應用於正交分頻多工系統中一種有效降低峰值對平均功率比方法

Abstract

OFDM是一種可以滿足高速資料傳輸需求的多工技術，但OFDM有兩項主要的缺點：高峰值對平均功率比(PAPR)以及對頻率飄移敏感。高峰值對平均功率比會同時降低功率放大器的效率，並且使系統的效能惡化。結果高峰值對平均功率比使得OFDM實作上變得困難。 這篇論文整理現行許多降低PAPR方法，並針對這些方法進行電腦模擬，而其結果作為比較的依據。首先，解決PAPR問題的基本演算法，包括：訊號變形、編碼，和多信號表示方式，將會在此論文中描述。更進一步，對基本演算法的修正也包含在此篇論文。最後，根據模擬所得到的結果，我們想出一種在OFDM系統中有效降低PAPR的方法。

Orthogonal Frequency Division Multiplexing (OFDM) is a promising transmission technique which satisfy the requirement of high data rate communication. However, OFDM has two main disadvantages: high PAPR and sensitivity to frequency offset. High PAPR reduces the power amplifier efficiency and degrades the performance of the system. Consequently, high PAPR makes implementation of OFDM difficult. This thesis reviews several PAPR reduction methods and provides computer simulations to evaluate these methods. The basic algorithms of PAPR reduction methods, including signal distortion, coding, and multiple signal representation, are described in this thesis. Furthermore, the modified algorithms are also investigated. Finally, we propose an efficient PAPR reduction method, attenuation, in OFDM based on the simulation result.