共查询到19条相似文献,搜索用时 46 毫秒
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在现有的基于最大似终估计的同步算法的基础上提出了一种改进算法,并通过仿真比较,验证了本改进算法的可行性。 相似文献
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《现代电子技术》2015,(19):91-93
分集接收技术由于能够获得分集增益,可提高多径信号的接收质量,因此在直接序列扩频系统中被广泛采用。常用的信号分集合并方法主要有选择性合并、等增益合并和最大比合并三种,其中最大比合并效果最佳,但需要准确地计算每路信号的信噪比,而采用自适应算法有效解决了准确计算信噪比的问题。因此,提出一种将RLS自适应算法与多径信号分集接收相结合的方法,它首先将接收到的多径信号分离为多路不同延时的信号,然后应用RLS自适应算法根据最小方差准则计算每一路信号的加权系数,通过对加权系数的更新获得最大分集增益,通过对不同的信号合并方式在多径信道下的性能进行仿真比较可知,采用RLS自适应算法的信号合并方式取得的性能最好。 相似文献
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针对低信噪比条件下宽带高速跳频信号的参数估计问题,提出一种多通道数据融合跳频信号频率跳变时刻估计算法。该算法利用无盲区数字信道化预处理实现宽带跳频信号的全概率、全盲接收,通过数据融合得到一路包含全部频率跳变信息的参考信号,并利用该参考信号进行最大似然估计得到频率跳变时刻精确估计值。给出了所提出跳变时刻估计算法的Cramer-Rao下界并进行实验仿真。理论推导和仿真结果表明:针对一定的输入信噪比,适当选择信道化数和估计时间可实现较高的估计精度。在0dB信噪比条件下,采用16通道数字信道化处理,估计方差小于10-3。 相似文献
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该文在二发一收的空时分组码(STBC)单载波块传输系统中,提出一种空时和多径分集合并接收算法。通过基于STBC的单载波频域均衡(STBC-SC-FDE)算法得到对发送信号的估计,以此和信道状态信息(CSI)分离接收信号中的各多径分量,对各多径分量分别采用STBC合并,最后再将各多径分量的合并输出结果按照最大比(MRC)的方式进行合并,从而实现空时二维RAKE接收。该算法在较低的计算复杂度情况下,可以同时获得发射分集和多径分集,Monte Carlo仿真验证了该算法的性能。 相似文献
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自适应滤波在扩频信号分集接收中的应用研究 总被引:1,自引:0,他引:1
使用自适应滤波器完成对扩频信号的扩频码捕获后,传输信道中由于信号衰落造成的多径信号的幅度就可以从自适应滤波器收敛后的系数权值向量上体现出来.根据分集接收的理论分析,依据多径信号的信号幅度值进行分集接收在理论上是可行的,因此利用自适应滤波器对接收到的多径信号进行隐分集接收是完全可行的.使用自适应滤波器在完成扩频码捕获的同时,在不增加额外硬件支路的情况下就可以实现对多径信号的分集接收功能,从而改善在多径衰落环境下的信道传输性能. 相似文献
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移动微波传输在多项体育赛事的直播中有着广泛应用,由于其传输条件复杂,往往接收效果受到不良影响.为了获得更好的接收效果,提出采用空间分集接收和最大比合并,配合编码正交频分复用,进一步提高信噪比,降低了接收门限.经过竞走比赛移动数字微波传输的实际应用,该方法确能改善传输效果. 相似文献
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In cyclic prefixed wireless communication systems, the bit error rate (BER) is the primary design concern. However, most equalizers for these systems optimize proxy metrics that are easy to use but are suboptimal in terms of BER. In this work, a channel shortener and frequency domain equalizer (FEQ) are developed for cyclic prefixed systems, which directly attempt to minimize the BER. To do this, first we modify the FEQ structure of a single input multiple output (SIMO) system such that the diversity combining is after the FEQ (whereas usually it is before the FEQ); and extend adaptive equalization algorithms to the new structure. This greatly mitigates frequency nulls, improving the BER. Second, a Genetic Algorithm, which is an optimization method based on the principles of natural selection and genetics, is used to choose the channel shortener to directly minimize the BER. The new approaches lower the BER by 102 in simulations. 相似文献
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在多天线信号联合检测场景中,信号存在相关性和噪声方差无法准确确定问题会同时发生,导致经典的多天线能量检测算法性能不理想。为此,提出一种基于多天线信号等增益合成的信号盲检测算法。该算法通过多天线合成技术,补偿各路天线接收信号的差异性,然后进行等增益合成,并取合成信号能量与单路天线信号的能量比值作为检测统计量,利用统计理论推导出相应的检测门限和检测概率。仿真结果表明,新算法能够摆脱噪声的不确定性影响,且比现有盲检测算法具有更优的检测性能。 相似文献
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《现代电子技术》2016,(23):29-33
针对多点协作(Co MP)无线通信系统的下行传输问题,提出一种分布式快速空频编码(DF-SFC)的方案。通过将小区边缘用户分组和分享相邻小区间的子载波获得空间分集增益,有效缓解了载波间干扰(ICI),基于此设计分布式解码器,将用户的解码复杂度降低到相同的非分布式空频编码最佳解码器的50%。通过将所提方案与Alamouti多点协作和非多点协作方案做比较,对用户与其基站之间相对距离对比研究了可实现的传输速率,并且推断出它的性能上限和下限,用于确立小区边缘用户的阈值,实现在提出的多点协作和非多点协作模式之间切换,以提高整体性能。仿真结果表明,在服务小区边缘用户方面提出的方案均优于Alamouti多点协作和非多点协作方案。 相似文献
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本文深入研究了基于FFT运算进行相位扩展的宽范围自相关函数法和宽范围L&R算法,分析了这两种载波频偏估计算法的性能.在此基础上,本文结合TDMA信号的前导字和CZT(chirp z-transform)算法的高频率分辨率特性,设计了适于低信噪比信号的宽范围载波同步改进算法.该算法利用TDMA信号的前导字进行数据辅助(DA)型载波同步,有效地缩小了低信噪比信号的频偏范围;再利用CZT算法进一步缩小频偏范围,最后利用非数据辅助型(NDA)自相关函数法得到精确的载波频偏.改进算法的计算复杂度略高于宽范围自相关函数法,而远低于宽范围L&R算法.通过仿真比较,改进算法对低信噪比(SNR)环境(3-6dB)中的信号具有良好且稳定的估计性能. 相似文献
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Simeone Osvaldo Spagnolini Umberto BarNess Yeheskel Strogatz Steven H. 《Signal Processing Magazine, IEEE》2008,25(5):81-97
Synchronization refers to the process of achieving and maintaining coordination among independent local clocks via the exchange of local time information. Different synchronization schemes differ in the way such information is encoded, exchanged, and processed by the clocks toward the end of overcoming the unavoidable nuisance effects of inaccurate clocks and propagation/processing delays. Wireless communications provide the natural platform for the exchange of local time information between synchronizing clocks. Conversely, synchronization of local clocks enables a wealth of signal processing and communication applications in wireless networks. It is this mutual link between synchronization and wireless networks, with emphasis on decentralized structures such as ad hoc and sensor networks, that constitutes the main subject of this article. 相似文献
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Linear diversity combining techniques 总被引:8,自引:0,他引:8
Brennan D.G. 《Proceedings of the IEEE. Institute of Electrical and Electronics Engineers》2003,91(2):331-356
This paper provides analyses of three types of diversity combining systems in practical use. These are: selection diversity, maximal-ratio diversity, and equal-gain diversity systems. Quantitative measures of the relative performance (under realistic conditions) of the three systems are provided. The effects of various departures from ideal conditions, such as non-Rayleigh fading and partially coherent signal or noise voltages, are considered. Some discussion is also included of the relative merits of predetection and postdetection combining and of the problems in determining and using long-term distributions. The principal results are given in graphs and tables, useful in system design. It is seen that the simplest possible combiner, the equal-gain system, will generally yield performance essentially equivalent to the maximum obtainable from any quasilinear system. The principal application of the results is to diversity communication systems and the discussion is set in that context, but many of the results are also applicable to certain radar and navigation systems. 相似文献
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We propose a postdetection phase combining (PC) scheme for the two branch diversity reception of differential phase shift keying (DPSK) over multipath fading channels. The receiver has a differential phase detector (DPD) in each diversity branch, and the combiner weights each detector output in proportion to the vth power of the signal envelope at the detector's input. For π/4-shift QDPSK over frequency-flat Rayleigh fading channels, we find via computer simulation that the optimum weight factor is v=2, and that our simple, practical combining scheme performs almost as well as postdetection maximal ratio combining (MRC). We demonstrate similar relative performances for frequency-selective fading channels and for channels with co-channel interference (CCI) 相似文献