广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统的灵活调制特性使其应用于低轨(Low Earth Orbit,LEO)卫星通信系统中可以带来诸多增益,但多个调制符号的叠加,导致GFDM的高峰均功率比(Peak-to-Average Power Ratio...广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统的灵活调制特性使其应用于低轨(Low Earth Orbit,LEO)卫星通信系统中可以带来诸多增益,但多个调制符号的叠加,导致GFDM的高峰均功率比(Peak-to-Average Power Ratio,PAPR)问题。针对此问题,在分析GFDM系统PAPR产生的原因后,对传统选择性映射(Conventional Selective Mapping,C-SLM)算法做出改进,利用Logistic混沌序列代替传统相位因子,解决边带信息冗余问题,采用线性重组的方式,进一步生成更多的备选信号,得到基于Logistic混沌序列的低复杂度选择性映射(Low Complexity SLM Based on Logistic Chaotic Sequences,LC-SLM)算法。在利用LC-SLM算法破坏符号间的相位一致性后,为解决单一算法对GFDM系统PAPR抑制不足的问题,将LC-SLM算法与指数压扩算法结合,提出一种低复杂度选择性映射联合指数压扩(LC-SLM with Exponential Companding,LC-SLM-EC)算法,使系统的PAPR进一步降低。实验结果表明,LC-SLM算法与生成相同数量备选信号的C-SLM算法相比,在大幅降低运算复杂度的前提下具有相近的PAPR性能,提出的LC-SLM-EC算法能够在不提升复杂度的基础上,使PAPR抑制效果更优。展开更多
Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called informat...Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.展开更多
文摘广义频分复用(Generalized Frequency Division Multiplexing,GFDM)系统的灵活调制特性使其应用于低轨(Low Earth Orbit,LEO)卫星通信系统中可以带来诸多增益,但多个调制符号的叠加,导致GFDM的高峰均功率比(Peak-to-Average Power Ratio,PAPR)问题。针对此问题,在分析GFDM系统PAPR产生的原因后,对传统选择性映射(Conventional Selective Mapping,C-SLM)算法做出改进,利用Logistic混沌序列代替传统相位因子,解决边带信息冗余问题,采用线性重组的方式,进一步生成更多的备选信号,得到基于Logistic混沌序列的低复杂度选择性映射(Low Complexity SLM Based on Logistic Chaotic Sequences,LC-SLM)算法。在利用LC-SLM算法破坏符号间的相位一致性后,为解决单一算法对GFDM系统PAPR抑制不足的问题,将LC-SLM算法与指数压扩算法结合,提出一种低复杂度选择性映射联合指数压扩(LC-SLM with Exponential Companding,LC-SLM-EC)算法,使系统的PAPR进一步降低。实验结果表明,LC-SLM算法与生成相同数量备选信号的C-SLM算法相比,在大幅降低运算复杂度的前提下具有相近的PAPR性能,提出的LC-SLM-EC算法能够在不提升复杂度的基础上,使PAPR抑制效果更优。
文摘Orthogonal frequency division multiplexing (OFDM) is vastly used in wireless networks. Its superiority relies on the fact that information can be split in large amount of frequencies. Each frequency is called information subcarrier. OFDM exhibits excellent annotation in channel fades and interferers as only a few subcarriers can be affected and consequently a small part of the original data stream can be lost. Orthogonality between frequencies ensures better spectrum management and obviates the danger of intersymbol interference. However, an essential problem exists. OFDM systems have high peak to average power ratio. This implies large fluctuations in signal power, ending up in increasing complexity of ADCs and DACs. Also, power amplifiers must work in a larger linear dynamic region. In this paper we present two new techniques for reducing Peak to Average Power Ratio (PAPR), that can be added in any OFDM system and we compare them with other existing schemes.
