Statistical estimation of delay fault detectabilities and fault grading

In this paper we present a technique to statistically estimate transition delay and path delay fault coverage. The basic method is an extension of STAFAN to include delay faults. By partitioning a combinational circuit into non-overlapping fanout free logic cones, we accurately calculate the transition sensitization controllabilities of 0 1 and 1 0 transitions of the lines within a fanout free logic cone to the output of the fanout free logic cone for each fanout free logic cone. A strategy to calculate the transition observabilities of fanout stems is proposed. The detectability of a path delay fault is evaluated as the product of the observabilities of the input line to its head gate within each fanout free logic cone on the path multiplied by the transition controllability of the path. When compared with the fault simulations, the estimations of transition delay fault coverage are within 2.3%. Also, the technique gives reasonably good path delay fault coverage estimation for large fault set of the ISCAS85 benchmark circuits.     

Statistical analysis of the performance of PMD compensators using multiple importance sampling

In this letter, we evaluate the performance of fixed and variable differential group delay (DGD) polarization-mode dispersion (PMD) compensators as the first- and second-order PMD varies using multiple importance sampling. We show that importance sampling yields estimates of the average penalty with low variance over the entire region of interest of first- and second-order PMD. We also show that there is little advantage in using a compensator with a variable-DGD element and that the performance of a compensator that minimizes the residual DGD at the central frequency of the channel is considerably worse than a compensator that maximizes the eye opening.     

Statistical optimization of dynamic importance sampling parametersfor efficient simulation of communication networks

Importance sampling (IS) is a powerful method for reducing simulation run times when estimating the probabilities of rare events in communication systems using Monte Carlo simulation and is made feasible and effective for the simulation of networks of queues by regenerative techniques. However, using the most favorable IS settings very often makes the length of regeneration cycles infinite or impractically long. To address this problem, a methodology that uses IS dynamically within each regeneration cycle to drive the system back to the regeneration state after an accurate estimate has been obtained is discussed. A statistically based technique for optimizing IS parameter values for simulations of queueing systems, including complex systems with bursty arrival processes, is formulated. A deterministic variant of stochastic simulated annealing (SA), called mean field annealing (MFA), is used to minimize statistical estimates of the IS estimator variance. The technique is demonstrated by evaluating blocking probabilities     

百分比抽样和固定数抽样的不科学性

针对百分比抽样和固定数抽样所存在的不科学、不合理性而导致不能有效地表示企业产品的合格率或不合格率的问题，用抽样方案的特性曲线进行了分析。     

Dynamic fault dictionaries and two-stage fault isolation

This paper presents dynamic two stage fault isolation for sequential random logic VLSI circuits, and introduces limited and dynamic fault dictionaries. In the first stage of the dynamic process, a limited fault dictionary identifies candidate faults, which are further distinguished in the second stage by a dictionary generated dynamically for the candidate faults and a subset of the test vectors. This provides high resolution but avoids the costs of full static dictionaries. Two-stage fault isolation is evaluated for benchmark circuits and on defects in industrial circuits     

Sub-Nyquist sampling process in presence of noisy sampling signal

A theoretical analysis of the frequency errors in the down-converted output frequencies of the sub-Nyquist sampling process due to a noisy sampling signal is presented.     

NFV故障关联及故障自愈方案研究

利用NFV实现电信网络设备软硬件解耦,摆脱了对专用硬件设备的依赖,并能利用NFV资源共享、自动部署、弹性伸缩等特性,但同时也带来了故障点多、故障定位分析困难等问题,导致NFV网络的运营维护难度增加。分析了NFV故障处理的流程及故障关联方案,为NFV场景下的故障定位处理提供指引。同时给出了VNF故障自愈实现方案,利用VNF特性,实现网元及业务自愈,提升自动化运维能力。     

Digital complex sampling

Complex sampling is often employed in digital signal processing schemes where the input signal is bandpass in origin and is to be processed using lowpass techniques. Conventionally the signal is first mixed to zero centre frequency in two quadrature channels, filtered to remove the high-frequency mixing products and then digitised in two A/D convertors. A method is proposed that employs only one A/D convertor followed by digital mixing to produce the required pair of signals, thus allowing a considerable saving in hardware.     

Biased multicanonical sampling

A modified multicanonical method is introduced that improves computational accuracy within selected regions of system parameters. The numerical accuracy of the method is established by evaluating the joint distribution function of first- and second-order polarization-mode dispersion in weakly birefringent optical fibers.     

Vector sampling expansion

The vector sampling expansion (VSE) is an extension of Papoulis' (1977) generalized sampling expansion (GSE) to the vector case. In VSE, N bandlimited signals, all with the same bandwidth B, are passed through a multi-input-multi-output (MIMO) linear time invariant system that generates M (M⩾N) output signals. The goal is to reconstruct the input signals from the samples of the output signals at a total sampling rate of N times the Nyquist rate, where the Nyquist rate is B/π samples per second. We find necessary and sufficient conditions for this reconstruction. A surprising necessary condition for the case where all output signals are uniformly sampled at the same rate (N/M times the Nyquist rate) is that the expansion factor M/N must be an integer. This condition is no longer necessary when each output signal is sampled at a different rate or sampled nonuniformly. This work also includes a noise sensitivity analysis of VSE systems. We define the noise amplification factor, which allows a quantitative comparison between VSE systems, and determine the optimal VSE systems     

Beyond bandlimited sampling

Digital applications have developed rapidly over the last few decades. Since many sources of information are of analog or continuous-time nature, discrete-time signal processing (DSP) inherently relies on sampling a continuous-time signal to obtain a discrete-time representation. Consequently, sampling theories lie at the heart of signal processing devices and communication systems. Examples include sampling rate conversion for software radio and between audio formats, biomedical imaging, lens distortion correction and the formation of image mosaics, and super-resolution of image sequences.     

ps超高速电光采样

本文报道了一种用于表征超快电脉冲瞬态特性的超高速电光采样技术,利用电光晶体行波普克尔效应和高重复率飞秒脉冲染料激光系统,获得结果是时间分辨率小于1ps,电压灵敏度小于50μV。测出了Cr:GaAs光电导微带开关的瞬态波形和微带传输线的色散特性。     

HgCdTe sampling circuit

The demonstration, using HgCdTe MISFETs, of a sampling circuit with output buffer amplifier is reported. Using the circuit, correlated double sampling is demonstrated at speeds typical of those required for focal plane arrays. Using a swept sine input, the circuit's transfer function is verified. The circuit was fabricated on epitaxially grown HgCdTe, with a cutoff wavelength of 3.56 mu m at 77 K.<>     

Picosecond optical sampling

A 10-channel optical-sampling technique has been developed to give oscilloscope displays of picosecond laser pulses in a single shot. Pulses with durations of 10-30 ps and powers ranging down to ∼ 1 W have been displayed with this technique. An ultrafast optical gate and a 10-channel multibeam splitter are used to cut out in one laser shot ten samples centered at 4.1-ps intervals from the leading to the lagging edge of the pulse. The ten optical samples are then spaced out at 10-ns intervals by means of an optical fiber array, detected by a fast photomultiplier, and displayed on a real-time oscilloscope. The envelope of the sample pulses represents a display of the laser pulse. This technique could substitute for picosecond streak cameras in certain applications.     

Integral sampling networks

Integral sampling is a technique where the sample is taken over a whole sampling period. This then permits an increased sampling rate. Two integnd samplen am described where RC networks are used as the integrating blocks.     

Picosecond optical sampling

A high speed sampling technique is proposed using a cascade of optical waveguide interferometers driven by CW sinusoidal traveling or standing microwaves. Each interferometer multiplies the optical signal by a function closely approximated bycos^{4} omegat, where ω is the frequency of its microwave drive. A cascade of four interferometers with 2.6 V microwave drives at 10, 20, 40, and 80 GHz and a total length of 2 cm can sample an optical signal with 2 ps resolution and 50 ps between samples. The sampler might be used in a picosecond sampling oscilloscope or in experiments requiring a jitter-free train of identical pulses.     

A sampling amplifier

A method of amplifying wide-band sisnals using narrow-band amplifiers is proposed. It uses the principle of undersampling a signal and amplifying the narrow-band signals generated by several sets of undersamples of the signal.