Abstract
Orthogonal frequency division multiplexing (OFDM) is an efficient technique for high-bit-rate transmission. One major drawback of OFDM is the high peak-to-average power ratio (PAPR). To deal with this problem, many PAPR reduction schemes have been proposed. In these schemes, we have to exam the distribution of the PAPR value of an OFDM signal. Since the real PAPR value is defined on the continuous OFDM transmitted signal after the digital-to-analog converter (DAC) in the end of transmitter, we will get optimistic result if we calculate the PAPR value directly from the discrete OFDM signal sampled by Nyquist rate. Traditionally, -times zero-padding oversampling is used to increase the resolution of time-domained OFDM signal, thus the peak of oversampled signal is close to the real peak. It needs -points IFFT when -times zero-padding oversampling is implemented. is generally four, however, it still costs high computational complexity especially in certain application system with large subcarrer number . In this thesis, we propose a low-complexity PAPR estimation method without padding zeros in the frequency-domained OFDM signal. This estimation algorithm is based on the concepts of typical upsampling system, called interpolator, and is designed to approximate the four-times zero-padding oversampling. After passing through the -points IFFT, the estimated PAPR value of the time-domained OFDM signal is obtained by Peak Search and Partial Interpolation process. The simulation results show that either in common PAPR distribution of an OFDM signal or in specific application such as multiple signal representation (MSR) techniques, the proposed PAPR estimation method could get well-approximated results and low computationally complexity compared with four-times zero-padding oversampling.