K-distribution

About: K-distribution is a research topic. Over the lifetime, 1281 publications have been published within this topic receiving 51774 citations.

On the performance analysis of energy detection of unknown signals in Gamma shadowed Ricean fading environments

Abstract: In this paper, we analyze the performance of an energy detector operating over Gamma shadowed Rice fading channels, namely Rice fading channels with the fluctuating line-of-sight components following the Gamma distribution. This composite multi-path/shadowing model has been shown to provide remarkably accurate fading characterization while leading to closed-form expressions for important channel statistics. For the considered system, we first derive analytical expressions for the average probability of detection, using either the probability density function method or the moments generating function method. The application of the former method, yields a rapidly convergent infinite series representation for the average probability of detection. The latter method is based on a contour integral representation for the Marcum Q-function. Finally, an infinite series representation for the area under the receiver operating characteristic curve is derived. Extensive numerically evaluated results, accompanied with Monte-Carlo simulations, are presented to corroborate the proposed analysis, for composite multi-path/shadowing scenarios of practical interest.

On the Sum of Kappa Stochastic Variates and Applications to Equal-Gain Combining

Abstract: In this paper we study the statistics of the sum of not necessarily identically distributed kappa, that is, K, random variables (RV)s. Assuming half-integer values for the shaping parameters, novel closed-form expressions for the probability density function (PDF) of the sum of independent K RVs are obtained, while for arbitrary values of the shaping parameters, a corresponding PDF expression is derived in terms of fast converging infinite series. Furthermore, an infinite series representation for the PDF of the sum of two arbitrarily correlated K RVs is derived. The proposed analysis is employed to the performance analysis of equal-gain combining (EGC) receivers operating over composite fading/shadowing channels modeled by the K distribution. More specifically, the outage and the average bit error probabilities, as well as the average channel capacity of EGC receivers operating over such composite environment are studied. Considering different channel fading/shadowing conditions and correlation effects, various numerical performance evaluation results are presented. These results are complemented by equivalent computer simulated ones that validate the accuracy of the proposed analysis.

Design and evaluation of a sea clutter simulator

Abstract: This paper outlines the design of a sea clutter simulator based on the K distribution. Sea clutter is the radar backscattered return from the sea surface. Any radar operating in maritime environment must have the ability to compensate for this clutter effect to achieve effective target detection. This is usual done by applying appropriate signal processing techniques. In order to test algorithms, modelling of clutter with appropriate distributions is the preferred technique. In this paper, a method used to generate correlated K distributed clutter as described By Tough and Ward [12] and implemented in software by Glen Davidson [5] have been used to investigate the amplitude characteristics of sea clutter. By using the Kolmogoroff-Smirnoff test, the correlated clutter generated is shown to fit the theoretical K distribution, which is known to model very well the behaviour of sea clutter. This work will be extended to include temporal correlation, and bistatic sea clutter, to be tested against measurement made with the NetRad system described in these proceedings [1].

Investigations of Reynolds-Averaged Turbulence Quantities

Abstract: The equations for the higher-order moments and probability density function of turbulent velocity fluctuations are considered. These are derived utilizing the basic hydrodynamic equations of fluid flow. Using truncated cumulant expansions as approximations for the probability density distributions of the corresponding turbulence quantities, an alternative set of equations for the moments is formulated that contains only velocity correlations. From these equations, interrelations between the higher-order moments are deduced. Several theoretically derived relationships between correlations of different orders are experimentally verified using data available in the literature and also data measured by the authors. In the paper, an attempt is made to reconstruct the entire probability density distributions from derived inter-relations between the higher-order moments.