| Summary: | 碩士 === 臺灣大學 === 電信工程學研究所 === 98 === In a multichannel system, space-time codes are usually used to achieve the optimal diversity-multiplexing gain (D-MG) tradeoff. Nevertheless, these pace-time codes will make transformations on signal constellation, and often lead to relatively higher peak to average power ratio (PAPR) so that the signal will suffer nonlinear distortion through power amplifier. The design difficulty for transmit power amplifier will undoubtedly increase. By the use of integer reversible mapping method, the signal constellation can be shaped to lower down the PAPR without losing the optimal diversity-multiplexing gain (D-MG) tradeoff. However, in other precoding multi-input multi-output (MIMO) or orthogonal frequency division multiplexing (OFDM) system, this technique will lead to performance loss in bit error rate. Thus, we will introduce the list sphere decoding for closest lattice point search and a further iterative decoding to make the performance near to the theoretically optimal value.
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