Browsing by Author "Sharfuddin, Md."

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    Analysis of LTE Radio Parameters based on Present and Future Networks
    (Department of Electrical and Electronic Engineering, Islamic University of Technology,Board Bazar, Gazipur, Bangladesh, 2019-11-15) Javed, Farhan; Nabil, Masudur Rahman; Sharfuddin, Md.
    Scheduler scheme in 4G LTE and its future releases, LTE-A an LTE-A Pro, is a major parameter which has direct impact on the UE demands (e.g. throughput) and efficiency. While deploying a new network at a particular site, we have to consider as to what scheduler needs to be adopted. Transmission mode, on the other hand, indirectly decides how much UE and also coverage area can be provided by the base stations (eNodeB). An extensive study of what transmission modes & scheduler are to be chosen for different sites, has been made in our book. The analysis was carried out by a MATLAB based noncommercial simulator where a downsized version of the original source was used, incorporating all the necessary network parameters, to better understand impacts of changing network parameter in a practical environment. Necessary simulations were carried out and results were observed. Based on the speculations, we reached some inferences, of which the most significant would be that, no one transmission mode or scheduler configuration is the absolute best. It all depends on what goals are to be achieved for a network at a particular site. Another work was based on study of NOMA, a transmission technique based on PDMA, whose main focus is to increase the number of UE per cell, by using the power domain, i.e. the UE will have different power levels according to their position. Here a general discussion along with some drawbacks (ICI) and their possible feasible solutions were described in this book. Since, 5G network aims to provide a higher bandwidth with an increased number of users, NOMA is one of the feasible choices in terms of transmission techniques over OFDMA, due to its capability to accommodate higher number of users
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    Fabrication and characterization of ZNS buffer layer for thin film solar cell using chemical bath deposition (CBD) method
    (University of Dhaka, 2016-11-13) Sharfuddin, Md.
    Zinc sulfide thin films were prepared by chemical bath deposition technique using zinc sulfate (ZnSO 4 .7H 2 O) and thiourea [SC(NH 2 ) 2 ] as sources of Zn 2+ and S ions, and ammonia (NH 3 ) and hydrazine hydrate (N 2 H ) as complexing agents. ZnS is an important semiconductor compound of excellent physical properties such as wide band-gap energy of 3.7 eV at 300 K, high refractive index (2.35 at 632 nm), transparent to practically all wavelengths of the solar spectrum, non-toxic and environmentally friendly buffer materials that are suitable for industrial production. A very attractive method for producing ZnS thin films, due to the possibility of large-area deposition at low cost is the chemical bath deposition (CBD) method. Chemical bath deposition (CBD) is known to produce solar cell grade films at simpleness, convenience, a low cost and low temperature. The depositions were carried out by varying PH of bath solution from 9.3 to 10.1 and keeping bath temperature fixed at 70 °C for two hours. The thickness of the films was tuned between 72 nm to 319 nm by controlling the ammonia and thiourea concentration. The structural, stoichiometric proportion, morphology and optical properties of the ZnS thin films were investigated as a function of thiourea and ammonia concentrations using X-ray diffraction (XRD), energy-dispersive spectroscopy (EDS), scanning electron microscopy (SEM) and UV- visible spectro-photometry measurements. X-ray diffraction analysis of the as-deposited films showed that the films have amorphous structure and poor crystallinity. Energydispersive spectroscopy (EDS) showed that all ZnS thin films exhibited both Zn and S. The UV–visible spectrophotometric measurement showed that, the transmittance of the ZnS thin films vary from 45% to 65%, while the band gap vary from 3.85 eV to 3.89 eV for different ammonia and thiourea concentration.