Stefan Panic

Unmanned aerial vehicles (UAV) assisted edge computing has risen as an assuring technique to accommodate ubiquitous edge computation for resource-limited devices. Thus, this paper proposes an approach to maximize the latency fairness in a UAV-assisted multi-access edge computing (MEC) system. To maximize latency fairness, the authors focus on minim...

The paper considers level crossing rate (LCR) and average fade duration (AFD) of the product of independent and identically distributed (i.i.d) Nakagami-m (NM) and double NM squared (also known as gamma-gamma) random variables (RVs). The derived statistics are then directly applied to the radio-frequency (RF) - free space optical (FSO), dual-hop (D...

This article investigates outage statistics of double gamma–gamma random variable (RV) modeled as the product of two independent and identically distributed gamma–gamma RVs. The outage closed‐form statistics in terms of the first‐order statistical measures (probability density function and cumulative distribution function) and the second‐order stat...

The repair rate is a very important parameter for system maintainability and can be defined as a frequency of successfully performed repair actions on a failed component per unit of time. This paper analyzes the integral characteristics of a stochastic repair rate for corresponding values of availability in a system operating under maintenance cont...

This paper considers a system of macro diversity (MD) that consists of a macro receiver of SC diversity (MD SC) and two micro MRC (mD MRC) receivers, which operate in a correlated Gamma-shadowed Rayleigh multipath fading environment. The combination of the maximum L-branch ratio (SNR signal-to-noise) is realized at the micro level, and the optional...

In this paper we will propose new analytically traceable probability density function (PDF) model for free space optics (FSO) turbulence, obtained as a generalization of double Ricean turbulence model, that encompasses both large-scale and small-scale turbulence eddy effects along by taking into account performance decreasing influence of misalignm...

In this paper, the Average Bit Error Rate of the signal in the Free Space Optical system modulated with On-Off keying scheme is calculated and analysed. The Average Bit Error Rate is determined in the case of an atmospheric channel modelled with Gamma-Gamma distribution, Log-Normal distribution, K distribution and I-K distribution. The results are...

Reliability, the number of spare parts and repair time have a great impact on system availability. In this paper, we observed a repairable system comprised of several components. The aim was to determine the repair rate by emphasizing its stochastic nature. A model for the statistical analysis of the component repair rate in function of the desired...

Repair rate is very important parameter in a system maintainability and it can be defined as frequency of the successfully performed repair actions on failed component per unit of time. This paper analyses the integral characteristics of a stochastic repair rate for corresponding values of availability in the system operating under maintenance cont...

Unmanned-aerial-vehicles (UAVs) are intended to be a vital part of beyond 5G (B5G) and 6G communication networks. UAV-to-ground communications in urban and populated areas are usually exposed to highly variable propagation conditions that can be often characterized by composite fading channels. This paper provides mathematical framework for the per...

In this paper, we derive an average symbol error rate (ASER) expression of rectangular quadrature amplitude modulation (RQAM) scheme for unmanned aerial vehicle-enabled communication systems operating over double-shadowing and double-scattering composite fading channel. A moment generating function for the receiver output signal-to-noise ratio is o...

The paper explores N-hop FSO communications assisted by amplify-and-forward relays (AFRs) over N-gamma-gamma (N-gg) turbulence induced (TI) fading channels. We model TI fading signal as the product of independent but not necessarily identically distributed (i.n.i.d) N number of gg random processes (RPs) in order to address N-hop AFR FSO communicati...

In order to provide a novel analytically traceable free space optics (FSO) channel model for describing turbulence based irradiance fluctuations, following basic scintillation theory principles, we have derived closed-form expression for probability density function (PDF) of a new statistical Gamma–Chi-square model. Further, capitalizing on provide...

This paper, by using Borjesson’s and Benitez’s approximation of Q-function, presents a novel and improved composite approximation of Q-function with wide applicability. The presented approach is very general and can be implemented on any observed interval. Based on the proposed approximation of Q-function, the average bit error rate is assessed by...

Covid-19 causes one of the most alarming global health and economic crises in modern times. Countries around the world establish different preventing measures to stop or control Covid-19 spread. The goal of this paper is to present methods for the evaluation of indoor air quality in public transport to assess the risk of contracting Covid-19. The f...

This chapter provides a unified framework for channel modelling and performance evaluation of the wireless systems envisioned for 5G and beyond 5G (B5G) communications in terms of the first and the second order statistical measures (probability density function - PDF, cumulative density function - CDF, level crossing rate - LCR, average fade durati...

Rapid emergence of wireless sensor networks (WSN) faces significant challenges due to limited battery life capacity of composing sensor nodes. It is substantial to construct efficient techniques to prolong the battery life of the connected sensors in order to derive their full potential in the future Internet of Things (IoT) paradigm. For that purp...

In this paper, the performance of cellular communication system operating over η-µ fading channel, is considered. Using a Decode-and-Forward (DF) multi-hop relay system transmission performances can be enhanced. The closedform expression for the outage probability (Pout) of the system has been derived. In the proposed system, the transmission time...

In this paper, we consider a macro diversity (MD) system consisting of a macro SC diversity (MD SC) receiver and two micro MRC (mD MRC) receivers operating over correlated Gamma-shadowed Rayleigh multipath fading environment. The combination of the maximum L-branch ratio (SNR signal-tonoise) is realized at the micro level, and the optional selectio...

In this paper, a stochastic problem of multicenter location on a graph was formulated through the modification of the existing p-center problem to determine the location of a given number of facilities, to maximize the reliability of supplying the system. The system is represented by a graph whose nodes are the locations of demand and the potential...

In this paper, a resource allocation and data gathering scenario of an unmanned aerial vehicle (UAV) assisted wireless powered sensor network is investigated, in which the sensor nodes (SNs) are remotely powered by power beacons (PBs) via radio-frequency wireless power transmission (RF-WPT). A time-block structure with two phases is proposed to acc...

Radio frequency energy harvesting (RF-EH) offers an unorthodox solution to the painstaking energy constraint drawback in wireless sensor networks (WSNs). In this paper, a data-gathering scenario from a UAV assisted WSN that consists of multiple sensor nodes (SNs) and power beacons (PBs) is considered. All the SNs are remotely powered by the PBs via...

Mobile networks have significant impact on many aspects of our everyday lives. The number of users and requirements increase continuously, which poses many challenges to service providers. Efficient resource planning and ability to adapt to current demands are crucial when it comes to deployment of large-scale and high-performance commercial mobile...

In this paper we consider a wireless receiver model that employs the macro diversity (MD) technique, consisting of a selection combining (SC) receiver fed by two micro diversity (mD) SC branches, which is used to simultaneously reduce the effects of Nakagami-m short term fading, Gamma long term fading, and co-channel interference on the system perf...

Efikasno planiranje resursa i razmatranje performansi su od ključnog zanačaja za realizaciju mobilnih mreža poslednje generacije velikih brzina i širokih razmera. Upotreba alata za modelovanje i simulaciju omogućava bržu i jeftiniju analizu potencijalnih realizacija. U ovom radu, prikazano je softversko rešenje za modelovanje i simulaciju pojedinih...

The paper investigates mobile-to-mobile (M2M) dual-hop amplify-and-forward relay (AFR) communications in composite fading environments. We model composite fading signal as the product of Nakagami-m (Nm) and Gamma (G) random processes (RPs) in order to address multipath-shadowing scenario and derive novel, fast computing, closed form mathematical fo...

Covid-19 causes one of the most alarming global health and economic crises in modern times. Countries around the world establish different preventing measures to stop or control Covid-19 spread. The goal of this paper is to present methods for the evaluation of indoor air quality in public transport to assess the risk of contracting Covid19. The fi...

This paper proposes a new approach to edge detection on the images over which the wavelet decomposition was done to the third level and consisting of different levels of detail (small, medium and high level of detail). Images from the BSD (Berkeley Segmentation Dataset) database with the corresponding ground truth were used. Daubechies wavelet was...

In this paper, we are observing scenario of unmanned aerial vehicle (UAV) data collection from sensor network, where each sensor harvests energy from the data-collecting UAV for its own information transmission. In first time instant, the wireless energy transfer (WET) to sensor nodes is performed, while in the second time instant UAV collects data...

The aim of this paper is to set framework for the repair rate in order to achieve required availability of a repairable system with alternating renewal process where the failure rate is Weibull distributed. In order to accomplish this goal, this paper proposes a novel model for a complete stochastic analysis of the repair rate. The resulting equati...

In this study, the authors investigate average capacity of free space optics communication over Málaga atmospheric turbulence channel with pointing errors and path loss, for intensity modulated/direct detection (IM/DD) and heterodyne detection. Various algorithms which use adaptive transmission with both types of detection are considered, such as:...

In this paper, we consider an unmanned aerial vehicle (UAV) assisted wireless sensor network (WSN), where each sensor nodes' transmission capability is powered by the UAV using wireless power transfer (WPT). Sensor nodes harvest energy from the signal broadcast by the UAV in the down-link (DL) and all the harvested energy will be used for informati...

In this paper, an approximation of the average bit error rate (ABER) probability expression, standard performance measure of wireless transmission over fading channels using linear spline functions with corresponding number of segments has been provided. Further, possible approximation improvement obtained by appliance of composite piecewise spli...

In this paper, we present a few novel simultaneous wireless information and power transfer (SWIPT) schemes that can be effectively used in various 5G wireless network implementations. First, we study the possibility of integrating distributed energy beamforming with the data rate fairness beamforming in a cooperative communication system with multi...

We present a gradient descent algorithm with a line search procedure for solving unconstrained optimization problems which is defined as a result of applying Picard-Mann hybrid iterative process on accelerated gradient descent SM method described in Stanimirović and Miladinović (Numer. Algor. 54, 503–520, 2010). Using merged features of both analyz...

In this paper macrodiversity system consisting of two microdiversity SC (Selection Combiner) receivers and one macrodiversity SC receiver are analyzed. Independent ?-? fading and correlated slow Gamma fading are present at the inputs to the microdiversity SC receivers. For this system model, analytical expression for the probability density of the...

We improve the convergence properties of the iterative scheme for solving unconstrained optimisation problems introduced in Petrovic et al. [‘Hybridization of accelerated gradient descent method’, Numer. Algorithms (2017), doi: 10.1007/s11075-017-0460-4 ] by optimising the value of the initial step length parameter in the backtracking line search p...

Today’s world depends largely on information and communication technologies. These technologies are in use in different areas of human life and work. Each day, more examples of possible application of information and communications technology are being discovered. In most cases, computer science is used to solve complex problems which have mathemat...

This paper presents a novel approach for estimation of repair rate in an observed system comprised of two or more components. The presented approach is based on calculation of probability density function of maximal and minimal system’s repair time by observing the repair rates of its components. Based on the obtained information it can be conclude...

Modelling of complex wireless transmission scenario over fading channels in the presence of multiple co-channel (CCI) interferers will be presented in this paper. Propagation environment will be modelled with general kappa-mu shadowed model, which can be reduced to other well-known model as its singularities. Probability density function (PDF) and...

We will provide statistical analysis of the square ratio of κ-μ and η-μ random processes and its application in the signal-to-interference ratio (SIR) based performance analysis of wireless transmission subjected to the influence of multipath fading, modelled by κ-μ fading model, and undesired occurrence of co-channel interference (CCI), distribute...

Performance Based Logistics (PBL) concept has an aim to improve the system availability and it has been extensively researched in the recent years. These researches showed that inventory level does not impact system availability as much as component reliability and repair time in repairable system operating under PBL contract. Based on that, in thi...

In this paper, an approximation of the optimal compressor function using the quadratic spline functions with 2L = 8 segments is described. Since the quadratic spline with 2L = 8 segments provides better approximation of the optimal compression function than quadratic spline with 2L = 4 segments, capitalizing on the benefits of the obtained spline a...

In this paper, we will analyze signal-to-interference ratio (SIR) based selection combining (SC) diversity system over dual correlated \(\kappa -\mu \) fading channels, in the presence of mutually \(\kappa -\mu \) correlated interferences. Infinite series expressions for probability density function (PDF), and cumulative distribution function (CDF)...

In this paper, capitalizing on novely introduced interval approximation of Q-function, we have presented simple and tight approximation for the evaluation of the average symbol error probability (ASEP) over fading channels. First, comparison to other known Q-function closed-form approximations has been performed, and it has been shown that accuracy...

Macrodiversity (MACD) system with MACD selection combining (SC) receiver and two microdiversity (MICD) selection receivers in the presence of Gamma long-term fading, Rayleigh short-term fading, and co-channel interference affected to Rician short-term fading is studied in this article. The closed-form expressions for probability density function (P...

In this paper we will observe wireless propagation in non-homogenous environment under non-deterministic line-of-sight (LOS) conditions, when the random nature of dominant/scattering components ratio has been considered and modeled as Gamma distribution. First closed-form expressions have been derived for the probability density function (PDF) and...