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一种优化的OFDM符号定时与频偏估计算法及其FPGA实现 总被引:3,自引:2,他引:1
符号定时与频偏估计是OFDM系统中的关键技术之一.本文分析了符号定时偏差与载波频偏对OFDM系统性能的影响,提出了一种优化的最大似然同步算法,并给出了在FPGA中的硬件实现方案,得到其仿真结果.传统的循环前缀符号同步算法,仅仅利用一个OFDM符号的循环前缀及其相应部分的相关性,其相关峰值不明显,同步效果不理想.本文提出一种充分利用连续多个OFDM符号同时进行相关功率运算,在同样信噪比的情况下,相对于单个OFDM符号进行同步估计的系统,符号定时与频偏估计的精度更高,误差更小. 相似文献
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同步系统是 DAB 接收机的关键之一,针对其中的载波同步算法进行了分析。在理论分析载波频率偏差对 DAB 系统性能影响的基础上,介绍了2种分别用于载波粗频偏估计和细频偏估计的算法。粗频偏估计算法基于 DAB 信号所特有的相位参考符号(PRS),细频偏估计算法基于 OFDM 信号所特有的循环前缀(CP),对其它采用 OFDM 技术的系统具有很好的通用性。仿真结果表明这2种算法估计性能良好。 相似文献
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刘平 《信息安全与通信保密》2010,(11):31-32,35
OFDM符号是由多个子载波信号叠加而成,为确保各子载波之间的正交性,就对载波间的同步有很严格的要求,否则将造成信道间干扰和符号间干扰,严重影响OFDM系统的性能。提出一种新的基于循环前缀的OFDM时频同步算法,通过仿真,将新算法和传统的ML算法及集相关算法相比较。仿真结果表明,新算法定时捕获更快,且能更准确地确定无IBI干扰的循环前缀采样部分,具有更好的频偏和定时估计性能。 相似文献
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提出了一种改进的基于训练符号的频偏估计方法.该方法通过综合利用训练符号和循环前缀的信息得到时域的细频偏估计,通过峰值检测得到频域的粗频偏估计.仿真结果表明,在多径衰落信道下,在频偏估计范围达到整个信号带宽的同时,本算法的估计精度也有了明显的提高,并且当信噪比达到12dB时,可以使剩余频偏限制在子载波间隔的2%以内. 相似文献
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In this paper, we address the problem of carrier frequency offset (CFO) estimation for orthogonal frequency division multiplexing
(OFDM) systems with multi-antenna receiver. The received signal can be reconstructed to form data model with multi-invariance
property, and then a multi-invariance MUSIC algorithm for CFO estimation is proposed. This algorithm has better performance
of CFO estimation than ESPRIT method, multi-invariance ESPRIT method and trilinear decomposition algorithm, and also qualifies
the estimation for both integer CFO and fractional CFO. Simulation results illustrate validity of this algorithm. 相似文献
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In this paper, we address the problem of carrier frequency offset (CFO) estimation for Orthogonal Frequency Division Multiplexing
(OFDM) communications systems with multiple antennas. We reconstruct the received signal to form data model with multi-invariance
property, and subsequently derive a multiple-invariance ESPRIT algorithm for CFO estimation. This algorithm has improved CFO
estimation compared to ESPRIT method and maximum likelihood method. Simulation results illustrate performance of this algorithm. 相似文献
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This paper addresses the problem of carrier frequency offset (CFO) estimation for orthogonal frequency division multiplexing (OFDM) systems with multiple antennas, and links CFO estimation problem in OFDM systems to the compressed sensing trilinear model. Exploiting this link, we derives a compressed sensing trilinear model-based CFO estimation algorithm. The signal model can be expressed as a trilinear model, and there exists three compressed matrices which can compress the trilinear model to be a lower dimensional one. After that, trilinear decomposition is performed for the compressed model to get the estimations of compressed data matrices, and then the CFO can be estimated through solving the sparse recovery problem via \(\ell _0\) -norm constraint. The proposed algorithm has much better CFO estimation performance than ESPRIT method, and performs very close to the trilinear decomposition-based approach which has heavier computational burden and requires much greater storage capacity. Furthermore, our proposed algorithm can even work in condition of no virtual carrier. We derive the Cramer-Rao bound of CFO estimation for multiple antenna OFDM system. Simulation results illustrate performance of our algorithm. 相似文献
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Zhang Xiaofei Li Jianfeng Wu Hailang Xu Dazhuan 《Wireless Personal Communications》2012,67(2):139-147
In this letter, we develop a blind carrier frequency offset (CFO) algorithm for orthogonal frequency division multiplexing (OFDM) systems by utilizing a generalized precoding. Generalized precoding is employed to obtain multiple covariance matrices, and then a CFO estimation algorithm for OFDM system using joint diagonalization is proposed. Comparing to estimation of signal parameters via rotational invariance techniques (ESPRIT) method, the algorithm that we presented has improved CFO estimation performance. Furthermore, our algorithm even works well without virtual carrier. Simulation results illustrate performance of this algorithm. 相似文献
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Khaled Ramadan Khalil F. Ramadan Ahmed S. Fiky Hasna Alam Moawad I. Dessouky Fathi E. Abd El‐Samie 《International Journal of Communication Systems》2020,33(3)
Frequency synchronization has a great importance in preserving the performance of the underwater acoustic (UWA) orthogonal frequency division multiplexing (OFDM) systems. The carrier frequency offset (CFO) estimation can be blind or data‐aided. In this paper, the Zadoff‐Chu (ZC) sequences are used for OFDM synchronization in UWA communications, and they are compared with different data‐aided algorithms. We propose a low‐complexity algorithm for CFO estimation based on ZC sequences. Also, a joint equalization and CFO compensation scheme for UWA‐OFDM communication systems is presented. Simulation results demonstrate that the proposed CFO estimation algorithm allows estimation of the CFO accurately with a simple implementation in comparison with the traditional schemes. Also, the performance of the UWA‐OFDM system can be preserved in the presence of frequency offsets. 相似文献
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Orthogonal frequency division multiplexing (OFDM) systems are highly sensitive to carrier frequency offset (CFO), especially in doubly-selective fading environment. Cyclostationarity-based blind synchronization methods are appealing in high-data-rate applications and low signal-to-noise regions. However, the cyclostationarity has not been exploited for frequency synchronization of OFDM systems under doubly-selective fading channels. In this paper, we derive the close-form second order cyclic statistics of the received OFDM signal in presence of CFO, by modeling the doubly-selective fading channel with basis expansion model. Both transmitter-induced cyclostationarity and doubly-selective channel information are contained in the derived cyclic moments, and they are efficiently utilized for CFO estimation. Simulation results demonstrate that the proposed estimator provides significant improvements on frequency synchronization performance. 相似文献
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Non-data-aided carrier-frequency offset estimation for pulse-shaping OFDM/OQAM systems 总被引:2,自引:0,他引:2
In this paper we consider the problem of blind carrier-frequency offset (CFO) estimation for pulse-shaping orthogonal frequency-division multiplexing (OFDM) systems based on offset quadrature amplitude modulation (OQAM). In particular, under the assumption of low signal-to-noise ratio, three maximum-likelihood (ML) CFO estimators for non-dispersive channels are derived. Due to their significant computational complexity a more feasible closed-form CFO synchronization algorithm is considered. The performance of the derived blind estimators is assessed via computer simulations and compared with that of a blind CFO estimator previously proposed in the literature, exploiting the second-order cyclostationarity property of the OFDM/OQAM signal. 相似文献
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电力无线专网在1.8 GHz频段建设4G TD-LTE网络,正交频分复用(OFDM)是其关键技术之一,OFDM系统对信道产生的载波频率偏移(CFO)很敏感,频率偏移会造成系统性能的严重下降。因此,需要对OFDM系统中的频率载波偏移精确估计并补偿,以保证系统的性能。本文提出了一种用于OFDM系统中基于局部搜索的多重信号分类(MUSIC)盲CFO估计的算法,该算法利用频率偏移矩阵列矢量与噪声子空间的正交性和CFO的单峰特性,构造一个改进空间谱函数,然后通过局部谱峰搜索得到频偏估计值。该算法的CFO估计性能优于传统CFO估计算法,且能够克服传统MUSIC算法低信噪比下谱峰缺失的问题。仿真结果证明了该算法的有效性。 相似文献