共查询到20条相似文献,搜索用时 125 毫秒
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单载波频域均衡系统因具有峰均比低、适用于高速率传输的优势,具有广泛的应用前景,同时对其信道估计性能也提出了一定的要求。针对传统一维MMSE估计算法性能较差,而二维算法运算复杂度又较高的问题,依据信道的时频分离特性提出了一种低复杂度二维MMSE信道估计算法。将二维估计转化为两个一维估计,再通过改进的SVD算法减小一维估计的复杂度,并通过在帧结构插入特殊字(UW)序列作为循环前缀来减小系统开销,进行噪声方差估计。理论分析及仿真结果表明,本文算法比传统的LS及MMSE信道估计算法在未编码系统及编码系统中的性能都更好,且运算复杂度比传统一维MMSE算法更低。 相似文献
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提出了一种适用于时间频率选择性衰落信道的MIMO-OFDM系统的组合信道估计方法。采用AR过程对信道进行建模,利用基于导频的低维Kalman滤波算法进行信道估计,并采用LS算法估计时变的信道衰减因子。Kalman滤波跟踪了信道的时域相关性,为了同时跟踪信道的频域相关性,采用了一种基于MMSE(minimum mean square error)的合并器对Kalman滤波算法进行修正。仿真表明,提出的这种组合算法降低了传统的Kalman滤波结构的复杂度,能够跟踪信道的时频变化,改进了基于LS准则的信道估计算法,并且与复杂的高维Kalman滤波算法的信道估计性能相当。 相似文献
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OFDM系统基于二维核回归算法的衰落信道估计 总被引:1,自引:0,他引:1
提出了一种低复杂度的基于二维核回归平滑的时间频率双衰落信道估计算法.该方法首先采用LS算法估计导频处的信道增益并利用分段线性插值方法得到数据子载波处的信道增益,然后分别利用两个级联的一维核回归平滑器在时域和频域对信道矩阵进行二维平滑,以消除由信道噪声、ICI和插值误差等引入的估计误差.对插值和平滑分别进行优化处理,因此具有计算复杂度低、性能优良等优点.数值仿真表明:该算法性能较LS算法和1维DFT算法有较大的改进;与1维LMMSE算法相比性能相差很小,在低信噪比时甚至超过了后者. 相似文献
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NGB-W广播信道估计实现算法设计 总被引:1,自引:0,他引:1
针对下一代广播电视网无线系统(NGB-W)广播接收信道估计,提出了一种基于二次一维维纳滤波的信道估计实用算法.该算法实时估计信道多普勒频偏、时延扩展和噪声方差等参数,并根据参数估计值分别从离线获得的预选集中选择时域和频域的一维维纳滤波系数.通过Cocentric System Studio(CCSS)平台仿真,给出了参数估计对算法性能的影响,以及所提信道估计算法的均方误差和误块率性能.仿真结果表明该算法在不同移动速度下,与采用理想插值系数信道估计相比性能损失不超过0.4 dB,与理想信道估计相比性能损失在1 dB以内. 相似文献
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在Mobile WiMAX OFDMA系统下,研究了线性插值、二阶多项式插值和三次样条插值等几种经典的内插拟合的信道估计方法,仿真发现它们不能很好地支持高速移动性,基于分段线性插值算法提出了一种改进方法。在ITUVA60和Va120信道环境下,对这几种内插算法的误比特率和均方误差性能进行了仿真。仿真结果证明,在高速移动环境下,提出的改进方法要比其他几种算法的性能要好。 相似文献
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在正交频分复用(Orthogonal Frequency Division Multiplexing,OFDM) 系统中由于快衰落导致信道特征不连续,常规的信道插值方法无法准确反应导频与整个信道之间的关联性。针对这一问题,提出了一种基于宽深超分辨率(Wide Deep Super-resolution,WDSR)网络的信道估计方法,把导频值通过最小二乘估计(Least Squares,LS)初步插值,再通过WDSR网络再次放大重构整个信道的响应。将信道估计插值上采样替换成初步插值和图像超分辨率上采样两步。仿真结果表明,与超分辨率卷积神经网络(Super-resolution Convolutional Neural Network,SRCNN)信道估计算法相比,在不同种类的信道以及导频数下WDSR信道估计方法均方误差性能提升约4.6 dB。 相似文献
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全球微波互联接入(WIMAX,Worldwide Interoperability for Microwave AccesS)系统采用正交频分复用技术实现无线宽带接入,信道估计是WIMAX系统的关键技术。这里主要研究了WIMAX系统信道估计中的内插算法,包括线性内插、二阶内插、DFT内插、DCT内插和幅度相位内插等算法,分析并比较了不同内插算法在各种SUI信道中对系统性能的影响,仿真结果表明,在视距信道中,二阶内插以及幅度相位内插算法性能较好;在非视距信道中,DCT-II内插和二阶内插算法性能较好。综合而言,二阶内插算法以增加适当复杂度的代价在各种信道中均获得了较好的性能,推荐采用。 相似文献
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本文提出了4G OFDM移动通信系统中一种新型的自适应信道估计方法.利用信道冲激响应的最重要分量,本自适应信道估计方法能有效地降低子载波间干扰和高斯白噪声的影响.根据性能仿真结果比较,本方法在MSE、BER上表现优于变换域插值、时域插值方法. 相似文献
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《Digital Communications & Networks》2019,5(2):76-83
In this paper, the problem of high mobility channel estimation in the Long-Term Evolution for Railway (LTE-R) communication system is investigated. By using a Basis Expansion Model (BEM), the channel impulse response is modeled as the sum of several basis functions multiplied by coefficients. By estimating the basis function coefficients, the fast time-varying channel can be approximated. In order to reduce the estimation error resulting from the high frequency basis function, the Generalized Complex Exponential BEM (GCE-BEM) is modified to form an Improved GCE-BEM (IGCE-BEM) by adding a correction coefficient to the basis function. Moreover, an Improved Baseline Tilting (IBT) method is proposed to reduce the Gibbs effect. In addition, linear interpolation, Gauss interpolation, and three-order Hermite interpolation are adopted to obtain the channel impulse response at non pilot locations based on the channel estimation results at pilot positions. The simulation results show that the IGCE-BEM outperforms the CE-BEM and GCE-BEM in terms of the Normalized Mean Squared Error (NMSE). The IBT method is better than the BT method in reducing the Gibbs effect. In addition, combined with the IBT, the IGCE-BEM also has low NMSE under high moving speed and high noise power. The performance of the three-order Hermite interpolation method is higher than that of the linear interpolation and Gauss interpolation approaches. 相似文献
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In OFDM systems, time‐varying channels destroy orthogonality between subcarriers causing Inter‐Carrier Interference. To reduce this effect, a Kalman filter, as a benchmark, is used for channel estimation, based on comb‐type pilot arrangements of the OFDM system. An advantage of comb‐type pilot arrangements in channel estimation is the ability to track the variation of the channel caused by Doppler frequency. Kalman method has been proposed to estimate the channel frequency response (CFR) at the pilot locations, then CFR, at data subchannels, is obtained by means of interpolation between estimates at pilot locations. The low‐complexity Kalman method is introduced to reduce the complexity of the system while achieving the same BER/SNR. Different types of interpolations have been also compared such as Low‐pass, Spline‐cubic and Linear interpolation methods. The BER/SNR performance of BPSK modulation schemes are considered for time varying Rayleigh fading channels. Our results has shown that the low‐complexity Kalman estimation, used with the pilot arrangement and a suitable interpolation method, gives almost the same performance as that of the Kalman method specially for low SNR values and hence the effect of Doppler shift effect is controlled. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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In single frequency network (SFN), there exist some special long delay spread channels as well as conventional multipath channels.
For pilot-aided orthogonal frequency division multiplex (OFDM) systems, channel estimation is usually accomplished by interpolation
with pilots. However, few pilot sub-carriers exist within the coherent bandwidth of the long delay spread channels in SFN.
In this case, conventional frequency domain interpolation methods cannot work properly. In a narrowband channel, this paper
indicates that both the real and the imaginary parts of channel frequency response can be accurately approximated as a sine-wave
with DC offset. For many practical pilot-aided OFDM systems, the bandwidth of the narrowband channel mentioned before is comparable
with the interval between several adjacent pilot sub-carriers. Then this paper proposes a sine-wave based frequency domain
interpolation method for the channel estimation of pilot-aided OFDM systems in SFN. As simulation results show, the proposed
method performs well in the long delay spread channel, whereas the mismatched Wiener interpolation filter (WIF) estimates
channel response inaccurately. Moreover, the proposed method gives accurate channel estimation in conventional multipath channels,
especially for the systems which adopt high order modulations. 相似文献
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OFDM系统中多导频的FFT信道估计算法 总被引:5,自引:1,他引:4
论文提出了OFDM系统中基于FFT的信道估计方法,包括基于时域插值及变换域插值方法。时域插值算法的理论基础是利用FFT频域采样定理,可由频域有限频点的采样值经过IFFT/FFT得到整个频域传输函数的估计值,而不发生混叠。变换域插值算法的理论基础是利用FFT时域抽样定理,利用OFDM信号特点和信道特性,经过FFT/IFFT将信号和噪声分离,并在此基础上进行加窗改进算法,以减小插值中的频谱泄漏,提高估计效果。仿真结果说明,加窗的基于FFT变换域的方法性能有了很大改善。 相似文献
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两种插值信道估计方法的比较 总被引:1,自引:0,他引:1
在瑞利衰落信道中,使用时分复用的导频信号辅助的信道估计方案时,提出了在使用极大似然方法估计出导频符号的信道参数之后,再利用一个时隙上所有导频符号的Chebyshev多项式的数学插值估计数据符号信道参数的方法。同时比较了分段线性插值加递归的信道估计方法。仿真结果表明,使用Chebyshev多项式的数学插值估计信道参数的方法比使用线性插值加线性递归的信道估计方法能更好的改善系统的性能。 相似文献