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標題: | 適用於行動正交分頻多工系統之結合通道估計與資料偵測之巢狀疊代式接收機設計 Nested Iterative Receiver Design with Joint Estimation and Detection for Mobile OFDM |
作者: | Chien-Yi Wang 王荐一 |
指導教授: | 闕志達(Tzi-Dar Chiueh) |
關鍵字: | 正交分頻多工,巢狀疊代式接收機,SAGE演算法,結合通道估計與資料偵測,雙重選擇性通道, Orthogonal frequency division multiplexing (OFDM),nested iterative receiver,space-alternating generalized expectation-maximization (SAGE) algorithm,joint estimation and detection (JED),doubly selective channel, |
出版年 : | 2010 |
學位: | 碩士 |
摘要: | 無線通訊為人類帶來極大便利,日常生活中隨處可見無線技術之應用,如手機、無線上網、數位電視、衛星導航等等。下世代無線通訊系統的研究正如火如荼地進行中,目標是增加傳輸率以及支援高速移動。正交分頻多工(OFDM)是目前最為熱門的調變技術之一,已經被眾多無線傳輸標準採納。OFDM能有效利用頻寬,提供高傳輸率;然而OFDM易受通道快速變化之影響,因而產生之載波間干擾會大幅降低傳輸品質。
在靜態或低速的無線通訊應用中,廣義靜態通道的假設是合理的。然而高速移動時,以往被忽略的通道特性突顯出來,如延遲漂移與路徑生滅。若仍然秉照廣義靜態假設,則設計出來的接收機無法在高速下正常使用。為了使OFDM系統能夠應付日常生活中會遇到的高速移動環境,如高鐵、高速公路,本論文提出一複雜度低且實用性高的演算法,結合通道估計與資料偵測,有效解出訊號。為了證明實用性,本論文採用第二代歐規數位電視地面廣播標準(DVB-T2)驗證提出演算法之效能。搭配DVB-T2採用的低密度奇偶校驗碼(LDPC)進行渦輪解碼(turbo decoding),本論文提出之演算法能夠在高速下成功解出訊號。 Wireless communication makes our life much more convenient. In everyday life, we can see applications of wireless technology everywhere, for example, cell phone, WLAN, digital TV, and GPS, etc. The research of wireless communication systems for next generation is going on. The objective is to increase data rate and to support high mobility. Orthogonal frequency-division multiplexing (OFDM) is one of the most popular modulation techniques and already adopted in many wireless standards. OFDM systems utilize bandwidth efficiently and provide high data rate. However, OFDM is vulnerable to rapid channel variation which causes the degradation of transmission quality. For wireless communication in stationary or low-speed applications, we may assume the wireless channel is wide-sense stationary (WSS). Nevertheless, regarding the receiver design for high-speed applications, some channel characteristics shall not be neglected, say, delay drift and multipath birth/death. If we still make the WSS assumption, such design cannot survive in highly mobile scenarios. In order for OFDM systems to support high mobility in daily life, for example, high-speed trains and vehicles on highway, we propose a low-complexity and practical algorithm which considers channel estimation and data detection jointly. To justify the practicability, we verify our algorithm in a DVB-T2 system. Combined with LDPC, the forward error correction adopted by DVB-T2, to implement the turbo principle, the proposed algorithm is able to detect signals at high mobility successfully. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/45983 |
全文授權: | 有償授權 |
顯示於系所單位: | 電子工程學研究所 |
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