuzzy measures is investigated especially weighted owa operators several examples are included

dynamic estimation of linear systems constrained by bounds this correspondence deals with the minimum variance estimation of a gaussian process constrained by bounds a special truncated gaussian probability is shown to be fairly well adapted to this filtering scheme as its set is linearly closed with respect to convolution and multiplication operations

a statistical basis for lognormal shadowing effects in multipath fading channels empirical justifications for the lognormal rayleigh and suzuki 1977 probability density functions in multipath fading channels are examined by quantifying the rates of convergence of the central limit theorem clt for the addition and multiplication of random variables the accuracy of modeling the distribution of rays which experience multiple reflections diffractions between transmitter and receiver as lognormal is quantified in addition it is shown that the vector sum of lognormal rays such as in a narrow band signal envelope may best be approximated as being either rayleigh lognormal or suzuki distributed depending on the fading channel conditions these conditions are defined statistically

induced weighted operators based on dissimilarity functions based on the minimization considering dissimilarity function d x y f x f y 2 induced ordered weighted averaging operators iowa and induced ordered generalized mixture operators iom g are discussed in general these operators need not be monotone non decreasing thus they need not be the aggregation operators this paper introduces conditions for their monotonicity and weak monotonicity several examples are included

another look at the performance of mrc schemes in nakagami m fading channels with arbitrary parameters in this letter we take a close look at the performance of maximal ratio combining mrc schemes operating in a flat nakagami m fading environment with arbitrary fading parameters we derive an expression for the probability density function pdf of the output signal to noise ratio snr by expressing the moment generating function of the output snr in the form of multiple barnes type contour integrals by evaluating the inverse transform and converting the multiple contour integrals into infinite series we are able to derive an expression for the pdf of the output snr when the nakagami fading parameters along the diversity branches take on real and arbitrary values consequently the average bit error rate can now be expressed in terms of lauricella s multivariate hypergeometric function which can be easily evaluated numerically special cases of the main results reduce to known results in the literature the results which apply to independent as well as correlated diversity branches will be useful for predicting the system performances when the nakagami fading parameters are real and arbitrary

target tracking problems subject to kinematic constraints filtering problems with kinematic constraints which may arise in target tracking problems are considered a novel approach which treats kinematic constraints as additional fictitious or pseudomeasurements is proposed a numerical example is provided to show the technical feasibility of the proposed idea for target tracking problems this example shows that the proposed method can improve estimation accuracy significantly for velocity and acceleration states in the tracking problem however it is noted that the tracking performance may be deteriorated if the constraints do not properly represent the target characteristics and a small r sub c is chosen

a smoothly constrained kalman filter this paper presents the smoothly constrained kalman filter sckf for nonlinear constraints a constraint is any relation that exists between the state variables constraints can be treated as perfect observations but linearization errors can prevent the estimate from converging to the true value therefore the sckf iteratively applies nonlinear constraints as nearly perfect observations or equivalently weakened constraints integration of new measurements is interlaced with these iterations which reduces linearization errors and hence improves convergence compared to other iterative methods the weakening is achieved by artificially increasing the variance of the nonlinear constraint the paper explains how to choose the weakening values and when to start and stop the iterative application of the constraint

toward a general theory of information aggregation abstract information aggregation is a pervasive issue in the field of decision making in this paper we begin an attempt to develop a comprehensive theory of this process we investigate the use of a penalty function to help guide in the aggregation process it is suggested that an aggregated value which violates a given piece of data is charged a penalty the problem of aggregation can be seen as finding the aggregated value with the least penalty we show that logical inference systems are characterized by infinite penalty functions this implies that deviation from the data are not easily accepted probability theory is characterized by equal finite penalty costs nonmonotonic logics appear to be characterized by a case in which we have at least two different levels of penalties of differing magnitudes we discuss the relationship between the relevance or bearing a piece of data has on the problem and the penalty cost associated with it we see the central role of the intersection operation

ber performance of dqpsk in nakagami fading with selection diversity and maximal ratio combining a new expression for the average bit error rate ber of differential quadrature phase shift keying in slow frequency nonselective nakagami fading is derived for a space diversity receiver having a cascade arrangement of l groups of m branch selection combiners and an l branch maximal ratio combiner mrc this allows the use of a large number of antennas for performance improvement and a small number of m inputs to the combiners for low complexity the average ber performance of the cascade receiver is investigated for different fading severity conditions characterized by the nakagami m factor and compared with the conventional mrc receiver as the fading gets less severe m increases performance improvement over the conventional mrc scheme is only noticeable for the larger range of average signal to noise ratio

backscatter communications over correlated nakagami m fading channels in this paper we consider a radio frequency identification rfid backscatter system with two scenarios single input multiple output simo and multiple input single output miso we investigate the impact of channel correlation between the forward and backscatter links on the symbol error rate ser and we compare the performance of simo and miso rfid systems with maximum ratio combining reception over arbitrarily correlated nakagami m fading channels in order to gain an insight for the system design closed form expressions for the asymptotic ser and an upper bound are derived for m ary phase shift keying and quadrature amplitude modulation the diversity order in the fully correlated cases revealed from these expressions is half of that in the partially correlated and uncorrelated cases finally simulations are performed to validate the theoretical analysis

gaussian class multivariate weibull distributions theory and applications in fading channels ascertaining on the suitability of the weibull distribution to model fading channels a theoretical framework for a class of multivariate weibull distributions originated from gaussian random processes is introduced and analyzed novel analytical expressions for the joint probability density function pdf moment generating function mgf and cumulative distribution function cdf are derived for the bivariate distribution of this class with not necessarily identical fading parameters and average powers two specific distributions with arbitrary number of correlated variates are considered and studied with exponential and with constant correlation where their pdfs are introduced both cases assume equal average fading powers but not necessarily identical fading parameters for the multivariate weibull distribution with exponential correlation useful corresponding formulas as for the bivariate case are derived the presented theoretical results are applied to analyze the performance of several diversity receivers employed with selection equal gain and maximal ratio combining mrc techniques operating over correlated weibull fading channels for these diversity receivers several useful performance criteria such as the moments of the output signal to noise ratio snr including average output snr and amount of fading and outage probability are analytically derived moreover the average symbol error probability for several coherent and noncoherent modulation schemes is studied using the mgf approach the proposed mathematical analysis is complemented by various evaluation results showing the effects of the fading severity as well as the fading correlation on the diversity receivers performance

exact analysis of postdetection combining for dpsk and nfsk systems over arbitrarily correlated nakagami channels postdetection combining is a popular means to improve the bit error performance of dpsk and noncoherent fsk nfsk systems over fading channels nevertheless the error performance of such systems in an arbitrarily correlated nakagami environment is not available in the literature the difficulty arises from inherent nonlinearity in noncoherent detection and from attempts to determine explicitly the probability density function of the total signal to noise ratio at the combiner output we directly determine the error probability from the characteristic function of decision variables resulting in closed form solutions involving matrix differentiation the performance calculation is further simplified by developing a recursive technique the theory is illustrated by analyzing two feasible antenna arrays used in base stations for diversity reception ending up with some findings of interest to system design

aggregation functions based on penalties this article studies a large class of averaging aggregation functions based on minimizing a distance from the vector of inputs or equivalently minimizing a penalty imposed for deviations of individual inputs from the aggregated value we provide a systematization of various types of penalty based aggregation functions and show how many special cases arise as the result we show how new aggregation functions can be constructed either analytically or numerically and provide many examples we establish connection with the maximum likelihood principle and present tools for averaging experimental noisy data with distinct noise distributions

lever aggregation operators we make use of the physical concept of lever to generalize well known operators based on weights all these operators can be understood as levers in equilibrium with weights masses located at the points in 0 1 that opinions represent

microdiversity reception of spread spectrum signals on nakagami fading channels an analytical framework to evaluate the performance of different predetection diversity techniques in various mobile radio environments is developed the average bit error rate analysis applies to phase coded spread spectrum systems over nakagami multipath fading channels a simple and practical selection combining rule is considered our numerical results reveal that this new low complexity receiver structure exhibits comparable performance to that of an optimum linear diversity combiner when the channel does not experience severe fading and for small diversity orders conditioned on the situation that all the diversity branches have identical mean signal strengths in this study we also investigate the effect of variations in the mean signal and noise power levels on each of the independent diversity branches this is an important consideration because in practice equal mean signal strengths rarely occur which results in loss of diversity gain we found that the signal plus noise and interference selection model outperforms the traditional signal to interference plus noise ratio selection scheme if the discrepancy between the mean signal strengths are small owing to the statistical nature of the multiple access interference

constrained signal restoration via iterated extended kalman filtering the problem of estimating the input signal restoration to a known linear system point spread function given the noisy observations of the output is considered the input signal is assumed to satisfy certain known physical constraints such as positivity it is proposed to incorporate the constraints by introducing a memoryless non linearity in the system a statistical approach is taken leading to a closed form type of recursive solution in the form of iterated extended kalman filtering with two local iterations at every new data point a simulation example is presented which demonstrates the superiority of the proposed approach over the conventional kalman wiener filtering

simple closed form asymptotic symbol error rate of selection combining and its power loss compared to the maximal ratio combining over nakagami m fading channels this paper derives closed form asymptotic symbol error rates asers for mpsk and mqam signals with selection combining sc over nakagami m fading channels it also presents a closed form expression for the power loss of sc compared to maximal ratio combining mrc over a nakagami m fading channel it is found that this power gap is a function of only the number l of independent nakagami m channels and the fading parameter m for a fixed m the gap monotonically increases with l for a fixed l the gap monotonically increases with m and approaches 10 log10 l db the asymptotic gap between mrc and sc in an awgn channel as m in addition numerical results show the accuracy of the asers obtained from closed form expressions for both mrc and sc with mpsk and mqam signals for large snrs they also show that the snr gap is identical to that predicted by the analysis for arbitrary l and m

h transforms for wireless communication the h transforms are integral transforms that involve fox s h functions as kernels a large variety of integral transforms can be put into particular forms of the h transform since h functions subsume most of the known special functions including meijer s g functions in this paper we embody the h transform theory into a unifying framework for modeling and analysis in wireless communication first we systematize the use of elementary identities and properties of the h transform by introducing operations on parameter sequences of h functions we then put forth h fading and degree 2 irregular h fading to model radio propagation under composite specular and or inhomogeneous conditions the h fading describes composite effects of multipath fading and shadowing as a single h variate including most of typical models such as rayleigh nakagami m weibull alpha mu n ast nakagami m generalized k fading and weibull gamma fading as its special cases as a new class of h variates called the degree zeta irregular h variate the degree 2 irregular h fading characterizes specular and or inhomogeneous radio propagation in which the multipath component consists of a strong specularly reflected or line of sight los wave as well as unequal power or correlated in phase and quadrature scattered waves this fading includes a variety of typical models such as rician nakagami q kappa mu eta mu rician los gamma and kappa mu los gamma fading as its special cases finally we develop a unifying h transform analysis for the amount of fading error probability channel capacity and error exponent in wireless communication using the new systematic language of transcendental h functions by virtue of two essential operations called mellin and convolution operations involved in the mellin transform and mellin convolution of two h functions the h transforms for these performance measures culminate in h functions using the algebraic asymptotic expansions of the h transform we further analyze the error probability and capacity at high and low signal to noise ratios in a unified fashion

on the definition of penalty functions in data aggregation abstract in this paper we point out several problems in the different definitions and related results of penalty functions found in the literature then we propose a new standard definition of penalty functions that overcomes such problems some results related to averaging aggregation functions in terms of penalty functions are presented as the characterization of averaging aggregation functions based on penalty functions some examples are shown as the penalty functions based on spread measures which happen to be continuous we also discuss the definition of quasi penalty functions in order to deal with non monotonic or weakly directionally monotonic averaging functions

applying hankel s expansion for performance analysis in double nakagami generalized k fading channels the double scattering fading models have found applications in many transmission scenarios in this paper approximate probability density functions pdfs are proposed for double nakagami fading and gamma gamma fading based on hankel s expansion of the modified bessel function of the second kind the proposed pdf is not only consistent with the exact pdf when the difference between the two shape parameters is equal to an integer plus one half but also accurately approximates the distribution when the shape parameters are both greater than or equal to 2 the proposed approximate pdf has been compared with the power series expansion and the mixture gamma model it is found that the proposed pdf is in simple form and no parameters need to be tabulated moreover the proposed pdf does not require an increasing number of terms to maintain precision with increasing diversity order of the reception scheme closed form outage probability ergodic capacity and symbol error rate expressions have been derived using the proposed approximate pdfs for equal gain combining selection combining and two stage reception schemes the proposed approximations are also leveraged for performance analysis of space time block codes and free space optical links the precision of the proposed approximations is validated by comparing with the simulation results

on the second order statistics of the multihop rayleigh fading channel second order statistics provides a dynamic representation of a fading channel and plays an important role in the evaluation and design of the wireless communication systems in this paper we present a novel analytical framework for the evaluation of important second order statistical parameters as the level crossing rate lcr and the average fade duration afd of the amplify and forward multihop rayleigh fading channel more specifically motivated by the fact that this channel is a cascaded one and can be modeled as the product of n fading amplitudes we derive novel analytical expressions for the average lcr and the afd of the product of n rayleigh fading envelopes or of the recently so called nrayleigh channel furthermore we derive simple and efficient closed form approximations to the aforementioned parameters using the multivariate laplace approximation theorem it is shown that our general results reduce to the corresponding ones of the specific dual hop case previously published numerical and computer simulation examples verify the accuracy of the presented mathematical analysis and show the tightness of the proposed approximations

product of two envelopes taken from alpha mu kappa mu and eta mu distributions 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

generalized mixture operators using weighting functions a comparative study with wa and owa abstract in the context of multiple attribute decision making we present an aggregation scheme based on generalized mixture operators using weighting functions and we compare it with two standard aggregation methods weighted averaging and ordered weighted averaging specifically we consider linear and quadratic weight generating functions that penalize bad attribute performances and reward good attribute performances an illustrative example borrowed from the literature is used to perform the operators comparison we believe that this comparative study will highlight the potential and flexibility of generalized mixture operators using weighting functions that depend on attribute performances

noncoherent diversity reception over nakagami fading channels a method for computing the average bit error probability of binary differential phase shift keying dpsk and frequency shift keying fsk signals transmitted over nakagami asymptotically slow fading channels with postdetection diversity reception is presented to extend previously published results the previously published results apply only for maximum ratio combining i e with predetection combining where phase coherency is necessary the results for postdetection combining are derived with the explicit expressions for the most practical cases of independent channels and particular cases of correlated channels

n ast nakagami a novel stochastic model for cascaded fading channels a generic and novel distribution referred to as nakagami constructed as the product of n statistically independent but not necessarily identically distributed nakagami m random variables rvs is introduced and analyzed the proposed distribution turns out to be a very convenient tool for modelling cascaded nakagami m fading channels and analyzing the performance of digital communications systems operating over such channels the moments generating probability density cumulative distribution and moments functions of the n nakagami distribution are developed in closed form using the meijer s g function using these formulas generic closed form expressions for the outage probability amount of fading and average error probabilities for several binary and multilevel modulation signals of digital communication systems operating over the n nakagami fading and the additive white gaussian noise channel are presented complementary numerical and computer simulation performance evaluation results verify the correctness of the proposed formulation the suitability of the n nakagami fading distribution to approximate the lognormal distribution is also being investigated using kolmogorov smirnov tests the rate of convergence of the central limit theorem as pertaining to the multiplication of nakagami m rvs is quantified

deviation based aggregation functions abstract based on the original idea of daroczy deviation functions expressing the deviation of two real values x and y are generalized into basic moderate deviation functions subsequently a new type of deviation based aggregation function is introduced studied and exemplified our approach generalizes among others several types of mixture operators and can be seen as an alternative to penalty based constructions of aggregation functions

constrained state estimation for nonlinear discrete time systems stability and moving horizon approximations state estimator design for a nonlinear discrete time system is a challenging problem further complicated when additional physical insight is available in the form of inequality constraints on the state variables and disturbances one strategy for constrained state estimation is to employ online optimization using a moving horizon approximation we propose a general theory for constrained moving horizon estimation sufficient conditions for asymptotic and bounded stability are established we apply these results to develop a practical algorithm for constrained linear and nonlinear state estimation examples are used to illustrate the benefits of constrained state estimation our framework is deterministic

performance of mrc diversity systems for the detection of signals with nakagami fading bit error rate ber is analyzed theoretically for diversity reception in nakagami fading environment using an m branch maximal ratio combiner mrc coherent and incoherent reception of frequency shift keying fsk are considered using the multiple branch diversity system for both identical and different diversity branch fading parameters the effect of correlation is also considered for the dual diversity case the results are extended to include coherent phase shift keying cpsk and differential phase shift keying dpsk

minimum variance estimation of parameters constrained by bounds this correspondence deals with an extension of minimum variance estimation when the parameter to be estimated is constrained by bounds it is shown that a particular initial distribution allows finite dimensional calculation and leads to a nonlinear filter more precisely it is shown that a truncated gaussian distribution is preserved a long time leading to a finite number of parameters to be computed proof of the main theorem is straightforward with significant application such as positive real amplitude estimation performance gains are shown on the loran c signal reception example

statistical analysis and characterization of the indoor propagation channel this paper presents statistical analysis of data obtained by measuring narrowband path loss at dect digital enhanced cordless telecommunications frequency 1 89 ghz in an indoor environment specific goodness of fit tests are applied to the data the tests assess whether the data generating source belongs to a known family of random variables results obtained support that local path loss distribution can be represented as weibull or nakagami in most environments the close resemblance between such distributions and rice distribution with rayleigh as a special case confirms that rice rayleigh description of fading can be applied to indoor environments that similarity leads to a general simple approximate expression for the cumulative distribution function of the signal to interference ratio the expression can be used without limitations to the number and the parameters of the rice interferers

aggregation with generalized mixture operators using weighting functions this paper regards weighted aggregation operators in multiple attribute decision making and its main goal is to investigate ways in which weights can depend on the satisfaction degrees of the various attributes criteria we propose and discuss two types of weighting functions that penalize poorly satisfied attributes and reward well satisfied attributes we discuss in detail the characteristics and properties of both functions moreover we present an illustrative example to clarify the use and behaviour of such weighting functions comparing the results with those of standard weighted averaging operators

closed form statistics for the sum of squared nakagami m variates and its applications we present closed form expressions for the probability density function pdf and the cumulative distribution function cdf of the sum of non identical squared nakagami m random variables rvs with integer order fading parameters as it is shown they can be written as a weighted sum of erlang pdfs and cdfs respectively while the analysis includes both independent and correlated sums of rvs the proposed formulation significantly improves previously published results which are either in the form of infinite sums or higher order derivatives of the fading parameter m the obtained formulas can be applied to the performance analysis of diversity combining receivers operating over nakagami m fading channels

bounds for multihop relayed communications in nakagami m fading we present closed form lower bounds for the performance of multihop transmissions with nonregenerative relays over not necessarily identically distributed nakagami m fading channels the end to end signal to noise ratio is formulated and upper bounded by using an inequality between harmonic and geometric means of positive random variables rvs novel closed form expressions are derived for the moment generating function the probability density function and the cumulative distribution function of the product of rational powers of statistically independent gamma rvs these statistical results are then applied to studying the outage probability and the average bit error probability for phase and frequency modulated signaling numerical examples compare analytical and simulation results verifying the tightness of the proposed bounds

sum and difference of two squared correlated nakagami variates in connection with the mckay distribution general formulas for the probability density function of the sum and the difference of two correlated not necessarily identically distributed squared nakagami variates or equivalently gamma variates are derived these expressions are shown to be in the form of the mckay bessel function distributions in addition formulas for the moments of these distributions in terms of the gauss hypergeometric function are provided an application of these new results relevant to the calculation of outage probability in the presence of self interference is discussed