基于多目标满意优化的计算机通信网流量和容量分配

将满意优化理论应用到计算机通信网中,提出了基于多目标满意优化的计算机通信网优化设计方法,通过设计满意度函数,构造出计算机通信网的满意优化数学模型,并用改进遗传算法实现计算机通信网的容量和流量分配的满意优化设计。仿真结果显示,所设计的网络具有更满意的综合性能指标,证实了该方法的有效性和实用性。     

The design of distributed control computer systems

The top-down approach in the design of Distributed Control Computer Systems, DCCS, is presented. The starting point of the study is three statements: (i) the design approach should be production process control oriented; (ii) for real time process control applications, computer networks require an efficient communication subsystem, the most important features of which are high reliability and short message transmission times and (iii) recent research has shown that the tools and methodologies used in both computing and control should be complementary to each other in order to solve some of the distributed control computer system/distributed computer control system design problems. The paper contains the design problems of distributed control computer systems, the presentation of the methods and tools for the study and design of the DCCS, the top-down approach in the design of the DCCS, and examples of two design stages.     

Network management in a local computer network

The functions and structure of the network management subsystem of the GAMMA-NET, a local computer network at the University of Tsukuba, are presented. The network management subsystem is an integrated subsystem that offers a convenient man-machine interface for the network users during the execution of required jobs, and levels the workload throughout the system, as well as managing the network operations.     

一种分布式结构飞行控制计算机内部总线节点设计

根据分布式样例飞行控制计算机特点和内部数据通信需求,提出了以C8051F120单片机与FlexRay共同组成的内部总线通信节点设计方案,完成了通信节点硬件的详细设计,开发了通信软件并讨论了若干设计要点.对所设计的FlexRay通信节点进行了常温和低温下的功能和性能测试,验证了通信效率和可靠性,可满足新型飞行控制计算机的...     

Framework of a flexible computer communication network

With the increasing speed of computers and communication links, and the successful convergence of both fields, computers connected by high speed links now represent an enormously large distributed computing system. At the same time, communication between man and machine is also becoming more diverse and personalized. Networking issues such as evolution of user services, seamless communication between hosts, failure recovery and integration of new technologies arise daily. Problem-specific approaches and corresponding solutions are available at considerable cost. However, a common requirement is adaptability of the computer network to a variety of changes. In this paper, we propose Flexible Computer Communication Networks (FN) as a uniform solution to most of these networking problems. The framework of Flexible Networks can be considered as an intelligent shell enclosing existing networking architectures. An agent-oriented implementation of a flexible network is outlined. The conversion of existing networks to flexible networks is shown to be incremental, and therefore practicable.     

Traffic routing in a computer network

This paper presents a technique for tuning Decnet networks so as to minimize the average end-to-end packet delay for the entire network. It represent an adaptation of theoretical work on network flows to the realistic case of Decnet. Using this technique to configure hypothetical networks, it then discusses the behaviour of the Decnet routing algorithm with respect to network size, topological connectivity and traffic configuration.     

Capacity assignment in computer communication networks with unreliable links

This paper considers the problem of selecting the optimum capacities of the links in a computer communication network which employs unreliable links. Given the nodes, links, link probabilities, grade of service and cost functions of the network, the objective of this problem is to find the optimum link capacities that minimize the network design cost, subject to the constraint equation involving the grade of service. This is essentially a combinatorial optimization problem. A general methematical model for this problem is formulated and a set of feasible solutions is obtained using Lagrangean relaxation and subgradient optimization techniques. A simulation study has been performed to verify the model, and favourable results obtained for a variety of nontrivial networks.     

Banet — a local area network for distributed data processing

A broadcast architecture network (Banet) suitable for distributed data processing is proposed. One feature of Banet is that the broadcast-within-a-group function is supported not only by the datalink level but by the transport or session-level network structure. The commitment control scheme is included in the network protocol. Design goals, physical structure and protocols are discussed.     

Necessary and sufficient optimality conditions of a design decision on the structure of a local computer network

A problem of nonlinear programming with Boolean variables is considered, for which the possibility of extension of the optimality conditions of solving a special problem of nonlinear programming (with continuous variables) is shown by statistical estimation of possible design decisions. This contributed to the solution of the initial problem by simpler methods. Translated from Kibernetika i Sistemnyi Analiz, No. 5, pp. 133–137, September–October, 1999.     

第三代短波通信HDL协议性能研究

我国第三代短波通信技术的研究仍处于起步阶段,并且国内的大多短波通信系统都是基于第二代的短波通信标准。相比于第二代短波通信的数据链路协议,第三代短波通信的自动链路建立系统以其简洁而高效的设计解决了第二代短波系统所面临的各种问题,在建立数据链路的高效性、稳定性、可靠性等方面都有了很大的改进。根据美军标MIL-STD-188-141B中给出的第三代短波通信技术标准,对第三代短波数据链路协议的高速数据链路传输协议（HDL）进行了研究,通过理论分析与Matlab仿真相结合的方法,对数据包的误码率、丢包率、平均传输次数以及采用不同数据分组时的吞吐量等方面进行了性能分析。     

计算机网络应用中的安全性评价及对策研究

在现代社会中,信息技术的发展给人们带来了以前所不可想象的方便与便捷.计算机网络技术作为信息技术的重要方面之一,也得到了前所未有的进步,从而使得信息资源得到充分的分享和高效的利用.然而,人们在享受计算机网络应用的便利的同时,在计算机网络应用过程中所出现的安全性问题也不可忽视.本文在介绍了部分计算机网络应用现状的基础上,分析了计算机网络应用中所出现的一些安全性问题,并在此基础之上探讨和研究了几点解决计算机网络应用安全问题的对策.     

延迟容忍网络中多Ferry路由设计及改进

针对延迟容忍网络多Ferry路由设计方案MRT-Tree中普通节点的缓存和能量消耗过多的不足之处,提出了星型拓扑多Ferry路由设计MRT-Star.新设计使用专用的缓存装置来取代普通节点作为转发节点,并改变了普通节点的分配方式和Ferry节点的交互方式.最后,通过数学计算和数学分析表明MRT-Star在不额外消耗普通节点的缓存和能量的同时,还能获得比MRT-Tree较低的数据传输延迟.     

计算机互联网与通信网络建设的安全性探讨

目前,出现的各类计算机互联网与通信网络安全问题引起了人们广泛关注.本文主要探讨计算机互联网与通信网络建设中存在的安全问题、主要特点和需要实施的对策.     

无线Ad hoc网络中分布式极大吞吐率调度算法研究*

针对无线Ad hoc网络广播链路的特点,在更一般的链路干扰约束模型下,设计了一种分布式、贪婪的极大吞吐率调度算法。通过运用Laypunov定理,证明了该调度算法的稳定区域是网络最大稳定区域的γ倍（0<γ<1）。通过仿真验证了该算法性能接近集中式的GMM（贪婪极大匹配）调度算法。     

Hopf bifurcation and oscillations in a communication network with heterogeneous delays

In this paper, we investigate stability, bifurcation and oscillations arising in a single-link communication network model with a large number of heterogeneous users adopting a Transmission Control Protocol (TCP)-like rate control scheme with an Active Queue Management (AQM) router. In the system considered, different user delays are known and fixed but taken from a given distribution. It is shown that for any given distribution of delays, there exists a critical amount of feedback (due to AQM) at which the equilibrium loses stability and a limit cycling solution develops via a Hopf bifurcation. The nature (criticality) of the bifurcation is investigated with the aid of Lyapunov-Schmidt perturbation method. The results of the analysis are numerically verified and provide valuable insights into dynamics of the AQM control system.     

星地链路建模与分析

卫星网络技术以其独特优势成为研究热点,本文以卫星地面链路作为研究对象,对星地链路进行深入分析,细致刻画链路特性,在此基础上归纳星地链路延时的构成因素,从固定延时、可变延时和突发延时3个方面考虑,建立了时变的星地链路延时模型.详细分析了链路中影响误码率的各种损耗和噪声源,建立了基于卫星链路功率预算的链路误码率模型,基于给定的星地链路场景对延时和误码率模型进行了对比验证.结果表明本文提出的延时模型能够更细腻地刻画星地链路的延时,更精细地反映链路延时的变化特性;误码率模型考虑的因素更加全面,能够更真实地刻画星地链路的误码特性.两个模型可以作为卫星链路分析和设计的一个有效辅工具.     

IEEE 802.16中改进的VoIP服务调度算法设计

提出了一种应用于IEEE 802.16系统的改进的VoIP服务上行链路调度算法,此算法是一种基于语音活动检测的调度算法,BS根据SS的语音状态转换来分配上行链路资源。它可以弥补传统的调度算法中的一些不足,例如对上行链路资源的浪费、增大MAC负载和引入附加的接入时延等。就系统的吞吐量和接入时延两方面分别对传统的算法和提出的算法作了具体地分析和仿真,结果表明,提出的算法在吞吐量和系统容量方面具有更优的性能。     

Signal shaper with a distributed delay: Spectral analysis and design

Input shapers with time delays have proved useful in many applications related to controls for various oscillatory devices, for example flexible manipulators and cranes. In the paper, a novel approach for designing a zero-vibration signal shaper based on equally distributed delay is proposed. The parameter assessment of the shaper is based on the spectral approach. Various characteristics of the shaper are analyzed and compared with the classical zero-vibration shaper with a lumped delay. The analysis shows that the novel shaper is a slower, but more robust alternative to the classical shaper. Besides, the discrete implementation of the shaper is proposed and tested. It includes zero placement based parameter adjustment with the objective to preserve full compensation of the oscillatory mode by the discrete algorithm.