共查询到19条相似文献,搜索用时 171 毫秒
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针对收发两端已知信道状态信息的MIMO(multiple input multiple output)系统,研究基于GMD(geometric mean decomposition)算法的VBLAST(vertical bell lab layered space-time)系统空间分集与复用性能。该算法将MIMO信道分解为多个具有相同信噪比的并行子信道,其编解码复杂度低,易于实现。在高信噪比下,对该算法的分集与复用曲线进行分析,结果表明该算法的空间分集与复用性能与最优曲线相比是次优的,但优于其他VBLAST方案。 相似文献
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IR-UWB能量检测接收机中基于门限的TOA估计 总被引:1,自引:0,他引:1
为提高能量检测模式下脉冲超宽带(IR-UWB)测距的精度和可行性,该文提出基于最优门限和次优门限的两种到达时间(TOA)估计算法。最优门限算法以接收机信号统计特性与UWB小尺度衰减特性关系式为基础推导出门限选择的闭合表达式,并在最小均方误差(MMSE)指标下求解TOA估计值;次优门限算法以最优门限分析为基础,在虚警概率约束下使用牛顿迭代给出求解门限的递推算法。仿真表明,与同类算法相比,最优门限算法测距精度有较大提升;次优门限算法易于实现,且性能无明显下降。 相似文献
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研究了频率选择性信道下多天线系统的空间线性发射预编码设计问题.针对有循环前缀的块传输系统,通过理论分析指出,在频率选择性信道下设计空间预编码可以等效成现有的在频域为多个相邻频点设计相同的空间预编码,并可以通过凸优化方法对最优方案进行数值求解.为了降低计算复杂度,提出了一种以信道容量上界最大为目标的次优预编码算法.在进行等功率分配时,这种次优方法退化为现有的特征波束形成(EBF).针对非块传输系统,分析了EBF算法存在的问题,提出了一种基于串行搜索的EBF算法.仿真分析表明,这种方法在高信噪比下的性能明显优于EBF算法. 相似文献
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常规宽带能量检测在多目标、强干扰环境下输出信噪比(SNR)降低,检测性能大幅度下降。针对此问题,该文提出一种将子阵导向最小方差(STMV)宽带空域自适应波束形成与频域Eckart滤波结合的空-频联合最优滤波宽带检测方法。该方法首先通过子阵导向最小方差波束形成进行空间自适应处理,利用自适应波束形成的干扰抑制能力在空域实现最优滤波;然后通过最大似然估计实时估计信号和噪声的功率谱,构造Eckart滤波对自适应波束形成的输出分配不同权重进行加权滤波,从而实现频域信噪比最大化。所提方法通过空-频联合最优滤波,降低空域旁瓣干扰和频带内噪声的影响,使得输出信噪比最大,从而有效地改善目标宽带检测能力,提高被动声呐的宽带检测性能。仿真和试验数据处理结果验证了该方法的有效性。 相似文献
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常规宽带能量检测在多目标、强干扰环境下输出信噪比(SNR)降低,检测性能大幅度下降.针对此问题,该文提出一种将子阵导向最小方差(STMV)宽带空域自适应波束形成与频域Eckart滤波结合的空-频联合最优滤波宽带检测方法.该方法首先通过子阵导向最小方差波束形成进行空间自适应处理,利用自适应波束形成的干扰抑制能力在空域实现最优滤波;然后通过最大似然估计实时估计信号和噪声的功率谱,构造Eckart滤波对自适应波束形成的输出分配不同权重进行加权滤波,从而实现频域信噪比最大化.所提方法通过空-频联合最优滤波,降低空域旁瓣干扰和频带内噪声的影响,使得输出信噪比最大,从而有效地改善目标宽带检测能力,提高被动声呐的宽带检测性能.仿真和试验数据处理结果验证了该方法的有效性. 相似文献
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基于FPGA的实时持续数据记录系统设计 总被引:4,自引:1,他引:3
文章介绍了一种实时保持数据记录系统的原理设计和基于FPGA的实现方法,在此类实时数据记录系统中,实时性和吞吐率是设计中的两个关键问题,为达到实时数据流记录的目的,在分析传统设计的I/O瓶颈后,提出了一种新型存储系统结构以缩短数据存取路径,提高系统性能,并用FPGA予以实现,这种新的存储系统结构和基于FPGA的实现方法可以应用其它要求保证数据实时在座的领域以提高系统性能。 相似文献
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1 IntroductionInDiscreteMulTitone (DMT)systems,eachsymboliscomprisedofNdatasamplesandvCyclicPrefixes (CP) ,andthelatterissimplythelastvsamplesoftheformer.TheCPlengthisdeterminedbythelengthofthechannelimpulseresponse,andischosentominimizeInterSymbolInterference(ISI) .Ifthechannelimpulseresponseisoflengthv + 1orshorter,thenaCPoflengthvissufficienttoeliminateISI[1~4] .SincetheefficiencyofthetransceiverisreducedbyafactorofN/(N +v) ,itiseitherdesirabletomakevassmallaspossibleorutilizea… 相似文献
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In a discrete multitone receiver, a time-domain equalizer (TEQ) reduces the intersymbol interference (ISI) by shortening the effective duration of the channel impulse response. Current TEQ design methods such as the minimum mean-squared error (MMSE), maximum shortening SNR (MSSNR), and maximum geometric SNR (MGSNR) do not directly maximize bit rate. We develop two TEQ design methods to maximize the bit rate. First, we partition an equalized multicarrier channel into its equivalent signal, noise, and ISI paths to develop a new subchannel SNR definition. Then, we derive a nonlinear function of TEQ taps that measures the bit rate, which the proposed maximum bit rate (MBR) method optimizes. We also propose a minimum-ISI method that generalizes the MSSNR method by weighting the ISI in the frequency domain to obtain higher performance. The minimum-ISI method is amenable to real-time implementation on a fixed-point digital signal processor. Based on simulations using eight different carrier-serving-area loop channels, (1) the proposed methods yield higher bit rates than MMSE, MGSNR, and MSSNR methods; (2) the proposed methods give three-tap TEQs with higher bit rates than 17-tap MMSE, MGSNR, and MSSNR TEQs; (3) the proposed MBR method achieves the channel capacity (as computed by the matched filter bound using the proposed subchannel SNR model) with a five-tap TEQ; and (4) the proposed minimum-ISI method achieves the bit rate of the optimal MBR method 相似文献
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在OFDM系统中,时域均衡器用来抵消因循环前缀长度不足而引起的码间串扰。本文提出了一种新的时域均衡器的设计方法,该方法同时考虑了码间串扰和噪声对传输速率的影响。最佳均衡器的系数通过快速傅立叶变换在频域进行计算,并可通过求取矩阵的特,征向量来获得。仿真结果表明所提出来的方法能有效地提高系统传输速率。 相似文献
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Ysebaert G. Vanbleu K. Cuypers G. Moonen M. 《Signal Processing, IEEE Transactions on》2005,53(3):1132-1146
In discrete multitone (DMT) receivers, as for instance in asymmetric digital subscriber lines (ADSLs), the classical equalizer structure consists of a (real) time domain equalizer (TEQ) combined with complex 1-tap frequency domain equalizers (FEQs). Additionally, receiver windowing can be applied to mitigate the bad spectral containment of the demodulating DFT sidelobes. We focus on a combined equalizer and windowing design procedure to maximize the achievable bit rate in DMT-based modems. Whereas the combination of a TEQ with a single window treats all the data carrying tones in a common way, the presented design method can also be used in a "per group" fashion, where smaller groups of tones receive each a different equalizer-window pair. When such groups contain only one single tone, the design procedure can be linked to the performance of an unbiased minimum mean square error (MMSE) per tone equalizer (PTEQ), which then also implicitly implements a per tone window. The general framework introduced Allows us to treat equalizer-only and window-only designs as well, which appear as special cases in a natural way. This set of bit rate maximizing techniques can serve either as practical design methods or as upper bounds for existing (suboptimal) methods. We will also show that for the same achievable bit rate, equalizer taps can be exchanged for windowing coefficients to reduce complexity during data transmission. 相似文献
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Time-domain equalizers (TEQ) are used in the discrete multitone (DMT) transceivers in order to reduce the duration of the overall response of the transmission system, so that a shorter-length cyclic prefix could be used. The optimum TEQ is the one that results in maximum bit allocation to each block of the DMT. However, the optimum design of TEQs turns out to be a very difficult task. We give the general guidelines that one should follow in the design of TEQ to achieve a good performance. Based on the suggested guidelines, we first propose an eigenapproach design method which results in TEQs with comparable performance to those of a previously reported method, but at a much lower computational cost. Further study of the proposed guidelines reveals that the choice of target-impulse response in the design of TEQ only weakly depends on the channel response. Noting this, we propose a second design method that is even simpler than our first method, but still results in comparable designs to those of our first method and also those obtained from the much more complex methods of the present literature 相似文献
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The fully automated design of optimal or near-optimal feedback controllers is considered for least-pth and minimax cost functions. Solutions are obtained by approximating to the desired optimal output by a rational function. Optimal results for a 2nd-order model and suboptimal responses for the corresponding 7th-order linear system are used to illustrate the method. 相似文献
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Jibing Wang Xiaodong Wang 《Communications, IEEE Transactions on》2006,54(7):1267-1276
The training-based scheme constitutes an efficient method for noncoherent multiantenna communications. In this paper, we propose a superimposed training-based linear dispersion (STLD) transmission scheme, where the transmitted symbols are superposition of the training pilots and the data symbols. The STLD system enjoys simple encoding and efficient suboptimal decoding. Since for noncoherent multiple-input multiple-output systems employing the STLD scheme, analytical expressions of block- or bit-error probabilities do not exist, deterministic optimization methods cannot be used to design the optimal STLD system. We therefore propose to design the optimal STLD systems using simulation-based optimization techniques, together with gradient estimation. Simulation results show that with either maximum-likelihood or suboptimal decoding, the STLD systems obtained by the proposed design algorithm generally outperform the conventional training-based scheme employing space-time codes designed for coherent channels. 相似文献