- 學位論文
DVB-T通道估測之效能比較
Performance Comparison of DVB-T Channel Estimation
摘要
DVB-T是採用正交分頻多工(OFDM)的技術來傳送，在訊號傳輸的過程中，傳送訊號會受到通道以及白色高斯雜訊(AWGN)影響，導致接收端需要利用通道估測來將通道求出，並且補償，在本論文中，我們實作一維線性內插(1D Interpolation)，二維線性內插(2D Interpolation)等常見之通道估測方法，在特殊的通道估測法上我們實作了決策回饋法(DF)，自迴歸法(AR)，轉換域處理(Transform Domain Process)，並且在實際接收，或是用TU6及Longdelay的模擬通道下，比較這些通道估測的效能。 在高速移動環境下，DVB-T訊號經過時變的通道，接收到的訊號會有都普勒擴展(Doppler Spread)的現象，破壞了子載波間的正交性，而引起載波間干擾(ICI)，使得最高容許的接收速度下降。為了降低高速移動所引起的載波間干擾(ICI)，本論文實做出自動調整截止頻率(Adaptive Selection Cutoff Frequency)之轉換域處理方法，Frank Window處理方法及反覆式推論法，並比較其移動接收之效能。
並列摘要
DVB-T adopts OFDM modulation technique to transmit signal, during transmission of the signal, it is affected by channel effect and AWGN. The channel effect causes receivers to derive channel frequency response, and then to compensate it. In our research, we implement various channel estimation methods, including 1D Interpolation, 2D Interpolation, Decision Feedback, Auto Regressive, and Transform Domain Process channel estimation. In this thesis, we compare the performance of the above channel estimation methods in real environment and simulated channels such as TU6 and Longdelay. In high speed environment, DVB-T signal passes through time-varying channel. Doppler Spread occurs in received signal, and it destroys carrier orthogonality and ICI effect come up. In the experiment, we implement Adaptive Selection of Cutoff Frequency of Transform Domain Process and Frank Window Process to compare the relative performance of these approaches at mobile reception condition.