| Summary: | 碩士 === 國立臺北科技大學 === 電機工程系所 === 98 === This thesis focuses on the high Peak-to-Average Power Ratio (PAPR) reduction of OFDM systems using companding transform technique with bit error rate constrained. In transmitter, the output signal will be severely distorted due to the high instantaneous power input signal passing through the nonlinear region of power amplifier. The companding transform technique uses a compressor in transmitter to compress the dynamic range of signal’s amplitude. In receiver, it uses an expander to rebuild the dynamic range of signal’s amplitude. The linear nonsymmetric companding transform (LNST) function is a low complexity peak cancellation technique which is easy to be implemented. It can decrease large signals and enlarge small signals simultaneously by adjusting parameters appropriately. In this thesis, we aim to design a LNST method by a searching mechanism of finding the best parameters. After finding an optimal set of parameters, we use computer simulation to compare the PAPR of this method with the PAPRs of the original OFDM signals and of some other compressing OFDM signal methods, including A-law companding, μ-law companding, exponential companding, and linear symmetric companding.
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