臺灣博碩士論文加值系統

DMB-T是中國大陸的數位電視地面廣播標準，調變技術採用時域同步正交分頻多工(TDS-OFDM)。同步及通道估測是利用信號框頭中的PN序列來實現。由於PN序列之週期性自相關函數只是近似脈衝而不是完美脈衝，旁峰值為-1，所以DMB-T接收機的通道估測準確度受到旁峰值的影響而未盡理想。

由於格雷互補對具有成對序列非週期性自相關函數和為完美脈衝的特性，故本論文提出以格雷互補對取代PN序列做為信號框頭，以期提升通道估測性能。本文提出格雷互補對信號框頭的序列配置方法，並以TU6與CT8兩種測試通道，模擬比較兩種信號框頭通道估測效能。電腦模擬結果顯示，採用格雷互補對組成的信號框頭，通道估測準確性會比使用PN序列為佳。格雷互補對信號框頭亦可用於同步。以電腦模擬比較同步與通道估測之綜合性能，使用格雷互補對之優勢更為明顯。

Digital multimedia broadcasting – terrestrial (DMB-T) is the standard of mainland Chinese digital television terrestrial broadcasting system. DMB-T adopts time domain synchronous-orthogonal frequency division multiplexing (TDS-OFDM) signals. Synchronization and channel estimation are achieved based on pseudo-noise (PN) sequences in the signal frame headers. Since the periodic autocorrelation functions of PN sequences are not perfect impulse functions and have nonzero sidelobe values, the DMB-T receivers’ channel estimation accuracy is affected.

Golay complementary pairs have the property that the sum of the aperiodic auto-correlation functions for pairing sequences is an impulse function. We propose to use a Golay complementary pair to replace the PN sequence in the frame header, in hope of improving the channel estimation accuracy. We introduce the configuration of the Golay pair frame header, and conduct simulations to compare channel estimation performance under TU6 and CT8 channels. Computer simulation results show that the channel estimation accuracy with Golay complementary pair frame header is better than the performance with the original DMB-T PN sequence frame header. The proposed Golay pair frame header can also be used for synchronization. Computer simulation comparison for the combined synchronization and channel estimation performance shows that the performance advantage of the Golay pair frame header compare to the PN frame header is even more obvious.

中文摘要.................................................I
ABSTRACT................................................II
誌謝....................................................IV
目錄.....................................................V
表目錄.................................................VII
圖目錄................................................VIII
符號表..................................................XI
第一章 緒論.............................................1
1.1 研究動機與目的...................................1
1.2 各章節提要.......................................2
第二章 DMB-T系統、格雷互補對與通道估測背景簡介..........4
2.1 DMB-T系統簡介....................................4
2.1.1 系統架構.........................................4
2.1.2 信號框結構.......................................5
2.1.3 信號框頭模式.....................................7
2.1.4 信號框體結構....................................10
2.2 格雷互補對簡介..................................11
2.2.1 格雷互補對定義..................................11
2.2.2 格雷互補對建構..................................12
2.3 通道估測........................................14
2.3.1 序列相關法(Sequence Correlation)................14
2.3.2 最小平方法(Least Squares).......................15
第三章 格雷互補對於DMB-T系統通道估測方法與效能.........17
3.1 無線通訊系統通道模型............................17
3.2 格雷互補對通道估測方法..........................20
3.2.1 信號框頭序列配置方式............................21
3.2.2 序列相關時域同步與通道估測法....................22
3.3 通道估測性能比較................................33
3.3.1 信號框頭內部配置對通道估測之影響................33
3.3.2 假設已同步時通道估測性能比較....................39
3.3.3 同步及通道估測綜合性能比較......................51
第四章 結論............................................54
參考文獻................................................55

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