共查询到19条相似文献,搜索用时 170 毫秒
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针对高速移动场景下信道快衰落、非平稳等特性导致下行链路信道估计性能受限的问题,提出了一种适用于高速移动环境下行链路的信道估计方法.采用自回归过程对信道建模,构造自反馈的扩展卡尔曼滤波器(Extended Kalman Filter,EKF)追踪信道响应及其时域相关系数.为了解决EKF自反馈结构引起的误差传播问题,采用了迭代检测译码的接收机结构,以利用信道编码的冗余提升EKF的信道估计精度.仿真分析表明,在高速移动环境下所提方法相较于最小二乘估计和线性最小均方误差估计等传统方法提升了信道估计的均方误差和系统的误码率性能,可应用于高速列车无线通信设备的接收机基带信号处理系统. 相似文献
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基于扩展卡尔曼滤波的MIMO迭代信道估计方法 总被引:1,自引:1,他引:0
针对高速移动场景下信道快衰落、非平稳等特性导致下行链路信道估计性能受限的问题,提出了一种适用于高速移动环境下行链路的MIMO信道估计方法.采用自回归过程对信道建模,构造自反馈的扩展卡尔曼滤波器(EKF)追踪信道响应及其时域相关系数.采用迭代接收机的结构解决了在MIMO环境下观测方程欠定的问题.仿真结果表明,在高速移动环境下所提方法相较于最小二乘估计等传统方法提升了信道估计的均方误差和系统的误码率性能,可应用于高速列车无线通信设备的接收机基带信号处理系统. 相似文献
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针对频率选择性衰落信道下的分布式空频编码协同通信系统,提出了基于导频辅助的各种频域信道估计算法,包括最小二乘、线性最小均方误差、低阶近似线性最小均方误差算法,并给出了相应的均方误差性能表达式.理论分析和仿真结果表明本文提出的信道估计算法在协同通信系统中具有很高的实用性和精确度. 相似文献
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该文提出了采用实测的信道自相关系数作为权重的信道估计处理方法,并给出其误差性能的数学表达式,同时给出了经典的滑动平均信道估计方法的误差性能的数学表达式。理论分析及仿真结果表明所提的方法能自动适应移动信道的时变模型及衰落速率,具有有效地抑制噪声的优点;同时克服了滑动平均估计方法的估计长度对估计准确性影响较大的缺点,在移动速度固定及移动速度变化很大的环境下都具有稳定的误差性能;尤其在移动速度变化很大的环境下具有比滑动平均估计方法更低的估计方差,大大提高了RAKE接收机的性能。 相似文献
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Mobility-induced Doppler spread and multipath propagation introduce the time- and frequency-selectivity (doubly selectivity) in fading channels. Based on the complex exponential basis expansion model (BEM) to approximate the doubly selective channel (DSC), a low-complexity channel estimation scheme for block transmission systems over DSC are developed in this paper. Using the developed scheme, the long data block is divided into a few short data subblocks in terms of the maximum normalized Doppler frequency and block length, and each subblock is performed to respective channel estimation. Thus the total calculation complexity is effectively decreased because the number of the BEM channel coefficients to estimate is greatly reduced for each sub-block. Moreover, by utilizing these channel estimation values to refit the true channel, we can obtain better channel estimation. Besides, the normalized mean square error (NMSE) expressions for the developed scheme and the existing scheme are derived in detail, respectively. Compared to the existing scheme, the proposed scheme has lower calculation complexity and superior performance. The simulation results verify the effectiveness of the developed scheme, and the theory values of the derived NMSE accord with corresponding simulation values. 相似文献
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Liu Yingnan Gao Yonghui Zhang Nu Liang Qinglin 《电子科学学刊(英文版)》2008,25(1):115-119
By analyzing the relationship between Basis Expansion Model (BEM) and Doppler spectrum, this letter proposed a quasi-MMSE-based BEM estimation scheme for doubly selective channels. Based on the assumption that the basis coefficients are approximately independent and have the same variance for the same channel tap, the quasi-MMSE estimation shows approximately optimal performance and is robust to noise. Moreover, it can avoid a high Peak-to-Average Power Ratio (PAPR) by using continuous pilots. Performance of the proposed estimation scheme has been shown with computer simulations. 相似文献
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Intercarrier Interference Suppression for OFDMA Uplink in Time- and Frequency-Selective Fading Channels 总被引:1,自引:0,他引:1
《Vehicular Technology, IEEE Transactions on》2009,58(6):2741-2754
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数据的高速率传输以及终端的高速移动,导致无线通信信道具有时间选择性与频率选择性两个特征。该文主要研究了数据分组传输方式下,基于导频符号辅助调制(PSAM)的多输入多输出(MIMO)时间-频率双选择性信道的信道估计问题。首先,将时间-频率双选择性MIMO信道,建模为一个随时间变化的多项式内插信道模型;然后,根据信道Doppler衰落速率、多项式模型中的误差项,确定出模型的阶数以及整个数据块的长度;最后,基于该多项式内插信道模型,提出了采用PSAM的MIMO双选择性信道估计方法。实验结果表明该算法在时间-频率双选择性衰落信道下具有较好的性能。 相似文献
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In this article, we propose a time-spreaded quasi-orthogonal space-frequency coded OFDM system with constellation rotation.
A constellation rotated quasi-orthogonal OFDM system could offer full rate and full diversity in a frequency selective fading
channel. Time spreading can give additional time diversity gain in a fast fading channel. Assuming that complex channel gains
between adjacent subcarriers are approximately equal, we develop a coding scheme for 4 × 1 MISO transceiver and its BER performance
is evaluated for different Doppler frequencies in an OFDM system. The simulation results show that 2 dB gain can be achieved
at BER of 10−3 using the proposed scheme compared to a scheme without time spreading and constellation rotation when 512 subcarriers are
used at maximum Doppler frequency of 300 Hz. Also, the proposed system is analyzed for different delay spread of the channel
and the results show that if adjacent subcarriers are correlated, it is better in SF-OFDM decoding. 相似文献
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Accurate estimationand real-time compensation for phase offset and Doppler shift are essential for coherent multi-input multi-output (MIMO) systems. Here, a spatial multiplexing MIMO scheme with non-coherent frequency-shiftkeying (FSK) detection is proposed. It is immune to random phase interference and Doppler shift while increasingcapacity. It is valuable that the proposed spatial multiplexing MIMO based on energy detection (ED) is equivalentto a linear system, and there is no mutual interference caused by the product of simultaneous signals in square-lawprocessing. The equivalent MIMO channel model is derived as a real matrix, which remains maximal multiplexingcapacity and reduces the channel estimation complexity. Simulation results show that the proposed scheme hasoutstanding performance over Rician flat fading channel, and experimental system obtains four times the capacitythrough 4 antennas on both transmitter and receiver. 相似文献
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《Vehicular Technology, IEEE Transactions on》2009,58(3):1170-1176
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本文利用空时联合检测的方法,提出了在频率选择性信道下多天线发送的单载波频域均衡方案,它可以提供和一个发送天线多个接收天线单载波系统相同的分集增益,和单载波时域均衡相比具有低的复杂度。分析了信道估计误差对系统的影响,类似于基于迫零算法的线性均衡器的情形,在低信噪比下,信道估计误差对系统影响很大,给出了一种简单的克服方法。在不增加发射功率的情况下,使用信道编码可以进一步改善系统的性能。本方案的系统性能在6径典型城市信道模型下进行了评估,仿真的结果证明了本方案的有效性。 相似文献