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In this paper the problem of data-aided symbol timing and frequency offset estimation in OFDM systems is considered. A synchronization
scheme based on a pilot symbol containing two identical parts obtained by transmitting BPSK data symbols on the even subcarriers
and setting zero on the remaining subcarriers is proposed. In this case, if the number of subcarriers is sufficiently large,
the pilot symbol can be modeled as a noncircular (NC) complex Gaussian random vector (CGRV). By exploiting the joint probability
density function of NC-CGRVs, the joint maximum likelihood estimator for the parameters of interest is derived. Since its
implementation complexity is high, a simpler synchronization scheme is obtained. Moreover, refined symbol timing and frequency
offset estimators, that assure relevant performance in multipath channels, are proposed.
T. Fusco was born in Naples, Italy, on March 22, 1977. She received the Dr. Eng. degree (summa cum laude) in electronic engineering
from the Second University of Napoli in 2002. Since November 2002 she has been a Ph.D. student at the Department of Electronic
and Telecommunication Engineering of the University of Napoli Federico II. Her current research and study interests lie in
the area of statistical signal processing, with emphasis on parameter estimation problems in the context of OFDM communications.
M. Tanda was born in Aversa, Italy, on July 15, 1963. He received the Dr. Eng. degree (summa cum laude) in electronic engineering
in 1987 and the Ph.D. degree in electronic and computer engineering in 1992, both from the University of Napoli Federico II.
Since 1995, he has been an Appointed Professor of Signal Theory an the University of Napoli Fe-de-ri-co II. Moreover, he has
been an Appointed Professor of Electrical Communications (from 1996 until 1997) and Telecommunication Systems (from 1997)
at the Second University of Napoli. He is currently Associate Professor of Signal Theory at the University of Napoli Federico
II. His research activity is in the area of signal detection and estimation, multicarrier, and multiple access communication
systems. 相似文献
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一种LOFDM系统定时和频偏的盲估计算法 总被引:1,自引:0,他引:1
基于网格正交频分复用(LOFDM)信号的周期平稳性,该文提出一种LOFDM系统定时和载波频率偏差的盲估计算法。理论分析和仿真实验证实由该算法构造的估计器能够有效地对抗频率选择性慢时变信道引起的衰落;在信道噪声广义平稳的情况下,估计器性能与信噪比无关,于是估计器在低信噪比条件下也能很好地工作;另外,符号定时和频率偏差估计器的性能互不影响。 相似文献
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在正交频分复用(OFDM)系统中,频率偏移会破坏子载波间的正交性,降低整个系统的性能。在研究传统频偏估计算法的基础上,利用简单的实数训练序列,进行OFDM系统的载波频偏估计,只需要一个训练序列,就可以有效地在时域内同时对小数倍和整数倍的频率偏移进行估计。仿真结果表明,基于实数训练序列的载波频偏估计算法不仅方法简单,易于实现,而且可提高频偏估计精度。 相似文献
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跳频电台中的CPM符号定时同步和频偏估计 总被引:1,自引:0,他引:1
提出了一种CPM的符号定时同步和频偏估计方法.首先分析了符号定时同步精度和频率偏差对解调性能影响.针对超短波跳频电台,提出了采用波形相关和最大似然估计定时偏差的方法,将同步精度提高到Ts/16;同时提出了采用预置频偏校正法减小频偏的影响.计算机仿真表明,该方法能使CPM的解调性能接近准确同步、无频偏的性能,验证了CPM... 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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文章基于正交频分复用(OFDM)系统对频偏的敏感性特点,介绍和分析了在OFDM接收机中的一种快速采样和精确跟踪技术。这种技术基于Kalman滤波算法和它快速的收敛速度,通过改变OFDM系统和接收端的设计参数来研究载波频率及估计器在接收端错误率中的影响。通过研究将得到一个最佳的频率偏移估计。该方法应用良好,有快速收敛能力,能在极短信号间歇中获取频偏,并拥有良好的跟踪能力。 相似文献
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提出了-种新的适用于LTE-TDD系统的新的频偏估计算法,整数倍频偏估利用PSS自身良好的自相关性,采用滑动相关估计出整数倍频偏;小数倍频偏估计利用PSS共轭相乘的方式得到. 相似文献
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符号定时估计是OFDM系统中的关键问题之一,该文就此问题提出了一种新的基于训练符号的定时估计算法。研究表明,新算法的性能基本不受载波频偏的影响,且具有很强的抗噪特性。通过采用这种算法可将定时误差缩小到只有抽样时间间隔的一半。并且,还可利用这个频域训练符号来进行载波频偏的估计,从而只需一个训练符号就能完成符号定时和载波频偏的联合捕获。 相似文献
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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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提出了一种通过峰值联合检测和频偏联合计算实现快速、宽范围、高精度、鲁棒性的频偏联合估计方法.采用并行双自相关器和鲁棒性的自相关峰值检测机制实现相关峰值的联合检测.采用频偏取值状态控制器和取值执行器完成包括小数倍和整数倍频偏的精确估算.该方法在WLAN接收机系统的频偏仿真测试表明,在IEEETGN多径信道A~F条件下,峰值检测正确率达100%(SNR>5),频偏估计均方误差<10-2.12(误差SNR>10),频偏估计范围达正负2.5倍子载波频率间隔. 相似文献