Selection Diversity Reception Research Articles

IRS-Enhanced Energy Detection for Spectrum Sensing in Cognitive Radio Networks

Energy detection is of crucial importance in cognitive radio networks. However, its performance is poor when the channel fading is severe, which causes interference to the primary users. In order to tackle this issue, an intelligent reflecting surface (IRS)-enhanced energy detection for spectrum sensing is proposed. Both the cases with and without the direct link between the primary user and the secondary user are considered. By using the Gamma distribution approximation and central limit theorem, the closed-form expressions for the average probability of detection are derived. In order to further improve the detection performance, IRS-enhanced energy detection for cooperative spectrum sensing and multiple IRSs-enhanced square-law selection diversity reception are also proposed. Expressions for the average probability of detection for these two schemes are provided by using the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${K}$ </tex-math></inline-formula> -rank fushion criterion and square-law selection, respectively. Simulation results verify our theoretical analysis and demonstrate the superiority of our proposed IRS-enhanced energy detection compared with the benchmark schemes in terms of the spectrum sensing performance.

Cooperative Spectrum Sensing with Selection Diversity Reception in Cognitive Radio

Spectrum sensing is the key component of cognitive radio technology. But, detection is compromised when a user reports shadowing or fading consequences. In such instances, the customer cannot apprehend between an unexploited band and a profound fade. Hence, communal spectrum sensing is suggested to optimize sensing overall performance. We recognition performance of communal Spectrum Sensing with Selection Diversity Reception in Cognitive Radio. This study presents a simulation evaluation of choice diversity Reception based totally on the fusion rule. The fusion rule is finished at the fusion center (FC) to make the very last selection about the presence of PU. This leads that spectrum sensing is enthusiastically in the presence of Rayleigh.

Entropy and Energy Detection-Based Spectrum Sensing Over $\mathcal{F}$ -Composite Fading Channels

In this paper, we investigate the performance of energy detection-based spectrum sensing over $\mathcal {F}$ composite fading channels. To this end, an analytical expression for the average detection probability is first derived. This expression is then extended to account for collaborative spectrum sensing, square-law selection diversity reception, and noise power uncertainty. The corresponding receiver operating characteristics (ROC) are analyzed for different conditions of the average signal-to-noise ratio (SNR), noise power uncertainty, time-bandwidth product, multipath fading, shadowing, number of diversity branches, and number of collaborating users. It is shown that the energy detection performance is sensitive to the severity of the multipath fading and the amount of shadowing, whereby even small variations in either of these physical phenomena can significantly impact the detection probability. As a figure of merit to evaluate the detection performance, the area under the ROC curve (AUC) is derived and evaluated for different multipath fading and shadowing conditions. Closed-form expressions for the differential entropy and cross entropy are also formulated and assessed for different average SNR, multipath fading, and shadowing conditions. Then, the relationship between the differential entropy of $\mathcal {F}$ composite fading channels and the corresponding ROC/AUC is examined where it is shown that the average number of bits required for encoding a signal becomes small (i.e., low differential entropy) when the detection probability is high or when the AUC is large. The difference between composite fading and traditional small-scale fading is emphasized by comparing the cross entropy for Rayleigh and Nakagami- $m$ fading. A validation of the analytical results is provided through a careful comparison with the results of some simulations.

Novel Results for the Multivariate Ricean Distribution With Non-Identical Parameters

This paper studies the multivariate Ricean distribution, which is the most important distribution for modeling the magnitude of the received signal when line-of-sight propagation conditions exist. In this paper, assuming different mean values for the Ricean distributed random variables, generic expressions for the multivariate Ricean probability density function, cumulative distribution function, and the joint moments are derived in terms of integral representations. As an application example, these results have been used to analyze the performance of a multi-branch selection diversity receiver, operating in spatially correlated Ricean fading environment. Moreover, an asymptotic closed-form expression has been also provided, which approximates quite well to the exact one, and has been used to study various performance metrics. Finally, a complexity analysis has been performed and simulation results have been also presented.

An integrated performance evaluation of ED‐based spectrum sensing over α−κ−μ and α−κ−μ‐Extreme fading channels

AbstractThis paper presents a comparative performance evaluation of energy detector (ED) under the assumption that the propagation signal experiences fading modeled by the nonlinear generalized α−κ−μ or α−κ−μ‐Extreme fading channels. Novel closed‐form analytical expressions for the average probability of detection and the average area under the receiver operating characteristic (ROC) curve (AUC) are derived in terms of the now highly prevalent bivariate Fox H‐function under single‐user spectrum sensing, cooperative spectrum sensing, and square law selection diversity reception. The results derived in the present work are generic as both channel models are compound distributions containing as special cases several other well‐known fading models such as the Nakagami‐m, Rice, the one‐sided Gaussian distribution, and the Weibull distribution, among others. The performance of ED is evaluated by employing the traditional ROC and AUC curves over additive white Gaussian noise by varying model parameters and observing system performances. Analytical results are verified via Monte Carlo simulations in MATLAB®.

Performance of ED Based Spectrum Sensing Over α–η–μ Fading Channel

Internet of things contains the hefty number of devices communicating with each other; give rise to the problem of spectrum scarcity. Cognitive radio has emerged as the promising solution to this problem. Spectrum sensing is the important function of cognitive radio and energy detector is the most popular technique used for spectrum sensing. In this paper, the performance of energy detector (ED) over α–η–μ fading channel has been analyzed. The analytical expressions for average probability of detection and average area under the receiver operating characteristics curve (AUC) are derived for the generalized fading channel in terms of the bivariate Fox H-function. The closed-form mathematical expressions for the average probability of detection for cooperative spectrum sensing as well as square law selection diversity reception are derived. The implication of the system parameters on the performance of ED is studied in terms of complimentary receiver operating characteristics and AUC. It is shown that the performance of ED can be improved when cooperation and diversity are employed. The derived results are generic and can be directly used for the performance analysis of η–μ and α–μ fading channels and their special cases. Monte-Carlo simulations are incorporated for validating the accuracy of the derived results.

MGF Approach Based Analysis Of Energy Detection In &lt;sub&gt; K -M&lt;/sub&gt; Shadowed Fading Channels And Diversity Receivers

In this paper, the performance of Energy Detection (ED) over K-M shadowed fading channel is investigated using the Moment Generating Function (MGF) of the received Signal-to-Noise Ratio (SNR). The K-M shadowed is a generic composite fading channel of K- M fading and which represents the impact of multipath in line-of sight (LoS) communication scenario and Nakagami - m distribution. The study is then extended to include Maximal Ratio Combining (MRC), Square Law Combining (SLC), and Square Law Selection (SLS) diversity receivers. The simulation and numerical results for the Complementary Receiver Operating Characteristics (CROC) and average Area under the CROC (CAUC) curves are given for different scenarios and compared with some previous works. These results show an improvement in the overall detection capability of ED is noticed when the diversity receptions are employed. In contrast to previous works which are limited by the values of the fading parameters, the proposed approach is not restricted by any condition.

Energy Detection based Spectrum Sensing over Two-wave and Diffuse Power Fading Channels

One of the most important factors that affects the performance of energy detection (ED) is the fading channel between the wireless nodes. This paper investigates the performance of ED-based spectrum sensing, for cognitive radio (CR), over two-wave with diffuse power (TWDP) fading channels. The TWDP fading model characterizes a variety of fading channels, including well-known canonical fading distributions, such as Rayleigh and Rician, as well as worse-than-Rayleigh fading conditions modeled by the two-ray fading model. Novel analytic expressions for the average probability of detection over TWDP fading that account for single-user and cooperative spectrum sensing and square law selection diversity reception are derived. These expressions are used to analyze the behavior of ED-based spectrum sensing over moderate, severe, and extreme fading conditions and to investigate the use of cooperation and diversity as a means of mitigating the fading effects. The obtained results indicate that TWDP fading conditions can significantly degrade sensing performance; however, it is shown that detection performance can be improved when cooperation and diversity are employed. The presented outcomes enable identifying the limits of ED-based spectrum sensing and quantifying the tradeoffs between detection performance and energy efficiency for CR systems deployed within confined environments, such as in-vehicular wireless networks.

Mobile Communication Systems in the Presence of Fading/Shadowing, Noise and Interference

In this paper, the effects of interference on composite fading environments, where multipath fading coexists with shadowing, are investigated. Based on some mathematical convenient expressions for the sum of squared K-distributed random variables, which are derived for the first time, important statistical metrics for the signal to interference and noise ratio (SINR) are studied for various cases including non identical, identical and fully correlated statistics. Furthermore, our analysis is extended to multi-channel receivers and in particular to selection diversity (SD) receivers, investigating two distinct cases, namely, signal-to-noise ratio based and SINR-based SD. For all scenarios, simplified expressions are also provided for the interference limited case, where the influence of thermal noise is ignored. The derived expressions are used to analyze the performance, in terms of the average bit error probability (ABEP) and the outage probability (OP), of such systems operating over composite fading environments. A high SNR analysis is also presented for the OP and the ABEP, giving a clear physical insight of the system's performance in terms of the diversity and coding gains. The analysis is accompanied by numerical evaluated results, clearly demonstrating the usefulness of the proposed theoretical framework.

Energy detection of unknown signals in Gamma‐shadowed Rician fading environments with diversity reception

This study presents a comprehensive performance analysis of an energy detector over Gamma-shadowed Rician fading channels, namely Rician fading channels with the fluctuating line-of-sight components following the Gamma distribution. This composite multi-path/shadowing model has been shown to provide a remarkably accurate fading characterisation while leading to closed-form expressions for important channel statistics. Rapidly convergent infinite series representations are firstly derived for the average probability of detection and the area under the receiver operating characteristic curve for the no-diversity reception case. These results are then extended to the case of maximal ratio, equal gain and selection diversity. To this end, novel analytical expressions for the statistics of the end-to-end signal-to-noise ratio of equal gain and selection diversity receivers, operating over Gamma-shadowed Rician fading channels are derived. Analytical results are substantiated by Monte Carlo simulation, as well as by extensive numerically evaluated results.

Unified analysis of energy detectors with diversity reception in generalised fading channels

In this paper, the authors present a novel moment generating function-based technique to unify the performance evaluation of an average energy detector for detecting unknown deterministic signals over generalised fading environments (including the η-μ, κ-μ, α-μ, K, G and KG generalised fading distributions) with diversity reception. Specifically, the authors exploit a known exponential-type integral representation for the generalised Marcum Q-function Qv (a, b) that is valid for any ratio of a/b but for positive integer order v to greatly simplify the task of finding the statistical expectations over the fading signal-to-noise ratio random variables in the computation of the average detection probability metric. This new approach leads to a very compact and an elegant solution for many practical cases of interest including the independent but non-identically distributed fading statistics and/or arbitrarily correlated diversity branches in maximal-ratio combining, square-law combining and square-law selection diversity receivers. The authors’ numerical results also show that the performance of average energy detector is superior to the classical total energy detector with the increasing number of samples owing to the noise averaging effect. We have also demonstrated the versatility and utility of the proposed analytical framework to investigate the impact of dissimilar mean signal strengths, fading parameters, time-bandwidth product, diversity order and signal combining techniques on the receiver operating characteristics of diversity energy detectors in a myriad of fading environments that had heretofore resisted simple solutions.

Adaptive hybrid ARQ for mode switching receiver in wireless cellular networks

In this paper, an adaptive error control (AEC) scheme is developed for a switched–and–stay combiner (SSC) of a dual–branch selection diversity receiver. It relies on a type–I hybrid combination of selective repeat SR–ARQ and BCH coding at the data link layer. The model is then called adaptive error control based switched–and–stay combiner (AEC–SSC) in mobile cellular networks. The aim is to provide maximal achievable throughput when AEC–SSC is employed in Rayleigh flat–fading channel. The results show that significant redundancy coding has a reasonable effect on the overall throughput performance. In contrary, the adaptive channel coding influences significantly on the lower range of operating channel SNR in hybrid ARQ compared to non–adaptive ARQ scheme.

Spectral efficiency of adaptive transmission and selection diversity on generalised fading channels

The spectral efficiency of L-branch selection diversity (SD) receiver with different adaptive transmission techniques operating over generalised-Gamma (GG) fading channels is studied. Novel expressions for important adaptive transmission techniques are obtained, namely optimal power and rate adaptation, optimal rate adaptation, channel inversion with fixed rate (CIFR) and truncated CIFR. Furthermore, simplified expressions for the capacities are obtained for SD reception in Nakagami-m as well as Weibull fading channels. The derived closed-from expressions extend previously published results to the GG fading model. Numerical results are given to demonstrate the usefulness of the theoretical approach.

Performance evaluation of selection diversity receivers over arbitrarily correlated generalised Gamma fading channels

The performance of multibranch selection diversity (SD) receivers over L arbitrarily correlated generalised Gamma (GG) fading channels is analysed and evaluated. Following a statistical approach previously proposed for the multivariate Nakagami-m distribution, a closed-form upper bound for the joint GG probability density function (PDF) and an infinite series upper bound for the joint GG cumulative distribution function (CDF) are obtained. For the special case of the trivariate GG distribution (L=3), exact expressions in the form of infinite series for the PDF and CDF are presented. The derived bounds are used to obtain tight upper bounds for the distribution of the SD output signal-to-noise ratio (SNR). Furthermore, based on the derived analysis, novel analytical expressions that accurately approximate the distribution of the SD output SNR are presented. The bounds and approximations are used to study important performance criteria of SD receivers such as outage and average symbol error probability. The accuracy of the derived expressions has been verified, on the one hand, analytically for triple-branch (L=3) and, on the other hand, by means of computer simulations for multibranch (L&gt;3) SD receivers.

Capacity of Correlated Generalized Gamma Fading With Dual-Branch Selection Diversity

The capacity of correlated generalized gamma (GG) fading channels with dual-branch selection diversity (SD) reception and channel side information (CSI) available at both the transmitter and the receiver is studied and analyzed. In particular, the capacity is evaluated under four adaptive transmission policies defined according to the operational CSI: 1) optimal power and rate adaptation (OPRA); 2) constant power with optimal rate adaptation (ORA); 3) channel inversion with fixed rate (CIFR); and 4) truncated CIFR (TIFR). Under these four adaptation policies, fast converging infinite series expressions for the capacity are derived and evaluated. Furthermore, for the simplifying cases of independent GG fading channels and/or single-channel reception (i.e., no diversity), closed-form expressions have been obtained. Previously published expressions are shown to be special cases of the derived expressions. Performance evaluation results obtained by means of numerical analysis clearly demonstrate the usefulness and accuracy of the analysis.

Performance of S + N Selection Diversity Receivers in Correlated Rician and Rayleigh Fading

The performances of two signal-plus-noise (S + N) selection diversity receivers employing noncoherent M-ary frequency shift keying (MFSK) in slow, flat, correlated Rayleigh and Rician fading channels are examined. The branches are assumed to be equally correlated for Rician fading. The correlation model for Rayleigh fading is more general than the equally correlated scenario and includes it as a special case. Analytical expressions are derived for the average symbol error rate (SER) and the average bit error rate (BER) of each receiver structure. Extensive Monte Carlo simulation results are presented to validate the analytical expressions. The performances of the S + N SC receivers are compared to the performance of the classical SC receiver. The effects of correlation, average fading power imbalance and diversity order on the performances of the S + N SC receivers are examined.

On the Correlated $K$-Distribution With Arbitrary Fading Parameters

The correlated bivariate K-distribution with arbitrary and not necessarily identical parameters is introduced and analyzed. Novel infinite series expressions for the joint probability density function and moments are derived for the general case where the associated bivariate distributions, i.e., Rayleigh and gamma, are both arbitrary correlated. These expressions generalize previously known analytical results obtained for identical parameter cases. Furthermore, considering independent gamma distributions, the cumulative distribution and characteristic functions are analytically obtained. Although the derived expressions can be used in a wide range of applications, this letter focuses on the performance analysis of dual branch diversity receivers. Specifically, the outage performance of dual selection diversity receivers operating over correlated K fading/shadowing channels is analytically evaluated. Moreover, for low normalized outage threshold values, closed-form expressions are obtained.

A novel reconfigurable microstrip antenna and its performance analysis in diversity reception system

AbstractA novel reconfigurable microstrip antenna with the capability of switching among four polarization senses is described. An analysis framework for assessing the performance of antenna selection diversity reception system with the proposed reconfigurable antenna is also presented for the first time. © 2007 Wiley Periodicals, Inc. Microwave Opt Technol Lett 49: 2516–2519, 2007; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.22795

Performance Analysis of Optimum and Suboptimum Selection Diversity Schemes on Rayleigh Fading Channels With Imperfect Channel Estimates

In this paper, we present a comparative analysis on the effects of channel estimation errors on the performance of optimum and suboptimum selection diversity (SD) receivers on Rayleigh-fading channels. By modeling the estimation errors as independent complex Gaussian random variables, we derive simple closed-form expressions for the average probability of error for both optimum and suboptimum SD schemes with noisy channel estimates. With dual diversity and imperfect estimates, we establish a connection between optimum SD and maximal-ratio combining (MRC), and between suboptimum SD and equal-gain combining diversity schemes. Interestingly, we show that the optimum SD receiver structure and the resulting performance for differential binary coherent phase-shift keying (DBPSK) signaling can be obtained, in a straightforward way, as a special case of the performance of the optimum SD scheme with binary PSK signaling and channel estimation errors. For a fixed average power and bit duration, in conjunction with pilot-assisted minimum mean-square error channel estimation, we show that the optimum coherent SD scheme coincides with that of the optimum noncoherent SD scheme with binary frequency-shift keying (BFSK) signaling, whereas the coherent MRC scheme coincides with the optimum noncoherent receiver (i.e., the square-law combiner) for BFSK. The optimum number of diversity channels, under an energy-sharing mode of operation, is also studied. Finally, we formulate the problem of optimal pilot placement, consider channel estimation with a practical pilot-symbol-assisted modulation technique, and present some numerical results illustrating the comparative performances of various SD receivers

Comments on “Average LCR and AFD for SC diversity over correlated Weibull fading channels”

In a recent paper, two formulae for the average level crossing rate and fade duration at the output of dual-branch selection diversity receivers have been derived. In this short communication, some previously published works including results being in a more general setting are reviewed and compared.