長期演進技術(Long Term Evolution，LTE)為第四代行動通訊重要技術之一，此技術之下行鏈路為正交分頻多重存取(Orthogonal Frequency Division Multiple Access，OFDMA)系統，而它是以正交分頻多工(Orthogonal Frequency Division Multiplexing，OFDM)演進而來。OFDM技術可使頻譜效益增加，但它對於都卜勒效應頻率偏移相當敏感，因此OFDMA技術如同OFDM技術，將須解決因通道環境下，進而引起子載波間正交性遭到破壞以及載波間互相干擾(Inter-Carrier- Interference，ICI)的相關問題。 此篇論文將利用可程式化邏輯閘陣列(Field-programmable gate array，FPGA)板實現，以LTE下行鏈路規格下所提出的兩種通道估測方法。其中，我們使資料直接決策(Decision Directed)與多項式模型(Polynomial Model Based)估測法來提升頻域方向通道估測的準確度，且透過模擬來說明通道估測之性能改善。 LTE (Long Term Evolution) is important for fourth generation of mobile communication technologies. On the downlink transmission, the LTE system uses OFDMA (Orthogonal Frequency Division Multiple Access) technology, which is based on OFDM (Orthogonal Frequency Division Multiplexing). It increases spectrum efficiency, but it is sensitive to Doppler spread and frequency offset. Therefore, the problem that we want deal with is the one operating in time-varying environments where the orthogonality among the subcarriers is destroyed and inter-carrier interference (ICI) is thus created. In this thesis, we conduct design and implementation of channel estimation with FPGA (Field-programmable Gate Array). We propose two channel estimation ways. One of the improved methods is data-aided and decision-directed polynomial model based estimation by frequency domain. The performance improvement is demonstrated through matlab simulations.
