Theses and Dissertations

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    Digital implementation of orthogonal frequency division multiplexing
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2017) Bhanushali, Artiben; Pillutla, Laxminarayana; Bhatt, Amit
    "OFDM (Orthogonal Frequency Division Multiplexing) is the most important part of 4G and 5G technology which is adopted by many standards because of its various advantages. In this thesis, firstly prototype of OFDM system is designed according to 802.11a standard in MATLAB to check its performance and then to implement the same in Verilog using Xilinx ISE 14.4 design suite. FFT (Fast Fourier Transform) and IFFT (Inverse Fast Fourier Transform) are the most complex part of the design which are implemented using radix-2 algorithm. For channel estimation, scattered pilot arrangement is used to insert pilots at regular period in OFDM frame. At receiver side, least-square estimation is used to estimate the channel’s impulse response at known pilot tones. The system analysis is done using MATLAB-Verilog co-simulation in which Verilog transmitter and receiver are connected with MATLAB channel using testbench to generate the text files. This files are used as connecting platform between MATLAB and Xilinx. Performance of channel estimation at different number of multipath is observed which shows that the combination of time interpolation followed by frequency interpolation performs better over only frequency interpolation. In later part, BER (bit error rate) vs. SNR (signal to noise ratio) is analyzed for different number of multipath. From graphs, it is clearly denoted that, BER performance improves with respect to increase in SNR. Finally, fixed point and floating point comparison is carried out which depicts that fixed point system implemented in Verilog performs almost similar to the floating point implementation done in MATLAB."
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    ItemOpen Access
    WideBand Dielectric Resonator Antenna at Ultra High Frequency (UHF) Band
    (Dhirubhai Ambani Institute of Information and Communication Technology, 2017) Karavadra, Raju; Ghodgaonkar, Deepak K.
    "Dielectric Resonator antennas are widely used because of their low loss, high efficiency, small size and wider bandwidth.Now a days several research institutes make antenna with,low-profile design, wider operational bandwidth, circular polarized radiations, high gain and, modified shape. Recently Hybrid DRA and shaped DRA are developed. In DRAs main characteristic parameters are wider bandwidth and compact in size. In our design stacking technique used. Using these method we get wider bandwidth and small size. In this DRA we use one segment below Dielectric resonator and one more segment above the Dielectric Resonator and triangular part is removed and fill these part with air. In the designing of DRA two stackes are made of materials TMM10 and FR4/Epoxy. one more material used with high Dielectric Constant for midian dielectric. By using conducting plate on the one face of the DRA, size of the antenna is reduce by 50% and we get compact antenna. In our design we get the return loss below 10dB in the frequency range of 0.75 GHz to 1.65 GHz and gain of the DRA is above 0dB in the frequency range of 0.65 GHz to 1.8 GHz and theoretical resonance frequency of the DRA is 1.3 GHz and radiation pattern and beam width approximately 60 degrees."