利用混沌選擇性映射結合預編碼技術降低正交分頻多工存取系統之峰值對均值功率比

PAPR Reduction in OFDMA Systems by Using Chaotic SLM Combined with Precoding Scheme

何政霖(Cheng-Lin Ho)

指導教授 ： 曾德璋

國立臺北科技大學/電資學院/電腦與通訊研究所/碩士(2014年)

摘要

正 交 分 頻 多 重 存 取 (Orthogonal Frequency Division Multiple Access,OFDMA) 以正交分頻多工(Orthogonal Frequency Division Multiplexing,OFDM)技術為基礎，具有提高頻譜使用率及傳送不同使用者資料的優點，卻也存在著具有高峰值對均值功率比(Peak-to-Average Power Ratio, PAPR)的缺點。選擇性映射(Selection Mapping, SLM)能有效降低PAPR 技術，但複雜度的增加與額外傳送輔助資訊(Side Information, SI)是其問題所在。本文主要針對 OFDMA 系統使用SLM 技術以降低PAPR 值及運算複雜
度問題加以探討，為了降低SLM 技術中IFFT 的運算複雜度，首先將SLM技術得到之候選訊號，經由反快速傅立葉轉換(Inverse Fast Fourier Transform,IFFT)後，利用線性組合方法得出更多組候選訊號，以降低運算複雜度，並結合Generalized Chirp-Like (GCL)矩陣之預編碼降低系統PAPR值，再利用混沌(Chaotic)相位序列進一步降低系統PAPR 值。由模擬結果顯示，本文提出的方法能有效地降低SLM 技術之運算複雜度及PAPR 值。

關鍵字

正交分頻多重存取 ； 混沌序列 ； 選擇性映射

並列摘要

Orthogonal frequency division multiple access (OFDMA), based on an orthogonal frequency division multiplexing (OFDM) technique, provides high data rates with flexible bandwidth allocation and high spectral efficiency.However, OFDMA systems also inherit the principal disadvantage of traditional OFDM systems, namely a high peak-to-average power ratio (PAPR).Selected mapping (SLM) scheme is effective in the reduction of the PAPR, yet it may suffer from complexity and spectral efficiency.This thesis is mainly to investigate the effect of both the PAPR reduction
and the computational complexity of the system. To generate more candidate signals, the proposed scheme uses the linear combination of the tranditional SLM method, enabling the computational complexity to be effectively reduce.
Combing the generalized chirp-like precoding scheme, chaotic sequence can effectively reduce the PAPR. Simulation results show that the proposed method can effectively reduce the computational complexity and the PAPR of the SLM scheme.

並列關鍵字

OFDMA ； Chaotic Sequence ； Selected Mapping

參考文獻

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