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Introduction: In this paper, we consider a fundamental problem of testing faced by the health staff on testing COVID 19 patients. In general, the number of testing kits or testing capabilities is limited, and the number of COVID 19 patients is much larger than that. This paper tries to answer this fundamental question that how to perform COVID 19 testing to reduce the death rate. Materials and Methods: We consider that the survival rate of patients is dependent over two parameters: their age and severity of symptoms at a time. Based on these observations, we propose a survival rate function. Using the survival rates, the death rate for an individual is obtained. MATLAB was used for plotting the graphs. Results: It is shown by numerical results that by using the proposed mechanism, the average death rate can be significantly reduced. Conclusion: It is proposed to conduct the testing for those patients who lie in the high death rate regimen.

The strong dependency of the free-space optical (FSO) communication systems on the line-of-sight link put forward an inevitable challenge. Motivated by this fact, in this work, we aim to present and analyze a practical approach to model and design the intelligent reflecting surface (IRS)-assisted FSO communication system incorporating the impact of random misalignment. Contrary to the existing literature, an insightful IRS-assisted FSO model is proposed to envision the impact of the crucial system parameters. To this end, we propose a geometric and misalignment loss (GML) model that incorporates the random statistical modeling of the angle of incidence and the angle of reflection corresponding to the transmitted laser beam. Therefore, the proposed GML model allows us to inspect a realistic transmission and reception scenario of an IRS-assisted FSO system. Moreover, unlike the existing works, we consider independent fading statistics between the laser source (transmitter)-IRS link and IRS-photodetector (receiver) link. All these considerations allow us to envision the performance of a practical IRS-assisted FSO system. Several analytical closed-form expressions corresponding to the statistical distribution functions concerning the proposed GML model are also derived. Our derived closed-form expressions can be used as mathematical tools to examine the performance of an IRS-assisted FSO system under random misalignment. Further, our key findings indicate that under the impact of the random misalignment, the non-orthogonality of the lens with respect to the beam-line significantly impacts the system performance. Furthermore, simulation results validate the presented analysis and reveal unprecedented insights for the proposed IRS-assisted FSO system design.

Abstract Index modulation utilizes spatial dimensions for transmission of information in multiple‐input multiple‐output (MIMO) molecular communication systems. Molecular space shift keying (MSSK) is an IM‐based technique that modulates information in the antenna index and efficiently combats both intersymbol interference and interlink interference in molecular MIMO systems. In this paper, generalized form of the MSSK scheme, that is, generalized MSSK (GMSSK) is proposed which activates a fixed number of antennas for information transmission. The antenna constellation is selected judiciously to minimize the chances of errors in the proposed GMSSK strategy. Design guidelines are provided for the GMSSK antenna constellation for the case of two activated antennas at the transmitter side. Exploiting an additional degree of freedom, the presented GMSSK scheme is shown to achieve reasonably close or better error performance with a smaller antenna array size as compared to the traditional MSSK scheme.