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標題: 多載波分碼多工系統接收機之設計與性能分析
Designs and Performance Analysis on Receivers for Multi-Carrier Wireless CDMA Systems
作者: 曾慶輝
出版社: 電機工程學系
未來的B3G(beyond 3G)多媒體行動通信系統究竟需要傳送多快的數據速率(data rate),上下鏈路各佔用多少無線頻寬資源以及空間介面之無線傳輸技術等等,都是在未來十年內研究未來的多媒體行動通信系統的重要課題。本論文主要的研究方向首先提出並模擬2 states軟式抵銷(soft cancellation)遞迴濾波器接收機之性能,並與 [8] 之2 states硬式抵銷(hard cancellation)遞迴濾波器接收機之性能作一比較。又提出並模擬4/8 states軟式與硬式抵銷遞迴濾波器接收機之性能,再與 [8] 之2 states硬式抵銷遞迴濾波器接收機之性能作一比較。
tor)輸出端之多路徑信號解展頻標準化信號相抵銷,而非以回授判決器(decision device)的輸出數據位元與相關器輸出端之多路徑信號解展頻標準化後的信號相抵銷。所謂4 states遞迴濾波器係由2套相同2 states遞迴濾波器構成-1路徑與+1路徑。所謂8 states遞迴濾波器係由4套相同2 states遞迴濾波器構成-1 -1路徑、1 +1路徑、+1 -1路徑與+1 +1路徑。
我們以計算機在Matlab環境模擬軟式抵銷與硬式抵銷遞迴濾波器接收機於AWGN多路徑通道傳播之下鏈路(同步)與上鏈路(非同步)之性能,發現2 states軟式抵銷在P4之性能改善較多,而且軟式抵銷與硬式抵銷遞迴濾波器接收機於AWGN多路徑通道傳播之下鏈路(同步)與上鏈路(同步)之性能約略相同。對於2 states或4/8 states軟式與硬式抵銷遞迴濾波器接收機,即使接收機一開始就發生數據位元誤碼之情事,但因本論文所模擬的資料量很大,所以經歷一段很長的時間之後,該誤碼造成誤碼傳播(error propagation)的問題幾乎一樣變得不明顯。

The third generation of mobile communication systems (or 3G systems) will be able to provide a whole variety of voice, data and video services to the user. 3G systems will operate in the 2 GHz region and provide data rates of up to 2Mbps. However, the beyond third generation of multimedia mobile communication systems (or B3G systems) should be able to deliver a much higher data rate than is achievable in currently almost-ready 3G systems, Some people expect that the possible data rate for B3G systems should be roughly in the range of 10-100 Mbps [8]. Multicarrier direct sequence code-division multiple-access (MC-DS/CDMA) will be one of possible schemes for B3G systems, because this transmission scheme can accommodate very high data rate transmission over the hostile wireless channel.. In this thesis, the feasibility of a 2-state soft cancellation recursive filter on a MC-DS/CDMA over Multipath to overcome the problem of an unacceptable BER with conventional RAKE is studied.
It is well known that the perfect correlation between code sets is the distinguishing feature of complete complementary code (CC-code). In this thesis, we also designate the CC-code to the proposed MC-DS/CDMA architecture and use an offset stacked spreading modulation scheme in the transmitting side, but we use a 2-state soft cancellation recursive filter in the receiving side. Based on the use of the 2-state soft cancellation recursive filter is proposal in this work. We show that, under the proposed path pattern assumptions, the 2-state soft cancellation recursive filter is optimal than 2-state hard cancellation recursive filter on P4, and the performance at the downlink and the uplink of AWGN multipath channel are same.
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