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利用跨層編碼及階層調變以同時降低多符元之峰均值功率比的設計
The Designs to Simultaneously Reduce the PAPR Values of Multiple Symbols Using Cross-layer Coding and Hierarchical Modulation
摘要
近年來，湧泉碼之應用逐漸受到重視，以湧泉碼之概念進而降低峰均值功率比的研究已被提出並作為封包階層使用，然而此設計當一個湧泉碼編碼封包包含多正交分頻多工符元時，並不能為其峰均值功率比提供良好的效能。在本文中，我們提出跨層級結合湧泉碼及階層調變之設計，並針對網路中之各種應用使用正確的資源管理策略，以達到控制峰均值功率比之目的。我們亦提出了以湧泉碼結合迴旋碼之跨層級設計，此設計將迴旋碼字分割成若干部分，並結合部分傳輸序列之概念，以達成控制單/多使用者情況下之峰均值功率比，然而，透過維特比演算法中計算最大相似路徑增加量，可省略部分傳輸序列必須傳送之相位資訊。此兩種提出之設計經由分析及實驗驗證，皆可良好地控制峰均值功率比。
並列摘要
Recently, fountain codes have been attracted much attention. Fountain codes as packet-level codes to reduce PAPR for OFDM systems have been proposed. However, the PAPR can not be achieved as well as the SLM-type scheme when a encoded packet is carried over multiple OFDM symbols. In this thesis, a cross layer design for PAPR reduction by using fountain codes and hierarchical modulation. Due to existing versatile applications in networks, proper resource management which help solve the problem is discovered. We also proposed another cross layer design for PAPR reduction by using a fountain code and a convolutional code. We fragment a convolutional codeword into several segments and apply the PTS concept to reduce PAPR values in the Single/Multi user case. However, the transmission of the side information about the rotations can be avoided through calculating increasing rate of the minimal path metrics in a Viterbi decoder. Both designs provide good PAPR performance through analyses and simulations in this thesis.