Correction to "Statistical Estimation of Mean Signal Strength in a Rayleigh-Fading Environment"

An error in calculating the first and second moments of the "exponential-Rayleigh" distribution appears in a recent paper; this correspondence presents the correct calculations.     

Regression Based Mobility Estimation Method Using Received Signal Strength

Wireless Personal Communications - Privacy protection is a fundamental issue in the era of big data. For personalized privacy protection, it is necessary to measure the amount or the degree of...     

Theoretical and Practical Limits in Position Estimation Based on Received Signal Strength Measurements

Wireless Personal Communications - In this study, theoretical limits in position estimation in Wireless Sensor Network (WSN) using a trilateration method are derived in the form of probability...     

Fast-Fading Channel Environment Estimation Using Linear Minimum Mean Squares Error-Support Vector Regression

Wireless Personal Communications - In this article, we propose a Linear Minimum Mean Squares Error-Support Vector Machine regression (LMMSE-SVR) approach which is applied to Long Term Evolution...     

Gaussianization: An Efficient Multivariate Density Estimation Technique for Statistical Signal Processing

Multivariate density estimation is an important problem that is frequently encountered in statistical learning and signal processing. One of the most popular techniques is Parzen windowing, also referred to as kernel density estimation. Gaussianization is a procedure that allows one to estimate multivariate densities efficiently from the marginal densities of the individual random variables. In this paper, we present an optimal density estimation scheme that combines the desirable properties of Parzen windowing and Gaussianization, using minimum Kullback–Leibler divergence as the optimality criterion for selecting the kernel size in the Parzen windowing step. The utility of the estimate is illustrated in classifier design, independent components analysis, and Prices’ theorem.     

一种复杂环境中跳频信号检测和参数估计改进方法

信号检测与参数估计可为后续的信号解调分析提供依据,在电子对抗中起到重要的作用。针对复杂环境中跳频信号的盲处理问题,针对跳频信号模型进行分析,提出了一种基于滑动相关与小波变换结合的改进方法,更好地完成了检测与参数估计。该方法可较好地克服瑞利信道衰落和传播损耗的影响,检测性能良好,且跳频参数估计精度较高。最后,通过计算机仿真验证了改进方法结果的有效性,且正确率高,具有工程实用性,性能也优于过去的一些算法。     

Performance Analysis of Received Signal Strength Fingerprinting Based Distributed Location Estimation System for Indoor WLAN

Location Estimation has become important for many applications of indoor wireless networks. Received Signal Strength (RSS) fingerprinting methods have been widely used for location estimation. Most of the location estimation system suffers with the problem of scalability and unavailability of all the access points at all the location for large site. The accuracy and response time of estimation are critical issues in location estimation system for large sites. In this paper, we have proposed a distributed location estimation method, which divide the location estimation system into subsystems. Our method partitions the input signal space and output location space into clusters on the basis of visibility of access points at various locations of the site area. Each cluster of input signal space together with output location subspace is used to learn the association between RSS fingerprint and their respective location in a subsystem. We have performed experimentation on two RSS dataset, which are gathered on different testbeds, and compared our results with benchmark RADAR method. Experimental results show that our method provide better results in terms of accuracy and response time in comparison to centralized systems, in which a single system is used for large site.     

信号估计中的核回归方法

核回归方法是比较常用的一种非参数估计方法。讨论了核回归方法在一维信号估计中的理论与应用,实验比较了高斯核函数的平滑参数h及多项式阶数N对估计效果的影响。结果是在相同阶数N下,较小的h使所有的估计点都收敛到观察值,反之则是一个N阶多项式拟合。在相同h下,阶数N越大,误差越小,计算量也较大,但重构效果的提升并不明显。     

Capacity of Slotted ALOHA in Rayleigh-Fading Channels

Fading channels may improve the capacity of slottedALOHA networks. Rayleigh fading and spatially distributed packet transmitters diminish mutual packet interference and thus reduce the average blocking probability of a shared receiver. A transmission model, combining Poisson statistics of the offered data traffic with Rayleigh statistics for the fading channel, is developed. Analytical and numerical results are presented, indicating significant improvements to signaling in cellular mobile networks and in packet radio systems with fading radio channels.     

直扩信号的参数检测与估计综述

直扩信号自提出以来,其检测和参数估计就一直是电子对抗方所面对的难题。文章概述了现有的估计各参数的方法及其优缺点,并结合国内外的研究现状和现在的需求,对未来的发展作出了展望。     

Statistical Dependence Between Components of a Differentially Quantized Color Signal

The statistical dependence (redundancy) between three differentially coded color components of a video-telephone signal are explored by means of an entropy study. We measure the entropy of the differentially coded color baseband signals both jointly and as three separate signals. The source material consisted of a number of portraittype pictures. The color signal is treated in a format containing a baseband luminance channel and two baseband chrominance channels. Various orthogonal and nonorthogonal transformations, including the Karhunen-Loève transform, are applied to the chrominance signals to study the effect on the entropy. With a well-chosen format for the color signal, our results show that the redundancy resulting from using a separate encoding of the signals rather than a joint encoding ranges between 0.2 and 0.5 bits. The possible savings accruing from considering the relationship between coded color differential components was only about 1 percent of the total bit rate for most pictures and increased to a maximum of 4 percent for one particular picture.     

Mutual Information and Conditional Mean Estimation in Poisson Channels

Following the discovery of a fundamental connection between information measures and estimation measures in Gaussian channels, this paper explores the counterpart of those results in Poisson channels. In the continuous-time setting, the received signal is a doubly stochastic Poisson point process whose rate is equal to the input signal plus a dark current. It is found that, regardless of the statistics of the input, the derivative of the input-output mutual information with respect to the intensity of the additive dark current can be expressed as the expected difference between the logarithm of the input and the logarithm of its noncausal conditional mean estimate. The same holds for the derivative with respect to input scaling, but with the logarithmic function replaced by x log x. Similar relationships hold for discrete-time versions of the channel where the outputs are Poisson random variables conditioned on the input symbols.     

多径环境下距离与深度估计性能研究

多径时延可用于估计水下声源距离与深度,由时延估计协方差矩阵可知这些时延存在一定的相关性,时延的相关性影响距离深度估计方差,仅利用独立时延可提高估计精度。分析了存在直达波与水面反射两路多径情况下时延估计相关性及其对距离与深度估计的影响,并给出了仿真结果。     

一种快速估计二相编码信号参数的方法

由于二相编码信号的带宽与子脉冲带宽相近,利用信号的中心频率和带宽,可以获得类似于单个子脉冲的函数信号,该信号与二相编码信号作相关时,将分别出现极大值和极小值,这时的极小值反映了二相编码信号的相位跳变点;由于sinc函数的对称性,以上的过程相当于对二相编码信号进行频域加窗。利用这一特点,可以实现二相编码信号参数估计的快速算法,且算法简单有效,易于工程实现。仿真实验表明:在低信噪比情况下,算法可有效完成参数估计,其性能优于小波参数估计方法。     

一种BPSK信号符号速率估计算法FPGA实现

在对BPSK调制信号特性分析的基础上,介绍了对符号速率估计的一种方法,即通过提取信号包络中的重复频率来获得符号速率。在实际应用中发现,这种方法在数据符号个数较少时,受到非线性变换带来的低端噪声的影响较大,直接对信号包络的幅度谱求最大值难以正确估计出符号速率。在对问题进行分析的基础上引入了一种改进的方法,对导致估计错误的背景噪声进行抑制,从而突显出符号速率谱线。最后着重阐述了改进算法的FPGA实现方案。     

Bounds on Error in Signal Parameter Estimation

In this correspondence, the problem of lower bounds on mean-square error in parameter estimation is considered. Lower bounds on mean-square error can be used, for instance, to bound the performances, namely the attainable output signal-to-noise ratio, of pulse modulation transmission systems, such as pulse-position modulation (PPM) or pulse-frequency modulation (PFM). The tightest lower bounds to mean-square error previously known are the Ziv-Zakai bounds; the analysis carried out in this paper, which is based on an inequality first obtained by Kotel'nikov, leads to lower bounds tighter than previously known bounds.     

压缩域信号参数估计算法

参数估计作为盲信号处理的关键环节,对后续信号的侦察处理意义重大.提出一种压缩域信号参数估计算法,通过分析不同测量矩阵下稀疏系数的位置特征,对信号参数进行预判;通过引入降升调频思想,提高了参数估计的分辨率;利用多级搜索策略,大大减少了稀疏字典原子个数,降低了运算复杂度.仿真结果和理论分析表明,算法在没有增加运算复杂度的前提下信号参数估计性能明显提高.     

QPSK信号码元速率估计

接收端码元速率的估计,有助于获取信号调制规律,便于信号正确解调。以π／4-QPSK为例,在解决小波变换尺度优化选取和基带快速提取的难点的同时,旨在运用小波变换估计信号码元速率。具体方法是利用QPSK相位跳变发生在码元周期交替处的特点和Haar小波的相位特点,使小波变换系数极大模值出现在码元速率整数倍处;根据极大模值构造出同频率冲激序列,从其功率谱图上估计码元速率。经Matlab仿真,的确能估计出信号码元速率为500B。该方法所得估计值受噪声变化影响甚微,且在一定范围内小波变换尺度越大,分析效果越好。     

WLAN射频系统接收信号强度指示器的设计

设计了一个基于Jazz 0.35 μm SiGe BiCMOS工艺的接收信号强度指示器(RSSI),并成功应用于WLAN射频系统.该电路不仅具有低功耗、大动态特性,还有良好的温度和工艺稳定性.芯片测试结果表明:在输入信号频率为10 MHz、功率为-70～-10 dBm时,输出的直流电压为0.68～1.32 V,实现了功率指示功能.     

电子产品平均寿命的区间估计法

利用随机变量函数的分布,研究并证明了电子产品平均寿命的区间估计方法,并从置信区间的本质意义出发．通过极值理论给出了电子产品平均寿命的最小区间的估计方法。最后,用实例说明这种最小区间估计方法比传统方法更具优越性。