Statistical signal integrity analysis and diagnosis methodology for high-speed systems

This paper discusses an efficient statistical analysis methodology for system-level signal integrity analysis. In the proposed method, statistical variations of the design and operational parameters are mapped to system performance through simulations based on orthogonal Taguchi arrays. Using the sensitivity functions derived from these simulations, statistical distributions of the performance measures are computed. The sensitivity functions and probability distributions of the design parameters are utilized as a diagnosis tool to estimate the design parameters of a system for a given measured performance. The statistical methodology is applied for design space exploration to improve system performance. For demonstrating the concept, a source synchronous memory bus and a peripheral input-output (I/O) bus have been analyzed under design and operational variations.     

Investigation of 43-Gb/s Transmission With a Wavelength Preserving SOA-Based Optical Regenerator

Transmission with cascaded optical regeneration based on synchronous modulation combined with optical reshaping by cross-gain compression in a semiconductor optical amplifier is investigated at 43 Gb/s over transoceanic distances (10 000 km). The proposed optical regenerator configuration performs signal reshaping and retiming while preserving the input signal wavelength. The regenerator cascadability properties are investigated using a reconfigurable loop to assess the impact of different inter-regeneration spacing on the transmission signal properties.      

Angular bandpass filters: an alternative viewpoint gives improveddesign flexibility

An alternative approach for the design of angular bandpass filters composed of metal strip gratings is proposed. In the classic approach, frequency selective surfaces (gratings) are used as resonant elements and the spacing between them is adjusted to obtain the required electrical performance. Following this implementation, however, the electrical coupling to the individual resonators can not be fully controlled so that very limited design freedom is obtained. Following the approach that we propose, the resonant element is the spacing between surfaces while the individual grating geometries are adjusted to obtain the required inter-resonator couplings. With this arrangement the structure becomes effectively equivalent to a closed waveguide filter, all electrical parameters of interest can be individually controlled and considerably extended design freedom is achieved. The basic resonator performance is analyzed and complete filter design examples are discussed. Furthermore, it is shown that, following the approach proposed, the frequency behavior of the structure is completely decoupled from its angular behavior in the design process thereby further extending the design freedom     

400 Mbit/s Optical Regenerator Integrated Circuits

This paper discusses 400 Mbit/s optical regenerator integrated circuits, focusing on their circuit architecture and performance, and describes their application to a 400 Mbit/s optical regenerator. The basic design concepts for high-speed regenerator IC's are discussed and a new integrated circuit architecture based on these design concepts is proposed. The proposed architecture of regenerator IC's is used to fabricate five IC chips (Reshaping IC, Retiming IC, Decision IC, LD driver IC, and dc-to-dc converter IC) using a high-speed bipolar process with transistors having a unity gain bandwidth of 5 GHz. The combination of these IC's can achieve submarine and terrestrial long-haul optical transmission at bit rates up to 450 Mbits/s. These IC's are applied to a 400 Mbit/s IC optical regenerator. Experimental results show that the IC optical regenerator has an optical dynamic range of more than 27 dB without any adjustment and received average optical power required to maintain a 10^-11error rate is less than -38 dBm. Experimental results fully satisfy the system requirements, and the feasibility of commercial application is demonstrated.     

Interference estimation and its applications in cognitive radio networks

Cognitive Radio (CR) has been proposed as a system-level means to improve the spectrum utilization efficiency. The most significant premise for CR networks is to avoid harmful interference to the licensed users. Therefore, it is very important to estimate the potential interference introduced by the deployment of CR networks so that CR networks can be coexistence with Licensed User (LU) networks by designing proper system parameters. In this paper, two statistical models of potential interference due to CR networks are developed based on transmitter and receiver oriented spectrum sensing schemes, respectively. The approximate probability distributions of aggregate interference introduced by CR networks are then derived with respect to the obtained models. With the help of these probability distributions, a method is further presented to get the critical system parameter, i.e., sensing distance and user density of the CR networks, so that the introduced interference can be controlled to predefined level. Numerical results validate the proposed interference estimation method and confirm the effectiveness of interference distribution based system parameter design.     

Regeneration capabilities of passive saturable absorber-based optical 2R in 20 Gbit/s RZ DWDM long-haul transmissions

A semiconductor saturable absorber-based optical 2R regenerator is implemented in a 20 Gbit/s WDM-emulated dispersion-managed loop transmission with 'standard' 50% RZ signals. When reducing the channel spacing from 200 down to 50 GHz, the optical 2R regenerator is seen to ensure Q-factors at 9000 km distance of 14.5 and 11.2 dB, respectively.     

3×3多天线系统衰落相关与信道容量研究

为分析天线间距和散射角等信道物理参数对多输入多输出系统信道容量的影响,提出了一种相关衰落环境中信道容量的分析方法。该方法基于接收均匀圆阵构建了蕴含信道物理参数的衰落相关矩阵。并由此详细推导了3×3多天线系统信道容量的闭式表达。结果表明,相关矩阵特征值的个数和大小决定了系统信道容量的大小。该方法回避了已有算法需求取相关衰落信道特征值概率密度函数的问题,降低了运算量,可以被推广到任意收发天线数的多输入多输出和多输入多输出-频分复用系统。仿真结果表明,天线间距增大,信道容量随之增大。但是当天线间距增大到衰落相关的第一个过零点时,信道容量达到最大值,再增大天线间距对信道容量影响很小。散射角越大,信道容量收敛到最大值速率越快。     

Outage Performance with Handover Triggering in Cellular Mobile Networks

An approach to performance evaluation of cellular mobile networksis proposed, which includes the behavior of handover algorithmsin the computation of outage probability.In a general system scenario, with a central cluster and interferingbase stations, the average outage probability is computed along a trip of themobile terminal that involves crossing the boundary between adjacent cells.The effects of correlated co-channel interferersare accounted for in the computationof outage probability, as well as in the dynamics of a relative signalstrengthhandover algorithm.Numerical results are provided and discussed as obtained over a wide rangeof values of system parameters, namely cluster size and channel parameters.Trade-off curves are shown in terms of outage probability and cross-overpoint versus the average number of handovers, and possible design criteriaare outlined.It is also seen that the local outage analysis (without handover triggering)can be referred to as a lower performance bound in cases of practicalinterest.     

基于高斯混合模型的车辆字符识别算法

在基于统计方法的车牌字符识别算法中,为了更有效地描述车牌字符特征的类条件概率密度,提出了一种基于高斯混合模型(GMM)的识别方法.首先采用Gabor变换来提取车牌字符的特征参数,然后通过GMM来逼近字符特征的类条件概率密度分布,最后根据得到的类条件概率密度分布函数构造贝叶斯分类器.其中,GMM的参数估计采用EM算法.实验表明,这种方法具有良好的字符识别效果、较强的鲁棒性以及较大的应用价值.     

Optical frequency comb generation using two cascaded polarization modulators

A novel approach to generate the flattened optical frequency comb (OFC) with tunable frequency spacing is proposed. The proposed generator consists of two cascaded polarization modulators driven by two radio frequency signals with different frequencies. By adjusting the parameters, 9, 12, and 16 comb lines can be generated with tunable frequency spacing. The scheme requires no DC bias voltage of the modulators and no optical filter, which makes our method simple and stable. A concept proof simulation is conducted to confirm the feasibility of the generation schemes of the 9-, 12-, and 16-line OFCs.     

On the effect of channel spacing,launch power,and regenerator placement on the design of mixed-line-rate optical networks

Due to the increasing heterogeneity and the growing volume of traffic, telecom backbone networks are going through significant innovations. Wavelength-division multiplexed (WDM) optical networks can now cost-effectively support the growing heterogeneity of traffic demands by having mixed line rates (MLR) over different wavelength channels.The coexistence of wavelength channels with different line rates, e.g., 10/40/100 Gbps, in the same fiber brings up various design issues: in this study, we focus on (1) choice of channel spacing; (2) choice of launch power; and (3) regenerator placement. Channel spacing affects the signal quality in terms of bit-error rate (BER), and hence affects the maximum reach of lightpaths, which is a function of line rates. Various approaches to set an opportunistic width of the channel spacing can be considered, viz., (i) uniform fixed channel spacing specified by the ITU-T grid (typically 50 GHz); (ii) different channel spacing for different line rates; or (iii) optimal value of channel spacing for all line rates that leads to minimum cost.The launch optical power of a signal is another important parameter that affects the network cost. Adjacent channels on different line rates, especially 10 Gbps and 100 Gbps, may exhibit serious degradation of signal quality and optical reach for both the channels due to cross-phase modulation (XPM) between them. Launch power plays a role in such a scenario as it governs the BER by affecting both the signal power and the noise power due to XPM. Moreover, intelligent choice of launch powers on different line rates can significantly reduce the number of regenerators required in the network. The tradeoff between placement of regenerators and choice of launch power is an important problem to address for MLR network design.In this work, we investigate the effects of channel spacing and launch optical power by evaluating the cost of a MLR network for different values of these parameters. We also study the interplay between regenerator placement and launch power. Our results show that (a) it is possible to identify optimal values of channel spacing for a minimum-cost MLR network design, and (b) controlling the power of 10 Gbps and 100 Gbps channels shows maximum sensitivity to the network cost.     

OSNR margin brought by nonlinear regenerators in optical communication links

Computation using a semianalytical model of the optical signal-to-noise ratio margins brought by the introduction of a generic 2R regenerator in an optical transmission link is presented. The optimization of the discriminating level of the regenerator depending on the link conditions is discussed and a regenerator characterization method that can be used in system design is presented.     

A new statistical methodology predicting chip failure probability considering electromigration

We present a new approach to analyze chip reliability due to electromigration (EM). This new approach utilizes the statistical nature of EM failure in order to assess overall EM risk. It includes within-die temperature variations from the chip’s temperature map extracted by an Electronic Design Automation (EDA) tool to estimate the failure probability of a design. We first used the traditional EM approach to analyze the design with a single temperature across the entire chip that involves six metal and five via layers. Next, we used the same traditional approach but with a realistic temperature map. A comparison between these two results confirms that using a temperature map yields a less pessimistic estimation of the chip’s EM risk. Finally, we employed the statistical methodology developed by us considering a temperature map and different use-condition voltages and frequencies to estimate the overall failure probability of the chip. The results of this statistical analysis confirm that the chip level failure probability is higher (i) at higher use-condition frequencies for all use-condition voltages, and (ii) when a single temperature instead of a temperature map across the chip is considered.     

机载雷达空时三维非自适应预滤波方法

该文提出一种机载雷达空时3维非自适应预滤波方法。利用可提前确定的载机偏航角、脉冲重复频率、阵元间距等雷达系统和载机平台信息,通过分析阵元在相邻两脉冲采样数据的结构,设计了一种空时3维非自适应滤波器,先滤除大部分杂波,使得剩余少部分杂波在降维自适应处理时能被充分抑制,提高了动目标检测性能。理论分析和仿真实验表明,该预滤波方法对载机偏航具有兼容性,能大大降低杂波自由度,在整个杂波区都有一定的性能改善,尤其在主瓣杂波区性能改善明显。     

Performance evaluation of a modified PRMA protocol for joint voiceand data packet wireless networks

In this paper, a modified version of the packet reservation multiple-access (PRMA) protocol is proposed to provide spatially dispersed voice and data user terminals wireless access to a base station over a common short-range radio channel. An analytical approach is presented in order to derive system performance in terms of mean data message delay and voice packet dropping probability. A suitable permission probability design is also proposed to enhance system performance. Performance comparisons with an extension of the PRMA protocol to voice data systems previously reported in literature are shown to highlight the better behavior of this approach     

随机二相编码连续波雷达的研究

本文对新型噪声雷达即随机二相编码连续波雷达作了系统研究。分析了该雷达波形的概率分布、平均模糊函数以及脉冲压缩后距离旁瓣的概率分布，提出了一种抑制距离旁瓣的统计处理方法，通过多级统计处理后可保证峰值距离旁瓣低于－３０ｄＢ，同时给出了系统参数的设计，并讨论了该噪声雷达的多普勒容限扩展问题，分析表明，该噪声雷达能同时测定远距离和高速目标。     

Virtual path and link capacity design for ATM networks

A path and link capacity design method for asynchronous transfer mode (ATM) networks using statistical multiplexing of cells is proposed. By developing the design method, the statistical cell multiplexing effect can be exploited to significantly reduce required network resources. The necessary design procedures are identified. A simple and effective policing mechanism is proposed. An analytical method for the evaluation of cell multiplexing characteristics using declared parameters is provided. Path and link capacity design algorithms that use these techniques are proposed. The effectiveness of the proposed design procedure is confirmed by comparing analytical results to those from a computer simulation     

A novel wideband space‐time channel simulator based on the geometrical one‐ring model with applications in MIMO‐OFDM systems

In this paper, we extend the geometrical one‐ring multiple‐input multiple‐output (MIMO) channel model with respect to frequency selectivity. Our approach enables the design of efficient and accurate simulation models for wideband space‐time MIMO channels under isotropic scattering conditions. Two methods will be provided to compute the parameters of the simulation model. Especially, the temporal, frequency and spatial correlation properties of the proposed wideband space‐time MIMO channel simulator are studied analytically. It is shown that any given specified or measured discrete power delay profile (PDP) can be incorporated into the simulation model. The high accuracy of the simulation model is demonstrated by comparing its statistical properties with those of the underlying reference model with specified correlation properties in the time, frequency and spatial domain. As an application example of the new MIMO frequency‐selective fading channel model, we study the influence of various channel model parameters on the system performance of a space‐time coded orthogonal frequency division multiplexing (OFDM) system. For example, we investigate the influence of the antenna element spacings of the base station (BS) antenna as well as the mobile station (MS) antenna. It turns out that an increasing of the antenna element spacing at the BS side results in a higher diversity gain than an increasing of the antenna element spacing at the MS side. Furthermore, the diversity gain brought in by space‐time block coding schemes is investigated by simulation. Our results show that transmitter diversity can significantly reduce the symbol error rate (SER) of multiple antenna systems. Finally, the influence of the Doppler effect and the impact of imperfect channel state information (CSI) on the system performance is also investigated. Copyright © 2009 John Wiley & Sons, Ltd.     

Barrage technique for measurement of p.c.m. regenerator section loss limits

A direct method for the measurement of the maximum regenerator section loss which produces less than a specified error rate is proposed. No assumptions about the statistical properties of the crosstalk interference are necessary.