Showing papers on "Fading distribution published in 2023"
TL;DR: In this article , the Gaussian mixture distribution was proposed as a suitable small-scale fading model for outdoor terahertz (THz) wireless links, where multiple outdoor THz wireless measurements recorded at different transceiver separation distance were fed to an expectation-maximization fitting algorithm, which returned the parameters of the GM probability density function.
Abstract: Abstract Terahertz (THz) band offers a vast amount of bandwidth and is envisioned to become a key enabler for a number of next generation wireless applications. In this direction, appropriate channel models, encapsulating the large and small-scale fading phenomena, need to be developed for both indoor and outdoor communications environments. The THz large-scale fading characteristics have been extensively investigated for both indoor and outdoor scenarios. The study of indoor THz small-scale fading has recently gained the momentum, while the small-scale fading of outdoor THz wireless channels has not yet been investigated. Motivated by this, this contribution introduces Gaussian mixture (GM) distribution as a suitable small-scale fading model for outdoor THz wireless links. In more detail, multiple outdoor THz wireless measurements recorded at different transceiver separation distance are fed to an expectation-maximization fitting algorithm, which returns the parameters of the GM probability density function. The fitting accuracy of the analytical GMs is evaluated in terms of the Kolmogorov-Smirnov, Kullback-Leibler (KL) and root-mean-square-error (RMSE) tests. The results reveal that as the number of mixtures increases the resulting analytical GMs perform a better fit to the empirical distributions. In addition, the KL and RMSE metrics indicate that the increase of mixtures beyond a particular number result to no significant improvement of the fitting accuracy. Finally, following the same approach as in the case of GM, we examine the suitability of mixture Gamma to capture the small-scale fading characteristics of the outdoor THz channels.
2 citations
TL;DR: In this paper , power control in an RS-coded orthogonal frequency division multiplex (OFDM) system with error-and-erasure correction decoding in Rayleigh fading channels was investigated.
Abstract: Power control in an RS-coded orthogonal frequency division multiplex (OFDM) system with error-and-erasure correction decoding in Rayleigh fading channels was investigated. The power of each symbol within a codeword was controlled to reduce the codeword error rate (WER). Several RS-coded OFDM systems with power control are proposed. The WERs of the proposed systems as a function of the signal-to-noise ratio per bit were derived. We found that channel inversion at the transmitter in combination with the erasure generation by ordering fading amplitudes at the receiver provided the lowest WER among the considered systems. Furthermore, the erasure generation by ordering fading amplitudes was found to be better than the erasure generation by comparing fading amplitudes with a threshold.
TL;DR: In this paper , a finite signal-to-noise ratio hyper-Rayleigh mode (fHRM) metric was proposed for the generalized multipath fading channel analysis, and the proposed metric was applied to analyze the performance of the communication link physical layer security in terms of the probability of strictly positive secrecy capacity.
Abstract: The research studies hyper-Rayleigh behavior of a wireless communication system functioning in the presence of the generalized multipath fading. Although the initial metric (hyper-Rayleigh mode (HRM)) is quite informative, it is defined only asymptotically (i.e., for the infinitely increasing SNR). In spite of mathematical simplifications brought by such a definition (i.e., in this case most of the performance characteristics defining the HRM can be easily evaluated), it sufficiently limits its applications since, evidently, the real-life systems function in the presence of a finite (and usually not very high) SNR. The study presents a novel approach to the fading channel analysis (i.e., finite signal-to-noise ratio hyper-Rayleigh mode (fHRM)). The proposed metric (fHRM) is studied on the newly presented channel model-fluctuating double-Rayleigh with Line-of-Sight (fdRLoS) fading model. To accomplish this, the novel expressions for two channel-dependent system characteristics (i.e., the Amount of Fading (AoF) and the Outage Probability (OP)) were derived in exact form valid for arbitrary fading parameters. Based on the derived expressions, the finite SNR hyper-Rayleigh map is obtained, which helps to identify the parameters’ values corresponding to the specific propagation scenarios, which were further deployed to analyze the problem of the communication link physical layer security quantified in terms of the probability of strictly positive secrecy capacity (SPSC). Numerical verification of the derived closed-form expressions was performed. Several peculiarities of the system performance are observed and discussed.
14 Mar 2023
TL;DR: In this paper , the performance of UAV communications in the terahertz (THz) networks is analyzed under different fading channels which are major influence factors in the THz communication channel modeling.
Abstract: <p> Unmanned aerial vehicles (UAVs) are safer than manned vehicle and raise the interest to researchers for their huge applications in 5G and upcoming 6G. In 6G, terahertz (THz)-band communications can be used for fast communication. In this paper, the THz wireless communication between UAVs is considered. The performance of UAVs communications in the THz networks is analyzed under different fading channels which are major influence factors in the THz communication channel modeling. It is crucial to assess the performance of wireless devices taking into account their structure, wireless channel parameters, and transmission characteristics. Log-normal Fading, Weibull Fading Channel, Nakagami-m Fading Channel, Rician Fading Channel and Rayleigh Fading Channel are taken into account. Performance influencing parameters are considered and analytical expressions concerning capacity, outage probability, and bit error rate (BER) are obtained. Numerical results are presented which verify the analytical analysis. </p>
23 Feb 2023
TL;DR: In this paper , the collective impact of misalignment fading and multi-path fading in a Terahertz wireless network in the presence of Rician fading was analyzed and closed-form calculations for coverage, ergodic capacity, and probability of error, taking both ideal and non-ideal RF front-end instances into consideration.
Abstract: Terahertz frequencies are highly likely to be deployed for indoor use cases (like in femtocells) and fading in such a line-of-sight environment can be modelled using Rician distribution. In this paper, we analyze the collective impact of misalignment fading and multi path fading in a Terahertz wireless network in the presence of Rician fading. We first derive the probability density function (PDF) and cumulative distribution function (CDF) of the product of Rician multi path and misalignment fading. These results were used to derive closed-form calculations for coverage, ergodic capacity, and probability of error, taking both ideal and non-ideal RF front-end instances into consideration. The simulation was used to validate the outcomes of the derived analysis. These expressions have helped us easily explore the joint impact of different parameters corresponding to multi-path fading, misalignment fading, and non-ideal RF front-end effects on these metrics.
22 May 2023
TL;DR: In this article , an analysis of outage probability for selection combining (SC) receiver with multiple branches, used to mitigate these disturbances in the system, is carried out. And the expressions for probability density function (PDF), cumulative distribution function (CDF) and outage probability are derived.
Abstract: For realistic assessment of any wireless communication system performance an accurate modeling of this system is necessary. Till now, no many distributions were found to be able to characterize a channel with both, the line of sight (LOS) and the non-LOS (NLOS) components. One of such distribution unifying the non-central chi, generalized Rician and $\kappa -\mu$ distributions into a single fading distribution is Beaulieu-Xie distribution. Beaulieu-Xie fading, as disturbance in wireless system, will be considered in this work. Beside fading, co-channel interference (CCI) modeled by Rayleigh distribution, is present. An analysis of outage probability for selection combining (SC) receiver with multiple branches, used to mitigate these disturbances in the system, will be carried out. The expressions for probability density function (PDF), cumulative distribution function (CDF) and outage probability will be derived. A few graphs will be plotted and based on them an impact of fading and CCI parameters will be highlighted.
TL;DR: In this article , the exact closed-form expressions of the ARS fading channels capacity were derived for various coherent and non-coherent modulation schemes and the outage probability were also derived.
Abstract: The two-sided bimodality property of Alternate Rician Shadowed (ARS) fading channels makes it a suitable fading model for body-centric wireless communication. The ARS fading model consists of two fluctuating specular components in which only one is active at a time. To provide excellent spectral efficiency with higher quality of service, system transmitter employs an adaptive transmission scheme. This paper derives the exact closed-form expressions of the ARS fading channels capacity. Various adaptive transmission schemes such as channel inversion with a fixed-rate, truncated channel inversion with a fixed-rate, and optimal rate adaptation are considered. A comparison of these schemes is also highlighted. Performance expressions such as binary bit error rate for various coherent and non-coherent modulation schemes and the outage probability are also derived. The derived results are plotted and analyzed for varying fading parameters of the ARS channel. Finally, the results of all performance metrics are verified with Monte-Carlo simulation results.
21 Feb 2023
TL;DR: In this article , the performance of UAV communications in the terahertz (THz) networks is analyzed under different fading channels which are major influence factors in the THz communication channel modeling.
Abstract: <p> Unmanned aerial vehicles (UAVs) are safer than manned vehicle and raise the interest to researchers for their huge applications in 5G and upcoming 6G. In 6G, terahertz (THz)-band communications can be used for fast communication. In this paper, the THz wireless communication between UAVs is considered. The performance of UAVs communications in the THz networks is analyzed under different fading channels which are major influence factors in the THz communication channel modeling. It is crucial to assess the performance of wireless devices taking into account their structure, wireless channel parameters, and transmission characteristics. Log-normal Fading, Weibull Fading Channel, Nakagami-m Fading Channel, Rician Fading Channel and Rayleigh Fading Channel are taken into account. Performance influencing parameters are considered and analytical expressions concerning capacity, outage probability, and bit error rate (BER) are obtained. Numerical results are presented which verify the analytical analysis. </p>
TL;DR: In this paper , the authors proposed two tag-based PHY-layer authentication schemes under a frequency selective fading channel, where the negative effect caused by a frequency-selective fading channel is compensated for.
Abstract: Physical Layer Authentication (PLA) in wireless systems has drawn much attention because it can provide information-theoretic security. However, the performance of the prior PLA schemes significantly declines under a frequency selective fading channel and the theoretical analysis of a PLA scheme becomes extremely challenging under a frequency selective fading channel as compared to that under a frequency flat fading channel. This paper addresses the problem of authenticating transmitters at the physical layer under a frequency selective fading channel. We propose two tag-based PLA schemes under a frequency selective fading channel. The first scheme is the Generalized Tag-based PLA (GT-PLA) scheme, where the negative effect caused by a frequency selective fading channel is compensated for. If the channel reciprocity holds, we will propose the second scheme to further improve the performance of the GT-PLA scheme, named the Adaptive Generalized Tag-based PLA (AGT-PLA) scheme. We provide the theoretical analysis of both proposed schemes over wireless fading channels in terms of robustness, security, and compatibility, and derive their closed-form expressions. Moreover, we implement the proposed schemes and conduct extensive performance comparisons. Our experimental results demonstrate that the GT-PLA scheme achieves higher robustness over the prior PLA schemes while the AGT-PLA scheme can further improve the performance of the GT-PLA scheme in terms of robustness, security, and compatibility.
TL;DR: In this article , the impact of three Rician and Rician fading channel scenarios on cooperative communication performance in which a relay uses energy harvesting based on power splitting (EH-PS) was analyzed.
Abstract: Channel conditions strongly influence the performance of the wireless communication system. Fading is one of the main problems caused by signal propagation via various paths. Recently, cooperative communication systems have been extensively studied to overcome this problem. However, the power consumption in the system relaying information to the destination increases, shortening the network's life. Therefore, this paper analyzes the impact of three Raleigh and Rician fading channel scenarios on cooperative communication performance in which a relay uses energy harvesting based on power splitting (EH-PS). The three scenarios are Rayleigh-Rayleigh fading (I), Rician- Rayleigh fading (II), and Rician-Rician fading (III). Subsequently, the throughput performance and energy efficiency are evaluated based on the maximum power splitting (PS) ratio. The simulation results indicate that the PS ratio in scenario III is higher than in scenarios I and II. Thus, the Rician fading channel can accumulate more energy in the relay due to the line-of-sight path between the source and the relay. Hence, scenario III's throughput and energy efficiency are higher than the other scenarios. The energy efficiency for scenario III is 33.08% and 12.14% higher than scenarios I and II, respectively. Therefore, the EH-PS cooperative communication system with the Rician fading channels has the highest throughput and is promising for future 5G technology.
TL;DR: In this article , the effects of different shadowing parameters are explored, and corresponding results are plotted in terms of channel capacity, outage analysis, and ABER for dual-shadowed Rician fading channels.
Abstract: In the wireless network, many physical conditions may arise where received signal power is shadowed by moving objects along the propagation paths, and further shadowing of the received signal may result from moving objects around the transmitters or receivers. This phenomenon is mathematically modelled in terms of the double (or dual) shadowing process brought about by fading channels where both dominant and scattered wave components fluctuate together. In this present study, the outcome aspects of dual-shadowed wireless fading channels are explored in accordance with outage analysis, channel capacity, and average bit error rate (ABER) for coherent as well as non-coherent modulation schemes. Here, the Rician envelope, which undergoes two shadowing effects, is assumed. The channel format described here is such that both dominant and scattered signals are impacted by the Nakagami m random variable (RV). As a model, the mathematical expressions are derived for channel capacity, outage analysis, and ABER for dual-shadowed Rician fading channels. The effects of different shadowing parameters are explored, and corresponding results are plotted. All the evaluative results are recognised by emulating the simulation results for various values of the fading parameters.
22 Mar 2023
TL;DR: In this paper , the authors investigated the possibility of achieving a positive zero-outage secrecy capacity (ZOSC) for a wiretap channel with fading gains from finite alphabet sets, and proposed a systematic scheme to calculate the minimum secrecy outage probability by solving linear programming problems.
Abstract: When a transmitted signal encounters slow fading and the support of the fading gain contains zero, an outage event will happen inevitably, if the transmitter has no knowledge of the channel state. This will deteriorate the system performance metrics such as latency due to re-transmissions caused by the outages. For scenarios like this, we use the outage probability or the outage capacity to measure the system performance. In this work, we investigate the possibility of achieving a positive zero-outage secrecy capacity (ZOSC) for a wiretap channel with fading gains from finite alphabet sets. In particular, we investigate the minimum secrecy outage probability with respect to all possible joint distributions of the fading gains, given their marginal distributions. We propose a systematic scheme to calculate the minimum secrecy outage probability by solving linear programming problems. From this, the maximum ZOSC of the considered wiretap channel model directly follows. Interestingly, we find that scenarios with a ZOSC of zero for independent fading can support a positive ZOSC when the fading links are dependent.
15 Mar 2023
TL;DR: In this article , a novel simulation model for fading over the land mobile satellite (LMS) channel is developed, which has given first and second-order characteristics, and the accuracy of the developed simulator by confirming the analytical results for the probability density function (PDF), level crossing rate (LCR), average fade duration (AFD), and autocorrelation function (ACF) of the fading envelope.
Abstract: In this paper, we develop a novel simulation model for fading over the land mobile satellite (LMS) channel. Using this model, we generate fading samples that have given first and second-order characteristics. We demonstrate the accuracy of the developed simulator by confirming the analytical results for the probability density function (PDF), level crossing rate (LCR), average fade duration (AFD), and autocorrelation function (ACF) of the fading envelope.
12 May 2023
TL;DR: In this article , a dual quantized ILC was proposed to further reduce the deviation before and after channel fading while ensuring convergence, where two separate quantizers are used to relieve the transmission pressure and reduce the error caused by the channel fading.
Abstract: In the field of stochastic Iteration Learning Control (ILC) people tend to treat channel fading and data quantization as two separate random disturbances. In this paper, we give an analysis of the convergence of quantized ILC in the presence of channel fading. In addition, we design a dual quantized ILC, which can further reduce the deviation before and after channel fading while ensuring convergence. In the dual quantized ILC, two separate quantizers are set before and after the channel fading. The first quantizer is designed to relieve the transmission pressure; the second quantizer is designed to reduce the error caused by the channel fading. Here we use the multiplicative fading factor to describe the channel fading. We adjust the quantization interval of the quantizer to ensure that the dual quantized ILC has a greater probability of smaller errors than the quantized ILC. Illustrative simulations are provided to verify the theoretical results.
TL;DR: In this paper , a wireless analog feedback communication system (AFCS) using a Rayleigh fading channel is considered in forward transmission while AWGN was considered in the feedback channel and the performance of the system was evaluated based on the minimization of mean square error (MSE) at the receiver.
Abstract: In this work, we mathematically model a wireless Analog feedback communication system (AFCS) using a Rayleigh fading channel. AFCS system is a new research area and has promising applications, especially in low-power devices such as sensors. Compared to AWGN, Rayleigh fading channel more closely models the real wireless environment. In this work, AFCS Rayleigh fading channel is considered in forward transmission while AWGN is considered in the feedback channel. We evaluated the performance of the system which is mostly based on the minimization of mean square error (MSE) at the receiver. Even in presence of a wireless fading environment, the AFCS attains a 0 MSE value in 2-3 iterations if a noise power of 10dB is considered while in 10-15 iterations if a noise power of 20dB is considered.
01 Jan 2023
TL;DR: In this article , the authors derived the probability density function of the channel fading with zero-boresight pointing errors and derived the outage probability and the average bit error rate of the considered system.
Abstract: This paper presents the performance analysis for THz transmissions by considering a novel channel fading model for outdoor THz transmission with the combined effect of zero-boresight pointing error. We consider the recently proposed Gaussian mixture fading for outdoor THz transmissions to model the small-scale fading. We derive the probability density function of the channel fading with zero-boresight pointing errors. Using the derived PDF, we derived the outage probability and the average bit error rate (BER) of the considered system. We validate the derived analytical expressions with Monte Carlo simulations and demonstrate the effect of various system and channel parameters on the performance for single THz wireless communications.
09 May 2023
TL;DR: In this paper , the authors introduced and characterized a natural generalization of the Two-Wave with Diffuse Power (TWDP) fading model, by allowing that the incident waves arrive in different clusters.
Abstract: We introduce and characterize a natural generalization of the Two-Wave with Diffuse Power (TWDP) fading model, by allowing that the incident waves arrive in different clusters. The newly proposed model, referred to as the Multi-cluster Two-Wave (MTW) fading model, generalizes both the TWDP and the kappa-mu models under a common umbrella. The special case on which the model parameters reach extreme values is also analyzed, aimed to model harsh fading conditions reported in experimental measurements obtained in enclosed environments. The chief probability functions of both the MTW and the MTW Extreme fading models are obtained, including the probability density function, the cumulative distribution function and the generalized moment-generating function. A number of applications for these models are exemplified, including outage probability in interference-limited scenarios, energy detection, and composite fading modeling.
TL;DR: In this paper , the secrecy performance of amplify and forward (AF) relaying with triple selection over real valued Nakagami fading channels was analyzed and the secrecy outage probability was derived.
Abstract: This paper analyzes the secrecy outage probability of amplify and forward (AF) relaying with triple selection over real valued Nakagami fading channels. This paper derives the new upper bound cumulative distribution function expressions of the proposed system for the received signal to noise ratio in which maximal ratio combining and selection combining receivers are considered. Further, this paper derives the lower bound and asymptotic expressions for the secrecy outage probability. An interesting numerical result is that the secrecy performance of the AF relaying with selection combining is superior to the AF relaying with maximal ratio combining over arbitrary Nakagami fading channels.
21 Feb 2023
TL;DR: In this paper , the performance of UAV communications in the terahertz (THz) networks is analyzed under different fading channels which are major influence factors in the THz communication channel modeling.
Abstract: <p> Unmanned aerial vehicles (UAVs) are safer than manned vehicle and raise the interest to researchers for their huge applications in 5G and upcoming 6G. In 6G, terahertz (THz)-band communications can be used for fast communication. In this paper, the THz wireless communication between UAVs is considered. The performance of UAVs communications in the THz networks is analyzed under different fading channels which are major influence factors in the THz communication channel modeling. It is crucial to assess the performance of wireless devices taking into account their structure, wireless channel parameters, and transmission characteristics. Log-normal Fading, Weibull Fading Channel, Nakagami-m Fading Channel, Rician Fading Channel and Rayleigh Fading Channel are taken into account. Performance influencing parameters are considered and analytical expressions concerning capacity, outage probability, and bit error rate (BER) are obtained. Numerical results are presented which verify the analytical analysis. </p>
TL;DR: In this article , the average number of required bits are derived by calculating Shannon entropy for each case investigated and the number of measurements required for distribution reconstruction based on CS reduced complexity method is also computed.