Pateshwari Singh

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.

The field of Molecular Astrophysics or “Astrochemistry” has grown considerably since its inception in the late 1930’s. Molecules have been observed in astronomical environments as diverse as comets in the solar system and galaxies at the highest redshifts. The common thread in these studies is that molecules are excellent probes of the physical structure and dynamics of such regions, owing to the complexity of their energy level structure and the resulting emission and absorption spectra. In addition, the chemical characteristics provide a powerful tool to study the evolution of astrophysical regions. Molecules also play an active role in the energy balance of clouds. Interstellar space is a unique laboratory in which chemical processes can occur that are not normally found on Earth. Indeed, astrochemistry is a highly interdisciplinary subject, linking the macrocosm (galaxies, stars, planets) with the microcosm (basic chemical processes and spectroscopy). The increased potential of ground- and space-based observational facilities over the full wavelength range provides a wealth of information about the physical environments in which molecules occur and makes it possible to study the development of molecular complexity throughout the Universe.