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This paper presents a novel energy-efficient Radio Frequency (RF) Energy Harvesting (EH) scheme for secrecy performance in Internet of Things (IoT) network using cooperative communication approach under dissimilar faded channel environments. We have combined the concept of Destination Based Jamming (DBJ) with power beacon aided EH in our model. This paper provides three scenarios when the links undergo rayleigh fading, weibull fading, and nakagami-q (hoyt) fading where the effect of fading on the secrecy performance has been examined. Closed-form expressions for Secrecy Rate (SR) and System Energy Efficiency (SEE) are derived for the given scenarios. Analytical expressions have been well substantiated through extensive simulation results. The comparative analysis of system performance in terms of SR with respect to some important system parameters has been shown for various conventional protocols i.e., Decode-and-Forward (DF), Amplify-and-Forward (AF) and Hybrid-Decode-Amplify-Forward (HDAF). Furthermore, our scheme has been compared with benchmark techniques such as Cooperative Relaying (CR) and Cooperative Jamming (CJ) to quantify the performance improvement. Theoretical analysis and simulated results reveal the improvement of our proposed Signal-to-Noise (SNR) based hybrid decode-amplify forward Cooperative IoT (CIoT) scheme over existing relaying schemes which are further validated through statistical analysis. Results also depict the impact of eavesdropper position on secrecy performance at different channel mean power values. Finally, the SEE has been addressed and the impact of power splitting factor and transmit beacon power on the secrecy performance on the proposed model has also been analyzed with respect to change in fading parameters.

The paper presents a comprehensive closed-form performance analysis framework for multihop communications over Weibull fading channels. This framework may be of interest in different applications in the contexts of beyond-5G (B5G) and Internet of Things (IoT) use cases. The analyzed scheme consists generally of multiple regenerative relays, and we also consider generalized high-order quadrature amplitude modulation ( M -QAM) transmissions. To take into consideration the channel fading, we adopt the Weibull model for its largely flexible ability to cover different channel conditions in different application contexts. The end-to-end performance is evaluated in terms of outage probability, bit error probability (BER), symbol error probability (SER), block error rate (BLER), ergodic capacity, and energy efficiency (EE). For all the metrics, we present exact closed-form expressions—along with their asymptotic behavior—capitalizing on the powerful generalized hypergeometric functions. To illustrate the utility of the obtained analytical results, we derive two BER- and EE-optimal transmit power allocation strategies, and we discuss the resulting performance gains. The exactness of our analysis is illustrated by numerical examples, and assessed via Monte-Carlo simulations for different system and channel parameters. Finally, as a secondary contribution, and noting the increasing popularity of single and bivariate Fox’s H -function, we provide generalized Matlab codes for computing these functions which are of practical utility in many fields.

Unmanned aerial vehicles (UAVs) communications have been widely exploited in our daily life, which leads to rising concerns about the security issue. This work investigates the secrecy performance of a UAV-to-vehicle (UAV-2-V) communication system, where the information delivered over both downlink and uplink between a UAV ( $S$ ) acting as a temporary aerial base-station and a legitimate vehicle ( $D$ ) moving along a road which is overheard by an eavesdropping vehicle ( $E$ ) on the same road. The location of $S$ is assumed to be uniformly distributed in the sky, while the locations of $D$ and $E$ are uniformly distributed on the highway. The statistical characteristics, including the cumulative distribution function and probability density function of the received signal-to-noise ratio over both downlink and uplink, are characterized respectively. Closed-form expressions for the approximate and asymptotic secrecy outage probability (SOP) of the downlink experiencing Rician fading channels have been derived accordingly. Moreover, the secrecy outage performance of the uplink is investigated by deriving the closed-form expression of the exact and asymptotic SOP in two cases: the eavesdropping channel suffers Rician and Weibull fading, respectively. Finally, Monte-Carlo simulations are shown to verify our proposed analytical models.

Unlike Rayleigh or Nakagami-m fading which has been widely studied in hybrid satellite-terrestrial relay network, the multi-branch Weibull fading which can be an alternative has been less studied due to its high intractability. In the proposed satellite-terrestrial Weibull system, by applying multi-branch optimal transmitting beamforming/receiving combination strategy, an upper bound of signal to noise (SNR) based outage probability (OP) is analyzed compared with the exact OP. Besides, two different methods are used to calculate the intractable Ergodic Capacity. Moreover, the closed-form expressions of the average symbol error rate (ASER) and Effective Capacity are hard to derive. Hence, simplified theoretical results of ASER and Effective Capacity are presented via the proposed upper bound of SNR scheme. Finally, various parameters are verified to illustrate the performance of the proposed model and demonstrate the effectiveness of our method.

The usage of unmanned aerial vehicle (UAV) as a cooperative mobile relay is considered to be a promising technique to enhance the performance of future wireless networks. This paper studies the system performance of a dual hop decode and forward, full/half duplex (FD/HD) UAV assisted relay systems, in the presence of direct link between source and the destination. A radio frequency based energy harvesting mechanism underlying simultaneous wireless information and power transfer technique is employed at the UAV to improve the system energy efficiency. For the proposed system design, we derive a closed-form expression for outage probability and system throughput with respect to the key metrics such as transmit power and time splitting factor over generalised weibull fading channel. The impact of self-interference effect on the system performance is studied in different aspects. The obtained results demonstrated that, increasing the fading parameter $$(\beta)$$ improves the overall system performance, significantly. In addition, FD operation with selection combining at the receiver offers an improved performance as compared to HD systems. Finally, the numerical simulation results are given, in order to validate the derived expressions.

The Weibull distribution has received much interest in reliability theory. The well-known maximum likelihood estimators (MLE) of this fam- ily are not available in closed form expression. In this work, we propose a consistent and closed form estimator for shape parameter of three-parameter Weibull distribution. Apart from high degree of performance, the derived estimator is location and scale-invariant.

This paper introduces a new four parameters model called the Weibull Generalized Flexible Weibull extension (WGFWE) distribution which exhibits bathtub-shaped hazard rate. Some of it's statistical properties are obtained including ordinary and incomplete moments, quantile and generating functions, reliability and order statistics. The method of maximum likelihood is used for estimating the model parameters and the observed Fisher's information matrix is derived. We illustrate the usefulness of the proposed model by applications to real data.

Large intelligent surface (LIS) is considered as a new solution to enhance the performance of wireless networks[1]. LIS comprises low-cost passive elements which can be well controlled. In this paper, a LIS is invoked in the vehicular networks. We analyze the system performance under Weibull fading. We derive a novel exact analytical expression for outage probability in closed form. Based on the analytical result, we discuss three special scenarios including high SNR case, low SNR case, as well as weak interference case. The corresponding approximations for three cases are provided, respectively. In order to gain more insights, we obtain the diversity order of outage probability and it is proved that the outage probability at high SNR depends on the interference, threshold and fading parameters which leads to 0 diversity order. Furthermore, we investigate the ergodic achievable rate of LIS-assisted vehicular networks and present the closed-form tight bounds. Similar to the outage performance, three special cases are studied and the asymptotic expressions are provided in simple forms. A rate ceiling is shown for high SNRs due to the existence of interference which results 0 high SNR slope. Finally, we give the energy efficiency of LIS-assisted vehicular network. Numerical results are presented to verify the accuracy of our analysis. It is evident that the performance of LIS-assisted vehicular networks with optimal phase shift scheme exceeds that of traditional vehicular networks and random phase shift scheme significantly.

Increasing concerns regarding wireless systems’ security are leading researchers to exploit the physical properties of a medium while designing any secured wireless network. The secrecy performance of a mixed radio frequency-free space optical (RF-FSO) system with a variable gain relaying scheme is investigated in this paper under the attempt of wiretapping by an eavesdropper. We assume that the eavesdropper can intrude the target data from the RF link only. Both the RF links (main and eavesdropper) undergo the $\alpha -\mu $ fading statistics and the FSO link experiences the exponentiated Weibull fading statistics. Exploiting the amplify-and-forward (AF) relaying scheme while considering two detection techniques (i.e. heterodyne detection and intensity modulation/direct detection) with pointing error impairments, the mathematical formulations of the unified probability density function and cumulative distribution function are performed for the equivalent signal-to-noise ratio of the considered dual-hop RF-FSO link. Closed-form analytical expressions for average secrecy capacity, secrecy outage probability, and the probability of non-zero secrecy capacity are derived in terms of Meijer’s $G$ and Fox’s $H$ functions to quantify the system performance. Capitalizing on these expressions, the secrecy performance is further analyzed for various channel parameters of RF links, aperture sizes of the receiver, pointing errors, and atmospheric turbulence severity. The results reveal that aperture averaging can improve the secrecy performance remarkably by suppressing the effects of turbulence. Monte Carlo simulations are provided to justify the accuracy of the proposed model.

In this paper, the average symbol error rate (ASER) evaluation of multiple-input-multiple-output (MIMO) systems with transmit antenna selection (TAS) and maximal ratio combining (MRC) are analysed under Weibull fading conditions. The impact of additive white Gaussian noise (AWGN) and additive white generalized Gaussian noise (AWGGN) on the ASER evaluation of the MIMO TAS/MRC networks are considered. Closed form approximate and asymptotic ASER expressions of the considered network with AWGN for different quadrature amplitude modulation techniques are derived based on the probability density function approach. The closed-form approximate and asymptotic ASER expressions for the AWGGN case are also obtained. In addition, a comprehensive analysis of the ASER performance for the MIMO TAS/MRC networks is demonstrated by varying the fading parameter values, numbers of transmitter-receiver antennas and constellation size. Finally, the obtained theoretical results are confirmed through the exact simulation results.

With the rapid growth of wireless communication, there is an extensive growth in the demand of Radio frequency through electromagnetic spectrum allocation. Cognitive radio is considered to be a potential technology which helps to overcome the demand in radio frequency. Relaying protocol is applied in this paper in order to assist the transmission, improve the efficacy and to minimize the bit error rate. The performance of single hop (Amplify and Forward—AF) and multi-hop (Decode and Forward—DAF and Compress and Forward—CF) relaying protocols over a Weibull fading channels in cognitive radio are analyzed. The numerical outcomes are evidence that the bit error rate and Signal to Noise ratio proves that multi-hop is more promising as compared to single-hop relaying protocol.

Orientador: Michel Daoud Yacoub Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação Resumo: Esta dissertação analisa e valida, através de medidas de campo, estatísticas de ordem superior para canais com desvanecimento Weibull e Nakagarni-m. Considerando canais com desvanecimento Weibull, devido à ausência de um modelo físico, estatísticas conjuntas de duas variáveis Weibull correlacionadas foram obtidas em forma fechada e em função de parâmetros físicos bem conhecidos, se destacando as funções de autocorrelação e espectro de potência. Analisando canais com desvanecimento Nakagami-m, expressões simples e em forma fechada para as funções de autocorrelação e espectro de potência foram derivadas. Medidas de campo indoor e outdoor foram realizadas por meio de um sistema montado e configurado especialmente para investigar as estatísticas em estudo. Foram observados excelentes ajustes entre os dados teóricos e experimentais. Os resultados das medições validam as funções de autocorrelação e espectro de potência para envoltórias Weibull e Nakagarni-m Abstract: This dissertation analyzes and validates, through field trials, higher order statistics for Weibull and Nakagarni-m fading channels. Conceming Weibull fading channels, due to the absence of a physical model related to such channels, joint statistics for two correlated Weibull variables were obtained in closed-form and in terms of well-known physical parameters, in particular the autocorrelation and power spectrum functions. Conceming Nakagarni-m fading channels, simple and closed-form expressions for autocorrelation and power spectrum functions were derived; Indoor and outdoor field trial measurements were conducted in order to investigate these statistics. The mobile reception equipment was especially assembled for this purpose. Excellent fits between analytical and empirical metrics were observed. The measurements results validate the autocorrelation and power spectrum functions of the Weibull and Nakagami-m fading channels Mestrado Telecomunicações e Telemática Mestre em Engenharia Elétrica

We present a moments-based approach to the performance analysis of L-branch equal-gain combining and maximal-ratio combining receivers, operating in independent or correlated, not necessarily identically distributed, Weibull fading. For both equal-gain combining and maximal-ratio combining receivers the moments of the output signal-to-noise ratio are obtained in closed-form. An accurate approximate expression is derived for the moment-generating function of the output signal-to-noise ratio of the equal-gain combining receiver utilizing the Padé approximants theory, while a closed-form expression for the corresponding MGF of the maximal-ratio combining receiver, is obtained. Significant performance criteria, such as average output signal-to-noise ratio, amount of fading and spectral efficiency at the low power regime, are extracted in closed-forms, using the moments of the output signal-to-noise ratio for both independent and correlative fading. Moreover, using the well-known moment-generating function approach, the outage and the average symbol error probability for several coherent, non-coherent, binary, and multilevel modulation schemes, are studied. The average symbol error probability of dual-branch equal-gain combining and maximal-ratio combining receivers is also obtained when correlative fading is considered in the diversity input branches. The proposed mathematical analysis is illustrated by various numerical results and validated by computer simulations.

This study analyses the performance of a three-node cooperative relaying system with single amplify-and-forward fixed-gain relay. In most works, the source-to-destination (SD) link under deep fade condition is ignored. However, the link may experience a severe fading condition which can still contribute partially towards system diversity. Therefore, the authors assume that SD link undergoes severe fading (i.e. Weibull fading with severity parameter less than two), while the other asymmetric fading channels of the source-to-relay and the relay-to-destination links are subjected to Weibull and Rician fading, respectively. The derivations of analytical expressions for cumulative distribution function and probability density function of the instantaneous output signal-to-noise ratio at the destination terminal, allow the evaluation of outage probability, bit error probability with their diversity order of the particular system design. From the results, at a certain Weibull severity level, the SD link can be omitted and considered as deep fade since it offers insignificant diversity order.

Cooperative broadcast, in which receivers are allowed to combine received packets from different senders to combat transmission errors, has gained increasing attention. Previous studies showed that broadcast optimization solutions are sufficient in non-fading environments but may suffer a low delivery ratio under wireless channel fading. Although some previous works analyze the tradeoff between energy and delay in cooperative broadcast, no work has investigated the tradeoff in a fading environment. Thus, in this paper, we study this tradeoff with the consideration of different fading models (i.e., Rayleigh fading, Rician fading, and Weibull fading models). We formulate this problem as a Fading-resistant Delay-constrained Minimum Energy Cooperative Broadcast (FDMECB) problem and prove the problem to be NP-hard under the Rayleigh fading, Rician fading, and Weibull fading models. We then identify an approximation algorithm for theoretical interests and propose a time efficient heuristic algorithm for practical use. Furthermore, we propose a dynamic programming (DP) based algorithm, which can achieve global optimization of FDMECB given the ordering of nodes to be informed. Our experimental results show that both FREEB and DP algorithms outperform a previous non-fading resistant algorithm, and also, DP nearly achieves the optimal.

In this paper, the upper bound and asymptotical approximation for the bit error rate (BER) as well as for the frame error rate of linear block codes under maximum-likelihood decoding operating over exponentially correlated (EC) generalized-fading channels are proposed. Particularly, our analysis takes the convolutional codes as an example and three different fading scenarios are considered, namely Rice, Nakagami- $m$ , and Weibull fading. Such scenarios have a common property that is spherically invariant random process (SIRP). Our analysis relies on the derivation of new lower bounds per each eigenvalue since the BER as well as the FER expressions are written in terms of the pairwise error probability, which by its turn depends on the eigenvalues of the channel covariance matrix. Based on that, the upper bounds and asymptotic expressions of the considered metrics subject to the three above fading models are derived, which show to be tighter than the previous results published elsewhere in the literature, especially for the high signal-to-noise ratio regions.

Cognitive radio (CR) is developed as one of the important techniques to improve the utilization of the radio spectrum. A CR node shares the radio spectrum with a licensed primary user opportunistically. In this paper, we study the performance of an energy-efficient cooperative cognitive radio system (CCRS) in the presence of noise plus different fading conditions under channel error constraints. Two fading environments namely, Nakagami-m and Weibull fading are considered and performance characteristics are evaluated. More precisely, Every CR node uses the similar energy detectors to sense a primary user, and forwards their knowledge to fusion center (FC) as one bit binary information. Different hard-decision fusion operations are carried out at FC to take the global decision about the status of the primary user. The analytical and simulation models related to noise and fading for calculating missdetection performance, total error performance, and sensing time and throughput/energy efficiency trade-off are developed. Analytical frameworks are validated via computer based simulations. For comparison purposes, we also investigate the performance of CCRS in Rayleigh fading with and without channel errors constraints. Further, the performance CCRS is investigated for various hard-decision fusion rules under several parameters of the system. Finally, an optimal values of the number of CR nodes and sensing threshold for different fusion rules, and sub-optimal hard-decision fusion rule are also investigated. The energy efficiency is enhanced by 19% when CCRS is operated over Nakagami-m fading environment as compared to Rayleigh fading environment for a fixed parameter values of the network.

In this paper, we investigate the performance of decode-and-forward dual-hop mixed RF/FSO system in fifth-generation (5G) cloud radio access network. To describe the 5G channel characteristics properly, we assume that the RF link follows κ − μ shadowed fading which has been recently proposed to model small-scale multipath fading as well as line-of-sight (LOS) shadowing. For the FSO link, we adopt the Exponentiated Weibull distribution which can represent irradiance fluctuations at the finite receiving aperture over a wide range of turbulence conditions. We first derive the cumulative distribution function in terms of Meijer’s G function, and then use it to obtain the analytical expressions of the outage probability, average bit error rate and ergodic capacity. The system performances are analyzed with different κ − μ shadowed fading parameters, turbulence strength and receiver aperture sizes. The analytical results show an accurate match to the Monte-Carlo simulation.

In this paper, a new combining algorithm for selection combining (SC) receiver based on selection of diversity branch with the lowest interference is proposed. The system used for analysis consists...

The proposed cooperative spectrum sensing network gives potential attributes to improve the detection performance. This research paper mainly focuses on the identification of unknown signals in Weibull fading environment using an improved energy detector (IED). The proposed network consists of multiple cognitive radio (CR) nodes, at each CR node number of antennas are used and selection combining (SC) is used to select the maximum value of detection probability. Further, the activity of primary user (PU) is identified using fusion rules at fusion center (FC). Initially, closed-form of missed detection and false alarm probabilities are proficiently derived. Later on, energy efficiency and an average channel throughput analysis are evaluated using $k= 1 +n$ and $k=N- n$ rules at FC.

This work evaluates the sum rate performance for dual user with full duplex co-operative non-orthogonal multiple access (FD-CNOMA) over Weibull fading channel environment. For this, we derived closed form expressions for sum-rate in various scenario in downlink and uplink both. One user always acts as decode and forward full duplex relay to help far users in each scenario. In the first scenario, no direct link exists between base station (BS) and far user. In second scenario, direct link exists between BS and far user. The main investigation is to study the effect of fading parameters in different channel condition on sum-rate performance. Since, Weibull Distribution (WD) has an advantage to model different fading condition using varying parameter it is more suitable to study impact of fading condition on different wireless techniques for next generation mobile cellular communication. Therefore, WD is used in this study for sum rate performance evaluation with derived expressions. Finally, simulations were conducted on MATLAB to evaluate the system performance under different fading parameters of Weibull fading channels .

In this paper, we present the re-configurable intelligent surfaces (RIS) based space shift keying (SSK) and spatial modulation (SM) schemes with both perfect and imperfect channel phase knowledge over Weibull fading environments. At the receiver, we consider the sub-optimal Greedy Detection (GD) for proposed RIS-based SSK and SM schemes. Central Limit Theorem (CLT) caused by RIS schemes facilitates to adopt of a unified framework for error performance analysis of Weibull fading channels without loss of generality. In this study, it has been obtained the theoretical bit error probability (BEP) of the proposed schemes. It should be underlined that unlike the literature, the BEP of the proposed schemes is formulated in the presence of a Gaussian imperfect phase estimation at RIS. These analytical results were then validated with Monte-Carlo Simulations under the various system settings (e.g., the severity of fading parameters, number of reflectors, different antenna numbers).

Free-space optical (FSO) communications will play an important role in the backhaul of future generation of wireless networks in order to support high data rates. Because of narrow beamwidth inherent to an optical signal, acquisition and tracking form an important component of any FSO communication system. In this study, we have analyzed the optimization of received power allocation between tracking and data channels in an FSO receiver. In this regard, we have carried out a detailed analysis of the error statistics of the centroid estimator that is used for tracking the beam with the help of an array. The objective function that is optimized (minimized) are the probability of error and the probability of outage, and the optimization of power allocation is carried out as a function of parameters such as noise power, pointing error variance, pointing error correlation coefficient, and the threshold of outage. We have analyzed the optimization concerning the lognormal and exponentiated Weibull fading scenarios as well. We learn that the optimal power allocation is a function of the received signal-to-noise ratio: a lower signal-to-noise ratio dictates that a higher fraction of received power should be diverted to the tracking channel and vice versa.

Weibull distribution is a befitting prototype for explaining fading channels that consist of multipath environment in radio propagation surrounding it in indoor or outdoor. This work shows a review on the expression of channel capacity with L-branch maximal ratio combining system and over uncorrelated Weibull fading channel using optimum rate adaptation with constant transmit power scheme. An expression for the probability of outage has been also deduced in this paper. In this paper, an expression for a relation between the fading parameter of Rayleigh fading and Weibull fading has been also established.

The use of Unmanned Aerial Vehicles (UAVs) in the field of wireless communications has seen a substantial growth. The terrains where terrestrial communication setup is difficult, or hotspot areas in need of network capacity, or areas where the terrestrial setup is disrupted due to natural calamities, the UAVs play a major role. We have derived a closed form expressions for outage probability of UAV communications over the Weibull fading channel using Decode and Forward (DF) protocol at the UAV, concerning both half duplex (HD) and full duplex (FD) architecture. Moreover, we present the impact of loop back self interference (SI) on the system performance in case of FD system and investigate its performance through outage probability and throughput.

Multipath fading, hidden terminal and shadowing are problems faced by users in non-cooperative type spectrum sensing techniques. A solution to this problem is Cooperative Spectrum Sensing (CSS) technique. CSS allows users to collaborate to perform spectrum sensing which may be managed by a common receiver. Further, it has two categories Distributed CSS (DCSS) and Centralized CSS (CCSS). In this paper these two schemes are compared with each other and different fusion rules are applied over them. Mathematical formulas for detection probability (P d ) of two fading channels namely Weibull and Hoyt are shown and further different fusion rules are applied on cluster-based CSS to explore the performance of centralized and distributed CSS. This concept has been earlier used for the conventional fading channels i.e. Rayleigh, Rician, Nakagami-m. In this paper results for cluster-based CSS are examined for comparatively lesser studied Weibull and Hoyt fading channels. It is noticed for different fusion rules, Weibull fading channel generates better performance as compared to Hoyt fading channel. This paper focuses on the implementation of four different fusion rules such as AND-AND, AND-OR, OR-AND along with centralized AND for these two fading channels. Results have shown that at SNR d ) than the Hoyt fading channel for all four fusion rules. It is noticed that the slope of the curve for Hoyt fading channel is steep as compared to Weibull fading channel and reaches to 0.9 P d at SNR>5dB for OR-AND and AND-OR rule, while with these fusion rules, Weibull fading channel attains 0.9 P d at SNR less than 0dB. OR-AND fusion rule gives the best result amongst all 4 fusion rules for both the channels.