利用次通道降峰法以降低正交分頻多工系統的峰均比

Abstract

正交分頻多工系統是一項非常熱門的傳輸技術，但是通常系統的峰均比會很大。在這篇論文裡，我們提出一個低複雜度降低峰值的技術。設計的方法是藉由選出一些子載波分別乘上旋轉因子來達到降低峰值的目標。我們將會用模擬結果來說明所提出的方法能夠有效地降低峰值且複雜度很低。

Recently there has been great interest in the Orthogonal Frequency Division Multiplexing (OFDM) systems. However one disadvantage of OFDM systems is high peak-to-average power ratio (PAPR). In this thesis, we will propose a new method called Subchannel Peak Reduction (SPR). The symbols of a few selected subchannels are chosen to multiple a rotation individually so that PAPR is reduced. Transmission rate is slightly lower. However, no side information bit is needed. The optimal solution of the rotation can be found by exhaustive search (SPR-ES).We will propose an iterative ap- proach method (SPR-IT) to tnd suboptimal rotating for the selected subchannels. SPR-IT can have lower complexity than SPR-ES. Simulation results shows SPR-ES and SPR-IT can e±ciently reduce the peak value of the transmitted signal. The simulations will demonstrate that our method provide a nice tradeoff between bit rate and PAPR reduction.