Closed-form statistics are highly desirable in wireless communication while analyzing system performance. Nevertheless, at a few instances, the mathematical intricacy introduced by the probability density function (PDF) limits the analysis of the system. In this context, asymptotic analysis has been entertained in wireless communication to obtain the approximate closed-form statistics of the system performance metrics under high-power regime. With this motivation, the asymptotic framework for exponentiated Weibull (EW) distribution has been presented. First, the origin PDF for EW distribution is proposed. Later, the earlier derived result is utilized in obtaining asymptotic results for the average bit error rate (BER). In addition, we also provide a mathematical framework with maximal ratio combining and selection combining diversity over the average BER. In addition, aperture averaging technique is also implemented over the aforesaid asymptotic results for further improvements in system performance. The results of the asymptotic analysis have been validated using the Monte–Carlo simulation.
We have theoretically modeled the “giant” colloidal core–shell quantum dot with strain adapting alloyed interfacial layer between core and shell materials for optoelectronic applications. The intersubband optical properties, such as absorption coefficients (ACs), refractive index changes (RICs), oscillator strength, and transition lifetime of giant CdSe / CdSexS1 − x / CdS core–interfacial–shell quantum dot (g-CISQD) have been investigated for different alloying “x” of the interfacial layer with varying core radius. The results have been plotted considering the significant impact of strain between the heterojunctions and compared for different structural parameters. The results show that the oscillator strength and transition lifetime strongly depend on alloying x and core radius. The energy eigenvalue in g-CISQD decreases with increasing x and saturates beyond the value x = 0.5. The resultant redshift of the resonant peak in ACs and RICs is concurrence with the obtained energy eigenvalues. Further, the ACs and RICs have been investigated for different intensities of incident light ( I ) and core radius variation. The results provide the tuning possibility of the optical properties using appropriate alloying x and core radius for application in optoelectronic devices.
Intersubband transition energy is computed for both core-shell quantum dot (CSQD) and binary capped core-shell quantum dot (CCSQD) of cubic geometry by solving the time-independent Schrodinger equation using the finite difference method. The discretization of the structures in all three spatial directions generates sparse Hamiltonian matrices, which are diagonalized to obtain energy eigenstates for the conduction band. The transition energy for the lowest three energy eigenstates is compared for different structural parameters considering GaAs / Al0.42Ga0.58As CSQDs. CSQD capped with AlAs (CCSQD) viz GaAs / Al0.42Ga0.58As / AlAs shows higher eigenstates and transition energy, which decreases with the increase in core thickness. Furthermore, the optical properties of these structures have been investigated which are in concurrence with the obtained eigen energy. The broader tuning range and blueshifted higher absorption coefficient of CCSQD support significant application in quantum dot detectors and lasers.
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