| This dissertation focuses on the development of low cost, effective Peak to Average Power Ratio (PAPR) reduction methods to enhance the performance of Orthogonal Frequency Division Multiplexing (OFDM) transceiver implementation.;OFDM is a digital multi-carrier modulation method widely adopted in modern wide-band wire-line and wireless communication standards. The popularity of the OFDM stems from its robustness against the frequency selective fading channel, high bandwidth efficiency, and relatively simple receiver implementation. A trend of OFDM development is to increase the number of sub-carriers to enhance efficiency. When the number of sub-carriers increases, certain time domain OFDM coefficients are likely to acquire excessively large magnitudes. As such, the OFDM baseband waveform is susceptible to high PAPR value and may suffer from non-linear distortion at subsequent power amplifier stage. Excessive nonlinear distortion, unfortunately, translates to increased bit error rate (BER) at the receiver, and hampers the overall performance of the OFDM transceiver.;To alleviate these potential performance problems, in this dissertation, two novel, computationally efficient, and distortion-free PAPR reduction methods are proposed. The first method, called the Sparse Bit plane Coding (SBC) method, seeks to truncate and encode excessively large magnitudes of time domain OFDM symbols at transmitter to reduce PAPR value; and to decode and recover the encoded side information to restore original sub-carriers without losing information in the process. A second method, called Modulation Re-Mapping (REMAP) seeks to apply alternative modulation mapping schemes to reduce PAPR value when high PAPR situation is detected. The SBC method achieves excellent PAPR reduction performance with very moderate computation costs and about 1--6% side information overhead. The REMAP method also achieves very good PAPR reduction effect with extremely low computational complexity. Both the SBC and REMAP methods provide practical, cost effective alternative to existing PAPR reduction methods for enhancing the performance of state of art OFDM transceiver designs. |
