框化OFDM：設計與分析

Abstract

多載波調變系統近年引起相當多的注意，由其是正交分頻多工系統。由於正交分頻多工系統使用的是方形窗，所以發送端信號的頻譜在截止頻帶擁有較高能量。 對發送端信號加非方型窗是一種減低其能量的做法。在這篇論文中，我們將討論這種使用非方形窗的框化OFDM系統，並且設計非方形窗及其所對應與通道特性無關的後處理矩陣使得整個收發器有ISI-free的特性。我們也提出了雜訊放大常數來量測整個系統的效能，並且發現可以適當的犧牲接收端的訊雜比來換取截止頻帶能量的減小。

The multicarrier modulation (MCM) scheme received a lot of attention in recent years, especially the OFDM system. Since the conventional OFDM uses rectangular window function, the spectrum of the conventional OFDM signal have slowly decreasing sidelobes. Windowing is a method to reduce the sidelobes of the transmitter output. In this thesis, the windowed OFDM systems are studied. We will design the ISI-free transceivers for the windowed OFDM systems with a channel independent post processing matrix. And we propose the use of a noise amplification factor to evaluate the performance of the windowed system. And we observe that it provides a trade-off between the roll-off of the PSDs of the transmitter output and the SNR at the receiver output.