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Title: | 提供通道估測之截斷根升餘弦脈衝調變系統具循環前綴領航信號的設計分析 Design and Analysis of Cyclically-Prefixed Pilot Sequence for Channel Estimation in Truncated-Root-Raised-Cosine Pulsed Modulation System |
Authors: | Shu-Yu Li 李曙宇 |
Advisor: | 鐘嘉德(Char-Dir Chung) |
Keyword: | 通道估測,領航訊號,循環前輟,截斷脈衝,克拉馬-羅限, channel estimation,pilot sequence,cyclic-prefix,truncated pulse,Cramér Rao bound., |
Publication Year : | 2020 |
Degree: | 碩士 |
Abstract: | 為了達到最佳的功率效率,大多通訊系統採用符合奈奎斯零符元干擾準則(Nyquist zero ISI criterion)的有限頻寬脈衝進行傳輸。有限頻寬脈衝在時間上無限長的特性是不可實現的,必須在時間上先被截斷成截斷脈衝。然而截斷操作破壞脈衝原有的特性,使得符元間干擾產生。無線通訊情境中大多使用領航訊號協助通道估測,以補償通道效應對傳輸訊號產生的扭曲與符元間干擾。這類截斷脈衝調變系統的符元間干擾源自脈衝與通道,然而過往文獻對截斷脈衝調變系統的通道估測的討論並不多。 在本論文中,我們將循環前輟(cyclic prefix)的概念使用在領航訊號區間,如此一來,前方傳輸資料不會干擾領航訊號,且利用將線性卷積轉換成循環卷積的特性使領航訊號可以減弱脈衝造成符元間干擾並估測通道的效應。在這個架構下,系統化設計最佳領航訊號的方法被提出,提出的領航訊號可使通道估測值方均差(mean square error)達到理論上的下限,即克拉馬-羅限(Cramér Rao bound)。除此之外,設計出領航訊號在接收端還有低計算複雜度的優點。 In order to achieve better power efficiency, most adopt bandlimited pulse which satisfies Nyquist zero ISI criterion in communication system. Bandlimited pulse which is infinitely long in time domain is impractical, and it needs to be truncated firstly, and then it becomes truncated pulse. However, truncating operation makes pulse not satisfy Nyquist zero ISI criterion anymore and then ISI (intersymbol interference) occurs. In wireless communication scenario, pilot-aided method is widely used to assist channel estimation, and channel effect which distorts transmitting signal and occurs ISI is compensated. In this thesis, we apply CP (cyclic prefix) technique in guard interval which precedes pilot interval. On one hand CP can reject interference from preceding interval to pilot interval, on the other hand its property which transforms liner convolution into circular convolution is used to mitigate the ISI resulting from pulse. Under this structure, systematic design procedure is proposed to develop optimal pilot sequences which let mean square error of channel estimator achieve its minimum value, i.e. CRB (Cramér Rao bound). Besides, receiver can perform channel estimation in low computational complexity way when proposed pilot sequences are adopted. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/15499 |
DOI: | 10.6342/NTU202001517 |
Fulltext Rights: | 未授權 |
Appears in Collections: | 電信工程學研究所 |
Files in This Item:
File | Size | Format | |
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U0001-1407202016242700.pdf Restricted Access | 3.7 MB | Adobe PDF |
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