Rake Reception With Channel Estimation Error

Several digital cellular systems employ coherent RAKE reception, wherein channel estimates are used to combine despread values. In this paper, a maximum likelihood (ML) approach to RAKE combining that accounts for channel estimation error, including error correlation across despread values, is examined. Fading and noise correlation are also considered. The performance of the ML approach is compared to traditional RAKE combining as well as approximate ML-based approaches. Results show that when the channel estimation error and noise are of the same order, ML-based approaches can provide gains on the order of 1 dB over traditional RAKE reception     

Error Probability of FSK Incoherent Diversity Reception with Fast Rice Fading

In this paper we compute the error performanceof noncoherent detection receivers for FSK signalstransmitted over fast frequency-flat Rician fadingchannels. Linearly time-varying fading models are used to derive closed-form expressions for the errorprobability of binary FSK signaling. Error bounds areestablished for the performance of M-ary orthogonal FSK.Simulation results are in excellent agreement with analytical predictions.     

一种新的DS-CDMA系统多径角度时延联合估计方法

本文针对DS－CDMA系统，提出了一种新的期望用户多径信号波达方向和时延联合估计方法。在匹配滤波器输出中，期望用户信号的平方与多址干扰信号的平方具有不同的频谱特性。对各个频率上的空域相关矩阵进行预处理后，本文采用两维unitary-ESPRIT算法完成角度时延的闭式估计和自动配对。本文方法计算量小，并且在存在远近效应的情况下，仍能完成参数的准确估计。     

基于高阶小波累量的时间延迟和多普勒伸缩联合估计

基于小波的宽带互模糊函数可用来对宽带信号的时间延迟和多普勒伸缩进行联合估计,但它不能抑制相关高斯噪声.本文结合小波和高阶累积量,给出一种四阶小波累量的定义,并在此基础上提出一种基于高阶小波累量的宽带互模糊函数算法,该算法能克服传统算法的不足,可用于相关性未知的高斯噪声环境.仿真结果表明了该方法的有效性.     

Cross-Layer Design for MRT Systems with Channel Estimation Error and Feedback Delay

Multiple-input multiple-output (MIMO) beamforming is a joint spatial diversity scheme applied in frequency selective channels to enhance system performance. In uplink transmission, the impact of correlation of path gains and mutual coupling at transmitters cannot be ignored because of the size constraint on mobile terminals. In this paper, an iterative MIMO beamforming algorithm with maximal ratio transmit-maximal ratio combining (MRT-MRC) strategy is presented to improve the output signal-to-noise and interference ratio in the presence of spatial correlation and mutual coupling between transmit elements. To reduce the complexity of systems, we also propose an equal gain transmit-maximal ratio combining (EGT-MRC) scheme. In contrast to MRT-MRC scheme, this algorithm can provide better system performance. The results of numerical simulations verify the advantages of this scheme.     

Joint Angle and Delay Estimation (JADE) in Antenna Array CDMA Systems

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时延估计技术研究

时延是表征信号的一个重要特征参数,准确、迅速地估计时延及其他参数可以进一步确定信源距离、方位、速度等信息.因此,对时延参数的估计一直是信号处理领域中的十分活跃的研究课题.在分析时延估计发展现状的基础上,对时延估计理论和方法进行了归纳和总结,介绍了基于二阶统计量、高阶统计量的时延估计方法,以及近年来广泛应用的现代信号处理工具--分数阶Fourier变换及其在时延估计中的应用,并对各时延估计方法的性能进行了分析和比较,指出了时延估计的研究方向.     

基于最小均方误差的时延估计方法研究

文章对最小均方误差时延估计方法做了详细的讨论,研究经典LMSTDE算法和约束类ETDE算法和ETDGE算法的原理,并从非相关背景噪声和相关背景噪声两方面入手,来分析静态时延下的估计性能。在非相关背景噪声下LMSTDE算法、ETDE算法和ETDGE算法均有着良好的估计性能;在相关背景噪声下,传统LMSTDE算法不能准确估计时延,而ETDE算法和ETDGE算法依然具有时延估计的能力。     

On Joint Fine Time Adjustment and Channel Estimation for OFDM Systems

This paper addresses training-sequence-based joint fine time adjustment and channel estimation for orthogonal frequency-division multiplexing systems. The proposed approach first derives an optimized threshold that adapts to the channel statistic and the signal-to-noise ratio. Then a practical suboptimal threshold is presented to avoid the estimation of the channel statistic. The suboptimal threshold requires no pre-simulations and performs as well as the optimal one. For performance analysis, the probability of perfect fine time adjustment given a particular threshold is also derived. The theoretical results agree well with the simulation results in both Rayleigh and Ricean channels.     

一种相干分布目标的DOA-时延联合估计算法

在城市密集环境情况下,基于传统点目标模型的多径空时参数(波达方向与相对时延)联合估计算法往往出现性能恶化。本文通过重新构造空间流形与时间流形,给出了一种更符合密集环境的空时相干分布信号模型,并在获得空时联合信号子空间后,分别抽取空间、时间子矩阵构造空间谱与时间谱,通过搜索谱峰得到所需空、时多径参数,最后利用空时流形向量与空时联合噪声子空间的正交性质实现空时参数配对。与TST-MUSIC等算法相比,该算法仅需要两次搜索及一次配对过程。仿真实验表明,该方法能够有效估计相干分布信号空时参数,抑制分布扩展影响,实现多个参数的自动配对。     

LCR波应力检测中互相关时延估计的误差分析

根据声弹性理论,将应力检测转化为超声波的传播时延估计,建立基于互相关时延估计的临界折射纵波(LCR波)应力检测系统.LCR波在发射、传播及接收过程中存在各种影响因素,这些因素导致接收到的LCR波波形及信噪比发生了较大变化.通过克拉美罗下界(CRLB)理论得到这些变化是限制时延估计精度的根本因素.利用MATLAB进行仿真验证,得到了不同的影响因素对时延估计精度的影响不同.     

脉冲噪声环境下一种韧性的时延与 多普勒频移联合估计法

由于α稳定分布噪声会降低基于二阶循环统计量的传统方法的性能,本文基于分数低阶统计量理论提出p阶循环相关的概念并给出相应性质及证明,在此基础上对已有的循环模糊函数进行了广义化.计算机仿真表明,这种广义的循环模糊函数能够在高斯和α稳定分布噪声条件下有效地联合估计时延和多普勒频移,其性能不仅优于基于二阶循环相关的CCA(循环模糊函数)法,也优于FLOAF(分数低阶模糊函数)法,是韧性的、具有更广泛应用意义的方法.     

Time Delay Estimation Based on Entropy Estimation

Abstract--This paper presents a novel time delay estimation （TDE） method using the concept of entropy. The relative delay is estimated by minimizing the estimated joint entropy of multiple sensor output signals. When estimating the entropy, the information about the prior distribution of the source signal is not required. Instead, the Parzen window estimator is employed to estimate the density function of the source signal from multiple sensor output signals. Meanwhile, based on the Parzen window estimator, the Renyi＇s quadratic entropy （RQE） is incorporated to effectively and efficiently estimate the high-dimensional joint entropy of the multichannel outputs. Furthermore, a modified form of the joint entropy for embedding information about reverberation （multipath reflections） for speech signals is introduced to enhance the estimator＇s robustness against reverberation.     

随机布局多天线信号联合时差估计Cramer-Rao下界

该文针对随机布局多天线信号联合时差估计Cramer-Rao下界（CRLB）开展研究,在深入研究多路联合参数估计和经典时差估计算法的基础上,首先建立信号模型,进而得到频域的联合概率密度函数,然后推导出Fisher信息矩阵和Cramer-Rao下界的解析表达式。最后,对结果进行了讨论分析,并同两路时差估计Cramer-Rao下界进行了对比。结果表明,多天线联合时差估计能够利用各信号的相同信息,有效提升时差估计性能,而且在低信噪比条件下估计性能改善更为明显。此外,可以看到增加天线数目不可能无限降低时差估计Cramer-Rao下界,其受待估时差的两路信号信噪比限制。      

LMS自适应时间延迟估计

数字基带预失真线性化技术是一种通过在功率放大器前端引入与其幅度和相位特性相反的预失真电路使输入和输出信号在整体上呈线性关系,从而实现高频谱效率传输的一种新型线性化技术．然而,预失真电路的引入必然引起环路延时。因此,数字基带预失真线性化技术的关键问题之一就是环路延时的估计,文中研究了基于Widrow的最小均方（LMS）算法的自适应时间延迟估计的基本原理,结构,和算法,分析了这种估计方法的性能,并给出了计算机仿真结果。从仿真结果中可以看出,LMSTDE可以精确的检测出系统的时间延迟,使功率放大器的线性化性能得到很大的改善。     

一种基于多循环频率的韧性时延与多普勒频移联合估计算法

本文提出了一种基于分数低阶循环模糊函数的多循环频率时延与多普勒频移联合估计算法.该方法将分数低阶矩与循环平稳特性相结合,能够在SαS(Symmetric α Stable)脉冲噪声条件下检测信号的循环平稳特性.算法充分利用了信号的循环频率信息,具备较强的抑制干扰能力.仿真结果表明,在脉冲噪声和干扰环境中本文提出的算法均...     

信道估计偏差对空时编码的OFDM系统性能的影响

本文研究了采用空时编码的OFDM系统的性能，通过Monte Carlo仿真分析了系统性能和信道估计偏差对系统的影响。     

Joint Transmission Method in Coordinated Multi-Point Transmission and Reception Systems

In this paper,we propose a multi-point joint transmission method for Coordinated Multi-Point (CoMP) systems.This solution combines space time/frequency coding and precoding with beamforming technology.The multi-path data obtained by space time/frequency coding and precoding can be mapped by beamforming technology to multiple coordinated nodes for transmission.The signal receiver can also obtain bigger diversity gain and beamforming gain as well through the combination of space time/frequency coding and beam...     

LFM脉冲雷达回波Doppler与多径时延的联合估计

基于最大似然参数估计,本文提出了一种对LFM脉冲雷达回波Doppler频移和多径时延联合估计的方法.该方法先利用WHT估计Doppler频移,然后结合发射信号的先验知识重构参考信号,最后利用WVD能将时间上有重叠的多径信号在时频域分开的特性,采用本文称之为"修正时频相关函数"估计多径时延.该方法只需一个周期的脉冲信号就能完成频移和时延的联合估计,对加性高斯白噪声具有强的鲁棒性,其运算量小.     

Detector Time Delay in Band-Limited Systems

The effect of the integration interval in an integrate and dump detector in a band-limited system is analyzed. It is found for optimum performance that the interval must be delayed by τ seconds, which can be approximated by finding the interval giving maximum area under the system pulse response.