Reliability optimization of communication networks using simulated annealing

Two concepts of communication network reliability are considered. The first one, the ‘s-t’ reliability, is relevant for communication between a source station and a terminal station as in the case of a two way telephone communication. The second one, the overall reliability, is a measure of simultaneous connectedness among all stations in the network. An algorthm is presented which selects the optimal set of links that maximizes the overall reliability of the network subject to a cost restriction, given the allowable node-link incidences, the link costs and the link reliabilities. The algorithm employs a variaton of the simulated annealing approach coupled with a hierarchical strategy to achieve the gobal optimum. For complex networks, the present algorithm is advantageous over the traditional heuristic procedures. The solutions of two representative example network optimization problems are presented to illustrate the present algorithm. The potential utilization of parallel computing strategies in the present algorithm is also identified.     

Network design taking into account breakdowns and traffic overloads

Models and algorithms are presented enabling an evaluation of the traffic efficiency of a telephone network under abnormal working conditions and an optimization of network structures with reliability requirements.     

Reliability and cost efficiency analysis for deep space habitat network based on Nash bargaining solution

Focusing on the deep space habitat network requirements of high reliability and expensive links,two impact factors to the network performance were regarded as a multi-objective optimization problem,which were network reliability and cost efficiency model,and the relations between the two factors were formalized.Thereafter,the Nash model of cooperative game was used to make a fairness compromise to the network reliability and cost efficiency,and the Nash bargaining solution set was acquired through the Matlab platform with CVX.Further,through changing the threat value dynamically and performing the repeated game,the Pareto optimal solution could be obtained which can ensure the fairness of reliability and cost efficiency simultaneously.Finally,the Nash bargaining method was applied to a typical deep space habitat network topology,and described in detail how to set up the link numbers and link capacity in order to reduce the cost when the network traffic and the link capacity were given.The proposed work is important for the deployment and optimization of the deep space habitat network.     

Significance of Equipment Reliability in a Telephone Network

A reliability concept is considered in which telephone traffic is taken into account for a telephone network. An analytic model of a simple network with parallel paths shows how telephone traffic is included in the telephone network reliability analysis. Examples are given to demonstrate the usefulness of this concept in the investigation of an optimum inspection policy for each path, and the effects of path age and failure rate on telephone network service.     

A General Neural Network Model for Estimating Telecommunications Network Reliability

This paper puts forth a new encoding method for using neural network models to estimate the reliability of telecommunications networks with identical link reliabilities. Neural estimation is computationally speedy, and can be used during network design optimization by an iterative algorithm such as tabu search, or simulated annealing. Two significant drawbacks of previous approaches to using neural networks to model system reliability are the long vector length of the inputs required to represent the network link architecture, and the specificity of the neural network model to a certain system size. Our encoding method overcomes both of these drawbacks with a compact, general set of inputs that adequately describe the likely network reliability. We computationally demonstrate both the precision of the neural network estimate of reliability, and the ability of the neural network model to generalize to a variety of network sizes, including application to three actual large scale communications networks.      

连通局部通信网络与保证系统可靠性的优化设计

讨论了若干个局部网络合并成一个大网络使之达到系统可靠性限值并使连通费用最小的优化问题，通过采用系统可靠性上界算法加速了优化过程。     

Interference-aware node access scheme in UAV-aided VANET

In vehicular Ad Hoc network (VANET),frequent link handovers and channel interference can lead to increased transmission delay and decreased network throughput.To address the issues,unmanned aerial vehicle (UAV) were introduced to cooperate with vehicles and construct UAV-assisted air-ground integrated VANET.An interference-aware node access scheme was proposed.The node access problem was formulated as a multi-objective optimization problem considering link transmission rate,link handovers and transmit power.Then the optimization problem was decomposed into two convex optimization sub-problems by dual decomposition method,the sub-problem jointly optimizes handovers and link transmission rate while the sub-problem optimizes the transmit power based on link reliability.Finally,simulation results show that the proposed mechanism can effectively improve data delivery ratio,average end-to-end delay and network throughput.     

基于列生成的毫米波多连接链路配置调度算法

多连接技术允许用户同时建立和保持与多个小区/接入点的连接,通过网络元素之间的协调在吞吐量和可靠性方面大幅提高网络性能。针对毫米波通信中超高频段的链路中断问题,研究了多连接基于链路配置的调度算法,以提高链路调度效率,降低复杂度。首先,在系统模型中采用链路配置作为优化变量;其次,设计了多连接比例公平的调度准则;最后,提出一种基于列生成算法的链路配置调度优化算法,利用Dantzig-Wolfe分解将原问题分解为限制主问题和定价问题,并结合分支定界方法获得最优解。仿真结果表明,所提算法能够在数值上逼近全局最优,并且比现有的毫米波蜂窝网络链路调度方案增益平均提高40%以上。     

LTE系统中RRC连接重建失败原因分析及处理方案

无线资源控制子层(RRC)连接重建失败是LTE网络优化中常见事件类问题,严重影响了网络质量,减低了无线链路的可靠性、服务的连续性,提高了掉线率。本文结合LTE网络优化实例,针对重建过程中RCC连接失败的几种情形进行分析和研究,并提出相应的处理方案。     

无线传感器网络中基于效用模型的分布式功率控制机制

本文将效用模型引入无线传感器网络的功率控制设计中,提出了一种基于效用模型的分布式功率控制机制(简称UMDPC).该机制建立了网络中所有传感器节点的功率与效用模型的对应关系,将链路可靠性、网络能耗归纳到统一的网络效用优化框架中,并证明该效用优化问题是凸优化问题,构造基于对偶分解的分布式的优化算法,获得网络效用最大化条件下各节点的优化发射功率.最后,通过模拟实验对所提机制及其实现算法的性能进行比较和评价.实验结果表明,本文所提机制最大化了网络的效用,提高了网络的能量利用效率.     

ATC ground communications system optimization techniques

The authors address the optimization of three major components of the US Federal Aviation Administration's (FAA's) hybrid leased/owned ground communications system supporting air traffic control (ATC). The optimizations are performed with respect to cost, performance, and reliability. First, optimization of the radio communications link (RCL) backbone microwave transmission system is discussed. A heuristic optimization procedure that minimizes cost subject to capital cost and availability constraints is presented. Second, two levels of user access network (UAN) optimization are discussed. The first level is optimization of the selection of RCL sites to open as drop-and-insert points for access by private leased-line UANs. The second level is optimization of the selection of transmission media used for implementing UANs. A dynamic programming method is presented for identifying FAA facilities where low-density microwave UANs are cost-effective. Third, optimization of the National Airspace Data Interchange Network (NADIN) II packet data switching system is discussed. Because this network will use the FAA-owned RCL transmission resources, the primary measures for optimization are performance and reliability instead of cost. Two methods are presented for this problem: an analytic method and a simulation method     

Minimum-cost dimensioning model for common channel signalingnetworks under joint performance and reliability constraints

The common channel signaling (CCS) network using the signaling system no.7 protocol is a special-purpose packet switching network transporting various types of network signaling messages between telephone exchanges and/or network databases. Because of the criticality of the information that is being carried, CCS networks should be highly reliable and provide fast response times. They should be dimensioned with sufficient redundancy so that the performance requirements of the networks are satisfied even when a large number of the network components fail. An efficient method is developed to calculate the joint performance and reliability measure, called performability, between an arbitrarily chosen source-destination pair of signaling points in a CCS network. An iterative optimal dimensioning procedure is developed to minimize the total link cost of the network subject to the required end-to-end performability constraints between the signaling points. Using examples, it is shown that the developed dimensioning method overcomes shortcomings of a conventional link-by-link dimensioning method     

机动干线通信网抗毁评估方法

机动干线通信网具有机动、灵活、多变性,对网络的抗毁性、可靠性、生存性有着特殊的要求。针对机动干线通信网的特点,提出一种快速评价网络整体抗毁性的方法,给出抗毁性定量计算的数学解析式,同时给出网络中各节点、链路对网络抗毁能力的贡献量度。建立合理、有效的抗毁量度指标对机动干线通信网络优化、网络调整以及网络评估都有着重要意义。     

Maximum Reliability Route Subject to k-Improvements in a Directed Network

The network consists of links and perfect nodes. Each link has several known reliability numbers associated with it; each reliability number is related to the number of improvements made on that link. The network reliability is to be maximised subject to a constraint on the sum of the number of link improvements, by finding the appropriate route through the network. Dynamic programming is used to solve the problem. A numerical example illustrates the solution.     

基于深度强化学习的服务功能链可靠部署算法

针对当前关于服务功能链(SFC)的部署问题都未考虑到虚拟网络功能(VNF)的失效重要度,该文提出了基于深度强化学习的SFC可靠部署算法。首先建立VNF和虚拟链路可靠映射模型,为重要的VNF设置高可靠性需求,并通过链路部署长度限制尽可能保证虚拟链路可靠性需求。其次,以负载均衡为资源协调原则,与VNF可靠性联合优化,最终使用深度强化学习得到服务功能链部署策略。另外,提出了基于重要度的节点备份和链路备份策略,用于应对部署过程中VNF/链路可靠性难以满足的情况。仿真结果表明,该文的可靠部署算法在保证可靠性需求的基础上能够有效减少SFC失效损失,同时使虚拟网络更加稳定可靠。

     

有线无线融合的卫星时间敏感网络流调度研究

随着空间通信任务日趋复杂化,尤其是对时间敏感的需求不断提升,一方面要求星内系统的高带宽、可靠性和实时性;另一方面星间无线链路也应具备低时延和高可靠性。但由于卫星内部有线链路与星间无线链路差异大,业务数据经过有线和无线链路联合传输时,容易引发节点拥塞,而无法保障时敏业务的时延有界需求。为了提升数据在空间网络传输的实时性,该文提出了一种有线无线融合的时间敏感网络(TSN)流调度方案,首先对有线和无线链路资源分配与终端时延关系进行分析建模,并通过TSN控制器收集终端时敏需求,构建以全网时敏业务端到端最小平均时延为优化目标,然后采用基于增强精英保留遗传算法进行方案的快速求解。通过Pycharm对比测试时隙分配算法的性能,同时设计实现基于EXata网络仿真平台的低轨卫星TSN系统,并搭建实验场景进行试验验证。测试结果表明,该文所提出的流联合调度方案能够为空间时敏任务提供有界、稳定的时延保障。     

CO2激光大气通信机并入市话长话网的应用

本文讨论了CO2激光大气通信机并入市话网的基本问题，提出了解决些问题的具体措施，从而实现了CO2激光大气通机机与市话网的自动接续，扩大了CO2激光大气通信的应用范围，为民用电信提供了一条新途径。     

On the One-Moment Analysis of Telephone Traffic Networks

In this paper is a formulation of the one-moment method of analysis for a telephone traffic network in terms of the link offered traffics. By using a slightly strengthened version of the assumptions hitherto used in one-moment analysis, and by developing a type of limited availability link model, it is shown how the offered traffic to each link may be found, and thus how the network analysis may be reduced to a valid set of link analyses.     

Reliability optimization of computer-communication networks

The evaluation of the reliability of a given computer communication network is a NP-hard problem. Hence, the problem of assigning reliabilities to links of a fixed computer communication network topology to optimize the system reliability is also NP-hard. A heuristic method is developed to assign links to a given topology so that the system reliability of the network is near optimal. The method provides a way to assign reliability measures to the links of a network to increase overall reliability. It is based on the principle that the most reliable link should be assigned to the most vulnerable edge. The method computes an importance order for the edges of the network and uses the order to assign link reliabilities. If there are fewer than six links in a network, it can be shown that the method gives optimal assignment