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The wireless communication system is one of the most favorable fields of communication in computer science because of its mobility and dynamicity. But it is very important to use some efficient techniques in terms of bandwidth and speed to cope with the wide range of user's demands. In order to fulfill these demands, Orthogonal Frequency Division Multiplexing (OFDM) multicarrier technique holds some magnificent features namely multipath fading, delay spread, frequency selective fading, and inter channel interference (ICI). In this paper, the performance of OFDM system is analyzed to lessen the multipath fading and the inter symbol interference (ISI) over an Additive White Gaussian Noise (AWGN). We find out the variation of the output signal after removing unnecessary noise and bit error rate (BER) of the input signal using AWGN, and it shows better results for BER curve for Binary Phase Shift Keying (BPSK) in the OFDM system.

Multiple-input Multiple-output (MIMO) systems use multiple antennas at the transmitter and receiver end, are a key technology to meet the growing demand for high data rate wireless systems. The aim of this thesis is to investigate MIMO system capacity with the aim of achieving optimum Bit Error Rate (BER) while increasing the system capacity using multicarrier delay diversity modulation (MDDM), proposed for fifth generation systems. In principle, the capacity of MIMO system can increase linearly with the number of antennas. Multiple antennas at the transmitter and receiver provide diversity in a fading environment. Furthermore, the research work in this thesis consists of different investigations of the basic principle of MIMO, Multiple-input Single-output (MISO) and Single-input Single-output (SISO) wireless communication systems with Space Time Codes (STC). A MISO systems and MIMO systems are schematized using MDDM which incorporated with Orthogonal Frequency Division Multiplexing (OFDM). OFDM is chosen over a single-carrier solution due to lower complexity of equalizers for high delay spread channels or high data rates. The design is implemented with binary Phase Shift Keying (BPSK) and simulated using MATLAB, which is examined in associated Additive White Gaussian Noise (AWGN) channel. The receiver-design is included with the maximal ratio combiner (MRC) receiving technique with perfect wisdom of channel state information (CSI). The theoretical performance is derived for AWGN channels and compared with the simulated results as well as compared between each system to another.

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The aim of this work is to measure the effect of band-gap on TiO2 thin films by changing tetrabutylorthotitanate (TBOT), diethanolamine (DEA), and temperature. The sol-gel method is experimentally introduced to find out the better band-gap of TiO2 thin films by varying the concentration of TBOT (4 ml to 10 ml), DEA (2 ml to 5 ml), and temperature (350°C to 650°C). With the help of an ultraviolet-visible spectrophotometer for the wavelength of 300-900 nm, these thin films are characterized concerning optical properties (transmittance spectra, absorbance spectra, direct band-gap, and indirect band-gap). The direct and indirect band-gaps are found 3.38 eV and 3.25 eV respectively, which are close to or within the standard band-gap range of TiO2 (3.2 eV to 3.35 eV) and are found at 8 ml TBOT, 3 ml DEA, and a temperature of 550°C.