用於DVB-T系統之通道估測方法之設計與模擬

Abstract

DVB-T的系統將於2004年6月1日正式在台灣開播，它擁有比傳統類比電視更高畫質的收視品質(HDTV、SDTV)。本論文將介紹一些用於DVB-T系統的OFDM通道估測方，在DVB-T的標準中是定義使用散射領航訊號來估計通道，藉由內插法，即可還原通道的頻率響應，使用高維度的內插法，將使系統能運作於高速移動的環境，但相對地也必需附出更高的運算複雜度。除此之外，散射領航信號的放置密度也必需在通道估計的準確度及頻寬的使用效率間做一協調，想要在高速移動的環境下準確的估計通道勢必要增加散射領航信號的密度，但此同時，頻寬的使用效率也必下降。為了有效解決這樣的問題，我們將介紹一種使用互補碼做為領航信號的通道估測方法。模擬的結果顯示，使用互補碼做為領航信號的通道估計方法將比使用散射領航訊號的方法有更好的效能，同時更能節省頻寬。

The DVB-T system will be started broadcasting in Taiwan formally on June 1 , 2004. It has higher quality (HDTV、SDTV ) than the traditional analogue TV. This thesis will introduce some OFDM channel estimation methods which is used in DVB-T system. In DVB-T System we use the Scattered Pilots to estimate channel frequency respond by interpolation. By using high degree interpolation, it will enable system to operate in high-speed moving environment. But it cost higher operation complexity relatively. In additional, the density of scattered pilots must be trade-off between the performance and bandwidth efficiency. We must increase the density of scattered pilots to get better performance in high-speed moving environment, but it will sacrifice bandwidth efficiency at the same time. In order to solve the problem, we recommend a channel estimation method by using pilot signal. In this thesis, we choice complementary code to be pilot signals. Computer simulation results show that using pilot signals have better performance than using pilot symbol, and also have more bandwidth efficiency .