歐規數位電視系統於移動式接收之錯誤率效能分析與改善

The Error Probability Performance Evaluation and Improvement of Mobile Reception for DVB-T System

周先倫(Hsien-Lum Chou)

指導教授 ： 林信標

國立臺北科技大學/機電學院/電腦與通訊研究所/碩士(2006年)

https://doi.org/10.6841/NTUT.2006.00108

摘要

數位電視系統已在國內開始普遍，最初標準的制定方向是用於室內的固定式接收，但如今多數消費者將其使用在室外的移動接式接收，移動接收會造成都普勒效應而導致訊號受到載波間干擾，因此如何減少載波間干擾成為重要的課題。此篇論文使用框化方法來分析歐規數位電視系統於移動接收的效能。
首先依據歐規數位電視標準建立Matlab/Simulink模擬平台，並搭配框化的方法以及理想的通道估測，探討在不同的移動速度以及參數設定下，框化方法對數位電視系統效能提升的程度。從模擬結果發現，當接收訊號只有直視波成份且車速為70Km/h時，分別使用一倍、1/2倍及1/4倍的保護區間於BER= 條件下，BER效能比沒有使用框化方法的效能分別提升了9dB、7dB及5dB；當車速達到200Km/h且BER= 時，BER效能改善了13dB、10dB及7dB。此外若增加通道的最大延遲時間，則會因可用的保護區間減少而使效能改善幅度降低。
論文中更探討框化方法在常用的通道估測方法下的效能。觀察結果得知，線性內插通道估測雖然方法簡單、容易實行，但在錯誤率效能表現上不盡理想，在EbNo=40dB時錯誤率高達 ；引入框化方法後，其效能雖有改善但於BER= 時改善了7dB。而快速傅利葉轉換通道估測雖較線性內插通道估測複雜，但其錯誤率效能和理想通道估測的效能相差約1dB至2dB。

關鍵字

歐規數位電視 ； 載波間干擾 ； 框化 ； 保護區間

並列摘要

Doppler effect caused by mobile reception will destroy the orthogonality between subcarriers of OFDM system and result in ICI. Therefore how to reduce the ICI in DVB-T system is an important research topic. This paper utilized windowing method to provide the performance evaluation of DVB-T system in outdoor mobile channels.
In this paper, we build simulation platform based on DVB-T standard and utilize windowing method under different conditions of guard intervals and configuration parameters to improve the BER performance. The result of simulation shows that when guard intervals are 1, 1/2, and 1/4, the performance under the condition of BER= are about 9dB, 7dB, and 5dB, respectively.
This paper also observes the performance improvement with windowing method by introducing non-perfect channel estimation. The result of simulation shows that channel estimation with FFT interpolation can lead to the better BER performance than with linear interpolation. And the difference in BER performance between channel estimation with FFT interpolation and perfect channel estimation is about 2dB.

並列關鍵字

Digital Video Broadcasting- Terrestrial(DVB-T) ； Inter-Carrier Interference (ICI) ； windowing ； guard interval

參考文獻

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