在超高速移動環境下使用正交分頻多工技術之頻率同步

Abstract

本篇論文主要研究在超高移動速度下使用正交分頻多工技術的頻率同步。台灣高速鐵路的超高移動速度環境下將導致嚴重的都卜勒效應，所以通道將會是一個快速衰變且多路徑干擾(雙選擇性通道)。傳送端與接收端的振盪器彼此不匹配與通道的都卜勒效應會產生載波頻率偏移量。為了能在超高移動速度環境下使用正交分頻多工技術，我們提出多段式訓練符元、權重法與預測機制法來抵抗時變通道的破壞並進行載波頻率偏移量估測。當載波頻率偏移量估測完成後，我們在接收端會進行頻率補償來完成整個頻率同步。

This thesis emphasize on frequency synchronization for OFDM in very high mobility environment. The very high mobility environment for TAIWAN HIGH SPEED RAIL (300km/hr) leads to critical doppler effect, so the channel will cause fast fading and multipath interference (doubly selective channel).The mismatch between transmitter and receiver and doppler effect will bring about carrier frequency offset. In order to working OFDM technique in very high mobility environment, we propose multiple sections training symbol method、weighting method and prediction mode method to resist time-variant channel and then do carrier frequency offset estimation。After we finish carrier frequency offset estimation, we do frequency compensation to reach whole frequency synchronization.