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論文名稱 Title |
LTE系統的雜訊估測研究 Research on Noise Estimation for LTE systems |
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系所名稱 Department |
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畢業學年期 Year, semester |
語文別 Language |
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學位類別 Degree |
頁數 Number of pages |
48 |
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研究生 Author |
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指導教授 Advisor |
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召集委員 Convenor |
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口試委員 Advisory Committee |
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口試日期 Date of Exam |
2011-10-11 |
繳交日期 Date of Submission |
2011-10-18 |
關鍵字 Keywords |
關係訊號、通道估測、雜訊功率估測、正交分頻多工、長期演進 reference signal, Term-LTE, channel estimation, noise power estimation, orthogonal frequency division multiplexing |
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統計 Statistics |
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中文摘要 |
下一代4G行動通訊標準--長期演進(Long Term Evolution, 簡稱 LTE)在下行鏈路使用正交分頻多工(Orthogonal Frequency Division Multiplexing, 簡稱 OFDM)為主要傳送技術, 在傳送時會加入關係訊號(Reference Signals ,簡稱RS)做為輔助,雖然加入關係訊號會減少原先可以傳送的頻寬,但有效的利用關係訊號可以使得整個通訊系統效能上升,所以如何利用關係訊號進行通道和雜訊的估測是重要的議題。 本論文是基於LTE系統的標準,利用關係訊號之間的交相關和自相關,探討估測通道響應(Channel impluse response, 簡稱CIR)和雜訊功率(Noise Power),主要的貢獻是在改良雜訊功率估測。理想的情況下,估測的資料越多準確度越高,但因為雜訊估測必須在資料量被限制的情況下進行,本篇論文提出一個改進的方式,將在有限資料進行雜訊估測。 |
Abstract |
In this thesis, we study the noise power estimation in the LTE system. Two approaches, the weight method and the subspace method, are considered. The performance of noise power estimation using the weight method highly depends on the accuracy of the channel estimation. The channel estimation usually gets poor results under scenarios with long delay spreads. Therefore, the weight method also gets poor result. To overcome the mentioned drawback, we propose the subspace method which is independent from the channel estimation. From simulation results, we observe that the subspace method gets bias results. However, the bias depends on the length of the observation window and only gets a little influence from the channel conditions. Therefore, we can correct the bias using a simple look-up-table approach. Computer simulations show that the subspace method gets the more accurate result than the weight method. |
目次 Table of Contents |
目錄 摘要i Abstract ii 目錄iii 圖次v 表次vii 1 緒論 1 2 背景與文獻調查 2 2.1 正交分頻多工. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.2 長期演進系統描述. . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3 問題描述 14 3.1 系統模型. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 3.2 通道估測. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15 3.3 估測設計. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3.4 一維通道估測. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.5 雜訊功率估測. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21 4 模擬結果 24 4.1 通道估測. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24 iii 4.2 雜訊估測. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32 5 結論 38 參考文獻 39 |
參考文獻 References |
[1] “3GPP TS 36.211 Evolved Univerasl Terrestrial Radio Access (E-UTRA) physical channels and modulation (release 8 ),” 3rd Generation Partnership Project. [2] Y. Zheng and C. Xiao, “Improved models for the generation of multiple uncorrealated rayleigh fading waveforms,” IEEE Commun. Lett., vol. 6, no. 6, pp. 256 - 258, jun. 2002. [3] S. Sesia, I. Toufik and M. Baker, LTE the UMTS long term evolution : from theory to practice . A John Wiley and Sons, Ltd, Press, 2009. [4] Alan J. Laub, Matrix Analysis for Scientists and Engineers. SIAM : Society for Industrial and Applied Mathematics Press, 2005. [5] L. Hanzo, M. Muenster, B. Choi, and T. Keller, OFDM and MC-CDMA For Broadband Multi-User Communications, WLANs and Broadcasting. New York: Wiley Press, 2003. [6] D. Wang , L.-G. Jiang and C. He, “Robust noise variance and channel estimation for SC-FDE UWB systems under narrowband interference,” IEEE Transactions on Wireless Communications , vol. 8, no. 6, pp. 3249 - 3259, jun. 2009. [7] V. D. Nguyen , H.-P. Kuchenbecker and M. Patzold, “Estimation of the channel impulse response length and the noise variance for OFDM systems,” Vehicular Technology Conference, 2005. VTC 2005-Spring. 2005 IEEE 61st , vol. 1, pp. 429 - 433, jun. 2005. [8] S. Shen , H. Long , J. Kuang , K. Zheng and W. Wang, “Two novel noise estimation meth- ods with low complexity for the OFDM system,” Communications, Circuits and Systems (ICCCAS), 2010 International Conference on , pp. 6 - 9, jul. 2010. [9] G. Huang, A. Nix and S. Armour , “DFT-Based Channel Estimation and Noise Variance Es- timation Techniques for Single-Carrier FDMA,” Vehicular Technology Conference Fall (VTC 2010-Fall), 2010 IEEE 72nd , pp. 1 - 5, 6 - 9 Sept. 2010 |
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