使用時域視窗和信號重建提升陸規數位電視接收器之通道估測效能

Utilizing windowing and signal reconstruction for improving channel estimation performance of DMB-T receiver

廖昱勝(Yu-Sheng Liao)

指導教授 ： 林信標

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2011年)

https://doi.org/10.6841/NTUT.2011.00222

摘要

DMB-T數位電視廣播採用時域同步正交分頻多工(TDS-OFDM)調變技術，利用PN序列取代傳統的CP-OFDM系統的循環字首做為保護間隔，並同時作為系統同步與通道估測。因為信號在頻域上沒有導引信號，比典型CP-OFDM系統具有更高的頻譜效率。
在本論文提出時域視窗和信號重建消除在TDS-OFDM系統中的PN序列，以減輕ISI對通道估測影響。在此使用兩種通道模型，如TU6和COST 207，分別為短、中的時間延遲用來驗證以及評估通道估演算法和等化器。在此使用電腦程式，模擬陸規數位電視收發機制。其中使用兩種通道估測演算法，一個為基本的通道估測演算法，另一個為本論文所提通道估測演算法，然後運用以上兩種方法來評估不同的通道模型下之效能。
由結果顯示，在此演算法下可以有效得消除ISI的影響；在慢速衰落和快速衰落的TU6通道上，即使在延遲時間較長的COST 207通道，也有很好的效果。

關鍵字

時域同步正交分頻多工 ； 信號重建 ； 通道估測 ； 時域視窗

並列摘要

The digital multimedia broadcasting-terrestrial(DMB-T)adopts the time domain synchronization-orthogonal frequency division multiplexing(TDS-OFDM).Instead of cyclic prefix scheme in traditional CP-OFDM systems, PN sequence has been proposed for guard interval, system synchronization and channel estimation in DMB-T system. TDS-OFDM provides higher spectrum efficiency than CP-OFDM due to no pilot in the transmitted signal.
In this paper, windowing and signal reconstruction are introduced to subtract the PN sequence padding for the TDS-OFDM systems to mitigate the residual inter symbol interference (ISI) from the imperfect channel estimation. Two kinds of channel models, TU6 and COST 207, there are short time delay and long time delay respectively to verify and evaluate channel estimation algorithm and equalizer. In this thesis, using Matlab simulated DMB-T transceiver and two kinds of channel estimation algorithm, one is convention channel estimation algorithm and the other is proposed channel estimation algorithm, two kinds of channel estimation algorithm are used to verify and estimate the performance of channel estimation algorithm.
Results show that this algorithm can effectively remove the impact from the residual ISI on the slow-fading and fast-fading TU6 channels, even in the presence of large channel delays in the COST 207 channel.

並列關鍵字

TDS-OFDM ； Signal reconstruction ； Channel Estimation ； Time window

參考文獻

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