Research On PAPR Reduction Schemes For OFDM System

Multicarrier communication has been employed for wire-line communications and has been adapted for use in the future mobile communication systems. The term multicarrier modulation includes a number of transmission schemes whose main characteristic is the decomposition of any wideband channel into a set of independent narrowband channels. With this family, the most commonly used schemes are Orthogonal Frequency Division Multiplexing (OFDM) which is based on the Discrete Fourier Transform, resulting in a realizable, high performance structure. Due to its robustness against multipath fading with certain implementation advantage over single-carrier system, OFDM has become a popular technique in various high-speed wireless data transmission system. One of the main implementation disadvantages of OFDM is the high peak-to-average power ratio (PAPR) of the transmitted signals. In this thesis, some main PAPR reduction methods are reviewed, including the selective mapping (SLM) approach and the partial transmit sequences (PTS) approach. The two approaches involve high system complexity, where several parallel IFFTs are required. To alleviate this problem, we propose an IFFT conversion method. Since the proposed IFFT conversion method does not involve any multiplication, it has much lower complexity than the IFFT computation. With this IFFT conversion method, the complexity of the SLM and PTS techniques can be reduced significantly.