共查询到19条相似文献,搜索用时 171 毫秒
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信道估计是对无线信道频率响应的估算,目的是识别每组发送天线和接收天线之间的信道冲击响应。本文探讨了MIMO-OFDM系统的多种信道估计方法。重点对MMSE、LS、导频辅助估计、盲\ 半盲方法及它们之间的特点进行分析和比较。 相似文献
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MIMO-OFDM系统中的信道估计方法分析 总被引:1,自引:0,他引:1
信道估计是对无线信道频率响应的估算,目的是识别每组发送天线和接收天线之间的信道冲击响应。本探讨了MIMO-OFDM系统的多种信道估计方法。重点对MMS、LS导频辅助估计、盲\半盲方法及它们之间的特点进行分析和比较。 相似文献
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跳时超宽带无线通信系统中信道估计的准确度对系统接收性能具有重要影响,首先对超宽带系统收发模型进行介绍,然后对TH-UWB系统中基于训练序列的非结构化最大似然信道估计算法进行分析,最后在超宽带信道模型下对估计算法性能进行仿真.仿真结果表明基于训练序列的非结构化最大似然信道估计算法能够有效估计出信道参数. 相似文献
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本文研究了OFDM空时发射分集系统的子空间信道盲估计方法。该方法仅利用空时编码及OFDM调制引入的冗余,在接收天线小于发射天线时,也可以对信道进行盲估计。对盲估计方法所共有的估计模糊性问题进行了详细的论述,证明估计仅存在两个标量不确定因子。这种方法不需要对信号进行冗余预编码,系统将有更高的速率;同时也不需要对系统输出进行过采样或采用多天线接收。由于不需要确切知道信道的阶数,算法对信道阶数过估计有较好的鲁棒性。 相似文献
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信道估计技术作为获得信道衰落信息的方法,是提高无线信道传输接收性能的关键技术。本文针对放大转发双向中继系统的时间选择性平坦衰落信道,利用信道在多普勒域的稀疏性进行压缩信道估计。相比于传统的线性估计方法,压缩信道估计考虑了信道的固有稀疏性,降低了导频的开销,改善了信道估计性能,提高了频谱利用率及系统吞吐量。文中通过对双向中继信道进行多普勒域的稀疏建模,仿真分析了信道估计性能随着导频数量增加、信噪比增加,得到不断改善;而不同的导频分布将影响观测矩阵的相关度,从而对信道估计产生影响。仿真表明,当导频随机分布时,信道估计效果最佳。同时,文中还仿真分析了最大多普勒频移对信道估计性能的影响。 相似文献
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TD-SCDMA中的信道估计实现及其性能分析 总被引:4,自引:2,他引:2
TD—SCDMA系统上行链路数据在基站通过天线接收后,接下来要进行信道估计和联合检测。如何高效得到准确的每个用户的信道冲激响应是后续基带算法实现的关键,如果信道估计算法太复杂和不够准确都将对后面的算法实现产生不利的影响,本文研究了低代价的Steiner估计器,他是一种简单且高效的信道估计算法,通过利用特定方法构造的用户midamble码,Steiner估计器能同时估计出同一时隙内所有用户的信道冲激响应,本文对其在TD—SCDMA系统中的应用进行了算法仿真和性能分析。 相似文献
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研究适用于无线信道测量的定时偏移和信道联合估计方法.发射机发送具有循环前缀结构的导频信号段.接收机根据粗同步信号确定快速傅里叶变换的窗口起始位置.利用改进时域最小二乘信道估计和变换域滤波,获得高精度的信道估计值.对频域接收导频信号段的定时偏移进行精细估计,对定时偏移量进行滤波并累加.最后,对频域接收导频信号段进行定时偏移补偿.信道估计器、定时延迟偏移精细估计器与补偿单元三者构成迭代相干延迟锁定环路.仿真结果表明:采用迭代相干联合估计方法进行精细定时延迟估计的性能明显优于非相干方法. 相似文献
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In this paper blind channel estimation methods for long code CDMA system with multicode transmission are proposed. By allocating
multiple codes, higher data rates may be provided to a user. Blind channel estimation allows reducing pilot signaling. Hence,
higher effective data rates may be achieved and larger sample support may be obtained by using both the information symbols
and known pilot symbols for channel estimation. Algorithms are extended to multi-antenna receiver which further improves the
performance. The performance of the algorithms is studied in extensive simulations using WCDMA system model. The effects of
code selection, interference and noise, number of antennas, antenna correlation are considered using frequency selective channel
models. The proposed methods are more robust in the face of interference and code selection than the well-known subspace method
in [7]. The computational complexity is lower as well. 相似文献
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针对Rake接收结构由于快衰落导致多普勒散布,导致系统性能下降的问题,在时频Rake、时空Rake接收机设计基础上,提出一种联合时空频3D-Rake接收结构。利用自适应天线在空间形成定向波束和利用联合时频处理技术,将频域多普勒频率分集的分析方法应用到时空二维处理中,实现基于天线阵列的时空频三维信号处理。通过接收合并具有不同时延、多普勒频移和来自不同方向的信号,实现最大信噪比准则下的最优接收,提高系统分集增益,和时频Rake、时空Rake相比,其系统性能得到进一步提高,数值仿真表明,联合时空频3D-Rake比时空Rake平均信干噪比提高了3dB。 相似文献
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Dongsik Kim Ui-Kun Kwon Gi-Hong Im 《Communications Letters, IEEE》2008,12(5):350-352
In this letter, we propose a simple pilot position selection/detection technique for channel estimation of single- carrier frequency domain equalization (SC-FDE). Unlike the conventional channel estimation techniques such as frequency domain superimposed pilot technique (FDSPT), the proposed scheme selects the pilot positions to minimize the distortion of original signals caused by the loss of useful data tones in frequency domain. The corresponding receiver structure is also presented, where the pilot positions are blindly detected and the distorted data symbols are iteratively reconstructed. Simulation results show that the proposed system gives better BER performance than the FDSPT and approaches the lower bound of SC-FDE. 相似文献
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Reliable coherent wireless communication requires accurate estimation of the time-varying multipath channel. This paper addresses two issues in the context of direct-sequence code-division multiple access (CDMA) systems: (i) linear minimum-mean-squared-error (MMSE) channel estimation based on a pilot transmission and (ii) impact of channel estimation errors on coherent receiver performance. A simple characterization of the MMSE estimator in terms of a bank of filters is derived. A key channel characteristic controlling system performance is the normalized coherence time, which is approximately the number of symbols over which the channel remains strongly correlated. It is shown that the estimator performance is characterized by an effective signal-to-noise ratio (SNR)-the product of the pilot SNR and the normalized coherence time. A simple uniform averaging estimator is also proposed that is easy to implement and delivers near-optimal performance if properly designed. The receivers analyzed in this paper are based on a time-frequency RAKE structure that exploits joint multipath-Doppler diversity. It is shown that the overall receiver performance is controlled by two competing effects: shorter coherence times lead to degraded channel estimation but improved inherent receiver performance due to Doppler diversity, with opposite effects for longer coherence times. Our results demonstrate that exploiting Doppler diversity can significantly mitigate the error probability floors that plague conventional CDMA receivers under fast fading due to errors in channel estimation 相似文献
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A robust iterative multicarrier code-division multiple-access (MC-CDMA) receiver with adaptive multiple-access interference (MAI) suppression is proposed for a pilot symbols assisted system over a multipath fading channel with frequency offset. The design of the receiver involves a two-stage procedure. First, an adaptive filter based on the generalized sidelobe canceller (GSC) technique is constructed at each finger to perform despreading and suppression of MAI. Second, pilot symbols assisted frequency offset estimation, channel estimation and a RAKE combining give the estimate of signal symbols. In order to enhance the convergence behavior of the GSC adaptive filters, a decisions-aided scheme is proposed, in which the signal waveform is first reconstructed and then subtracted from the input data of the adaptive filters. With signal subtraction, the proposed MC-CDMA receiver can achieve nearly the performance of the ideal maximum signal-to-interference-plus noise ratio receiver assuming perfect channel and frequency offset information. Finally, a low-complexity partially adaptive (PA) realization of the GSC adaptive filters is presented as an alternative to the conventional multiuser detectors. The new PA receiver is shown to be robust to multiuser channel estimation errors and offer nearly the same performance of the fully adaptive receiver. 相似文献
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针对正交时频空间(OTFS)调制系统中分数多普勒信道对应的物理路径信道状态信息估计困难及计算复杂度较高等问题,该文提出一种节省导频资源的脉冲匹配滤波(PRS-PMF)信道估计算法。该算法首先使用数据与导频联合成帧的嵌入式辅助导频方法获得等效信道的估计,然后通过互相关匹配滤波估计出各路径信道状态信息,相比于传统的脉冲导频互相关匹配滤波信道估计算法,能够在降低计算复杂度的同时减少导频资源的占用。在此基础上,对OTFS系统加窗,减少窗口响应主瓣的整数样点数量并降低旁瓣电平,有效改善了等效信道多普勒响应函数的自相关特性,从而降低了其他符号及噪声对估计符号的干扰。 相似文献
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WCDMA下行链路一种加权的信道估计方法 总被引:1,自引:0,他引:1
本文针对第三代移动通信标准WCDMA(FDD)下行链路的结构,提出了一种新的利用公共导频信道和专用数据信道中的导频符号进行加权的信道估计方法。仿真表明本方案有效地提高了信道参数估计的准确度,使Rake接收机的性能比传统的只利用公共导频信道进行信道估计的方案有了一定的改善,特别是在公共导频信道受到明显衰落时。 相似文献
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针对高速移动环境中双色散信道会出现信道估计可靠性下降的问题,该文在正交时频空(OTFS)调制系统的输入-输出模型中提出一种基于压缩感知的信道估计算法。该算法利用信道中最大多普勒频移和最大时延确定导频发送矩阵的大小,相比传统的正交匹配追踪(OMP)信道估计算法,能够在保证相似信道估计准确度的情况下节省导频资源;并在此基础上,对OTFS调制符号做相位旋转,增加差分矩阵的秩,理论分析和仿真结果表明,该方案能够提升OTFS系统的分集阶数进而降低噪声的干扰。 相似文献