Enhancing the Error Performance of 5G New Radio Using Hierarchical and Statistical QAM

Wireless Personal Communications - The latest mobile network technology, 5G New Radio (NR), utilizes the combination of Low-Density Parity Check (LDPC) codes, which are powerful forward error...     

Error Detection in the Presence of Synchronization Loss

Cyclic codes are very attractive for error detection because of their low cost encoding and decoding circuits, and because of their high guaranteed minimum distance, but they suffer from very poor protection when word frame synchronization is lost. This note suggests starting the encoder and decoder circuits in an essentially random state, instead of the usual all-zero state. Under this condition of operation it is shown that the undetected error rate against synchronization loss is2^{-p}wherepis the number of parity check bits.     

基于误差分析的雷达估测降水集成方法

以淮河流域为对象,在假设Z-I关系法、平均校准法、最优插值法、卡尔曼滤波和最优插值联合校准法以及卡尔曼滤波校准法等五种降水定量估测模式对于不同的降水类型而言能力有所差异的基础上,通过对前期降水定量估测结果误差变化的分析,以统计方差为判别标准来选取最佳的估算方法,进行多种估测结果的集成.对2007年7月上旬降水过程的应用结果分析表明:在降水强度较小的情况下,该方法是一种有效的集成方法,能够提高降水定量估测的能力;但是在降水强度较大的情况下,集成效果不佳.     

Nonconcurrent Error Correction in the Presence of Roundoff Noise

This paper analyzes the effects of roundoff noise on our ability to nonconcurrently detect and identify transient faults that corrupt state variables during the operation of a fault-tolerant discrete-time linear time-invariant (LTI) dynamic system. Our analysis leads to two decoding algorithms, i.e., one based on the Peterson–Gorenstein–Zierler algorithm and the other based on singular-value decomposition techniques. We analytically obtain bounds on the roundoff noise level (equivalently, the precision) at which both algorithms can guarantee the correct determination of the number of errors. Our simulations verify our analysis and suggest that our bounds can be very tight for certain choices of design parameters. The developments in this paper can be used to provide guidance about the design of fault-tolerant systems and have immediate implications for digital implementations of LTI dynamic systems (e.g., digital filters) because such implementations unavoidably have to deal with finite-precision effects.      

Mean-Squared Error Sampling and Reconstruction in the Presence of Noise

One of the main goals of sampling theory is to represent a continuous-time function by a discrete set of samples. Here, we treat the class of sampling problems in which the underlying function can be specified by a finite set of samples. Our problem is to reconstruct the signal from nonideal, noisy samples, which are modeled as the inner products of the signal with a set of sampling vectors, contaminated by noise. To mitigate the effect of the noise and the mismatch between the sampling and reconstruction vectors, the samples are linearly processed prior to reconstruction. Considering a statistical reconstruction framework, we characterize the strategies that are mean-squared error (MSE) admissible, meaning that they are not dominated in terms of MSE by any other linear reconstruction. We also present explicit designs of admissible reconstructions that dominate a given inadmissible method. Adapting several classical estimation approaches to our particular sampling problem, we suggest concrete admissible reconstruction methods and compare their performance. The results are then specialized to the case in which the samples are processed by a digital correction filter     

Fast Error Rate Evaluation in the Presence of Intersymbol Interference

In this paper, we present a general framework which describes a class of fast methods of error rate evaluation in the presence of additive noise and intersymbol interference. An analysis of this framework led us to propose a new method based on a Fourier series expansion which does not make use of the moments of the intersymbol interference. Its computing cost is low and it handles various kinds of noise as well as current coherent amplitude or phase modulation techniques.     

Methods of Determining the Distensibility of Blood Vessels

Methods of calculating the characteristic transmission parameters of arterial segments, which are very short compared to the wavelength, are presented. If the reflection coefficient is known (e.g., as with complete occlusion) two simultaneous measurements of pressure or flow suffice (Method I). If this is not known, as is generally the case, three measurements must be made (Method II). In either case, provided great attention is paid to the static and dynamic calibrations of the instruments, the results obtained are wholly reasonable and allow an estimation of vessel distensibility, and also a closer examination of the usefulness of various transmission-line hypotheses.     

Detecting the Presence of Speech Using ADPCM Coding

When speech is coded using a differential pulse-code modulation system with an adaptive quantizer, the digital code words exhibit considerable variation among all quantization levels during both voiced and unvoiced speech intervals. However, because of limits on the range of step sizes, during silent intervals the code words vary only slightly among the smallest quantization steps. Based on this principle, a simple algorithm for locating the beginning and end of a speech utterance has been developed. This algorithm has been tested in computer simulations and has been constructed with standard integrated circuit technology.     

Lower Bounds on Error Probability in the Presence of Large Intersymbol Interference

A lower bound on the symbol error probability achieved by any estimator of a digital pulse-amplitude-modulated sequence in the presence of white Gaussian noise and intersymbol interference is presented. The bound reduces to the well-known single-pulse error probability bound when intersymbol interference is small, but is tighter when interference is large. For example, on the singlepole (RC) channel, the effective signal-to-noise ratio for any estimator is shown to decrease by at least 3 dB for every doubling in pulse rate T^-1asT rightarrow 0and, on the double-pole channel, by at least 9 dB, thus disproving a recent conjecture [2] on the performance of nonlinear receivers.     

Statistical Methods for Vectorcardiographic Directions

Current statistical methods for treating vectorcardiographic directions are invalid because they treat the directions as points on a line or plane. It is more appropriate to consider the directions as points on a circle or sphere; the direction toward the center of gravity of such points is then a measure of the prevalent direction, and the distance from the center of the circle or sphere to the center of gravity is a measure of precision. The precision is a measure of how closely the directions cluster about the prevalent direction. The Fisher distribution is suggested as a probability model for spatial directions, and its usefulness is illustrated by 1) a test statistic for determining whether two samples of directions come from the same population, 2) the construction of a ``confidence circle' for the spatial prevalent direction, and 3) a method for obtaining planar prevalent directions and precisions from the spatial ones.     

Bias Removal Algorithm for 2-D Equation Error Adaptive IIR Filters

This paper proposes a bias removal algorithm for equation error-based 2-D adaptive cascade IIR filters with separable denominator function. As well known, equation error-based adaptive IIR filtering algorithms have the advantages of fast convergence and unimodal mean-square-error surface. These advantages, however, come along with the drawback of biased parameter estimates in the presence of measurement noise. The adaptive filter structure in the proposed algorithm is based on the concept of backpropagating the desired signal through a cascade of the denominator vertical and horizontal sections. To handle the bias problem, the proposed algorithm uses a scaled value of the output error of each of the cascaded sections as an estimate for the measurement noise embedded in the signal part of the coefficient-update procedure of that section. Thus, while maintaining the advantages of easy stability monitoring, fast convergence, and low computational load, the effect of the measurement noise is suppressed. Input-Output stability analysis is carried out, and the constraints required to maintain stability are derived. Simulation examples are presented to support the effectiveness and the usability of the proposed bias removal algorithm in 2-D system identification and image enhancement applications.     

Error Performance of M-ary Noncoherent FSK in the Presence of CW Tone Interference

The error probability performance ofM-ary noncoherent frequency-shift-keying (NCFSK) digital systems when under the influence of continuous wave (CW) interference is determined. Exact expressions are derived in terms of the signal-to-noise and the signal-to-interference ratios. Numerical results are given for quarternary and octonary NCFSK with the signal-signal-to-interference ratio as a parameter.     

AVS-M中的错误恢复技术

介绍了AVS-M中采用错误恢复技术对误码进行控制和隐藏的方法,实验结果显示,目前AVS-M中的错误恢复技术明显提高了视频码流抗误码的能力,可满足无线和实时应用.     

On the Performance of the MIMO Zero-Forcing Receiver in the Presence of Channel Estimation Error

By employing spatial multiplexing, multiple-input multiple-output (MIMO) wireless antenna systems provide increases in capacity without the need for additional spectrum or power. Zero-forcing (ZF) detection is a simple and effective technique for retrieving multiple transmitted data streams at the receiver. However the detection requires knowledge of the channel state information (CSI) and in practice accurate CSI may not be available. In this letter, we investigate the effect of channel estimation error on the performance of MIMO ZF receivers in uncorrelated Rayleigh flat fading channels. By modeling the estimation error as independent complex Gaussian random variables, tight approximations for both the post-processing SNR distribution and bit error rate (BER) for MIMO ZF receivers with M-QAM and M-PSK modulated signals are derived in closed-form. Numerical results demonstrate the tightness of our analysis     

High-Efficiency Power Amplifier Using Novel Dynamic Bias Switching

A novel bias-switching scheme for a high-efficiency power amplifier is proposed. Two voltage levels for the drain bias of the RF power amplifier are generated using a combination of a class E dc/ac inverter and a class E rectifier with offset voltage. When signal peaks occur, the output of the class E dc/ac inverter is rectified and the rectified dc is added to the offset voltage by the class E rectifier, which boosts the drain bias of the RF power amplifier. Except during peaks, the drain bias of the RF power amplifier is connected to the offset voltage directly. Since the efficiency when there are no peaks is very high due to the direct connection between the offset voltage and drain bias, the overall efficiency of the RF power amplifier can be improved dramatically in high peak-to-average power ratio (PAPR) systems. The measured results show that the drain bias of the RF power amplifier is boosted up to approximately 1.8 times the offset voltage when the RF peaks generate. The overall efficiency of the proposed bias-switching amplifier is improved by 62% compared to that of the fixed bias amplifier in high PAPR systems     

边缘探测技术的信号估算及误差分析

对边缘探测技术的信号估算及测量误差进行了详细的分析。给出了不同情况下误差因子的函数形式和具体数值。讨论了信号平均及背景信号对测量误差的影响。结论是：边缘探测技术具有高信噪比,很小的测量误差,较大的高精度测量范围,并对背景噪声有一定的抵抗作用。     

电子设备的可靠性统计试验方法研究

可靠性试验是可靠性工程的一个重要组成部分,已成为验证电子设备可靠性指标的必要手段.以某电子设备为例,对电子设备的可靠性统计试验方法进行了研究.     

A Model for the Statistical Characterisation of Fast Fading in the Presence of a User

The study of the statistical behaviour of thereceived signal when a user is present near thetransmitting handset antenna is presented in thispaper. The probability distribution function (pdf) isanalysed in two parts, with the first one examiningthe random movement of the antenna near the user'shead and the second one examining the fast fading ofthe radiated signal. Different probabilitydistribution functions are considered for the firstpart. Measurements of the statistical variation of thedistance between the user's head and the antenna arepresented and they are compared with the pdf'sconsidered. A new model is derived based on thecombination of two known pdf's and it is given thename ``VeCa distribution'. Measurements of thestatistical behaviour of the received signal from adistantly located antenna, when a user is present nearthe transmitting antenna, are presented and thecomparison with the VeCa distribution proves thesuperiority of the latter against the Rayleighdistribution which is only successful when the antennais left alone (with no scatterers in its proximity).     

利用相关检测技术确定光电探测器工作波段

介绍了光电探测器识别系统精度的影响因素.通过在系统中运用相关检测技术,抑制系统及背景噪声对理想回波信号的影响,提取有效信息.借此来分析回波信号携带信息,并与原始信号信息进行比较来确定光电探测器工作波段.     

随机振动试验中确定控制点布置方案的方法

针对多点控制随机振动试验实施过程中的控制点布置问题,讨论分析了控制点选择的两种方法。首先,阐述了选择控制点布置方案的必要性,归纳总结了确定控制点布置方案的两种方法：类比法和试验法;其次,对这两种方法的优劣和适用场合进行了讨论分析;最后,利用两个实例分别说明了这两种方法的应用情况和效果。