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OFDM系统基于自适应定阶的MMSE信道估计 总被引:5,自引:0,他引:5
MMSE估计是OFDM系统中常用的信道估计算法。针对MMSE信道估计的失配问题,该文提出了一种基于自适应定阶的MMSE估计算法。该算法通过对信道最大多径时延的估计,自适应地调整信道自相关函数的产生,获得接近匹配时的MMSE估计效果。 相似文献
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Yongfeng Guan Tao Xu Rene van Leuken Manyi Qian 《Circuits, Systems, and Signal Processing》2014,33(3):839-861
Mobile OFDM refers to OFDM systems with fast moving transceivers, in contrast to traditional OFDM systems whose transceivers are stationary or have a low velocity. In this paper, we use the basis expansion model (BEM) to model time-varying OFDM channels. Using different BEM’s, we investigate various architectures to implement the least-squares (LS) channel estimation and its corresponding zero-forcing (ZF) channel equalization. The experimental results show that our implementation for mobile OFDM systems is capable of combatting the time variation of mobile OFDM channels, and more hardware resource utilization is necessary compared with a traditional OFDM design which fails in a time-varying scenario. For mobile OFDM systems, different BEM’s are available for the channel modeling. We observe that the so-called Critically sampled Complex-Exponential BEM (CCE-BEM) leads to the most efficient hardware architecture while still maintaining high modeling accuracy. 相似文献
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In this paper, we propose a very low linear minimum mean square error (LMMSE) channel estimation technique for orthogonal frequency division multiplexing (OFDM) systems. The conventional LMMSE, based on the autocorrelation channel matrix, requires \(O(N_P^3)\) operations (\(N_P\) represents the total number pilot in one OFDM symbol). By exploiting the structure of the channel autocorrelation matrix, we propose a very low complexity LMMSE channel estimator which requires only \(O(N_PlogN_P)\) operations. Simulation results show that the proposed technique yields the same performances as well as the classical LMMSE in terms of bit error rate and mean square error. 相似文献
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Fu-Te Hsu Hsuan-Jung Su 《Wireless Communications, IEEE Transactions on》2009,8(10):4988-4992
We study a class of space-time codes constructed by linear dispersion encoding that allow low-complexity linear minimum mean square error (MMSE) decoding for a multiple access system. Considering that the information symbols are drawn from square QAM constellations, we optimize rate-one space time code designs with MMSE decoding to achieve minimum bit error rate (BER) for any channel realization. In addition, the performance is further improved with a simple MMSE successive interference cancellation (MMSE-SIC) method. Simulation results compare the proposed design with existing rate-one designs and show that simple rate-one circulant designs are also good candidates for deployment in multiple access systems. 相似文献
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对基于导频的信道估计中的插值算法,包括线性、高斯、变换域、低通滤波及三次样条插值算法的性能、特点进行分析比较。其中,三次样条插值算法在对复杂信道的估计方面,具有更好的性能和灵活性。最后,给出三次样条插值利于工程实现的简便算法。 相似文献
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Channel estimation is employed to get the current knowledge of channel states for an optimum detection in fading environments. In this paper, a new recursive multiple input multiple output (MIMO) channel estimation is proposed which is based on the recursive least square solution. The proposed recursive algorithm utilizes short training sequence on one hand and requires low computational complexity on the other hand. The algorithm is evaluated on a MIMO communication system through simulations. It is realized that the proposed algorithm provides fast convergence as compared to recursive least square (RLS) and robust variable forgetting factor RLS (RVFF-RLS) adaptive algorithms while utilizing lesser computational cost and provides independency on forgetting factor. 相似文献
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Maria Jose Canet Vicenç Almenar Santiago J. Flores Javier Valls 《Journal of Signal Processing Systems》2012,68(3):287-301
In this paper, a new time synchronization algorithm for OFDM systems with repetitive preamble is proposed. This algorithm makes use of coarse and fine time estimation; the fine time estimation is performed using a cross-correlation similar to previous proposals in the literature, whereas the coarse time estimation is made using a new metric and an iterative search of the last sample of the repetitive preamble. A complete analysis of the new metric is included, as well as a wide performance comparison, for multipath channel and carrier frequency offset, with the main time synchronization algorithms found in the literature. Finally, the complexity of the VLSI implementation of this proposal is discussed. 相似文献
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The high peak‐to‐average power is one of the main drawbacks in OFDM systems. This letter proposes a partial shift mapping (PSM) method for peak power reduction in OFDM systems. By utilizing the properties of the discrete Fourier transform, the proposed method generates a set of candidate signals without additional complex multiplication and selects the one with minimum peak power for transmission. Analyses and simulations confirm that the PSM method achieves satisfactory peak power reduction performance and low complexity compared with other kindred methods, for example, selected mapping and partial transmit sequences. 相似文献
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该文提出了一种新的信道估计算法,用于无线移动信道下的正交频分复用(OFDM)系统。该算法对接收的导频信号(Pilot)分别在多径展宽域和多普勒展宽域进行处理,显著地降低了子载波间干扰和高斯白噪声的影响。此外,多普勒展宽域处理的滤波器是动态设计的,具有良好的自适应性。仿真结果表明,在不同的多普勒频偏下,该算法都有良好的性能。 相似文献
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《Circuits and Systems II: Express Briefs, IEEE Transactions on》2008,55(9):922-926
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Seok-Joong Heo Hyung-Suk Noh Jong-Seon No Dong-Joon Shin 《Broadcasting, IEEE Transactions on》2007,53(4):804-808
In this paper, we propose a new peak-to-average power ratio (PAPR) reduction scheme of orthogonal frequency division multiplexing (OFDM) system, called a modified selected mapping (SLM) scheme, which considerably reduces the computational complexity with keeping the similar PAPR reduction performance compared with the conventional SLM scheme. The proposed scheme is analytically and numerically evaluated for the OFDM system specified in the IEEE 802.16 standard. For the OFDM system with 2048 subcarriers, the proposed scheme with 4 binary phase sequences can reduce the complex multiplications by 63.5% with the similar PAPR reduction compared with the SLM scheme with 16 binary phase sequences. 相似文献
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在宽带移动环境下,由于多普勒频移以及多径的影响,信道是时变的。为了消除信道对传输信号的影响,需要对信道进行估计。给出了2种基于离散余弦变换(DCT)的信道估计方法,可以很好的降低频谱泄露造成的混叠失真,适用于非整数倍的抽样信道。其中一种性能较好,另一种实现更加方便。仿真结果表明,这两种算法的性能均优于基于DFT的信道估计算法。 相似文献
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OFDM是第四代移动通信系统的核心技术之一,信道估计是OFDM中急需解决的一个关键技术。首先介绍了OFDM技术的基本原理及其系统组成,重点研究了基于导频的OFDM信道估计技术,针对块状导频插入方式,讨论了LS(最小二乘)、MMSE(最小均方误差)和SVD(奇异值分解)算法,并通过仿真对其性能进行了比较。结果表明:MMSE和SVD算法比LS算法有更好的性能,但是LS算法的复杂度较低。 相似文献