首页 | 官方网站   微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 93 毫秒
1.
在分析降低PAPR的常用算法的基础上,提出一种基于部分传输序列(PTS)算法和压扩变换(C变换)算法的联合算法.仿真结果表明所提联合算法能以较小的计算复杂度有效的降低OFDM系统的峰均比,算法具有一定的实用价值.  相似文献   

2.
降低正交频分复用系统峰均功率比的部分压扩算法   总被引:2,自引:0,他引:2  
针对现有压扩变换法系统性能差的缺点,提出了一种降低系统峰均功率比的部分压扩算法。该方法根据正交频分复用(OFDM)系统信号幅度服从瑞利分布的统计特性,仅压缩大幅度信号保持了系统信号幅度的分布特征,弥补了现有压扩变换的不足,且具有带外功率小的优点。在M阶调制方式下的系统仿真结果表明,部分压扩方法与选择性映射和部分传输序列等方法相比,可获得相近的峰均功率比压缩效果并且在同样的系统误码率条件下比指数压扩法获得约log2(M)dB信噪比增益。  相似文献   

3.
扈鹏 《无线电工程》2012,42(7):55-58
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   

4.
曹若云  江涛  秦家银 《电子学报》2007,35(6):1099-1101
本文通过理论推导和分析,确定了基于误差函数降低正交频分复用(OFDM)系统峰均功率比的非线性压扩方法中两个关键参数的取值,修正了以前的结果,并在此基础上提出了一种新的压扩函数来降低OFDM系统的峰均功率比.理论分析和仿真结果表明,新的压扩方法能够在保持原信号平均功率不变的情况下使峰均功率比降低到7.8dB以下,并且系统具有较好的误比特率性能.  相似文献   

5.
为了降低OFDM系统中的峰均功率比,提出利用反正切变换对OFDM信号进行压扩处理.反正切压扩可以在压缩大信号的同时,增强小信号,从而提高了OFDM系统的误码率性能.仿真结果表明,与著名的μ律压扩方法相比,反正切压扩可以获得更好的峰均功率比性能和更低的误码率.该方法应用简单,不受载波数量和调制方式的限制.  相似文献   

6.
针对正交频分复用(OFDM)系统的高峰均功率比(PAPR)问题,在对部分传输序列(PTS)算法和限幅法的基本原理进行简要介绍的基础上,提出了一种用哈达玛矩阵初始化翻转迭代PTS初始搜索相位的改进算法,将输出信号通过限幅处理进一步降低OFDM系统的峰均功率比。仿真结果表明,联合算法有效降低了系统的PAPR,证明了有效性。  相似文献   

7.
针对基于分数阶Fourier变换的OFDM系统(简称FrFT-OFDM系统)的高峰均功率比(PAPR)问题,该文提出一种低复杂度的峰均比抑制算法。通过对随机相位序列采用周期延拓至FrFT-OFDM符号长度,相位因子加权后与子载波调制前的数据相乘的方式,实现对高峰均比的有效抑制。该算法只需要一次逆离散分数阶Fourier变换(IDFrFT),所有备选信号直接通过时域chirp圆周移位的加权和得到。仿真结果表明,当备选信号个数相同时,该算法与选择映射(SeLecting Mapping,SLM)算法的PAPR抑制性能相当,比部分传输序列(Partial Transmit Sequence,PTS)算法具有更好的PAPR抑制性能,同时,该算法较SLM和PTS算法的运算量降低。  相似文献   

8.
直流偏置光正交频分复用(DC-biased optical orthogonal frequency division multiplexing,DCO-OFDM)可见光通信(visible light communication,VLC)系统具有较高的峰均功率比(peak-to-average power ratio,PAPR)。为解决此问题,提出一种联合限幅和归一化μ律压扩算法抑制DCO-OFDM系统的PAPR。首先,该联合算法利用限幅操作对时域信号中的大峰值信号进行削波来降低信号的幅值;其次,对限幅后的信号再进行压扩变换。通过这种联合算法,DCO-OFDM系统的PAPR可以显著降低。实验仿真结果表明,当采用16QAM调制方式,互补累计函数的值为10^(-3)时,相比较于联合限幅和传统μ律压扩算法,此联合算法的PAPR下降了约2.206 dB。  相似文献   

9.
介绍了OFDM技术的发展现状及应用前景.针对OFDM系统峰均比较高的缺点,研究降低PAPR的各种算法,分析与比较不同算法的优势与不足,并对降低峰均比的压扩变换法、PTS算法以及SLM算法进行了计算机仿真,同时给出不同算法下的系统误码率性能仿真结果,指出扰码类算法在降低PAPR方面的优势.仿真结果对PAPR问题的研究具有借鉴意义.  相似文献   

10.
为了降低OFDM信号的峰均功率比(PAPR),设计了一种分段线性压扩变换.对小幅度通过数乘变换进行线性放大,而对大幅度先利用数乘变换进行线性缩小,再对缩小后的幅度进行等量放大.得到的压扩变换是分段线性且连续的,用低复杂度的线性运算抑制峰均比,同时用分段的方法减小压扩对系统性能的影响.理论分析和仿真表明,通过数乘因子和增...  相似文献   

11.
The orthogonal frequency‐division multiplexing (OFDM) is a multicarrier modulation system that is used to transmit the large volume of data to the receiver. Reducing the peak‐to‐average power ratio (PAPR) in OFDM system is one of the demanding and crucial task in recent days. For this reason, various precoding and companding mechanisms are developed in the traditional works, but it remains with the limitations of increased complexity, reduced performance, and nonlinear distortion. The reduction of PAPR is achieved by minimizing the companding distortion with the enhancement of the bit error rate (BER) performance significantly. Then, in order to avoid clipping in OFDM, a multilateral piecewise exponential companding transform (MPECT) method has been utilized rather than using piecewise exponential companding transform (PEC) where PAPR is getting reduced. The OFDM is very sensitive to synchronizing error. To overcome this sensitivity, employ the Zadoff‐Chu sequence to carrier frequency offsets. Zadoff‐Chu matrix transform (ZCMT) has numerous merits among the other ODFM systems such as the improvement in the performance of the channels that are fading away and provides an ideal periodic autocorrelation and a constant magnitude periodic cross correlation. Both of these techniques provide improvement in the ODFM systems. To get more efficiency, this paper aims to develop a hybrid technique by integrating the ZCMT and MPECT techniques for reducing the PAPR in OFDM systems. Further, convolutional encoding is applied for better BER and PAPR. The simulation results of the proposed ZCMT‐MPECT technique are evaluated and compared with the conventional OFDM and other precoding methods.  相似文献   

12.
Exponential companding technique for PAPR reduction in OFDM systems   总被引:7,自引:0,他引:7  
In this paper, a new nonlinear companding technique, called "exponential companding", is proposed to reduce the high Peak-to-Average Power Ratio (PAPR) of Orthogonal Frequency Division Multiplexing (OFDM) signals. Unlike the /spl mu/-law companding scheme, which enlarges only small signals so that increases the average power, the schemes based on exponential companding technique adjust both large and small signals and can keep the average power at the same level. By transforming the original OFDM signals into uniformly distributed signals (with a specific degree), the exponential companding schemes can effectively reduce PAPR for different modulation formats and sub-carrier sizes. Moreover, many PAPR reduction schemes, such as /spl mu/-law companding scheme, cause spectrum side-lobes generation, but the exponential companding schemes cause less spectrum side-lobes. Computer simulations, which consider a baseband OFDM system with Additive White Gaussian Noise (AWGN) channels and a Solid State Power Amplifier (SSPA), show that the proposed exponential companding schemes can offer better PAPR reduction, Bit Error Rate (BER), and phase error performance than the /spl mu/-law companding scheme.  相似文献   

13.
Orthogonal Frequency Division Multiplexing (OFDM) systems have become the most promising wireless communication systems in the recent years. For OFDM systems, there is one major drawback, which is the high peak‐to‐average power ratio (PAPR). Companding techniques have been frequently proposed to reduce PAPR. Exponential companding technique offers efficient PAPR reduction with a low bit error rate (BER). However, the exponential companding technique is difficult to implement. This paper utilizes the Padé approximation to simplify the exponential companding technique. The simulation results demonstrate that the proposed companding technique offers the same performance results as those of the exponential companding technique, while Additive White Gaussian Noise (AWGN) or multipath fading channel is considered. Further, the hardware implementation results show that the complexity of the proposed companding technique is less than that of the exponential companding technique. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

14.
基于压扩变换的直接检测O-OFDM系统的实验研究   总被引:9,自引:9,他引:0  
仿真研究并实验验证了直接检测光正交频分复用(O-OFDM)系统中引入压扩变换(CT)技术可降低OFDM信号峰值平均功率比(PAPR)和提高接收灵敏度。仿真结果表明,压扩系数μ越大,信号PAPR越低;随着μ的增大,系统误码率(BER)呈现先下降后上升的趋势。权衡PAPR的降低度和系统BER,选择μ=2时为最佳。实验研究表...  相似文献   

15.
This paper proposes a companding scheme, where small signals are enlarged and large signals are reduced, to reduce the Peak-to-Average Power Ratio(PAPR). Computer simulation results show that the proposed technique has two advantages at least when compared with the conventional methods such as partial transmit sequence, selective mapping and the previous companding. First, it gets better PAPR performances with a lower complexity. Second, the scheme achieves greater performances gain with hardly any damnification of OFDM signals in some degree.  相似文献   

16.
In this paper, a companding technique is proposed to effectively reduce the peak-to-average power ratio (PAPR) in single-carrier frequency division multiple access (SC-FDMA) systems. By companding the samples with large amplitudes, while enhancing those with small amplitudes, a significant reduction in the PAPR can be achieved. The performance of the proposed SC-FDMA with companding system is studied and compared with that of the standard SC-FDMA system. Simulation results show that the SC-FDMA with companding system has a lower PAPR when compared with the conventional SC-FDMA system, while the complexity of the system slightly increases. Results also reveal that the companding coefficient must be chosen carefully in order to limit the PAPR without introducing degradations into the bit error rate performance.  相似文献   

17.
针对传统压扩变换方法存在计算复杂度较高或设计灵活性不够的问题,推导并提出了一种新的、更为高效的非线性压扩变换改进算法。通过引入适当的参数,简化了压扩变换中功率守恒时的参数计算问题,所提出的方法不仅可以降低计算复杂度,而且系统灵活性也得到进一步的改善。仿真实验表明该算法可在抑制PAPR和保证误码性能之间取得更好的折中。  相似文献   

18.
俞鹤伟 《电讯技术》2006,46(5):34-39
讨论了降低OFDM系统峰均比所采用的基于数值变换的压缩扩张算法,给出了几种压扩函数,推导出了使用压扩变换后OFDM系统的误码率公式,由此分析了压扩算法对OFDM系统性能的影响。可以看出,该算法不仅能有效降低OFDM系统的峰均比,而且能降低系统的误码率。仿真结果表明,本文给出的公式较好地反映了使用该算法后OFDM系统的误码性能。  相似文献   

19.
江涛 《电子学报》2005,33(7):1218-1221
本文提出了一种新的降低OFDM信号峰均功率比的压缩扩张技术.文中通过与传统压缩扩张技术的对比,详细介绍了新压缩扩张技术的方法和计算复杂度、并从统计角度分析了对峰均功率比及其用于OFDM系统时对系统误比特率的改善等方面的性能.数值仿真说明,与传统压缩扩张技术相比较,新压缩扩张技术不仅具有更低的计算复杂度,而且可以获得更为高效的性能增益.  相似文献   

20.
Nonlinear companding transform is a promising technique for the peak-to-average power ratio (PAPR) reduction in multicarrier transmission systems. However, conventional hard piecewise companding schemes often along with serious nonlinear distortion or complex companding parameters optimization embarrassment. In this paper, a novel designing criterion of nonlinear companding functions with more effective system performance is proposed. By transforming the Gaussian-distributed multicarrier signals into desirable statistics forms, we show that the smooth and differentiable concave probability distribution function of companded signals can obtain a better PAPR reduction and less out-of-band radiation as well as more simple companding parameters optimization than the traditional piecewise companding schemes. A detailed theoretical analysis and discussion is formulated, and then based on the analysis results, a novel trigonometric function companding scheme is presented and evaluated. Numerical results demonstrate that the companding schemes which consistent with the proposed criterion may significantly outperform conventional schemes by choosing the companding form and parameters appropriately.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司    京ICP备09084417号-23

京公网安备 11010802026262号