Faster than Nyquist signaling and analysis of Its performance under uncoded/coded transmission systems
1University of Oulu, Faculty of Information Technology and Electrical Engineering, Department of Communications Engineering, Communications Engineering
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|Master's thesis (tech)
The future demand of increased transmission rate and bandwidth efficiency is of prime concern in the modern wireless communication systems. Faster than Nyquist signaling (FTN) is under the great interest of research to address this issue of high data rate, which is also a major requirement, for the fifth generation (5G) communication networks. The data bits are transmitted at a rate higher than the conventional methods which are bounded by the Nyquist condition and the outputs are compared so as to analyze the benefits. Receiver processing techniques are implemented to achieve the high data rate with improved error performance at the lower decoding complexity. Considering the bandwidth efficiency as a key factor, more data symbols are sent at the given time interval by reducing the time period for signal transmission. This ensures more data being transmitted. In the scenario of perfect Nyquist signaling, pulse designs were based on the principle of orthogonality. The signal pulse form h(t) is orthogonal with respect to shifts by nT, where T is the signaling interval. In the thesis, the time period is reduced to T < 1, which prompt more symbols to be transmitted. The pulses are no longer orthogonal. These non orthogonal FTN signals are accepted as a promising approach for the required solution of increased data rate. FTN comes as a tradeoff between the high data rate achievement and error probability. Reduction of the time factor affirms good data rate but at the same time, cost of high error rate has to be paid. Efficient receiver processing techniques are designed to compensate between these two factors. Main obstacle due to the reduction of time period in FTN signaling is to tackle the unavoidable inter symbol interferences (ISI). Going beyond the Nyquist bound, as a consequence, results high ISI. This necessitates an effective receiver processing to overcome the ISI. Minimum mean square error (MMSE) detection algorithm is employed to equalize the received signals and analyze the performance of the FTN system. Finally, the system portrayal is studied by processing the results under the implementation of turbo coding systems. The bit error rate (BER) characteristics are analyzed under these circumstances. Efficient encoding pattern and decoding algorithm helps in reducing the errors. Analysis of the simulation results show that the turbo code proficiency is improved by increasing the number of iterations. Performance indication is also related to the frame size or the interleaver size and the signal power. In other words, it comes as a trade-off between energy efficiency, bandwidth efficiency, complexity and error rates. Furthermore, for the fair comparison of the performance analysis, transmission rates for turbo coded transmission systems under the conditions of Nyquist signaling and FTN signaling are made equivalent.
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