Sanjay Kumar Soni

In this work, the mathematical characterization of the cascaded fading channel based on multiplicative modeling is discussed. The proposed cascaded probability density function is derived by taking the product of statistically independent, but not necessarily identically distributed fading random variables, which encompasses various well‐known distributions as cascaded Nakagami‐m, Hoyt, and Rayleigh distributions. In particular, other statistical measures such as cumulative distribution function, moment generating function, and moment of the cascaded channels, are developed. This set of derived results is further utilized in studying the reliability performance of the wireless cascaded fading channels. The system reliability is comprehensively investigated through various statistical metrics like average symbol error probability, ergodic capacity, outage probability, and effective capacity. All the developed results are of intractable univariate Foxs H‐function form. The accuracy of the numerical results is extensively validated through Monte‐Carlo simulation.

Summary: Closed‐form statistics are highly desirable in wireless communications. With this motivation, this work presents the closed‐form expressions for the fundamental statistics of generalizedα‐η‐μ/Inverse‐Gamma (I‐Gamma) composite distribution. The proposed distribution encompasses well‐knownη‐μ/I‐Gamma,α‐μ/I‐Gamma and other variants. First, we derive a novel closed‐form expression for the probability density function (PDF), cumulative distribution function (CDF), and generalized moment generating function (MGF). Further, generalized MGF is utilized to access system performance with diversity reception. In addition, the high power solutions for derived performance metrics are also provided. The analytical findings of the paper are compared with the numerical results and also with the Monte Carlo simulation results to confirm their accuracy.

Multiple antennas are usually employed to improve the performance of the wireless communication system. To this context, we derive the effective capacity (EC) expressions for Inverse Gamma (I-Gamma) shadowed fading channel, employing maximal ratio combining (MRC) and selection combining (SC) diversity schemes at the receiver (Rx) side. The channels are assumed to be independent and identical distributed (i.i.d.). In addition to this, we also propose the simplified high-power approximation that enables direct interpretation of the system performance concerning system fading parameters. Furthermore, to diminish the effect of shadowing over composite statistics, macroscopic diversity analysis is presented as an application, where Weibull, and I-Gamma models are used to obtain composite statistics. At last, we validate our proposed formulations through the Monte-Carlo simulation.

Summary: The advancements towards the 5G technology are significantly reliant on the effective utilization of the radio spectrum. The scarcity of the spectrum is a barrier to the employment of emergent wireless multimedia. The cognitive radio (CR) technology has materialized as a reassuring remedy to the present problem of spectral scarcity. This study explores the statistical characterization of energy detector‐based cognitive radio device alongside diversity reception. The analysis is carried out with the postulation that the transmitting signal encounters fading, characterized by α‐μ fading channel. Initially, we present a PDF expression of the α‐μ fading model when subjected to maximal ratio combining (MRC) diversity reception. Utilizing this expression, the closed‐form expression of the average probability of detection (P_d) and the average area under the receiver operating characteristics curve (AUC) are derived in the terms of Fox's H function. The detection threshold has been optimized to improve the detection performance by curtailing the probability of error. Additionally, asymptotic results for P_d with various diversity combining cases are also obtained under high signal‐to‐noise‐ratio (SNR) regime. Furthermore, the result of P_d is applied to explore the execution of cooperative spectrum sensing (CSS) with diversity reception. The accuracy and validation of the presented results are assured by comparison with the Monte Carlo simulation.

Summary: In this work, we have comprehensively investigated the impact of non‐linearity (α − μ) and shadowing (inverse gamma) collectively over the wireless channel. To this effect, an approximate closed‐form probability density function (PDF) expression is derived over α − μ/inverse gamma fading channel by employing Gauss–Laguerre quadrature polynomial. The accuracy of the proposed approximate solution is validated through the Kullback–Leibler divergence test. Subsequently, the proposed solution is utilized in the development of various fundamental statistics like commutative distribution function (CDF), moment generating function (MGF) and nth moment. This contribution also includes the derivation of coding gain and diversity gain to study average symbol error probability (SEP) with MRC and EGC diversity. It is observed that diversity gain is independent of shadowing and as the channel condition improves, the coding gain decreases. Finally, the closed‐form solutions of spectral efficiency under different adaptive transmission policies are also developed specifically, optimal power and rate adaptation (OPRA) and effective capacity along with simpler low‐ and high‐power expressions. Monte‐Carlo simulations are utilized to validate the proposed analytical and numerical results.