| Summary: | 碩士 === 國立臺灣大學 === 電信工程學研究所 === 91 === Multi-carrier modulation is an effective technique for communication in frequency selective fading channels. Orthogonal frequency division multiplexing (OFDM) is one example that successfully combats multi-path fading for high data rate wireless communications. However, multi-carrier systems suffer from the peak-to-average power ratio (PAPR) problem, which causes efficiency loss in devices, such as the transmitter power amplifier. In this thesis, we propose a new method for lowering the PAPR of multi-carrier modulated signals. Our method performs bit loading with PAPR consideration. We slightly perturb the “optimal” loading in order to reduce PAPR. Simulation results show that PAPR as lower as 5dB is achievable using 3 iterations of the proposed algorithm when number of sub-carriers is 64. Complexity reduction and side information transmission issues are also investigated in the thesis. Our results show that it is possible to trade a slight loss of PAPR performance for significant reduction in computational complexity. The overhead caused by side information transmission is also acceptable compared to other PAPR reduction methods. We thus conclude that the proposed method is an effective scheme that can significantly reduce PAPR without sacrificing too much error performance of a multi-carrier system.
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