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URN etd-0730108-081912 Statistics This thesis had been viewed 2948 times. Download 1107 times. Author Hsin-Chieh Chao Author's Email Address No Public. Department Communication Engineering Year 2007 Semester 2 Degree Ph.D. Type of Document Doctoral Dissertation Language English Page Count 109 Title CONSTELLATION-SHAPING SELECTIVE-MAPPING SCHEME FOR PAPR REDUCTION IN OFDM SYSTEM Keyword OFDM PAPR PAPR OFDM Abstract Orthogonal frequency-division multiplexing (OFDM) is an attractive transmission technique for high-bit-rate communication systems. One major drawback of OFDM is the high peak-to-average power ratio (PAPR) of the transmitted signal. This dissertation presents a novel transform-kernel constellation-shaping scheme for reducing the PAPR. This scheme suppresses the peak envelope power of OFDM signals due to de-correlation among the original QAM constellation points in multiple OFDM symbols via unitary transformation. The performance of the reduction of PAPR for OFDM signals with various unitary transform kernels is also evaluated.
Furthermore, this dissertation also introduces a low-complexity selective mapping (SLM) scheme based on discrete Fourier transform (DFT) constellation-shaping. The DFT-based constellation-shaping algorithm applied with conventional SLM scheme usually requires a bank of DFT-shaping matrices to generate low-correlation constellation sequences and a bank of inverse fast Fourier transforms (IFFTs) to generate a set of candidate transmission signals, and this process usually results in high computational complexity. Therefore, a sparse matrix algorithm with low-complexity is proposed to replace the IFFT blocks and the DFT-shaping blocks in the proposed DFT constellation-shaping SLM scheme. By using the proposed sparse matrix, the candidate transmission signal with the lowest PAPR can be achieved with lower complexity than that of the conventional SLM scheme. The complexity analysis of the proposed algorithm shows great an improvement in the reduction of the number of multiplications. Moreover, this new low-complexity technique offers a PAPR that is significantly lower than that of the conventional SLM without any loss in terms of energy and spectral efficiency.
Advisor Committee Chau-Yun Hsu - advisor
Ching-Huang Wei - co-chair
Hsien-Hsin Chou - co-chair
Jie-Cherng Liu - co-chair
Teng-Pin Lin - co-chair
Tzuu-Hseng S. Li - co-chair
Files Date of Defense 2008-07-17 Date of Submission 2008-07-30