共查询到20条相似文献,搜索用时 15 毫秒
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凭借很强的抗符号间干扰(ISI)和抗衰落能力,采用正交频分信道的OFDM技术的无线通信越来越受到人们的重视。但是作为一种多载波调制方式,OFDM技术同样存在着高峰均比(PAPR)的问题,高的PAPR会导致信号畸变,造成子信道间的相互干扰,从而影响OFDM的性能。针对此,重点介绍了OFDM系统中的PAPR比问题的概念,并对降低PAPR的主要算法进行了论述。 相似文献
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多载波码分多址(MC-CDMA)被广泛认为是未来4G通信的核心技术,但MC-CDMA信号的高峰均功率比(PAPR)会引起非线性失真并导致误码率性能恶化。针对MC-CDMA系统的高峰均功率比的问题,对传统的选择性映射(SLM)算法进行改进。提出一种自适应选择复用帧数的选择性映射系统,在误码率满足一定条件的基础上,通过自适应选择复用帧数的算法选择出最适合系统的复用帧数的个数,使系统在复杂度较低的基础上仍能有效的降低信号的峰均功率比。仿真结果验证其有效性。 相似文献
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正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM)系统中,峰均功率比(Peak to AveragePower Ratio,PAPR)过高会导致收发器的非线性失真,严重影响系统的性能。传统的部分传输序列(Partial TransmitSequence,PTS)算法能够有效地降低PAPR,然而其计算复杂度随着分块数目增长呈指数增加。在研究PTS的基础上提出了双重迭代PTS算法,该算法利用增加迭代次数,并且每次迭代时选择不同的相位旋转因子集合来优化OFDM系统的峰均比性能。该算法在峰均比性能上优于常规OFDM系统以及普通迭代PTS算法,在降低峰均比性能和计算复杂度之间取得了较好的折衷。 相似文献
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Wireless Personal Communications - High Peak-to-average power ratio (PAPR) is one of the main issues in multicarrier modulation systems. PAPR is mainly caused due to the summation of various... 相似文献
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Md. Mahmudul Hasan 《Wireless Personal Communications》2013,73(3):791-801
Orthogonal frequency division multiplexing (OFDM) is perhaps the most spectrally efficient, robust transmission technique discovered so far for communication systems, and it also mitigates the problem of multipath environment. High peak-to-average power ratio (PAPR) has always been a major drawback of the OFDM systems. In this article, a new precoding technique has been proposed based on Vandermonde-like matrix (VLM) and selective mapping (SLM) to reduce PAPR in OFDM systems. VLM precoding reduces the autocorrelation of the input sequences while SLM takes an advantage of the fact that the PAPR is very sensitive to phase shifts of the signal. The main advantage of this proposed scheme is to achieve a significant reduction in PAPR without increasing the system complexity. Computer simulations show that, the proposed method outperforms the existing precoding techniques without degrading the error performance of the system. 相似文献
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Wireless Personal Communications - Selective mapping (SLM) is one of the core techniques to mitigate the problem of high PAPR in the MIMO-OFDM system. But the complexity of inverse fast Fourier... 相似文献
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正交频分复用(OFDM)具有较高的频谱利用率、良好的抗多径干扰能力,长期以来一直受到广泛的关注。目前,OFDM已经被公认为是下一代移动通信系统的核心技术之一,但其较高的峰值平均功率比(PAPR)却一直是制约OFDM技术发展的问题之一。如何降低OFDM系统的PAPR是目前通信领域的研究热点之一,本文对目前常用的降低PAPR方法进行了综合分析和比较,并讨论了各方法的优缺点。 相似文献
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《Broadcasting, IEEE Transactions on》2009,55(3):679-685
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无线通信OFDM系统中的高峰均比(PAPR)是限制OFDM技术实用化的主要障碍.介绍了一些抑制OFDM系统中PAPR的主要方法:信号畸变技术、概率类技术、信号编码技术,并对其中几种常用的方法:如限幅法、压缩扩展法、SLM(选择映射法)、PTS(部分传输序列法)进行具体分析,使用Matlab对它们进行仿真比较,讨论各自存在的优缺点. 相似文献
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Byung Moo Lee Youngok Kim Rui J. P. de Figueiredo 《Wireless Personal Communications》2012,63(2):331-344
Since one of major problems of OFDM-based systems is high peak-to-average-power ratio (PAPR) of its transmitted signal, many
PAPR reduction techniques and combined schemes with individual techniques have recently been developed. Among various techniques,
the clipping technique has been widely used as a practical scheme owing to its low computational complexity and simplicity
in implementation, while the selected mapping (SLM) technique is known to provide good PAPR reduction performance without
signal distortion. Generally, the combined scheme of two PAPR reduction techniques, which are the clipping and the SLM, is
expected to provide the enhanced performance of PAPR reduction, because the clipping noise of combined scheme would be less
than that of single clipping technique, when the SLM technique is employed before clipping. However, the performance of clipping
scheme with SLM technique has not been evaluated for practical systems over fading channels. In this paper, the performance
of the clipping scheme with the SLM technique is theoretically analyzed and compared with simulation results over fading channels.
The performance of combined scheme is analyzed with various clipping ratios, phase sets for SLM, and modulation schemes over
flat and frequency selective fading channels. In addition, the effects of the clipping at the receiver and the oversampling
on the BER performance are discussed. Based on the results of analysis, therefore, one can design the effective clipping scheme
with the SLM technique for the PAPR reduction of OFDM-based systems. 相似文献
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峰均功率比(PAPR)问题是OFDM系统的主要缺陷之一,在光OFDM系统中,由于调制器、D/A转换器、功率放大器和光纤的非线性,高峰均功率比的信号将会产生严重畸变,对系统的性能造成较大的影响。介绍了降低OFDM系统PAPR的主要方法,包括信号预畸变技术、编码技术和概率类技术,并对星座图扩展(ACE)方法和脉冲成形(PS)方法进行了仿真分析,讨论了各自的优缺点及改进的空间。 相似文献
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正交频分复用(OFDM)系统的主要缺点是峰均功率比(PAPR)增大会严重地降低了发射机中高功率放大器(HPA)的效率.部分传输序列(PTS)算法能有效地降低OFDM信号的PAPR概率,但随着PTS中分割子块的增多也带来了高的计算复杂度.为此,文中提出一种新的PTS算法,该算法比传统的穷尽搜寻法具有更佳的性能.仿真结果表明,文中所提PTS算法在降低PAPR相似的情况下,具有更小的计算复杂度. 相似文献
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为降低OFDM峰均功率比,提出一种改进的PTS算法,性能仿真分析的结果表明,改进算法与传统算法相比,系统复杂性降低,易于实现. 相似文献
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Seok-Joong Heo Hyung-Suk Noh Jong-Seon No Dong-Joon Shin 《Broadcasting, IEEE Transactions on》2007,53(4):804-808
In this paper, we propose a new peak-to-average power ratio (PAPR) reduction scheme of orthogonal frequency division multiplexing (OFDM) system, called a modified selected mapping (SLM) scheme, which considerably reduces the computational complexity with keeping the similar PAPR reduction performance compared with the conventional SLM scheme. The proposed scheme is analytically and numerically evaluated for the OFDM system specified in the IEEE 802.16 standard. For the OFDM system with 2048 subcarriers, the proposed scheme with 4 binary phase sequences can reduce the complex multiplications by 63.5% with the similar PAPR reduction compared with the SLM scheme with 16 binary phase sequences. 相似文献
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正交频分复用(OFDM)以其独特的优点已经被广泛的应用在移动通信系统中,但是峰均比问题是制约其发展的一个很大的瓶颈,针对OFDM通信系统中高的峰均比问题,设计出了一种新的基于选择性映射的发射和接收装置,该装置利用N点相关器来探察辅助信息,有效地解决了辅助信息判断错误的问题,而且经过深层次的理论分析和实验仿真表明,该方法不仅准确高效地传输辅助信息,而且不浪费系统资源,因而增强了系统抗干扰能力,提高了OFDM系统的性能。 相似文献