Control and optimization methods in communication network problems

The authors focus on two areas of communication network design in which methods of control and optimization theory have proven useful. These are the area of multiple access communication (for networks with shared links such as radio networks and local area networks) and the area of network routing (for networks with point-to-point interconnections). They review a few selected problems in each area to show the role of the control concepts involved and then proceed to identify other areas of communication network design in which the same control theoretic and optimization methodology may be applicable and useful. They attempt to bring to the attention of the control systems community the numerous instances of problems arising in the pure communication network design process that can benefit from the attention and the capabilities of this community     

基于最近社交圈的社交时延容忍网络路由策略

无稳定拓扑使时延容忍网络(delay tolerant networks,DTN)路由协议主要通过增加冗余数据包副本提高路由性能.社交网络是DTN的一种典型应用场景,但由于其网络规模相对较大,当网络负载高时,通常的DTN路由不能有效控制数据包副本的数量,从而产生大量丢包导致性能下降.借鉴MANET网络中利用分簇结构控制网络冗余路由数据包的思想,通过分析社交网络中节点的移动模型,定义了在社交关系的约束下,聚合移动规律相近的节点构成最近社交圈的节点簇组成策略.提出了一种基于该分簇结构的分为簇外喷射、簇间转发和簇内传染3个阶段的社交时延网络路由协议.实验证明,这种基于最近社交圈分簇结构的路由能有效地控制冗余数据包副本的产生,并在高网络负载的情况下仍然能够达到较好的性能.     

基于CAN总线和GPRS的车载传感器网络平台的实现

给出了基于CAN总线和通用分组无线业务(GPRS)的车载传感器网络平台的解决方案和软件、硬件的实现。结合汽车轮速传感器,说明了传感器节点的信号处理和数据计算。通过设计CAN通信模块,实现车载传感器数据的网络化传输;采用包含GPRS模块的传感器网关节点,实现车载传感器与远程计算机间的无线数据通信。该车载传感器网络平台具有很强的通用性。     

对等网络中平均最短路径长度的分析

对等网络理论上可以将它看成一个大的无向图，图中的顶点表示网络中的每个计算节点，图的边则表示计算节点之间的连接．P2P网络，类似于其他的复杂网络（如Internet、web和社会关系网络），这类网络中的节点的度的概率分布呈现出Power-law的分布特性．传统上对这些网络建模时采用的是随机图模型，然而随机图网络与Power-law（网络的一个表质区别是在随机图网络中节点度的概率分布呈现泊松分布，这种节点度的分布差异将导致对网络的建模分析不能反映实际网络的真实特性．通信网络（如Internet和P2P网络）中任意两点间的最短路径长度是衡量这种网络的一个重要特征量，它直接关系到诸如路由、搜索等相关算法的设计与实现，本文基于Power-law网络模型对P2P网络的最短路径长度进行理论建模与分析，并通过对实际网络的测量来验证理论分析结果的正确性．     

Detecting and Locating Failures in Communication Networks

The connectivity of a strongly connected network may be destroyed after link damage.Since many networks are connected by directed links,the reachability may be restore by altering the direction of one or more of the links and thus reconfiguring the network.The location of the failed link ust first be determined.In this paper,we examine new methods to determine the location of failed links and nodes in networks.A routing test approach is proposed and the conditions under which communication networks may be tested are discussed Finally,an adaptive algorithm and a heuristic algorithm that can locate a single failed link or a single failed node are presented.     

Reliability Optimization in the Design of Distributed Systems

The reliability of a distributed system depends on the reliabilities of its communication links and computing elements, as well as on the distribution of its resources, such as programs and data files. A useful measure of reliability in distributed systems is the terminal reliability between a pair of nodes which is the probability that at least one communication path exists between these nodes. An interesting optimization problem is that of maximizing the terminal reliability between a pair of computing elements under a given budget constraint. Analytical techniques to solve this problem are applicable only to special forms of reliability expressions. In this paper, three iterative algorithms for terminal reliability maximization are presented. The first two algorithms require the computation of terminal reliability expressions, and are therefore efficient for only small networks. The third algorithm, which is developed for large distributed systems, does not require the computation of terminal reliability expressions; this algorithm maximizes approximate objective functions and gives accurate results. Several examples are presented to illustrate the approximate optimization algorithm and an estimation of the error involved is also given.     

一种带侦察子群蚁群算法的无线传感路由协议

针对无线传感器网络（WSNs）路由面临安全威胁和节点能量有限的不足,提出一种基于引入侦察子群的改进蚁群算法（SACO）路由协议。通过改进的蚁群算法构造一条数据传输链,选择其中能量最大节点为簇头,信息通过相邻节点传送。结果显示：该算法兼顾到节点的能量和路径消耗,较标准蚁群算法和贪婪算法具有高效的路由选择功能,能够使网络中节点能量消耗更加均衡,从而延长网络的使用寿命。     

Using mobile agents to recover from node and database compromise in path-based DoS attacks in wireless sensor networks

Wireless sensor networks represent a new generation of real-time embedded systems with significantly different communication constraints from the traditional networked systems. With their development, a new attack called a path-based DoS (PDoS) attack has appeared. In a PDoS attack, an adversary, either inside or outside the network, overwhelms sensor nodes by flooding a multi-hop end-to-end communication path with either replayed packets or injected spurious packets. Detection and recovery from PDoS attacks have not been given much attention in the literature. In this article, we consider wireless sensor networks designed to collect and store data. In a path-based attack, both sensor nodes and the database containing collected data can be compromised. We propose a recovery method using mobile agents which can detect PDoS attacks easily and efficiently and recover the compromised nodes along with the database.     

基于NPV广义超立方体最佳容错路由算法

在网络可靠性研究中,设计较好的容错路由策略、尽可能多地记录系统中最优通路信息,一直是一项重要的研究工作.超立方体系统的容错路由算法分为可回溯算法和无回溯算法.一般说来,可回溯算法的优点是容错能力强:只要消息的源节点和目的节点有通路,该算法就能够找到把消息传递到目的地的路径;其缺点是在很多情况下传递路径不能按实际存在的最短路径传递.其代表是深度优先搜索(DFS)算法.无回溯算法是近几年人们比较关注的算法.该算法通过记录各邻接节点的故障信息,给路由算法以启发信息,使消息尽可能按实际存在的最短路径传递.这些算法的共同缺点是只能计算出Hamming距离不超过n的路由.在n维超立方体系统连通图中,如果系统存在大量的故障,不少节点对之间的最短路径大于n,因此,这些算法的容错能力差.提出了一个实例说明采用上述算法将遗失60%的路由信息.另外,由于超立方体的结构严格,实际中的真正超立方体系统不多.事实上,不少的网络系统可转换为具有大量错误节点和错误边的超立方体系统.因此,研究能适应具有大量错误节点和错误边的超立方体系统的容错路由算法是一个很有实际价值的工作.研究探讨了:(1) 定义广义超立方体系统;(2) 在超立方体系统中提出了节点通路向量(NPV)概念及其计算规则;(3) 提出了中转点技术,使得求NPV的计算复杂度降低到O(n);(4) 提出了基于NPV的广义超立方体系统最佳容错路由算法(OFTRS),该算法是一种分布式的和基于相邻节点信息的算法.由于NPV记录了超立方体系统全部最优通路和次最优通路的信息,在具有大量故障的情况下,它不会遗漏任何一条最优通路和次最优通路信息,从而实现了高效的容错路由.在这一点上,它优于其他算法.     

A fault-tolerant routing scheme in dynamic networks

In dynamic networks,links and nodes will be deleted or added regularly.It is very essential for the routing scheme to have the ability of fault-tolerance.The method to achieve such a goal is to generate ore than one path for a given set of source and destination.In this paper,the idea of inderval routing is used to construct a new scheme(Multi-Node Label Interval Routing Scheme,or MNILIR scheme)to realizee fault-tolerance.Interval routing is a space-efficinet routing method for netwroks ,but the method is static and determinative,and it cannot realize faulttoloerance.In MNLIR scheme some nodes will have more than one label,thus some parirs of destination and source will have more than one path;the pairs of nodes, which have inheritance relation,will have the shortest path.Using this character,MNLIR scheme has better overall routing performance than the former interval routing scheme,which can be proven by simulations.The common problem concerning the insertion and deletion of nodes and links is considered in this paper.So if the networks have some changes in topology,MNLIR scheme may find alternative path for certain paris of nodes.In this way,fault-tolerance can be realized with only a little space added to store the multi-node labels.     

基于遗传算法的防止无线移动网络路由攻击策略

在无线移动网络中,恶意节点可以通过发送虚假信息和假路由信息、广播假链接等中断路由操作对网络进行攻击。本文在分析了几种常见路由攻击的基础上,提出了一种基于遗传算法的路由优化策略。实验数据表明,这种优化策略可以较好地预防路由攻击,提高网络的整体性能。     

Loop-free constrained path computation for hop-by-hop QoS routing

We present the distributed multi-constrained routing (DMR) protocol for the computation of constrained paths for QoS routing in computer networks. DMR exploits distance vectors to construct a logical shortest multipath (LSM) for each destination with regard to a given optimization metric, from which a set of non-dominated paths are locally derived at each node. As such DMR is able to find feasible paths as well as optimize the utilization of routing resources.DMR operates in line with the hop-by-hop, connectionless routing model assumed in the IP Internet, and maintains instantaneous loop freedom. Nodes running DMR need not maintain a global view of network state (topology and resource information), and routing updates are sent only to neighboring nodes. This is in sharp contrast with all previous approaches that rely on complete or partial network state for constrained path computation, which incurs excessive communication overhead in large networks and is hard to achieve in practice.     

基于历史相遇间隔的机会网络路由协议

针对大多数机会网络路由协议在寻找端到端通信链路时不能很好地抓住节点社会性质的问题,提出一种基于历史相遇间隔(HICR) 协议的路由算法。HICR协议利用社会关系的特点,根据节点之间的历史相遇间隔判断它们的亲密程度,转发消息给离目的节点更亲近的节点,使得消息朝更靠近目的节点方向发送。仿真结果表明,该HICR协议在网络资源有限的的情况下,与Epidemic协议和Prophet协议相比,能获得更高的消息交付率。     

SafeMesh: A wireless mesh network routing protocol for incident area communications

Reliable broadband communication is becoming increasingly important during disaster recovery and emergency response operations. In situations where infrastructure-based communication is not available or has been disrupted, an Incident Area Network needs to be dynamically deployed, i.e. a temporary network that provides communication services for efficient crisis management at an incident site. Wireless Mesh Networks (WMNs) are multi-hop wireless networks with self-healing and self-configuring capabilities. These features, combined with the ability to provide wireless broadband connectivity at a comparably low cost, make WMNs a promising technology for incident management communications. This paper specifically focuses on hybrid WMNs, which allow both mobile client devices as well as dedicated infrastructure nodes to form the network and provide routing and forwarding functionality. Hybrid WMNs are the most generic and most flexible type of mesh networks and are ideally suited to meet the requirements of incident area communications. However, current wireless mesh and ad-hoc routing protocols do not perform well in hybrid WMN, and are not able to establish stable and high throughput communication paths. One of the key reasons for this is their inability to exploit the typical high degree of heterogeneity in hybrid WMNs. SafeMesh, the routing protocol presented in this paper, addresses the limitations of current mesh and ad-hoc routing protocols in the context of hybrid WMNs. SafeMesh is based on the well-known AODV routing protocol, and implements a number of modifications and extensions that significantly improve its performance in hybrid WMNs. This is demonstrated via an extensive set of simulation results. We further show the practicality of the protocol through a prototype implementation and provide performance results obtained from a small-scale testbed deployment.     

按需式ad hoc移动网络路由协议的研究进展

Ad hoc移动网络是一种完全由移动主机构成的网络，网络拓扑易变，带宽，能源有限是ad hoc移动网络的主要特点，针对这些特点，目前设计的ad hoc路由协议大多采用按需查找方式，该文介绍了这方面研究的最新进展，对几种典型的按需路由协议进行了说明，分析和综合比较，文中分析了目前协议存在的一些问题并提出了相应的改进方法，最后指出了下一步研究方向。     

A Flocking-Based on Demand Routing Protocol for Unmanned Aerial Vehicles

研究人员的某社区显示出到自治雄蜂或 UAV (无人的天线车辆) 的兴趣与无线通讯网络的来临增加了。这些网络允许 UAV 以一种特定的方式更高效地合作以便在特定的环境完成特定的任务。到那么,当保持经由收音机连接在它的组与另外的节点连接了时,每只雄蜂独立地遨游。这个连接能故意被维持一会儿抑制雄蜂的活动性。这将对涉及在来源和一个目的地之间的给定的传播的一条给定的路径的雄蜂合适。这限制能在传播过程的结束被移开,每只担心的雄蜂的活动性从其它变得再独立。在这个工作,我们建议为 UAV 的一个基于成群的路由协议叫了 BR-AODV。协议为当数据正在被播送时,维持的连接和线路为雷纳兹机制的按需的线路计算,和 Boids 利用一个众所周知的特定的路由协议。而且,自动扎根的基础车站发现机制为为即时应用程序的上下文需要的一个积极雄蜂和地面网络协会被介绍了。BR-AODV 的表演被评估,与古典 AODV 路由的相比,协议和结果证明 BR-AODV 以延期,产量和包损失超过 AODV。     

Exploring the Design Space of Self-Regulating Power-Aware On/Off Interconnection Networks

With power consumption becoming increasingly critical in interconnected systems, power-aware networks become part-and-parcel of many single-chip and multichip systems. As communication links consume significant power regardless of utilization, a mechanism to realize such power-aware networks is on/off links-network links that can be turned on/off as a function of traffic. In this paper, we investigate and propose self-regulating power-aware interconnection networks that turn their links on/off in response to bursts and dips in traffic in a distributed fashion. We explore the design space of such on/off networks, outlining a 5-step design methodology along with various building block solutions at each step that can be effectively assembled to develop various on/off network designs. We applied our methodology to the design of two classes of on/off networks with links that possess substantially different on/off delays, an on-chip network as well as a chip-to-chip network, and show that our designs are able to adapt dynamically to variations in network traffic. Three specific network designs are then constructed, presented, and evaluated. Our simulations show that link power consumption can be reduced by up to 54.4 percent, with a modest increase in network latency     

Optimizing self-organizing overlay network using evolutionary approach

Self-organizing overlay networks are emerging as next generation networks capable of adapting to the needs of applications at runtime. Applications performance significantly depends on the structure and behaviors of the underlying self-organizing overlay networks. To achieve desired performance, not only the logical overlay topology but also the behaviors of nodes in this overlay network need to be optimized. Moreover, self-organizing overlay networks are extremely dynamic, unreliable and often large-scale. It is therefore important to design new optimizing approaches to meet these challenges. In this paper, we present an evolutionary optimization methodology for self-organizing overlay network. The optimizations of self-organizing overlay networks are modeled as dynamically evolutionary process, in which the nodes interact with each other, change their internal structures and alter their external links to improve the collective performance. To design appropriate fitness functions and rules that guides the direction of the evolution, overlay network can reach a stable state with desired global application performance eventually. Such a methodology leads to our distributed algorithms for proximity-based overlay topology maintenance and Peer-to-Peer living media streaming, in which every node in the overlay network rewires their behaviors and connectivity according to local available information and embedded rules. These algorithms are shown to perform well using simulations.     

基于蚁群优化的无线传感器网络路由算法

如何在资源受限的无线传感器网络中进行高效的数据路由是无线传感器网络研究的热点之一。基于群智能优化技术的蚁群优化算法被广泛应用于网络路由算法。提出一种无线传感器网络蚁群优化路由算法,能够保持网络的生存时间最长,同时能找到从源节点到基站节点的最短路径;采用的多路数据传输也可提供高效可靠的数据传输,同时考虑节点的能量水平。仿真结果表明:提出的算法延长了无线传感器网络的寿命,实现无线传感器网络在通信过程中快速、节能的路由。