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標題: | 應用於正交分頻多工系統之頻譜預編碼與通道預等化技術及降低峰均功率比技術 Spectrally Precoded OFDM With Enhanced Capacity and Reduced PAPR |
作者: | Shang-Tien Yang 楊尚典 |
指導教授: | 鐘嘉德(Char-Dir Chung) |
關鍵字: | 正交分頻多工,頻譜緊湊,道道容量,預等化,峰均功率比, Orthogonal frequency-division multiplexing,spectrum compactness,channel capacity,channel preequalization,peak to-average power ratio, |
出版年 : | 2018 |
學位: | 碩士 |
摘要: | 當事先知通道資訊時,在固定頻率選擇性通道上研究用於使用正交分頻多工(orthogonal frequency-division multiplexing; OFDM)的頻譜預編碼(spectral precoding)以提供非常緊密的訊號頻譜、增強信道容量和降低峰均功率比(peak to-average power ratio; PAPR)。通過採用預編碼率1-2I/N並由此引入2I度的冗餘(redundancy),首先針對發送的N個子載波的OFDM訊號開發通用預編碼器形式,以提供非常小的頻譜旁瓣衰減,漸近地衰減為 f^(-2I-2),其中f是以Hz為單位的頻率,同時產生降低的PAPR,從而實現高頻譜緊密性。結合通道資訊,然後設計特定頻譜預編碼器以最大化固定接收端訊號雜訊功率比的通道道容量,並且還開發了線性最小均方誤差頻域均衡器相應的OFDM接收機。所提出的預等化和頻譜預編碼PSP-OFDM系統被示出提供非常接近預均衡OFDM的通道容量。當需要小的帶外功率比例來保證緊密的信號頻譜時,所提出的PSP-OFDM系統可以比預均衡OFDM,頻譜預編碼OFDM和非預編碼OFDM進一步提供更高的每單位帶寬的信道容量,全部傳送相同的資料速率。 When the channel information is known a priori, spectral precoding for rectangularly-pulsed orthogonal frequency-division multiplexing (OFDM) using cyclic prefix is studied on fixed frequency-selective dispersive channels to provide extremely compact signal spectrum, enhanced channel capacity, and reduced peak to-average power ratio (PAPR) jointly. By employing a precoding rate 1-2I/N and thus introducing 2I degrees of redundancy, a general precoder form is first developed for the transmitted N-subcarrier OFDM signal to provide extremely small spectral sidelobes decaying asymptotically as f^(-2I-2), with f being the frequency in hertz, while yielding reduced PAPR, and thus achieve high spectrum compactness. Incorporating the channel information, a particular spectral precoder following the general form is then designed to maximize the channel capacity for the fixed received signal-to-noise power ratio, and a linear minimum mean-square-error frequency-domain equalizer is also developed for the corresponding OFDM receiver. This particular spectrally precoded OFDM system preequalizes the channel effect at the transmitter and exploits frequency diversity on channel dispersion at the receiver, while enhancing channel capacity and providing compact signal spectrum with reduced PAPR. The proposed preequalized and spectrally precoded (PSP) OFDM system is shown to provide channel capacity in bits per second very close to pre-equalized OFDM which embodies water filling-typed power loading. When a small out-of-band power proportion is required to guarantee compact signal spectrum, the proposed PSP-OFDM system can further provide much higher channel capacity per unit bandwidth than pre-equalized OFDM, spectrally precoded OFDM, and nonprecoded OFDM, all conveying the same data rate. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/69308 |
DOI: | 10.6342/NTU201801512 |
全文授權: | 有償授權 |
顯示於系所單位: | 電信工程學研究所 |
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