Showing papers on "Fading distribution published in 2016"

Performance Analysis of Physical Layer Security Over Generalized- $K$ Fading Channels Using a Mixture Gamma Distribution

Abstract: In this letter, the secrecy performance of the classic Wyner's wiretap model over generalized-K fading channels is studied. The closed-form expressions for the average secrecy capacity, secure outage probability, and the probability of strictly positive secrecy capacity are derived. The new expressions provide a unified form, which can handle several of the well-known composite fading environments as special or limiting cases. Monte-Carlo simulations are performed to verify the proposed analysis models.

Physical-Layer Security Over Non-Small-Scale Fading Channels

Abstract: This paper investigates the performances of secure communications over non-small-scale fading channels. Specifically, considering three different cases when the main and eavesdropper channels experience independent lognormal fading, correlated lognormal fading, or independent composite fading, we study the average secrecy capacity and secrecy outage [including the probability of nonzero secrecy capacity (PNSC) and secure outage probability (SOP)] for these channel conditions. The approximated closed-form expressions for the average secrecy capacity, PNSC, and SOP are derived for these three different types of non-small fading channels. The accuracy of our performance analysis is verified by simulation.

Cooperative Wideband Spectrum Sensing Over Fading Channels

Abstract: In cognitive radio (CR) systems, it is crucial for secondary users to reliably detect spectral opportunities across a wide frequency range. This paper studies a novel multirate sub-Nyquist spectrum sensing (MS3) system capable of performing wideband spectrum sensing in a cooperative CR network over fading channels. The aliasing effects of sub-Nyquist sampling are modeled. To mitigate such effects, different sub-Nyquist sampling rates are applied such that the numbers of samples at different CRs are consecutive prime numbers. Moreover, the performance of MS3 over fading channels (Rayleigh fading and lognormal fading) is analyzed in the form of bounds on the probabilities of detection and false alarm. The key finding is that the wideband spectrum can be sensed using sub-Nyquist sampling rates in MS3 over fading channels, without the need for spectral recovery. In addition, the aliasing effects can be mitigated by the use of different sub-Nyquist sampling rates in a multirate sub-Nyquist sampling system.

Energy-Based Modulation for Noncoherent Massive SIMO Systems

Abstract: An uplink system with a single antenna transmitter and a single receiver with a large number of antennas is considered. We propose a single-shot noncoherent scheme which does not use the instantaneous channel state information (CSI), but rather only the knowledge of the channel statistics, a transmitter that modulates information only in the amplitude of the symbols, and a receiver which measures only the average received energy across the antennas. This system model is motivated by the simplicity of the circuit design and the energy efficiency it entails for both the transmitter and the receiver. We propose constellation designs which are asymptotically optimal with respect to symbol error rate (SER) with an increasing number of antennas, for any finite signal-to-noise power ratio (SNR), under different assumptions on the availability of CSI statistics. We describe in detail the case when there is a bounded uncertainty on the moments of the fading distribution. We present the numerical results on the SER performance achieved by these designs and find that they outperform the existing amplitude-modulation-based noncoherent scheme of amplitude shift keying (ASK). They also achieve a smaller peak-to-average power ratio (PAPR) for scenarios with a low SNR or a large line-of-sight (LOS) component.

Modeling of the Fading Statistics of Wireless Sensor Network Channels in Industrial Environments

Abstract: This paper presents an investigation of how to model the statistical properties of radio channels arising in industrial environments over long time horizons, e.g., hours and days. Based on extensive measurement campaigns, conducted at three different factory buildings, it is shown that for mobile transceivers the fading characteristics are Rayleigh or close to Rayleigh. However, for transceivers mounted at fixed locations, the use of conventional single fading distributions is not sufficient. It is shown that a suitable model structure for describing the fading properties of the radio channels, as measured by power, is a mixture of gamma and compound gamma-lognormal distributions. Furthermore, the complexity of the model generally increases with the observation interval. A model selection approach based on a connection between Kullback’s mean discrimination information and the log-likelihood provides a robust choice of model structure. We show that while a (semi)-Markov chain constitute a suitable model for the channel dynamics the time dependence of the data can be neglected in the estimation of the parameters of the mixture distributions. Neglecting the time dependence in the data leads to a more efficient parametrization. Moreover, it is shown that the considered class of mixture distributions is identifiable for both continuous and quantized data under certain conditions and under those conditions a maximum likelihood under independence assumption estimator is shown to give consistent parameters also for data which are not independent. The parameter estimates are obtained by maximizing the log likelihood using a genetic and a local interior point algorithm.

Quadrature Spatial Modulation Performance Over Nakagami- $m$ Fading Channels

Abstract: This paper analyzes the performance of the recently proposed quadrature spatial modulation (QSM) multiple-input-multiple-output (MIMO) system over Nakagami-m fading channel. In the analysis, the general distribution of the Nakagami-m channel phase is considered. In the literature, performance analysis of spatial modulation (SM) over Nakagami-m channel with uniform phase is conducted. However, apart from the very special case of m = 1, where Nakagami-m fading corresponds to Rayleigh fading, the phase of the Nakagami-m distribution is not uniformly distributed. It is shown in this paper that the phase of the channel has major impact on the performance of spatial multiplexing MIMO systems such as SM and QSM systems. A general upper bound expression for the average bit error ratio (ABER) performance of QSM is derived, and the impact of different channel parameters is studied. Monte Carlo simulation results are provided to corroborate the exactness of the derived analysis.

Performance Analysis of Digital Communication Systems Over $\alpha{-}\eta{-}\mu$ Fading Channels

Abstract: This paper analyzes and evaluates the performance of digital communication systems that operate over the $\alpha{-}\eta{-}\mu$ fading channels. More specifically, we derived novel, unified, and exact closed-form analytical expressions for the cumulative density function (CDF), the moment-generating function (MGF), the average channel capacity, and the average symbol error probability (SEP) for several coherent and non-coherent modulation schemes. Note that the derived expressions are valid for arbitrary values of the fading parameters. The derived expressions are then used to study the implication of the fading parameters on system performance. In addition, the performance over other well-known fading channels, such as $\eta{-}\mu$ and $\alpha{-}\mu$ , as well as their inclusive special cases, can be analyzed using our results. To validate the correctness of our derivations, the numerical results are compared with Monte Carlo simulation results. Both results are in perfect agreement over a wide range of average signal-to-noise ratio (SNR) and different values of the fading parameters.

Design of a New Differential Chaos-Shift-Keying System for Continuous Mobility

Abstract: Conventional differential chaos-shift-keying systems (DCSK) are not the most suitable for supporting continuous-mobility scenarios. Therefore, in this paper an improved continuous-mobility differential chaos-shift-keying system (CM-DCSK) is presented that provides greater agility and improved performance in fast fading channels without accurate channel estimation while still being simple compared to a conventional DCSK system. A new DCSK frame signal is designed to reach this goal. In our new frame design, each reference sample is followed by a data carrier sample. This modification of the system design reduces the hardware complexity of DCSK because it requires a shorter wideband delay line and significantly improves the performance over fast fading channels while keeping the non-coherent nature of the transmission system. Once the design is explained, the bit error rate performance is computed over a multipath fast fading channel and compared to the conventional DCSK system. Simulation results confirm the advantages of this new noncoherent spread-spectrum design that can support mobility.

Effective Rate Analysis in Weibull Fading Channels

Abstract: Recently, the theory of effective rate has attracted much attention, since it can take the delay aspect into account when performing channel capacity analysis. Weibull fading model is a flexible and practical model for describing fading channels in both indoor and outdoor environments. This letter derives the exact analytical expressions of effective rate over independent but not necessarily identical Weibull fading channels, which can be used in the system analysis in real-time communication scenarios. In addition, the closed-form asymptotic expressions under high signal-to-noise ratio (SNR) and low-SNR regimes are derived to provide useful insights into the effects of system and fading parameters on the effective rate.

Performance analysis of physical layer security over α–μ fading channel

Abstract: Recently, many works have focused on analyzing the metrics of physical layer security over different wireless channels, such as additive white Gaussian noise (AWGN), Rayleigh, Rician and Nakagami-m fading distributions. In order to extend the analysis to the general case, α-μ fading channel is considered, which can span the aforementioned cases. For this purpose, the physical layer security over α-μ fading channel is presented in this letter. The closed-form expressions for the probability of positive secrecy capacity and upper bound of the secrecy outage probability are derived. Their accuracies are assessed through comparison of theoretical analysis and simulations results.

Detection performance of cooperative spectrum sensing with hard decision fusion in fading channels

Abstract: In this paper, we investigate the detection performance of cooperative spectrum sensing (CSS) using energy detector in several fading scenarios. The fading environments comprise relatively less-studied Hoyt and Weibull channels in addition to the conventional Rayleigh, Rician, Nakagami-m and log-normal shadowing channels. We have presented an analytical framework for evaluating different probabilities related to spectrum sensing, i.e. missed detection, false alarm and total error due to both of them, for all the fading/shadowing models mentioned. The major theoretical contribution is, however, the derivation of closed-form expressions for probability of detection. Based on our developed framework, we present performance results of CSS under various hard decision fusion strategies such as OR rule, AND rule and Majority rule. Effects of sensing channel signal-to-noise ratio, detection threshold, fusion rules, number of cooperating cognitive radios (CRs) and fading/shadowing parameters on the sensing perform...

Online Power Control Optimization for Wireless Transmission With Energy Harvesting and Storage

Abstract: We consider wireless transmission over fading channel powered by energy harvesting and storage devices. Assuming a finite battery storage capacity, we design an online power control strategy aiming at maximizing the long-term time-averaged transmission rate under battery operational constraints for energy harvesting. We first formulate the stochastic optimization problem, and then develop techniques to transform this problem and employ techniques from Lyapunov optimization to design the online power control solution. In particular, we propose an approach to handle unbounded channel fade which cannot by directly dealt with by Lyapunov framework. Our proposed algorithm determines the transmission power based only on the current energy state of the battery and channel fade conditions, without requiring any knowledge of the statistics of energy arrivals or fading channels. Our online power control solution is a three-stage closed-form solution depending on the battery energy level. It not only provides strategic energy conservation through the battery energy control, but also reveals an opportunistic transmission style based on fading condition, both of which improve the long-term time-averaged transmission rate. We further characterize the performance bound of our proposed algorithm to the optimal solution with a general fading distribution. Simulation results demonstrate a significant performance gain of our proposed online algorithm over alternative online approaches.

Outage performance of cognitive cooperative networks with relay selection over double-Rayleigh fading channels

Abstract: This study considers a dual-hop cognitive inter-vehicular relay-assisted communication system where all communication links are non-line of sight ones and their fading is modelled by the double Rayleigh fading distribution. Road-side relays (or access points) implementing the decode-and-forward relaying protocol are employed and one of them is selected according to a predetermined policy to enable communication between vehicles. The performance of the considered cognitive cooperative system is investigated for Kth best partial and full relay selection (RS) as well as for two distinct fading scenarios. In the first scenario, all channels are double Rayleigh distributed. In the second scenario, only the secondary source to relay and relay to destination channels are considered to be subject to double Rayleigh fading whereas, channels between the secondary transmitters and the primary user are modelled by the Rayleigh distribution. Exact and approximate expressions for the outage probability performance for all considered RS policies and fading scenarios are presented. In addition to the analytical results, complementary computer simulated performance evaluation results have been obtained by means of Monte Carlo simulations. The perfect match between these two sets of results has verified the accuracy of the proposed mathematical analysis.

A Comprehensive Framework for Quadrature Spatial Modulation in Generalized Fading Scenarios

Abstract: In this paper, we present a comprehensive framework for quadrature spatial modulation (QSM) in generalized fading channels. In particular, the performance analysis of QSM systems in the presence of imperfect channel knowledge and under correlated fading channels is presented. A simple and closed-form expression for the pairwise error probability (PEP) is provided. Based on the obtained PEP, a closed-form upper bound expression for the average bit error probability (BEP) is obtained. The analysis is unified in the sense that it is applicable for any fading channel once its envelope and phase distributions are available. As such, different generalized fading distribution models, namely, $\eta $ – $\mu $ , $\kappa $ – $\mu $ , and $\alpha $ – $\mu $ distributions, are considered. The obtained results clearly show the influence of the fading parameters on the average BEP. In the case of the $\alpha $ – $\mu $ fading channels, increasing $\alpha $ has larger negative impact on the average BEP compared with increasing $\mu $ . For the $\kappa $ – $\mu $ channels, increasing $\mu $ results in increasing the average BEP dramatically when compared with increasing $\kappa $ . In the same context, in $\eta $ – $\mu $ fading channels, as $\mu $ increases the average BEP degrades whereas increasing $\eta $ slightly improves the average BEP. In addition, it is demonstrated that transmit-antenna correlation significantly deteriorate the average BEP when compared with receive-antenna correlation.

On the Performance of Multihop-Intervehicular Communications Systems Over n *Rayleigh Fading Channels

Abstract: We investigate the performance of multihop-intervehicular communication systems with regenerative and nonregenerative relaying. We consider the so-called “ n *Rayleigh distribution” as an adequate multipath fading channel model for vehicle-to-vehicle communication scenarios. We derive a novel approximation for the outage probability of maximum ratio combining (MRC) diversity reception. In addition, we analyze the amount of fading and optimize the power allocation for the investigated scenario. Numerical results show that regenerative systems are more efficient than nonregenerative systems when the cascading order ( ${{n}}$ ) is small; however, for large ${{n}}$ , our results demonstrate that the performance of both relaying techniques is rather similar.

Physical Layer Security for Multiple-Antenna Systems: A Unified Approach

Abstract: Secrecy capacity is a fundamental information-theoretic performance metric to predict the maximum data rate of reliable communication, while the intended message is not revealed to the eavesdropper. Motivated by this consideration in this paper, a unified communication-theoretic framework for the analysis of the probability of nonzero secrecy capacity, the secrecy outage probability, and the secrecy capacity of multiple-antenna systems over fading channels is proposed. Specifically, a powerful frequency-domain approach is first developed in which the integrals involved in the evaluation of the probability of nonzero secrecy capacity and secrecy outage probability are transformed into the frequency domain, by employing Parseval’s theorem. A generic approach for the evaluation of the asymptotic secrecy outage probability at high signal-to-noise ratio (SNR) region is also introduced, thus providing useful insight as to the parameters affecting the secrecy performance. Finally, a unified numerical approach for computing the average secrecy capacity of multiple-antenna systems under arbitrary fading environments is developed. The proposed framework is general enough to accommodate any well-known multiantenna transmission technique and fading model. Finally, the secrecy performance of several multiple-antenna system setups is assessed, in the presence of generalized fading conditions and arbitrary antenna correlation, while various numerical and computer simulation results are shown and compared to substantiate the proposed mathematical analysis.

Spectrum Sensing With Multiple Primary Users Over Fading Channels

Abstract: We investigate the impact of multiple primary users (PUs) and fading on the spectrum sensing of a classical energy detector (ED). Specifically, we present the novel closed-form expressions for the false-alarm and detection probabilities in a multiple PUs environment, assuming the Nakagami- $m$ fading and complex Gaussian PUs transmitted signals. The results reveal the importance of taking into consideration the wireless environment, when evaluating the ED spectrum sensing performance and selecting the ED threshold.

Kalman Filtering With Relays Over Wireless Fading Channels

Abstract: This note studies the use of relays to improve the performance of Kalman filtering over packet dropping links. Packet reception probabilities are governed by time-varying fading channel gains, and the sensor and relay transmit powers. We consider situations with multiple sensors and relays, where each relay can either forward one of the sensors' measurements to the gateway/fusion center, or perform a simple linear network coding operation on some of the sensor measurements. Using an expected error covariance performance measure, we consider optimal and suboptimal methods for finding the best relay configuration, and power control problems for optimizing the Kalman filter performance. Our methods show that significant performance gains can be obtained through the use of relays, network coding and power control, with at least 30–40% less power consumption for a given expected error covariance specification.

The Fluctuating Two-Ray Fading Model for mmWave Communications

Abstract: We introduce the Fluctuating Two-Ray (FTR) fading model, a new statistical channel model that consists of two fluctuating specular components with random phases plus a diffuse component. The FTR model arises as a natural generalization of the two-wave with diffuse power (TWDP) fading model proposed by Durgin, Rappaport and de Wolf; in this extended model, the two specular components exhibit a random amplitude fluctuation. Unlike in the TWDP model, we show that all the chief probability functions of the FTR fading model (PDF, CDF and MGF) can be expressed in closed-form. We also show that the FTR fading model provides a much better fit than the Rician fading model for recent small-scale fading measurements of the 28 GHz outdoor millimeter-wave channels.

Coverage Analysis In Downlink Poisson Cellular Network With $\kappa$-$\mu$ Shadowed Fading

Abstract: The downlink coverage probability of a cellular network, when the base station locations are modelled by a Poisson point process (PPP), is known when the desired channel is Nakagami distributed with an integer shape parameter However, for many interesting fading distributions such as Rician, Rician shadowing, $\kappa$-$\mu$, $\eta$-$\mu$, etc, the coverage probability is unknown $\kappa$-$\mu$ shadowed fading is a generic fading distribution whose special cases are many of these popular distributions known so far In this letter, we derive the coverage probability when the desired channel experiences $\kappa$-$\mu$ shadowed fading Using numerical simulations, we verify our analytical expressions

The Capacity of Gaussian MIMO Channels Under Total and Per-Antenna Power Constraints

Abstract: The capacity of a fixed Gaussian multiple-input multiple-output (MIMO) channel and the optimal transmission strategy under the total power (TP) constraint and full channel state information are well-known. This problem remains open in the general case under individual per-antenna (PA) power constraints, while some special cases have been solved. These include a full-rank solution for the MIMO channel and a general solution for the multiple-input single-output (MISO) channel. In this paper, the fixed Gaussian MISO channel is considered and its capacity as well as optimal transmission strategies are determined in a closed form under the joint total and per-antenna power constraints in the general case. In particular, the optimal strategy is hybrid and includes two parts: first is equal-gain transmission and second is maximum-ratio transmission, which are responsible for the PA and TP constraints respectively. The optimal beamforming vector is given in a closed-form and an accurate yet simple approximation to the capacity is proposed. Finally, the above results are extended to the MIMO case by establishing the ergodic capacity of fading MIMO channels under the joint power constraints when the fading distribution is right unitary-invariant (of which i.i.d. and semi-correlated Rayleigh fading are special cases). Unlike the fixed MISO case, the optimal signaling is shown to be isotropic in this case.

Energy detection based spectrum sensing over η-λ-μ fading channel

Abstract: This paper investigates the performance of Energy detection based spectrum sensing over η-λ-μ fading distribution. Novel analytic expressions are derived for average probability of detection. These results for single user detection are then extended to square low selection (SLS) diversity and for collaborative detection case. Since η-λ-μ includes the Nakagami-m, the Rayleigh, the one-sided Gaussian, Hoyt, the λ-μ and the η-μ distributions as special cases, the analysis for η-λ-μ distribution provides analysis for all these fading channels. The analysis for fading is then extended to composite fading and shadowing. Receiver operating characteristic (ROC) curves are presented for different scenarios using the derived expressions. Effect of different parameters on the average probability of detection is analyzed.

A Tractable Model for Turbulence- and Misalignment-Induced Fading in Optical Wireless Systems

Abstract: Composite models for the combined effect of both scintillation- and misalignment-induced fading in terrestrial optical wireless systems are often expressed in terms of higher order special functions, making, thus, the performance evaluation of such links quite complicated. In order to overcome this problem, we propose the mixture Gamma distribution as an accurate approximation of the turbulence effect. Then, a tractable mixture distribution is deduced, for the statistical description of the composite scintillation/pointing error effects. Some statistical metrics of the new model are also derived in closed form, which provides insight information for the system design.

Experimental Characterization of Radio Channel in Ruins Environment

Abstract: This letter addresses the fading statistics of a radio propagation channel in a ruins environment, which is of vital importance for a pedestrian localization system based on cellphone signals The channel of ruins is investigated in eight typical rescue scenarios at two common mobile communication bands (900 MHz and 18 GHz) To characterize the channel, an empirical path loss model is parameterized through experiments Based on extensive measurements, large-scale fading characteristics at different polarizations and various antenna heights are examined and analyzed Furthermore, the properties of small-scale fading including coherence bandwidth, decorrelation distance, and distance-dependent features are studied in this work The results reported here can be applied to simulate the ruins channel and design the rescue system

Capacity Analysis of Two-Wave With Diffuse Power Fading Channels Using a Mixture of Gamma Distributions

Abstract: In this letter, we analyze the capacity of a class of generalized fading channels represented by two-wave with diffuse power (TWDP) fading models. We obtain a new representation of TWDP fading model as a mixture of gamma distributions and apply the new representation to the approximate evaluation of TWDP channel capacity under different transmission policies. We also present upper bounds on approximation errors.

Performance of Multihop Wireless Networks in $\alpha$ - $\mu$ Fading Channels Perturbed by an Additive Generalized Gaussian Noise

Abstract: In the literature, the performance of multihop wireless networks is extensively analyzed over various fading channels subject to an additive white Gaussian noise (AWGN). However, and to the best of authors’ knowledge, the generalized Gaussian noise case has not been considered before. Motivated by this, we therefore analyze the system performance—in terms of the average bit error rate—of a multihop wireless communication system that operates over the $\alpha$ - $\mu$ fading channels perturbed by an additive white generalized Gaussian noise (AWGGN). To this end, we obtain an exact closed-form expression for the average bit error rate (BER) for $M$ -ary quadrature amplitude modulation ( $M$ -QAM) over the $\alpha$ - $\mu$ fading channels with AWGGN. Some representative numerical results are presented to study the influence of the fading parameters, as well as the influence of the shaping noise parameter. These results are supported with Monte-Carlo simulations to validate our analysis.

Unified Stochastic Geometry Modeling and Analysis of Cellular Networks in LOS/NLOS and Shadowed Fading

Abstract: Statistical characterization of the signal-to-interference-plus-noise ratio (SINR) via its cumulative distribution function (CDF) is ubiquitous in a vast majority of technical contributions in the area of cellular networks since it boils down to averaging the Laplace transform of the aggregate interference, a benefit accorded at the expense of confinement to the simplistic Rayleigh fading. In this work, to capture diverse fading channels that appear in realistic outdoor/indoor wireless communication scenarios, we tackle the problem differently. By exploting the moment generating function (MGF) of the SINR, we succeed in analytically assessing cellular networks performance over the shadowed {\kappa}-{\mu}, {\kappa}-{\mu} and {\eta}-{\mu} fading models. The latter offer high flexibility by capturing diverse fading channels including Rayleigh, Nakagami-m, Rician, and Rician shadow fading distributions. These channel models have been recently praised for their capability to accurately model dense urban environments, future femtocells and device-to-device (D2D) shadowed channels. In addition to unifying the analysis for different channel models, this work integrates, for the first time, the coverage, the achievable rate, and the bit error probability (BEP), which are largely treated separately in the literature. The developed model and analysis are validated over a broad range of simulation setups and parameters.

Performance of Turbo Coded OFDM Under the Presence of Various Noise Types

Abstract: A telecommunication system uses carriers in order to transmit information through a cable or wirelessly. If each time only one carrier is transmitted, then the system's signal will not be immune to frequency selective fading. If frequency selective fading includes the working frequency of the system, then the wireless link will not be established. Orthogonal frequency division multiplexing (OFDM) is the primary solution for coping with inter-signal interference and frequency-selective fading. Many carriers can be produced by splitting a fast information stream to slower data series. Different orthogonal frequencies carry slower data series. System's performance can be further enhanced with the utilization of turbo codes. Turbo codes make the system more immune to noise effects with excellent BER results. This paper presents the thorough analysis of a turbo coded OFDM scheme using a PCCC technique in the presence of a channel which includes AWGN, phase noise, Rayleigh fading, Rician fading and Doppler shift.

On the Effective Capacity of Amplify-and-Forward Multihop Transmission Over Arbitrary and Correlated Fading Channels

Abstract: This letter presents a novel approach for analyzing, in a unified way, the effective capacity performance of multihop transmission with channel state information assisted amplify-and-forward relay systems over arbitrary and correlated fading channels under a maximum delay constraint. Using a moment generating function based approach, an exact single integral expression for the effective capacity is deduced. This expression can be easily evaluated by means of standard numerical integration techniques for a great deal of fading distributions, such as the Nakagami- $m$ , Generalized- $\mathcal{K}$ , and Generealized Gamma. Several case studies, including uncorrelated and correlated fading environments, are employed to demonstrate the versatility of the proposed analytical approach. Extensive numerically evaluated results accompanied with complimentary Monte-Carlo simulations are used to substantiate the analytical derivations.