@article {Chaayra202133, title = {A Closed-Form Approximation to the Distribution for the Sum of Independent Non-identically Generalized Gamma Variates and Applications}, journal = {Mathematical Modelling of Engineering Problems}, volume = {8}, number = {1}, year = {2021}, note = {cited By 0}, pages = {33-44}, abstract = {Evaluating the sum of independent and not necessarily identically distributed (i.n.i.d) random variables (RVs) is essential to study different variables linked to various scientific fields, particularly, in wireless communication channels. However, it is difficult to evaluate the distribution of this sum when the number of RVs increases. Consequently, the complex contour integral will be difficult to determine. Considering this issue, a more accurate approximation of the distribution function is required. By assuming the probability density function (PDF) of a generalized gamma (GG) RV evaluated in terms of a proper subset H1,0 class of Fox{\textquoteright}s H-function (FHF) and the moment-based approximation to estimate the FHF parameters, a closed-form tight approximate expression for the distribution of the sum of i.n.i.d GG RVs and a sufficient condition for the convergence are investigated. The proposed approximate may be an analytical useful tool for analyzing the performance of certain numbers branch maximal-ratio combining receivers subject to GG fading channels. Hence, various closed-form performance metrics are derived and examined in terms of FHF. Numerical simulations are carried out to illustrate the theoretical results. {\textcopyright} 2021. All Rights Reserved.}, doi = {10.18280/mmep.080104}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85103500309\&doi=10.18280\%2fmmep.080104\&partnerID=40\&md5=128310fba0422f48576654498e755104}, author = {Chaayra, T. and Ben-Azza, H. and Bouanani, F.E.} } @conference {Chaayra2021, title = {Statistical Analysis of Uplink Massive MIMO Systems for MRC Linear Receivers over Weibull Fading Channels}, booktitle = {Proceedings - 4th International Conference on Advanced Communication Technologies and Networking, CommNet 2021}, year = {2021}, note = {cited By 0}, abstract = {This paper investigates the performance of maximum-ratio combining (MRC) linear receivers in a massive multiple-input multiple-output (mMIMO) uplink communication system, that in terms of their signal-to-interference-plus-noise ratio (SINR) operating under independent flat Weibull multipath fading channels (WFCs). Based on a tight approximate probability density function (PDF) expression of the signal-to-noise ratio at the considered receiver output, we derive new accurate closed-form expressions of PDF, outage probability (OP) for mMIMO employing MRC technique. The results show high accuracy for significant values of K{\texttimes}Nr mMIMO system at high/low transmission power and severity fading parameters as well. Indeed, the greater K{\texttimes}Nr, the better the PDF{\textquoteright}s accuracy, therefore, the better is the OP. Numerical outcomes have been assessed by using Mathematica Software to show up our results. {\textcopyright} 2021 IEEE.}, keywords = {Cummulative density function, G-functions, Linear receiver, Massive MIMO, Maximum ratio, Maximum-ratio-combining, Meije G-function, MIMO systems, Multipath fading, Multipath propagation, Outage probability, Probability density function, Signal interference, Signal receivers, Signal to noise ratio, Signalto-interference-plus-noise ratios (SINR), Weibull distribution, Weibull fading channel}, doi = {10.1109/CommNet52204.2021.9641935}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85123984751\&doi=10.1109\%2fCommNet52204.2021.9641935\&partnerID=40\&md5=3e44ae3af40139cd08615a702accf1ac}, author = {Chaayra, T. and El Ansari, Y. and El Bouanani, F. and Ben-Azza, H.} } @article {Chaayra20201121, title = {New Accurate Approximation for the Sum of Generalized Gamma Distributions and its Applications}, journal = {Applied Mathematics and Information Sciences}, volume = {14}, number = {6}, year = {2020}, note = {cited By 1}, pages = {1121-1136}, abstract = {By considering the probability density function (PDF) of a generalized Gamma (GG) random variable (RV) evaluated in terms of a proper subset (Formula presented) class of Fox{\textquoteright}s H-function (FHF) and the moment-based approximation to estimate the H-function parameters, a closed-form tight approximate expression for the distribution of the sum of independent and not necessarily identical GG distributed RVs is presented as well as a sufficient condition for the convergence is verified. Such proposed approximate PDF is useful analytical tool for analyzing the performance of L-branch maximal-ratio combining receivers subject to such a fading model. This result can be also of paramount importance when dealing with an intelligent reflecting surface subject to GG fading channels. Furthermore, various closed-form approximate expressions, such as the cumulative distribution function (CDF), moment-generating function, outage probability (OP), average channel capacity, nth moment of the signal-to-noise ratio (SNR), amount of fading, and average symbol error probability (ASEP) for numerous coherent digital modulation schemes, are derived and examined in terms of FHF. To gain further insight into the system performance, asymptotic closed-form expressions for the ASEP and OP are derived and interesting observations are made. Particularly, our asymptotic analysis reveals that the achievable diversity order for high SNR values depends essentially on the branches{\textquoteright} number. The proposed mathematical analysis is assessed and corroborated by Monte-Carlo simulations using computer algebra systems, while the PDF and CDF are validated further with the aid of the Kullback-Leibler divergence criterion and Kolmogorov-Smirnov test, respectively {\textcopyright} 2020. NSP Natural Sciences Publishing Cor.}, doi = {10.18576/amis/140619}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85100193483\&doi=10.18576\%2famis\%2f140619\&partnerID=40\&md5=a2ca278ea1f812f0a524e23e100a588c}, author = {Chaayra, T. and Ben-Azza, H. and Bouanani, F.E.} } @conference {Chaayra2018106, title = {Union bound on the bit error probability of TCM coded with TAS/MRC MIMO system subject to weibull fading channels}, booktitle = {ACM International Conference Proceeding Series}, year = {2018}, pages = {106-111}, doi = {10.1145/3289100.3289118}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85058642340\&doi=10.1145\%2f3289100.3289118\&partnerID=40\&md5=eb942c9b4a115381f43ab2d3015f0a49}, author = {Chaayra, T. and Bouanani, F.E. and Benazza, H.} } @conference {Chaayra2017, title = {Performance analysis of TAS/MRC based MIMO systems over Weibull fading channels}, booktitle = {2016 International Conference on Advanced Communication Systems and Information Security, ACOSIS 2016 - Proceedings}, year = {2017}, note = {cited By 0}, abstract = {In this paper, we investigate combining single transmit antenna selection (TAS) and receiver maximal ratio combining (MRC) based Multiple-Input-Multiple-Output (MIMO) systems over independent flat Weibull fading channels. In this system, a single transmit antenna, which maximizes the total received signal power at the receiver, is selected for uncoded transmission and is applied to reduce the system complexity without any loss in diversity. Since much research has been conducted on system performance under Rayleigh and Nakagami-m fading channels, this study will focus on new simple approximate closed-form of the post-processing signal to noise ratio (SNR) probability density function (PDF) over Weibull multipath fading channels. Based on this expression, approximate analytical expressions such outage probability (OP), the average channel capacity (CC), and the average symbol error rate (ASER) for several Mary modulation techniques are derived as infinite series, which converge by using a particular hypergeometric function, known as Meijer G-function. Theoritical analysis is verified by computed simulations using Mathematica software. {\textcopyright} 2016 IEEE.}, doi = {10.1109/ACOSIS.2016.7843937}, url = {https://www.scopus.com/inward/record.uri?eid=2-s2.0-85015207144\&doi=10.1109\%2fACOSIS.2016.7843937\&partnerID=40\&md5=d347aa5cd10e0b607b96ad3f8ddea83f}, author = {Chaayra, T. and El Bouanani, F. and Ben-Azza, H.} }