結合天線分集與頻域等化器技術
以應用於直序分碼多工接收機之設計以應用於直序分碼多工接收機之設計

展頻分碼多工(DS-CDMA)技術由於具有提供高速傳輸的特性，因此被廣泛的使用於現今的行動通訊系統當中。然而，隨著科技不斷的進步，使用者對於更高速下載的需求也隨之而起，因此，在如此高速的無線傳輸過程之中，多路徑通道在頻率選擇性衰減所造成的影響之下，傳統上DS-CDMA系統中所使用的耙式接收機，其系統效能將會嚴重的下降。因此，為了克服這個問題，並且同時考慮接收機設計的複雜度因素，我們選擇以頻域等化器設計作為本篇論文探討的主軸。除此之外，由於多工的維度不斷的增加及等化器設計不完美等種種因素，系統效能將會被限制而無法提供準確的資料傳輸，因此，為了克服這些問題，本篇論文提出以一種方塊平行干擾消除的技術以期進一步增進系統效能。同時，為了避免通道嚴重衰減(deep fading)效應對於接收訊號產生影響，接收端的多天線分集技術也將在本篇論文當中使用。最後，為了驗證本篇論文中所提出的接收機設計方法在效能改善上的成效，我們將使用蒙地卡羅(Monte Carlo)模擬法進行分析及驗證。結果顯示，無論使用何種展頻因子或多工維度，我們所提出的接收機設計方法都能夠有效的改善系統效能。若將我們所提出的方法結合接收端的多天線分集技術應用，則系統效能將有更進一步的改善。

關鍵字

展頻分碼多工；頻域等化器；干擾消除；接收端天線分集技術

並列摘要

Rake receiver has been proposed for DS-CDMA system since 1995s. However, the propagation channel suffers from severe frequency-selective fading due to high-speed data transmission so that the performance of Rake receiver severely degrades. Besides, the error floor scenario would appear if the system capacity is high enough. In order to overcome the drawbacks as mentioned above, FDE based receiver structure is introduced in this thesis. Three kinds of implementation methods are taken into account on designing FDE receiver, which are respectively MRC, ZF, and MMSE. From the theoretical and simulation results, MMSE-FDE receiver design method can obtain the best behavior since it can jointly deal with interference and noise effects. However, the system performance with FDE receiver is eliminated if the number of multiplex order increases or the equalization procedure is imperfect. To overcome these restrictions, MMSE-FDE receiver with BPIC technique is proposed to cancel the residual interference and improve the system performance. In addition, receiver antenna diversity technique is also employed in this thesis since it can combat the deep fading effects and provides a diversity gain to improve the system performance. Monte Carlo simulation is performed and the results would show that MMSE-FDE receiver design method can further improve the system performance through applying BPIC technique. Moreover, the performance would approach to the theoretical lower bound more closely if antenna diversity technique is employed.

並列關鍵字

DS-CDMA ； FDE ； interference cancellation ； receiver antenna diversity

參考文獻

[1]. T. S. Rappaport, “Wireless communications: Principles and Practices”, Prentice Hall, 2nd Edition, 2002.

[2]. S. Haykin, “Communication Systems”, 4th Edition, Wiley, 2001.

[3]. Andrew J. Viterbi, CDMA – “Principles of Spread Spectrum Communication”, Addison-Wesley Wireless Communication Series, 1995.

[4]. John G.. Proakis, “Digital Communications”, 4th Edition, New York: McGraw-Hill, 2001.

[5]. Falconer, D.; Ariyavisitakul, S.L.; Benyamin-Seeyar, A.; Eidson, B., “Frequency Domain Equalization for Single-carrier Broadband Wireless Systems”, Communications Magazine, IEEE , Volume: 40 , Issue: 4 , April 2002.

國際替代計量

結合天線分集與頻域等化器技術以應用於直序分碼多工接收機之設計以應用於直序分碼多工接收機之設計

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