| Summary: | 碩士 === 大同大學 === 通訊工程研究所 === 101 === Orthogonal frequency division multiplexing (OFDM) is an efficient technique for high-speed data rate wireless transmission systems because of high spectral efficiency and robust to multipath fading. One of the main drawbacks of OFDM systems is the high peak-to-average power ratio (PAPR) in the transmitted signals. Partial transmit sequences (PTS) scheme is a very attractive scheme because it has good PAPR reduction performance without any distortion in the transmitted signals for OFDM systems. However, the conventional PTS scheme requires high computational complexity for finding the optimal phase rotation vector. A new permutation-based PTS scheme for OFDM systems has been proposed to enhance the PAPR reduction performance method in this thesis. In the proposed PTS method, we increase the number of candidate signals by permuting the subblocks of the frequency-domain signal. Then we use the frequency shifting property of discrete-time Fourier transform (DTFT) to reduce the additional inverse fast Fourier transform (IFFT) computations of the permuted subblocks. In addition, we use a cost function to select the samples for PAPR estimation of each candidate signal, which can largely reduce the computational complexity of the process to find the optimal candidate signal. Simulation results show that the proposed PTS scheme has better PAPR reduction performance and less computational complexity than the conventional PTS scheme.
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