共查询到20条相似文献,搜索用时 78 毫秒
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分析了正交频分复用(OFDM)系统中剩余载波频偏在FFT之后对解调数据的影响,利用OFDM符号中插入的离散导频符号,对剩余频偏进行估计。在对算法进行仿真分析的基础上,提出了算法的现场可编程门阵列(FPGA)实现方案。整个设计过程在QuartusⅡ平台下进行,包括VHDL语言编程、逻辑综合和时序仿真,结果和理论分析相一致,可以用来对剩余频率偏差进行有效的纠正。 相似文献
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由于载波频偏会给多用户正交频分复用(Orthogonal Frequency—Division Multiplexing,OFDM)系统带来子载波之间干扰,从而造成多用户之间的干扰,导致系统性能下降.本文研究了多用户OFDM上行链路的频偏估计问题,通过使用多用户检测中的干扰抵消方法提出一种迭代参数估计算法用于估计多用户OFDM上行链路的频偏,该算法解决了使用似然估计(Maximum Likelihood,ML)进行多维搜索的问题,降低了ML估计器的复杂度,同时解决了多个频偏估计的问题。 相似文献
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基于DVB-T的OFDM频偏估计算法及DSP实现 总被引:3,自引:2,他引:1
由于OFDM调制是基于载波间正交的调制方式,频偏存在会使载波间正交性破坏,进而影响解调和性能。基于DVB-T提出了一种基于时域和频域相结合的频偏估计算法并对性能进行了仿真分析,并结合项目实际给出了DSP实现方法,最后对DSP实现后的数据进行了星座图验证和项目最后ARM接收端接收数据的验证。结果表明此算法对解决DVB-T物理层的频偏非常有效。 相似文献
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提出一种基于数据依赖叠加训练序列的OFDM载波频偏估计方法。叠加训练序列的周期性使其DFT能量间隔分布在特定的频点上,为了减小信息序列对叠加训练序列的影响,引入数据依赖序列使信息序列DFT在这些特定频点上为零,利用这个特性可进行频偏估计,只有得到正确的频偏估计时,这些旋转后的信息序列在这些特定频点的能量才得到最小值。仿真表明,该方法在不降低传输速率的情况下,有着较好的频偏估计性能。 相似文献
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面向CMMB接收机,本文分析了载波频率偏差对OFDM系统的影响,提出了一种OFDM频偏估计方法,实现了小数频偏和整数频偏估计。该算法在CMMB系统中的仿真结果表明,小数频偏估计方法具有较高的精度,整数频偏估计方法能够快速、准确地估计整数频偏。 相似文献
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针对正交频分复用(OFDM)系统,提出了一种低复杂度、高性能的载波频偏盲估计
方法。该方法充分利用载波频偏估计代价函数在一定区间内的单谷特性,采用黄金分割法搜
索载波频偏估计代价函数极值,从而大大降低其计算复杂度。最后对该方法和Tureli′s MU
SIC-like(TML)载波频偏估计方法在加性高斯白噪声信道和多径信道环境下进行了仿真,结
果表明,
在同等条件下该方法的计算复杂度大大低于TML载波频偏估计方法。 相似文献
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QIU Yan~ QIN Sheng-ping~ YUE Guang-xin~ .Qingdao Institute of Architecture Engineering Qingdao P.R. China .FibrLINK Networks Co. Ltd. .Beijing University of Posts Telecommunications Beijing P.R. China 《中国邮电高校学报(英文版)》2004,11(Z1)
1 Introduction OrthogonalFrequencyDivisionMultiplexing(OFDM )isamethodsuitableforhigh ratedatatransmissioninwirelesscommunications .However,thereareseverallimitingfactorsinthecommercialapplicationofOFDMforapplyingtohigh ratemo bilecommunication ,suchasDopplerfrequencyshift,synchronization ,channelestimation ,peak to averagepowerratio . Schmidl[1 ] completedsynchronizationusingspecialPNsequence,buttheestimateisnot precise.Minn[2~ 3] andByungjoon[4] improvethealgorithmperformance,butth… 相似文献
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LIU Xiao-ming LIU Yuan-an Wireless Communication Center Beijing University of Posts Telecommunications Beijing P.R. China 《中国邮电高校学报(英文版)》2004,11(Z1)
1 Introduction OrthogonalFrequencyDivisionMultiplexing(OFDM )isaneffectivetransmissionschemetocombatmultipathfading[1 ] .Byinsertingaguardin tervalbetweensymbolblockscalledcyclicprefix ,theInterSymbolInterference (ISI)canbemitigat ed.OFDMwasadoptedasthemodulationschemeforaDigitalAudioBroadcasting(DAB)system[2 ]andADSL (AsymmetryDigitalSubscriberLoop) [3]andwasalsoproposedastheterrestrialHDTVtransportinEurope[4] . OFDMsystemsareverysensitivetocarrierfre quencyoffset,andcarrie… 相似文献
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A Novel Carrier Frequency Offset Estimation for OFDM Systems Over Time-Varying Multipath Channels 总被引:1,自引:1,他引:0
This paper introduces a novel method to estimate fractional carrier frequency offset (CFO) under time-varying multipath channels
in OFDM systems based on the approximation of Basis Expansion Model (BEM). Due to the symmetrical character of the BEM basis,
we propose a new design of training sequence with trailing zeros. This training sequence can be used at the receiver to estimate
the frequency offset without channel estimation only in one OFDM symbol. We also compare our method with Beek’s ML estimator
and Lv’s fine synchronization estimator. The numerical results demonstrate that the proposed method provides an improved performance
when the training sequence has a short length.
相似文献
Chunming ZhaoEmail: |
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Orthogonal frequency division multiplexing (OFDM) systems are more sensitive to carrier frequency offset (CFO) compared to
the conventional single carrier systems. CFO destroys the orthogonality among subcarriers, resulting in inter-carrier interference
(ICI) and degrading system performance. To mitigate the effect of the CFO, it has to be estimated and compensated before the
demodulation. The CFO can be divided into an integer part and a fractional part. In this paper, we investigate a maximum-likelihood
estimator (MLE) for estimating the integer part of the CFO in OFDM systems, which requires only one OFDM block as the pilot
symbols. To reduce the computational complexity of the MLE and improve the bandwidth efficiency, a suboptimum estimator (Sub
MLE) is studied. Based on the hypothesis testing method, a threshold Sub MLE (T-Sub MLE) is proposed to further reduce the
computational complexity. The performance analysis of the proposed T-Sub MLE is obtained and the analytical results match
the simulation results well. Numerical results show that the proposed estimators are effective and reliable in both additive
white Gaussian noise (AWGN) and frequency-selective fading channels in OFDM systems.
相似文献
Feng YangEmail: |
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OFDM同步跟踪阶段的频偏估计算法 总被引:1,自引:0,他引:1
OFDM对栽频偏差是很敏感的,因此不仅在同步的捕获阶段,而且在同步的跟踪阶段,精确的频偏估计是很重要的。文献[3]提出了一种简化的相干判决反馈的迭代算法来估计同步跟踪阶段的载频偏差,对于128个子载波、QPSK调制的OFDM系统,在多径衰落信道下,当频偏小于子载波间隔的15%时,频偏估计的标准方差小于1%,但是这个结果是在假设信道频率响应、定时偏差、载波相位等参数已知的条件下取得的,而当这些参数的估计存在误差时,由仿真结果可看出,频偏估计性能恶化了,因此,提出了采用差分判决反馈的频偏估计算法,虽然只能估计小于子载波间隔 8%的频偏,但差分判决反馈算法不需要知道信道的参数,由于在同步跟踪阶段,频偏一般都较小,因此采用差分判决反馈算法可以很好地估计出同步跟踪阶段的频率偏差。 相似文献