共查询到18条相似文献,搜索用时 171 毫秒
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针对大时延稀疏多径信道条件下的单载波频域均衡系统(SC-FDE),本文提出了一种新的迭代均衡结构,记为IC-FDE-DFE。IC-FDE-DFE可以缩短频域均衡所需的循环前缀(CP)的长度,提高稀疏多径信道下SC-FDE系统的带宽效率和功率效率。与单纯的时频域混合判决反馈均衡器(H-DFE)相比,IC-FDE-DFE能够充分利用信道的‘稀疏’特性,其中的均衡器具有较低的运算复杂度和设计复杂度。仿真结果表明,IC-FDE-DFE能够在迭代过程中逐渐抵消大时延多径的影响,逼近H-DFE的理想性能。 相似文献
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在基于一阶统计量解圆周卷积的超宽带信道盲估计方法中,存在着要求信道长度必须小于符号周期长度的局限性.使用信道缩短技术,对实际信道的长度进行缩短,估计出缩短信道后再恢复成实际的超宽带信道,有效地解决了这个问题.仿真实验表明,在信道长度大于符号周期长度时,仍然能很好地估计出信道. 相似文献
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可靠的无线通信需要准确地知道下层信道的信息,因此需要进行信道估计。而许多真实信道表现为仅有一些相对较少的非零信道系数的稀疏多径信道。对于稀疏多径信道的估计,传统方法例如最小二乘法,没有利用稀疏信道本身的低维度特性,所需训练序列的长度较长,因此估计代价较大。基于压缩感知的信道估计方法,利用稀疏先验信息,能较大地缩短所需训练序列的长度,获得较好的估计效果。该文结合压缩感知观测矩阵的特点,证明了当训练序列的长度不长于信道冲激响应的长度,且托普利兹观测矩阵的行数小于列数时,观测矩阵仍然满足有限等距性质;明确提出了稀疏多径信道估计中所使用的观测矩阵的构造条件。实验结果验证了这种优化了的托普利兹观测矩阵的可行性和实用性。 相似文献
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针对较低信噪比下的深衰落稀疏多径信道,提出了一种基于信道缩短的自适应稀疏均衡改进算法。该算法采用前置分数间隔信道缩短均衡器与后置自适应稀疏均衡器级联的均衡器结构,其中,首先利用短训练序列设计基于最小均方误差准则的前置均衡器,前置均衡器与稀疏多径信道级联后得到能量集中于较短时间区域且分布稀疏的等效信道,使得原始信道的深衰落畸变得到部分有效补偿;然后采用能实现稀疏信号重构的随机梯度追踪算法调整后置自适应均衡器的抽头系数,后置均衡器用于消除等效信道的剩余符号间干扰。仿真结果表明,与传统的单级分数间隔自适应均衡器相比,该算法具有收敛速度快和运算复杂度低的优点。 相似文献
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In this paper, a semi-blind time-domain equalization technique is proposed for general multiple-input-multiple-output (MIMO) orthogonal frequency-division multiplexing (OFDM) systems. The received OFDM symbols are shifted by more than or equal to the cyclic prefix (CP) length, and a blind equalizer is designed to completely suppress both intercarrier interference (ICI) and intersymbol interference (ISI) using second-order statistics of the shifted received OFDM symbols. Only a one-tap equalizer is needed to detect the time-domain signals from the blind equalizer output, and one pilot OFDM symbol is utilized to estimate the required channel state information for the design of the one-tap equalizer. The technique is applicable irrespective of whether the CP length is longer than, equal to, or shorter than the channel length. Computer simulations show that the proposed technique outperforms the existing techniques, and it is robust against the number of shifts in excess of the CP length. 相似文献
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《Signal Processing, IEEE Transactions on》2006,54(11):4194-4203
Multicarrier modulation has the advantage of robustness to multipath, so long as the delay spread of the multipath is less than the guard interval between successive transmitted blocks. However, it has the disadvantage of sensitivity to a carrier frequency offset (CFO), which disrupts the orthogonality of the subcarriers. If a CFO is present, it must be estimated and then corrected. In addition, if the channel delay spread exceeds the guard interval, this must be accounted for as well, usually by a channel shortening equalizer. Hitherto, CFO estimation and channel shortening have been addressed individually. However, this leads to a circular set of assumptions, since standard CFO estimators perform poorly when the channel is longer than the guard interval, and standard channel shorteners assume that CFO estimation has already been perfectly performed. In this paper, we investigate a blind, adaptive method for jointly performing CFO estimation and channel shortening. 相似文献
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在数字用户线(DSL)系统中,每个符号在进行传输时要加入循环前缀(CP)以消除符号间干扰。理论上,CP的长度等于信道冲激响应的记忆长度,较长的CP大大降低了DSL系统的数据传输效率。为了避免使用较长CP,通常在接收端采用时域均衡缩短信道冲激响应长度。但是,信道冲激响应最优缩短算法的复杂度很高,为此,提出了一种实用的时延优化算法,该算法将信道的冲激响应与矩形序列进行卷积,用得到的序列进行时延估计,使得算法的复杂度大幅下降,满足了系统的实时性要求,并且缩短信噪比的损失很小。 相似文献
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Kameyama H. Miyajima T. Zhi Ding 《IEEE transactions on circuits and systems. I, Regular papers》2008,55(3):851-860
In multicarrier systems, when the order of a channel impulse response is larger than the length of the cyclic prefix (CP), there is a significant performance degradation due to interblock interference (IBI). This paper proposes a blind-channel shortening method in which the equalizer parameter vector is formed by the noise subspace of the received signal correlation matrix so that the output power is maximized. The proposed method can not only shorten the effective channel impulse response to within the CP length but also maximize the output signal-to-interference-and-noise ratio while eliminating the IBI. We point out that the performance depends on the choice of a decision delay and propose a simple method for determining the appropriate delay. We propose both a batch algorithm and an adaptive algorithm and show by simulation that they are superior to the conventional algorithms. 相似文献
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本文提出了一种用于克服MIMO信道时变性的自举均衡器.本文首先提出了用于MIMO通信系统的去相关均衡算法,该算法利用通信信源的统计特性实现不同源信号之间的去相关,从而克服了MIMO系统的同信道干扰.接着本文将去相关均衡算法用于时变的MIMO系统,提出了用于克服MIMO信道时变性的自举均衡器.该均衡器仅利用其输入信号来对时变的MIMO系统进行均衡,在仅增加很小的运算量的条件下,大大克服了因信道时变而在常规均衡器输出端产生的同信道干扰,提高了系统的误码性能.仿真实验证实,本文提出的去相关MIMO自举均衡器克服了信道时变的影响,明显改善了接收机的误码性能. 相似文献
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《Signal Processing, IEEE Transactions on》2009,57(4):1483-1493