臺灣博碩士論文加值系統

直接序列極寬頻的無線通訊技術，擁有低傳輸信號功率以及超高的傳輸頻寬等特性，因此造成有較細微的時間解析度，且時間延遲過長的通道也使的符號間干擾較為嚴重，使得傳統的時間同步方法在此已不再適用。
因此本文提出一修正型時間同步以及粗略通道估測演算法，並將這兩種演算法以不同方式組合成串列，並列及結合式三種策略，期望在有限的獲取序列中可以同時完成粗略時間同步及通道估測的工作。經測試後得知並列式策略最具強鍵性，仍舊能夠在符號間干擾較嚴重的極寬頻通道中正常運作，且在有限時間內完成粗略時間同步及通道估測的任務。

The direct sequence ultra-wideband (DS-UWB) system has the characteristics of low transmission power constraints and wide transmitted bandwidth. The wide bandwidth will introduce fine timing resolution and severe inter-symbol interference (ISI), which will is cause larger delay spread. Therefore, the traditional acquisition methods are no longer suitable here.
A modified acquisition method and a coarse channel estimation algorithm are proposed in this thesis. Three different strategies with composition of acquisition and channel estimation are compared. Based on three strategies, the tasks of coarse acquisition and channel estimation can be achieved with limited length of acquisition sequence. From simulation results, the parallel strategy is robust enough to operate under the UWB channel in severe ISI conditions and the time duration for completing the tasks of coarse acquisition and channel estimation meets the specification of IEEE 802.15.3a.

誌謝 i
摘要 ii
Abstract iii
目錄 iv
圖索引 vi
表索引 x
第一章 簡介 1
第二章 系統模型 4
2.1 極寬頻系統模型 4
2.2 信號模型 5
2.3 等效通道 6
第三章　傳統粗略時間同步演算法 8
3.1 命中集合（hit set）之定義 8
3.1.1 匹配濾波器邊界（matched filter bound，MFB） 9
3.2 成功獲取機率及平均獲取時間之統計方式 14
3.3 傳統時間同步演算法介紹 15
3.3.1 同步方塊之輸入信號 16
3.3.2 五種傳統時間同步演算法介紹 18
3.3.3 傳統型最大值搜尋演算法之效能 20
第四章　結合粗略時間同步及通道估測演算法 23
4.1 疊加最大值搜尋演算法 23
4.2 粗略通道估測方法 25
4.2.1 隨機位元之估測 28
4.2.2 α參數之設計 30
4.3 三種時間同步與通道估測之組合策略 31
4.3.1 疊加最大值搜尋與通道估測串列式策略 31
4.3.2 疊加最大值搜尋與通道估測並列式策略 33
4.3.3 疊加最大值搜尋與通道估測結合式策略 34
4.4 框架起始偵測方法 35
第五章　系統模擬 38
5.1 疊加最大值搜尋與通道估測串列式策略之效能表現 38
5.1.1 疊加次數對串列式策略之效能影響 38
5.1.2 犁耙接收機分支數Np對串列式策略之效能影響 42
5.2 疊加最大值搜尋與通道估測並列式策略之效能表現 44
5.2.1 疊加次數對並列式策略之效能影響 44
5.2.2 犁耙接收機分支數Np對並列式策略之效能影響 48
5.3 疊加最大值搜尋與通道估測結合式策略之效能表現 49
5.3.1 疊加次數對結合式策略之效能影響 49
5.3.2 步階值β對結合式策略之效能影響 53
5.3.3 犁耙接收機分支數Np對結合式策略之效能影響 56
5.4 三種策略組合之效能比較 60
5.4.1 成功獲取機率效能比較 60
5.4.2 平均獲取時間效能比較 62
5.4.3 估測通道之標準化均方差效能比較 65
5.4.4 框架起始偵測效能比較 68
第六章　結論 76
參考文獻 77

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