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PAPR Reduction in OFDM Systems with Large Number of Sub-Carriers by Carrier Interferometry Approaches 总被引:5,自引:4,他引:1
HE Jian-hui QUAN Zi-yi MEN Ai-dong School of Telecommunication Engineering Beijing University of Posts Telecommunications Beijing P.R.China 《中国邮电高校学报(英文版)》2004,11(4)
High Peak-to-Average Power Ratio(PAPR)is one of the major drawbacks of Orthogonal Frequency DivisionMultiplexing(OFDM)systems.This paper presents the structures of the particular bit sequences leading to the maximumPAPR(PAPR_(max))in Carrier-Interferometry OFDM(CI/OFDM)and Pseudo Orthogonal Carrier-Interferometry OFDM(PO-CI/OFDM)systems for Binary Phase Shift Keying(BPSK)modulation.Furthermore,the simulation and analysisof PAPR_(max) and PAPR cumulative distribution in CI/OFDM and PO-CI/OFDM systems with 2048 sub-carriers are pre-sented in this paper.The results show that the PAPR of OFDM system with large number of sub-carriers reduced evidentlyvia CI approaches. 相似文献
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Fang Zhi Xiao Wan'ang Shi Yin 《电子科学学刊(英文版)》2008,25(1):1-6
A new fine carrier frequency offset estimation algorithm in Orthogonal Frequency Division Multiplexing (OFDM) system is proposed. The correlation item is the training sequence instead of the received signal in the new algorithm. Simulation results show that the performance of the new algorithm is 4dB-9dB better than that of Schmidl's algorithm. Coarse frequency offset estimation is also discussed in this paper, which is the improvement of Zhang's method. The estimation range using the improvement method is twice as that using the Zhang's method. Based on the hardware of the receiver and the improved algorithm, a method using Fast Fourier Transform (FFT) is proposed to implement the coarse frequency estimation. The chip area of OFDM system can be reduced by using the proposed method. 相似文献
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以探测大气中水汽吸收谱线为应用背景,系统设计了一种基于快速傅里叶变换(FFT)的宽带宽的谱分析技术的微波辐射计。阐述了谱分析技术的微波辐射计的设计原理,详细介绍了系统结构设计、接收机方案设计和谱仪的方案设计,并分析了系统的主要技术指标、正交接收机指标及谱仪的设计。该系统可实现的辐射计探测频率为22.235 GHz,设计带宽达到500 MHz,谱分辨力为60 kHz。 相似文献
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Interference mitigating based on FRactional Fourier Transform in Transform Domain Communication System 总被引:2,自引:0,他引:2
Wang Chuandan Zhang Zhongpei Li Shaoqian 《电子科学学刊(英文版)》2007,24(2):181-186
The method of FRactional Fourier Transform (FRFT) is introduced to Transform Domain Communication System (TDCS) for signal transforming in the paper after theoretical analysis. The method yields optimal Basis Function (BF) by FRFT with optimal transform angle. The TDCS using the proposed method has wider usable spectrum, stronger robustness and better ability of anti non-stationary jamming than using usual methods, such as Fourier Transform (FT), Auto Regressive (AR), Wavelet Transform (WT), etc. The main simulation results are as follows. First, the Bit Error Rate (BER) Pb is close to theoretical bound of no jamming no matter in single tone or in linear chirp interference. Second, the interference-to-signal ratio J/E is at least 12dB more than that of Direct Spread Spectrum System (DSSS) under the same BER if the spectrum hopping-to-signal ratio is 1:20 in chirp plus hopping interfering. Third, the Eb/N0 (when estimation difference is 90% between transmitter and receiver) is about 3.5dB or about 0.5dB (when estimation difference is 10% between transmitter and receiver) more than that of theoretical result when no estimation difference under Pb = 10^-2. 相似文献
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Chu Zhenyong Ying Xiaofan Tian Hongxin Yi Kechu 《电子科学学刊(英文版)》2005,22(5):449-457
M-ary spread spectrum technique has been found wide applications in wireless communications, but it needs too many orthogonal spreading codes, and its despreading/demodulation is quite complex computationally, which limit its wider applications. This paper proposes a novel scheme for Code Division Multiple Access (CDMA) communication systems based on M-ary spread spectrum, where only one prototype spreading code is assigned to each user and the codes for different users are orthogonal or quasi-orthogonal with each other. The M spreading codes of each user to represent K bits data are generated by circularly shifting the assigned code and reversing its polarity. The spreading codes generated like that are called as BiOrthogonal Cyclic Codes (BOCCs). At the receiver of the system, a transform domain matched-filter implemented by means of Fast Fourier Transform (FFT) is employed to despread and demodulate the received signals, which has very low computational complexity. The results of simulation experiments and bit-error performance analysis show that the proposed scheme is practical and very useful in many cases. 相似文献
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提出了一套快速傅里叶变换深能级瞬态谱(FFT-DLTS)测试系统,分析了该系统的硬件构成和软件流程,并给出了一个实例分析。最后,将FFT-DLTS与常规DLTS作了对比。 相似文献
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1 IntroductionMuchinteresthasbeenfocusedonOrthogonalFrequencyDivisionMultiplexing (OFDM)inmanyareas,suchaswiredandwirelessapplications[1~ 1 5] .Synchronizationinbothtimeandfrequencydo mainisacriticalprobleminOFDMsystems.WEILandSCHLEGELC ,etalhavediscussedtheeffectsofsynchronizationerrorsandcarrierfrequencyoff sets[1~3] .ThemostremarkableworkbyBEEKJ[3]isajointMLestimatoroftimeandfrequencyoffsetutilizingtheCyclicPrefix (CP)withouttheaidofadditionalpilots.ThenJOHANSSONS ,eta… 相似文献
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ChuZhenyong YingXiaofan YiKechu TianHongxin 《电子科学学刊(英文版)》2005,22(3):273-280
A novel fast despreading scheme for M-ary Multi-Carrier Code-Division Multiple Access (MC-CDMA) system is proposed based on cyclic spreading codes and pre-equalizer. In the transmitter, the M spreading codes of each user are generated by circularly shifting the prototype spreading code. A feedback pre-equalizer is employed to process the M-ary MCCDMA signal before transmitted. The received signal is multiplied by the Inverse Discrete Fourier Transform (IDFT) result of the mirror image code of the prototype spreading code, and then demodulated by Orthogonal Frequency-Division Multiplexing (OFDM) demodulator. Compared with the conventional M-ary MC-CDMA receiver, the proposed scheme increases bandwidth efficiency, meanwhile, it achieves M-ary despread spectrum and multi-carrier demodulation, which reduces computation complexity remarkably. 相似文献
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A novel fast despreading scheme for M-ary Multi-Carrier Code-Division Multiple Access (MC-CDMA) system is proposed based on cyclic spreading codes and pre-equalizer. In the transmitter, the M spreading codes of each user are generated by circularly shifting the prototype spreading code. A feedback pre-equalizer is employed to process the M-ary MCCDMA signal before transmitted. The received signal is multiplied by the Inverse Discrete Fourier Transform (IDFT) result of the mirror image code of the prototype spreading code, and then demodulated by Orthogonal Frequency-Division Multiplexing (OFDM) demodulator. Compared with the conventional M-ary MC-CDMA receiver, the proposed scheme increases bandwidth efficiency, meanwhile, it achieves M-ary despread spectrum and multi-carrier demodulation, which reduces computation complexity remarkably. 相似文献
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在用电设备中广泛使用各种电力电子器件,往往会引起供电电网电压波形发生畸变,即谐波污染,会带来许多危害。在线电网谐波分析仪就是为了监测电力谐波污染而设计的。其整个设计过程采用模块化设计的思想。系统硬件主要包括电源模块,传感器前端电路模块,TMS320F2812数字信号处理器(DSP)主电路板模块。系统软件主要包括人机界面(HMI)程序模块,模数转换(ADC)程序模块,快速傅立叶变换(FFT)程序模块。 相似文献
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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
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Real-valued Fast Fourier Transform (FFT) plays an important role in today’s digital world because of the fact that most of the signals contain real values. The FFT computation of real signals using conventional techniques requires more hardware space with high power consumption, which is the most important task for a researcher while designing VLSI architectures. This can be eradicated by clearly analysing the symmetric property of the real-valued signals. In this paper, we have adopted the symmetric property and designed an efficient pipelined architecture for 16-point DIF FFT. The pipeline scheme reduce the processing time at the cost of some registers and in order to contribute efficiently for power reduction we have modified the complex multiplier with reduced internal real multipliers which are in turn replaced by an modified canonic signed digit multiplier (CSDM) with resource-sharing technique. The complete module is synthesised and simulated using Xilinx ISE 14.1 with the target device is Virtex-5 xc5vlx110T. The experimental results verify that our implemented design is more efficient in terms of speed, area and power when comparing with similar works. 相似文献
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High-throughput, high-performance OFDM via pseudo-orthogonal carrier interferometry spreading codes 总被引:1,自引:0,他引:1
The paper introduces to orthogonal frequency-division multiplexing (OFDM) systems a novel pseudo-orthogonal carrier interferometry spreading code which spreads each parallel data stream over all the OFDM carriers. Pseudo-orthogonal carrier interferometry (PO-CI) spreading codes are carefully selected to introduce the following benefits to OFDM: up to 2N parallel data streams can be coded onto N carriers, with little degradation in performance; when rate 1/2 channel coding is applied in addition to PO-CI spreading codes, the resulting binary phase-shift keying OFDM systems demonstrate the performance of coded OFDM and the throughput of uncoded OFDM; PO-CI codes are carefully selected to spread in a manner which eliminates the peak-to-average power ratio problems characteristic of traditional OFDM. 相似文献
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在脉组间步进频信号的脉组内利用傅里叶变换测速时,针对测速误差对合成距离像的影响,提出了二分迭代法。该方法通过log2N次迭代操作便可使测速精度提高N倍(N为脉组个数),通过相关补偿后的合成距离像的走动不超过半个距离分辨单元。此外,由于测速精度提高速率是以2为底的指数增长,且每次迭代为脉组内FFT操作,因此该方法具有较少的运算量。仿真实验验证了该方法的有效性。 相似文献
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为了在嵌入式设备中高效运行快速傅里叶变换算法,提出了一种针对小尺寸高速缓冲存储器优化的旋转因子的生成与访存策略,该方法能够有效提高缓存命中率及运算速率。给出了不同需求下配置参数的选取原则,基于典型算法配置参数和目标处理器平台进行算法测试。实验结果证明,优化后的方法在信噪比性能下降较小的情况下能够获有效地提升计算速率。 相似文献
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用于音乐作品版权保护的数字音频水印算法 总被引:2,自引:1,他引:1
提出了一种用于音乐作品版权保护的数字音频水印嵌入算法,该算法首先将视觉可辨的二值水印图像降维成一维水印序列并进行随机置乱,再从原始数字音频信号中随机选取采样数据并进行快速傅立叶变换(FFT),最后结合人类听觉系统(HAS)掩蔽特性选取绝对值较大的FFT系数嵌入水印信息。仿真实验表明:该数字音频水印嵌入算法不仅具有较好的透明性,而且对诸如叠加噪声、有损压缩、低通滤波、重新采样、重新量化等攻击均具有较好的鲁棒性。 相似文献