運用插入二位元搜尋序列法實現降低正交分頻多工訊號之峰均功率比

USING INSERTION BINARY SEARCH SEQUENCE FOR PAPR REDUCTION IN OFDM SYSTEM

王星仁(Shin-jin Wang)

指導教授 ： 許超雲

大同大學/電機資訊學院/通訊工程研究所/碩士(2010年)

摘要

正交分頻多工(Orthogonal Frequency Multiplexing，OFDM)，是一種具有高傳輸速率的無線傳輸技術，且還有高頻寬效益、抗通到衰減、抗脈衝干擾等優點，是現在很常用的無線傳輸技術，但正交分頻多工也有他的缺點所在，一個最主要的缺點是會發生偶發性的過高峰值對均值功率比(Peak-to-Average Power Ratio，PAPR)的問題，當峰值對均值功率比過高在通過功率發大器，會產生非線性失真，造成頻譜擴展與帶內失真，因此增加位元錯誤率的發生。
在這篇論文中主要是將另一作者所提出降低峰值對均值功率比的方法進行修改，原方法是將擇性映射法(Selective Mapping，SLM)與插入虛擬序列法(Dummy Sequence Insertion，DSI)結合，而修改法為插入二位元搜尋序列法，在修改的方法中將插入虛擬序列的內容值提高成原始的2倍，當插入模擬序列長度為4時，可比原始法降低68.75%的IFFT使用數，且可降低1.5dB峰值對均值比率，當插入模擬序列長度為8時，可降低96.48%的IFFT使用數，也可降低3.2dB峰值對均值比率，且二位元搜尋法降低峰值對均值比率的效能與原使法是相當接近的。

關鍵字

峰值對均值功率比 ； 正交分頻多工 ； 插入虛擬序列法 ； 選擇性映射

並列摘要

OFDM (Orthogonal Frequency Division Multiplexing) technique is a popular communication system, because the OFDM technique can be achieved high data rate transmission, robustness to the multipath fading and immunity to impulse interference. However, an OFDM signal have very high peak-to-average power ratio (PAPR) problem. The high peaks of an OFDM signal are distorted nonlinearly by the power amplifier (PA), because high peaks effects such as the in-band distortion and the out-of-band radiation due to the, and increase the bit error rate(BER).
In this paper, we propose method using combined selected mapping(SLM) and dummy sequence inserted (DSI) scheme, In the modified method we improve the energy dummy sequence inserted, when the dummy sequence insertion length is 4,lower 68.75% than the original method of using the number of IFFT and Can reduce the 1.5dB PAPR, when the dummy sequence insertion length is 8, lower 96.48% than the original method of using the number of IFFT and Can reduce the 3.2dB, and can keeping the similar orthogonal frequency division multiplexing (PAPR) reduction performance compared with the modified DSI scheme.

並列關鍵字

Selected Mapping ； Dummy Sequence Inserted ； Peak-to-Average Power Patio ； Orthogonal Frequency Division Multiplexing

參考文獻

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