| Summary: | 碩士 === 國立高雄科技大學 === 電腦與通訊工程系 === 107 === The Orthogonal Frequency Division Multiplexing (OFDM) technology is very popular in wireless networks, digital broadcasting, 4G and beyond mobile communications. The advantages of OFDM are making efficient use of the spectrum and anti-multipath fading. However, OFDM also has the drawbacks of a high peak average power ratio (PAPR) and the sensitivity to phase noise and frequency offset. The Active Constellation Extension (ACE) method is widely used among these techniques for reducing PAPR due to its effectivity and credible way.
In this thesis, we propose the Kalman-alike Gain method for improving the PAPR reduction performance on the ACE scheme. By setting a threshold value, the clipping noise power between the original signal and the clipped ones is computed as the system error power. Since clipping is a nonlinear deformation, the clipped signal points will spread over the constellation in the frequency domain. The measuring error corresponding to each particle is the distance between the actual point and the original position, and then the Kalman-alike Gain is obtained. The new constellation is attained by adjusting the position of each particle according to the measurement update equation. Repeat the procedure until the required PAPR reduction is reached. Simulation results show that the proposed method can reduce the PAPR value more effectively within the acceptable BER efficiency than the ACE method in the same computing time.
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