無線正交分頻多工通訊中利用雙維度導航符號之通道估測技術研究

因為在最近十幾年來無線通訊技術被迅速的發展，所以在未來的無線通訊系統中，高資料傳輸比率、高頻譜的效益和高品質的傳輸訊號都是不可或缺的。而在數位高速資料傳輸系統中，其中正交分頻多工(OFDM)技術無疑是最有用的技術之ㄧ。由於它的頻譜效益、多路徑延遲環境中的強健性和克服訊號間干擾(ISI)的特性，因此正交分頻多工技術被廣泛的使用。並且訊號頻寬效益也可以被增強許多。在正交分頻多工技術中為了保持通訊系統傳輸資料效益，其中通道估測技術是很重要的部份之ㄧ。而雙維度導航符號通道估測是其中一種通道估測技術，他是在時域和頻域中都使用導航符號，因此可以取得更多通道的資訊。通常傳送的導航符號在接收端都必須是已知的，才能夠作通道估測。然後藉由雙維度導航符號配置和最小平方估測，在時域和頻域的通道估測資訊可以被取得。而通道估測的效益通常是根據導航符號配置方式和所使用導航符號數量的選擇。在這篇論文裡面，我們使用了虛擬導航符號的觀念來幫助我們取得更多時域和頻域上的通道資訊。然後我們也比較了不同的導航符號配置去找出較好的導航符號配置方式。最後我們使用雙線性的內插方法來做剩下未估測部分的通道估測。

關鍵字

通道估測

並列摘要

Because the wireless communication techniques have been quickly developed in the recent years, the high transmission data rate, efficient spectral bandwidth and high quality of the transmission signals are necessary for the future wireless communications systems. Orthogonal frequency division multiplexing (OFDM) technology is effective and powerful in high data rate digital transmission because its spectral efficiency, robustness in multipath propagation environments and ability to cope with inter-symbol interference (ISI). By the advantages of OFDM technology, it has become the most useful wireless communication technique now. Channel estimation is an important part of OFDM technology to maintain the system performance. One of the most popular channel estimation techniques is the two-dimensional pilot-aided channel estimation which can use pilot symbols in both time and frequency domains. In practice, the channel estimation procedure can be assisted by transmitting pilot symbols that are already known at the receiver end. By using two-dimensional pilot arrangement and applying least-square (LS) estimation for the leading pilot symbols, channel information can be obtained in both time and frequency domains. The system performance of channel estimation usually depends on the choice of different pilot patterns and the total number of pilot symbols. In this thesis, we use the concept of the virtual pilot method, that can help us to use more real pilot information in both time and frequency domains. And the comparison of the different pilot patterns is investigated for finding out the better pilot pattern. Finally, the bilinear interpolation is utilized for the channel estimation.