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論文名稱 Title |
在配合各種中繼策略之合作式系統中採用噴泉碼之研究 On Fountain Codes for Cooperative Systems Using Various Relaying Strategies |
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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 |
52 |
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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 |
2012-07-27 |
繳交日期 Date of Submission |
2012-08-29 |
關鍵字 Keywords |
合作式網路、噴泉碼、無碼率、解碼後放大 Decode-and-forward, Cooperative communication, Fountain codes, Rateless |
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統計 Statistics |
本論文已被瀏覽 5657 次,被下載 1098 次 The thesis/dissertation has been browsed 5657 times, has been downloaded 1098 times. |
中文摘要 |
在無線通訊中因為多重路徑失真的情況,導致傳送資料會有相位及振幅偏移導致錯誤率(error rate)增加且影響著通訊品質。藉著多根天線的多重輸入多重輸出(multiple-input-multiple-output, MIMO)可以提高多樣性增益(diversity gain)降低錯誤率。隨著科技的進步個人手持式通訊設備訴求著體積短小且輕薄,已無法藉多根天線來改善通訊品質,這個緣故導致合作式通訊系統概念的產生。另一方面由於無線網路中通道的時變性(time varying),若來源端及中繼端採用固定碼率(fixed rate)的錯誤更正碼,傳送端需一直藉由接收端回饋(feedback)通道資訊來改變碼率以提升效能,此作法相當耗費資源,所以無碼率(rate less)的噴泉碼概念因此產生。近年來論文以討論消息理論的居多,少有以實際碼字進行分析。本篇論文探討在雙躍進(dual-hop)的合作式通訊系統(cooperative communication)使用噴泉碼(fountain codes)進行傳輸之編解碼機制,以實際的碼字進行模擬探討訊號傳送次數的差距。文獻路比轉換碼(Luby transform codes, LTC)是種應用廣泛的噴泉碼,使用抹除通道(erasure channel),即接收端只會接收到正確的碼字或沒有收到碼字。我們將LTC與低密度奇偶檢查碼 (low-density parity-check code, LDPC code)結合根據合作式通訊系統的通道特性設計網路中各傳接端的編解碼方式並分析不同協定效能上的差異。 |
Abstract |
In wireless communication, multipath fading distorts the phase and the amplitude of received signals and increases error rate, which degrades causes communication quality. Multiple-input-multiple-output (MIMO) techniques can be adopted to achieve diversity gain and reduce error rate. However, MIMO is hard to be implemented in mobile devices due to size limitation. With this regard, cooperative communications are proposed to allow users to cooperate each other’s and then achieve diversity without equipping multiple antennas. On the other hand, if source and relays adopt fixed-rate transmission under time-varying wireless channels, it requires timely feedback about channel-information for transmitters to adjust the rate of channel encoder. To reduce overhead required for aforementioned scheme, we adopt rateless fountain codes in cooperative networks. In recent year, most related studies focus on information-theoretical aspect, but it lacks discussion of practical coding. In our work, we use fountain codes in dual-hop cooperative communication and analyse transmission rate in terms of transmitting time. Fountain code was first proposed as Luby transform codes(LTC) for erasure channels. We combine low-density parity-check code( LDPC code) and LTC in cooperative communication networks, and analyze required transmission time under different cooperative protocols. |
目次 Table of Contents |
論文審定書 致謝…………………………………………………………i 中文摘要……………………………………………………ii 英文摘要……………………………………………………iii 目錄…………………………………………………………iv 圖次…………………………………………………………vi 第1章 簡介…………………………………………………1 第2章 相關背景……………………………………………3 第2.1節 噴泉碼……………………………………………3 第2.2節 傳輸協定相關論文………………………………5 第2.3節 LDPC編碼與解碼………………………………9 第3章 系統模型…………………………………………11 第3.1節 類同步合作式傳輸……………………………12 第3.2節 非同步合作式傳輸……………………………13 第3.3節 中繼站選擇策略………………………………14 第4章 噴泉碼編解碼設計………………………………16 第4.1節 訊號源編碼……………………………………17 第4.1.1節 內層編碼……………………………………18 第4.1.2節 外層編碼……………………………………19 第4.2節 中繼站編碼……………………………………20 第4.3節 中繼站解碼……………………………………20 第4.3.1節 外層解碼………………………………………22 第4.3.2節 內層解碼………………………………………24 第4.3.3節 碼字數值更新…………………………………25 第4.3.4節 改良型噴泉碼…………………………………27 第 4.4節 目的端解碼……………………………………29 第5章 模擬………………………………………………31 第6章 結論………………………………………………36 參考文獻…………………………………………………37 附錄A………………………………………………………38 附錄B……………………………………………………..40 附錄C……………………………………………………..41 附錄D……………………………………………………..43 |
參考文獻 References |
[1] I. Telatar, “Capacity of multi-antenna Gaussian channels,” Europ. Trans.Telecommun., vol. 10, pp. 585–596, Nov.-Dec. 1999. [2] A. Sendonaris, E. Erkip, and B. Aazhang, “User cooperation diversity, Part I: system description,” IEEE Trans. Commun.,vol. 51, no. 11, pp. 1927–1938, Nov. 2003. [3] A. Sendonaris, E. Erkip, and B. Aazhang, “User cooperation diversity. part II. implementation aspects and performance analysis,” IEEE Trans. Commun., vol. 51, no. 11, pp. 1939–1948, Nov. 2003. [4] M. Luby, “LT codes,” in Proc. 43rd Annu. IEEE Symp. Foundations of Computer Science, Vancouver, BC, Canada, pp. 271–280, Nov. 2002. [5] A. Shokrollahi, “Raptor codes,” IEEE Trans. Inf. Theory, vol. 52, no. 6, pp. 2551–2567, Jun. 2006. [6] R. G. Gallager, “Low-density parity-check codes,” IRE Trans. Inf. Theory, vol. IT-8, no. 1, pp. 21–28, Jan. 1962. [7] A. F. Molisch, N. B. Mehta, J. S. Yedidia, and J. Zhang, ”Cooperative relay networks using fountain codes,” IEEE Global Telecommunications Conference (GLOBECOM’06), pp. 1–6, Nov. 2006. [8] A. F. Molisch, N. B. Mehta, J. S. Yedidia, and J. Zhang, “Performance of fountain codes in collaborative relay networks," IEEE Trans. Wireless. Commun., vol. 6, no. 11, pp. 4108–4119, Nov. 2007. [9] D. J. C. MacKay, “Fountain codes,” IEE Proc.-Commun., vol. 152, pp. 1062–1068, Dec. 2005. [10] W. E. Ryan and S. Lin, Channel Codes: Classical and Modern. New York: Cambridge University Press, 2009, pp. 201–220. |
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