LTE-Advanced下行多輸出入傳輸之決策回授通道估計

Abstract

在本篇論文中，我們根據第四代行動通訊所設計的標準LTE-Advanced，討 論決策回授通道估計在LTE-Advanced 系統下行多輸出入之傳輸的效能。並且使 用MATLAB 進行通道估計之模擬。在我們所提出的通道估計方法裡，我們首先 使用最小平方差的估測在位於參考訊號(reference signal)子載波上的通道頻率響 應，接著使用決策回授幫助我們更新最小平方差的估計，然後在頻域上採用線性 內插來估計其他在資料載波上的通道頻率響應，同樣地，運用決策回授來更新資 料載波上的通道頻率響應當作初始化，最後，我們考慮兩種通道估計的方法，分 別命名為決策回授處理以及頻域移動平均。我們利用高斯可加性白雜訊通道以及 多路徑通道來驗證我們的通道估測方法。在本篇論文中，我們首先介紹LTE 和 LTE-Advanced 的標準機制，接著描述我們採用的通道估測方法，最後在不同傳 輸環境下模擬和實作並討論其效能。

In this thesis, we study downlink channel estimation for the LTE-Advanced downlink MIMO transmission. We investigate the performance of decision-feedback channel estimation method in the downlink system. And we simulate the channel estimation method with MATLAB. For the proposed channel estimation method, we first estimate the channel response for some subcarriers positions based on reference signal (RS) by least-squares (LS) estimation. We update the LS estimators with decision-feedback. Then we perform frequency domain interpolation to estimate the channel response at data subcarriers. Again we update the frequency domain interpolation for the initialization. After that, we consider two kinds of channel estimation techniques, namely, decision-feedback processing and frequency domain moving averaging. We verify our channel estimation program in additive white Gaussian noise (AWGN) channel and multipath channel for LTE-Advanced systems. In this thesis, we first introduce the system structure of LTE/LTE-Advanced standard. Then we describe the channel estimation method we use. Finally, we do the simulation and discuss the performance in each transmission condition.