Mixed-Domain Systems and Signal Processing Based on Input Decomposition

Using input decomposition as a starting point, a variety of new types of systems and signal processors, which mix together domains traditionally kept separate, are derived, and their properties are examined. In one of these systems, digital signals are processed in continuous time, thus avoiding sampling and consequent aliasing, while maintaining the advantages of digital implementations in terms of programmability and noise immunity. In another approach, digital bit waveforms are processed directly by conventional analog filters. In a third approach, a nonlinear input decomposition results in systems in which signals are processed with a compressed dynamic range; this is done in a way that avoids output transients that characterize other approaches to compression, and also avoids the need for precise nonlinearity control. Several other possibilities are discussed. In all cases, the resulting systems can be input–output linear.     

网络通信业务量的标值更新模型

本文利用标值更新过程，提出了一个较为通用的通信量统计模型。该模型可以对具有任意带宽分布和递减非凸自相关函数的通信量提供直接的拟合，不仅可以用于通信量的模拟，也可用于理论分析。讨论了该模型在通信量模拟中的应用，具有参数估计算法简单的特点，最后将该模型用于ＡＴＭ网络中的可变比特率视频源的模拟，数值结果表明其具有良好的模拟性能。     

Packet Loss Fair Scheduling Scheme for Real‐Time Traffic in OFDMA Systems

In this paper, we propose a packet scheduling discipline called packet loss fair scheduling, in which the packet loss of each user from different real‐time traffic is fairly distributed according to the quality of service requirements. We consider an orthogonal frequency division multiple access (OFDMA) system. The basic frame structure of the system is for the downlink in a cellular packet network, where the time axis is divided into a finite number of slots within a frame, and the frequency axis is segmented into subchannels that consist of multiple subcarriers. In addition, to compensate for fast and slow channel variation, we employ a link adaptation technique such as adaptive modulation and coding. From the simulation results, our proposed packet scheduling scheme can support QoS differentiations while guaranteeing short‐term fairness as well as long‐term fairness for various real‐time traffic.     

多重分形网络流量的单队列输入排队性能研究

多重分形已被证明能够较好地用于网络流量多尺度突发行为特性的研究.本文以队列处于满负荷状态的概率为指标研究了多重分形流量输入下单队列的排队性能问题,提出了以尺度函数与矩因子表示的队列满负荷运行概率的解析性框架.用FBM过程作为输入,从理论上验证了该概率框架的正确性,进一步用实测的网络流量数据对多重分形流量输入下单队列满负荷运行的概率进行了分析与比较,结果表明该框架能同时满足单、多重分形流量输入时排队性能的计算.结合文献[1]给出的联合多重分形(JMF)流量模型,为排队系统中队列深度的设计提供了有效的定量计算方法.     

基于标值更新通信量模型的ATM缓冲区信元丢失率分析方法

提出了一种不同于传统分析方法（如ＭＭＰＰ／Ｄ／１）的直接基于输入通信量带宽分布和自相关特性的信元丢失率分析方法,应用标值更新模型近似实际输入通信量的低阶统计特性,给出了一个基于马尔柯夫链极限概率的信元丢失率估计公式。该方法可以估计突发级的信元丢失率,而且具有算法简单,计算量小,数值稳定性好等特点。     

Performance Analysis of Reassembly and Multiplexing Queueing with Long-Range-Dependent Input Traffic

This paper studies the impact of long-range-dependent (LRD) traffic on the performance of reassembly and multiplexing queueing. A queueing model characterizing the general reassembly and multiplexing operations performed in packet networks is developed and analyzed. The buffer overflow probabilities for both reassembly and multiplexing queues are derived by extending renewal analysis and Bene fluid queue analysis, respectively. Tight upper and lower bounds of the frame loss probabilities are also analyzed and obtained. Our analysis is not based on existing asymptotic methods, and it provides new insights regarding the practical impact of LRD traffic. For the reassembly queue, the results show that LRD traffic and conventional Markov traffic yield similar queueing behavior. For the multiplexing queue, the results show that the LRD traffic has a significant impact on the buffer requirement when the target loss probability is small, including for practical ranges of buffer size or maximum delay.     

具有输入饱和的纯反馈系统有限时间跟踪控制

针对具有输入饱和及输出约束的非线性纯反馈系统,提出了有限时间自适应神经跟踪控制方法.利用有限时间控制理论、Barrier Lyapunov函数以及径向基函数(RBF)神经网络设计出新颖的虚拟和实际输入信号,解决了具有输入饱和及输出约束的非线性纯反馈系统的有限时间控制问题,同时,确保系统在满足输入饱和及输出约束的条件下,...     

Renewal Theoretic Aspects of Two-Unit Redundant Systems

This expository paper discusses four two-unit redundant systems: 1) parallel redundancy; 2) standby redundancy; 3) standby redundancy with priority; 4) standby redundancy with noninstantaneous switchover. In models 1), 2), and 3) the switchover time is instantaneous. The integral equation of renewal theory is applied by using the concept of a cycle. Applying the integral equation of renewal theory and the cycle, we obtain systematically for each model the Laplace-Stieltjes transform of the distribution of the time to first failure and its mean.     

Constrained State Estimation for Nonlinear Systems with Unknown Input

This paper extends the problem of state estimation for linear discrete-time systems with unknown input to the nonlinear systems. Based on physical consideration, the constraints of state are also considered. And the constraints which can improve the quality of estimation are imposed on individual updated sigma points as well as the updated state. The advantage of algorithm is that it is able to deal with arbitrary constraints on the states during the estimation procedure, Least-squares unbiased estimation algorithm can be used to obtain unknown input, and the unknown input which can be any signal affects both the system and the outputs. The state estimation problem is transformed into a standard Unscented Kalman filter problem which can easily be solved. Simulations are provided to demonstrate the effectiveness of the theoretical results.     

State Estimation for Linear Constrained Systems with Unknown Input

This paper deals with the filtering problem for linear discrete constrained dynamic systems with unknown input. The constraint matrix and constraint vector in this system are allowed to vary in the value and in the dimension. The original full state is separated into two parts, and the estimate of the state is reduced to find the optimal estimate of a singular system. The estimable condition is researched and a recursive estimator for the original full state is presented. A rigorous mathematical induction is given to compare the performance of our approach to that of the existing method without constraint. A numerical example is presented to demonstrate the effectiveness of the new method.     

Input Amplitude Compression in Digital Signal-Detection Systems

An implementation for digital coherent signal-detection systems is considered in which analog-to-digital conversion is achieved by a uniform quantizer preceded by a signal amplitude compressor. This configuration is a practical approximation to the optimum coherent-detection quantization scheme which has nonuniformly spaced output levels. An optimum input compression curve is derived and is seen to be an output-scaled version of the locally optimum detection nonlinearity. Performance analysis and design of these compressors as considered for several noise models, with the conclusion that this implementation, when properly scaled, yields nearoptimum performance for only a moderate number of quantization bits.     

Decomposition in Reliability Analysis of Fault-Tolerant Systems

Two important problems which arise in modeling fault-tolerant systems with ultra-high reliability requirements are discussed. 1) Any analytic model of such a system has a large number of states, making the solution computationally intractable. This leads to the need for decomposition techniques. 2) The common assumption of exponential holding times in the states is intolerable while modeling such systems. Approaches to solving this problem are reviewed. A major notion described in the attempt to deal with reliability models with a large number of states is that of behavioral decomposition followed by aggregation. Models of the fault-handling processes are either semi-Markov or simulative in nature, thus removing the usual restrictions of exponential holding times within the coverage model. The aggregate fault-occurrence model is a non-homogeneous Markov chain, thus allowing the times to failure to possess Weibull-like distributions. There are several potential sources of error in this approach to reliability modeling. The decomposition/aggregation process involves the error in estimating the transition parameters. The numerical integration involves discretization and round-off errors. Analysis of these errors and questions of sensitivity of the output (R(t)) to the inputs (failure rates and recovery model parameters) and to the initial system state acquire extreme importance when dealing with ultra-high reliability requirements.     

Optimal Controller for Stochastic Polynomial Systems with State-Dependent Polynomial Input

This paper presents an optimal quadratic-Gaussian controller for stochastic polynomial systems with a state-dependent polynomial control input and a quadratic criterion over linear observations. The optimal closed-form controller equations are obtained using the separation principle, whose applicability to the considered problem is substantiated. As an intermediate result, the paper gives a closed-form solution of the optimal regulator (control) problem for polynomial systems with a state-dependent polynomial control input and a quadratic criterion. Performance of the obtained optimal controller is verified in an illustrative example against a conventional linear-quadratic-Gaussian (LQG) controller that is optimal for linearized systems. Simulation graphs demonstrating overall performance and computational accuracy of the designed optimal controller are included.     

Congestion Probabilities in CDMA-Based Networks Supporting Batched Poisson Input Traffic

We propose a new multirate teletraffic loss model for the calculation of time and call congestion probabilities in CDMA-based networks that accommodate calls of different service-classes. The call arrival process follows a batched Poisson process, which is more “peaked” and “bursty” than the ordinary Poisson process. The call-admission-control policy is based on the partial batch blocking discipline. This policy accepts a part of the batch (one or more calls) and discards the rest, if the available resources are not enough to accept the whole batch. The proposed model takes into account multiple access interference, both the notion of local (soft) and hard blocking, the user’s activity, as well as interference cancellation. Although the analysis of the model does not lead to a product form solution of the steady state probabilities, we show that the call-level performance metrics, time and call congestion probabilities can be efficiently calculated based on approximate but recursive formulas. The accuracy of the proposed formulas are verified through simulation and found to be quite satisfactory. Comparison of the proposed model with that of Poisson input shows the necessity of the new model. We also show the consistency of the new model over changes of its parameters.     

信道成组ATM交换系统中混合业务的性能分析

本文分析了信道成组ＡＴＭ交换系统中混合业务的性能。混合业务包括突发业务和随机业务，为了满足两类业务不同的服务质量要求，本文将部分缓冲共享方案略作修改。用一个二维Ｍａｒｋｏｖ链来描述交换系统的状态，用Ｇａｕｓｓ－Ｓｉｅｄｅｌ迭代法求解系统稳态方程。研究了业务平均突发长度、缓冲门限、业务量及信道成组技术对系统性能的影响。模拟结果与理论分析吻合。     

Quantized Output Feedback Control of Uncertain Discrete-Time Systems with Input Saturation

This paper deals with the problem of quantized output feedback control for uncertain discrete-time systems with input saturation. Input quantization case and output quantization case are studied, respectively. The purpose of the study was to design of dynamic output feedback controllers such that all the trajectories of the closed-loop system converge to a small ellipsoid for every initial condition starting from large admissible domain. By solving the optimization problem, the corresponding domains can be obtained. Finally, two simulation examples are provided to demonstrate the applicability of the proposed approach.     

遥控钥匙门禁系统的路径损耗

在遥控钥匙门禁(RKE)系统中,可以用钥匙扣上的发射器从远端开锁,发射器将无线编码发送到汽车内的接收机。遥控钥匙门禁(RKE)系统通常工作在ISM频段,包括315MHz和433．92MHz。随着远程启动和带校验的RKE的出现,设计     

A Performance Model for Loss Systems with Crisis Calls

In this paper a mathematical model is developed for the performance of crisis calls. In such a system, a finite number of crisis calls attempt to use a communication link that has been receiving ordinary calls. The performance of the link with respect to the crisis calls is analyzed and studied. A numerical analysis is conducted to determine the behavior of the crisis calls under various scenarios. Some simple upper and lower bounds on the blocking and loss probabilities for crisis calls are given.     

Nonlinear Analysis of Correlative Tracking Systems Using Renewal Process Theory

A new method is presented which describes the behavior of an(N + 1)th-order tacking system in which the nonlinearity is either periodic [phase-locked loop (PLL) type] or a nonperiodic [delay-locked loop (DLL) type]. The cycle slipping of such systems is modeled by means of renewal Markov processes. A fundamental relation between the probability density function (pdf) of the single process and the renewal process is derived which holds in the transient as well as in the stationary state. Based on this relation it is shown that the stationary pdf, the mean time between two cycle slips, and the average number of cycles to the right (left) can be obtained by solving a single Fokker-Planck equation of the renewal process. The method is applied to the special case of a PLL and compared with the so-called periodic-extension (PE) approach. It is shown that the pdf obtained via the renewal-process approach can be reduced to agree with the PE solution for the first-order loop in the steady state only. The reasoning and its implications are discussed. In fact, it is shown that the approach based upon renewal-process theory yields more information about the system's behavior than does the PE solution.