Topological layout of links for optimising the overall reliability in a computer communication system

Overall reliability or global availability is an important parameter in the design of the large scale computer communication systems having efficient resource sharing amongst the various computer centres. In order to design an optimal topological layout of the various links connected between the set of various geographically-distant computers, one should have knowledge of the cost and reliability of all the possible links and the maximum permissible cost. In this paper a heuristic algorithm is presented for obtaining an optimal network topology which gives the maximum overall reliability of the computer communication network. The method is general and is easily implemented on a computer.     

The design and realization of a high reliability semiconductorlaser for single-mode fiber-optical communication links

Long-haul trunk telecommunication systems, particularly optical submarine cable systems, have especially demanding reliability requirements. The authors describe how the InGaAsP inverted-rib waveguide (IRW) laser was designed for use as the source for such single-mode systems by minimizing known degradation hazards. The results of an extensive reliability assurance program are summarized. This included wafer validation endurance tests, overstress tests, and package design and life tests. The results of 7 million life-test hours confirm that the IRW laser has extremely good reliability performance     

Topological optimization of distributed computer networks subject to reliability constraints

A method of topological optimization of the networks with minimum cost subject to reliability constraints is given in this paper. The proposed optimization algorithm is based on branch and bound method. The computational results of this algorithm are discussed.     

Empirical prediction of overall reliability in computer communication networks

Incorporation of an overall reliability parameter in the design of reliable computer communication networks makes the computation prohibitive. A composite reliability index based on the network topological parameters has been presented [1], which is very simple to evaluate and gives computation while designing maximally reliable computer networks as compared to the techniques based on several reliability measures. In this paper, we use the tabulated results of Soi and Aggarwal [1] and develop empirical formulae which can be used for quick estimation of overall reliability of a computer network for a specified value of the link reliability.     

计算机通信网络可靠性的分析与探究

本文针对计算机通信网络的可靠性问题,依据计算机通信网络可靠性理论,对影响计算机通信网络可靠性因素进行分析,并在遵循可靠性设计的原则的基础上,提出了具体的设计方法与策略。     

Estimation of reliability for communication/computer networkssimulation/analytic approach

A general simulation/analytic approach for jointly assessing the reliability and performance of a communication/computer network is proposed. The advantages of this approach are the following: (a) it allows consideration of a variety of performance measures, (b) it allows consideration of a general structure of network components failure distribution, (c) it reduces complexity of the model and related calculations, (d) it is relatively simple to implement, and (e) it can derive sensitivity information about network performance with respect to various parameters-the first step for an effective network optimization algorithm. The method is illustrated in a number of examples using network connectivity and weighted network bandwidth as a measure of performance     

Mathematical analysis of a transitional computer communication system

This paper investigates a mathematical model for a computer communication system of two units—a computer and a controller. Each unit has n components, i.e. the computer has an n-processor while the controller has n converters. The amount of change in the computer or controller depends on the change in the components of these two units. These changes bring the system to either a partially failed state or a completely (totally) failed state. Failure rates are assumed to be negative exponential; recovery and repair rates are arbitrary. Various cost-related reliability measures have been studied using the regenerative point technique.     

A decomposition technique for the overall reliability evaluation of large computer communication networks

A funtamental consideration in the design of a computer network is the determination of its overall reliability. For large computer networks the exact evaluation of overall reliability is prohibitive because of the complexity of the computations involved. In this paper an approximate technique for the overall reliability determination is proposed which is based on the m-hierarchical clustering of a network. By this approach a close lower bound for the exact overall reliability can always be obtained with important savings in computation time and available memory.     

On the reliability of links in a ring network

This paper analyzes the reliability of links in a computer network which is configured in a ring topology. It will be shown that the expression for reliability of elements connected in series is not adequate for computing the reliability of links in a ring network. Consequently, new expressions for computing such reliability for rings with and without back-up links are proposed. Furthermore, an optimal back-up links assignment which guarantees optimal links reliability is formulated.     

计算机通信网的可靠性设计方案优化策略

近年来计算机通信网络技术快速发展,应用领域也在不断扩大,这与其独特的通信结构是分不开的。计算机通信网络结构是由许多不同层次模块构成的,其中不同层次模块都有着不同性能与特征,正是因为计算机通信网络结构层次模块的独特性,所以后期运行和维修显得尤为便捷。文章对计算机通信网设计结构展开分析,并提出了相应优化意见和建议。     

Overall reliability evaluation for large computer communication networks: An MHC approach

An important parameter in the topological design of computer communication networks is that of overall reliability, rather than terminal-pair reliability, as one is interested in not allowing service disruption between any pair of nodes. Exact techniques for overall reliability evaluation based on the spanning trees idea fail for networks even of reasonable size because of the enormous amount of computer time and storage required. In this paper, we present a very simple and fast method based on an m-level hierarchical clustering (MHC) for network overall reliability evaluation which gives results as good as exact techniques for realistic values of link reliability (e.g. 0.9 or more). Adaptability of a practical clustering method (i.e. complete linkage, CL) to obtain near optimal clusters for overall reliability evaluation by incorporating suggested modifications is proposed.     

Fast algorithm for computing the reliability of a communication network

This paper presents a fast algorithm for computing the reliability of a communication network when each link has the same probability of success. The computational complexity of existing algorithms increases exponentially as the number of links increases. Our algorithm is based on combinatorics and we conclude, for the case when links have the same survival probabilities, that the computational complexity grows subexponentially as the number of links increases. Furthermore, the algorithm is mostly algebraic in nature.     

A knowledge-based system with learning for computer communication network design

Computer communication network design is well-known as complex and hard. For that reason, the most effective methods used to solve it are heuristic. In this paper, we list weaknesses of these techniques, and present a new approach based on artificial intelligence for solving this problem. This approach is particularly recommended for large packet-switched communication networks, in the sense that it ensures a high degree of reliability, and offers a very flexible environment dealing with many relevant design parameters such as link cost, link capacity and message delay.     

移动通信系统设备可靠性筛选试验的应力条件

结合实际工作经验和体会,参考相关标准、规范,以产品实际应 用环境条件为基础,总结了移动通信系统设备可靠性筛选试验的边界条件,探讨了非加速和 加速应力筛选试验的应力选取方法和原则。在传统的可靠性筛选试验基础上,增加了电磁应 力的新研究内容。这更贴近产品实际工作的应力环境,在测试案例中取得了很好的结果。对 科学合理地激发产品缺陷提出了新的思路和方法     

轨道交通无线网络通信中的可靠性评估系统改进设计

传统轨道交通通信网络可靠性评估系统无法均衡自身的硬件承载性能,常常丢失轨道交通运行中产生的数据,评估准确度较低。因此,对轨道交通无线网络通信中的可靠性评估系统进行改进设计。该系统由传感器模块、ZigBee技术模块、网关模块和计算机组成,传感器模块用于收集轨道交通通信网络系统运行节点数据,并交由ZigBee技术模块进行数据处理。ZigBee技术模块通过其中的路由器采集数据,通过ZigBee网络协调器解析路由器中的数据,构建持续工作体系,并将体系中的数据传输到网关模块。网关模块依据电平的变化将ZigBee技术模块处理过的数据转变为易于计算机解析的串口数据,将此数据交由通用分组无线业务进行协议更新后,传输到计算机中进行可靠性评估分析。评估软件中设计了对轨道交通无线网络通信可靠性进行评估的流程图和关键代码。结果表明,所设计的可靠性评估系统拥有较高的评估准确度。     

计算机通信与控制系统运行可靠性提升策略研究

网络时代计算机通信与控制技术应用在各行各业之中,在获得这项技术带来的便利之时,其可靠性也受到人们的关注,并成为计算机发展的重要研究课题。本文首先对其可靠性理论进行了探讨,并重点分析了影响其可靠性的因素,从而提出了提升计算机通信与控制系统的策略。     

星地激光通信链路地面集成测试系统的构建

针对星地激光通信链路的地面集成测试需求,提出了一种地面集成测试装置的构建方案,该方案可有效解决真实通信终端在地面环境下的相互捕获、跟踪、瞄准及通信等功能验证问题.     

Design of a transversal equalizer for electronic dispersion compensation in optical communication links

A programmable transversal equalizer for electronic dispersion compensation(EDC) in optical fiber communication systems is developed.Based on the SiGe technology with a cut-off frequency of 80 GHz,the equalizer consists of 6 seriesparallel amplifiers as delay units and 7 Gilbert variable gain amplifiers as taps,which ensure that the equalizer can work at the bit rate of 10 Gb/s.With different tap gains,the forward voltage gain of the transversal equalizer varies,which demonstrates that the equalizer has various filtering characteristics such as low pass filtering,band pass filtering,band reject filtering,and notch filtering,so it can effectively simulate the inverse transfer function of dispersive channels in optical communications,and can be used for compensating the inter-symbol interference and other nonlinear problems caused by dispersion.The equalizer(including pads) occupies an area of 0.40 mm × 1.08 mm,and its total power dissipation is 400 mW with 3.3 V power supply.     

Analytical models for communication links in emergency management simulation

Emergency response involves the management of several different types of critical infrastructures and resources. Because of the interdependent nature of these systems, it is often very difficult for human decision makers to determine what the second‐ or third‐order effects of their decisions or actions might be. This has resulted in the development of several simulation tools that could be used to evaluate decisions or behaviours and better inform decision makers about the potential impacts of their decisions. One area that remains underdeveloped in this regard is the engagement of communication technologies by human agents, which has the potential to seriously affect delay times in response coordination. Given the size and complexity of simulating the interconnection of heterogeneous systems, developing reduced‐order simulation models has become important to maintain reasonable computation times. This paper describes the derivation of the distribution of the total connection time for a communication link where multiple technologies are engaged. Results show that communication link simulation times, which are among the most time‐consuming simulation routines can be significantly reduced by using the closed‐form distributions.     

Accumulation of distortion in tandem communication links

The mean-square errors (mse) of individual links of a communication network generally do not add up to the overall mse because of mutual correlations among the errors on the individual links. This makes it difficult to interpret the magnitude of contribution of each link to the mse. It is shown that if the mse of each link is defined alternatively as the mse between conditional mean estimators of the original signal at the input and output of that link, then the overall mse is in fact the sum of the mse's on individual links. Several examples illustrate the usefulness of this principle, particularly in digital communications, in understanding the source of system impairments.