MANET中基于移动代理的路由策略

本文首先分析了现有移动Ad Hoc网络的两类路由协议及其优缺点，接着提出将移动代理应用于按需路由的方案。通过移动代理更新节点路由表，从而在网络负载增加不大的情况下，减小路由请求发起数，降低端到端的数据传输延迟。还可在移动代理中加入节点能量信息、节点负载信息等，通过移动代理在网络中漫游，收集并更新途经节点的相应信息，从而达到节能和缓解网络拥塞的目的。     

基于移动代理的群管理探讨

研究了智能移动代理在网管领域的应用优势,包括降低网络负载和延时、自主执行、动态适应环境、异构性、协作性等方面。接着设计了移动代理软件,移动代理软件由应用接口模块、移动代理模块、信息转换模块和信息传输模块组成。具有应用需求输入、移动代理管理功能,同时基于JAVA语言开发,具有跨平台能力。并将移动代理与群管理相结合,研究了工作原理。最后附实例验证。     

一种基于移动代理的P2P系统主动负载均衡算法

负载均衡是P2P系统的研究热点,针对现有负载均衡算法的不足,提出了一种基于移动代理的主动负载均衡算法.该算法使用移动代理收集负载信息、生成负载迁移决策,降低了系统的通信开销,而且避免了单点失效问题和"颠簸"现象.通过引入对用户请求的评估和迁移,预见性的处理负载问题,提高了系统的服务质量.     

基于移动代理的网络管理计费系统模型研究

提出了一种基于移动代理的网络管理计费系统模型，对其构成、计费管理过程和安全机制进行了详细的研究。该系统利用移动代理的移动性和智能性，能够基于不同的计费模式对网络进行持续、高效、灵活、实时和准确的计费管理。实验表明该系统能够减轻网络负载，具有良好的应变能力和实时处理能力。     

基于多播的移动IP位置管理的研究

提出了一种通过多播中组管理功能完成移动IP位置管理方法。每一个自治网络中都设置一个移动路由代理（MA），形成一个管理移动节点位置绑定信息的虚拟专用网，通过将与移动主机通信的节点联合起来构成一棵多播树，使网络中各节点相互合作维护移动节点的位置更新。设计了绑定信息表的存储结构和管理移动位置绑定信息的算法。模拟实验表明，提出的基于多播的位置管理方案能够使通信对端实时了解移动节点的转交地址，减少向家乡代理注册的时间和次数，减小了传输延迟，为实时业务传输提供较好的支持。同时减轻了家乡代理和各主机的负担，使移动IP的性能得到优化。     

基于角色访问控制的移动代理安全系统的UML建模

鉴于移动代理的安全机制，文中用统一建模语言(UML)描述了基于角色的访问控制安全模式基于角色的访问控制(RBAC)和移动代理系统的系统结构，利用RBAC控制代理对代理平台资源的访问，得出了若干结论。     

基于Java安全的移动代理访问权限的特化

移动代理是一种新的分布式计算模式，安全是其必须解决的问题。针对基于Java移动代理系统的移动代理权限问题，尝试提出一种解决方案。该方案主要包括2个方面内容：一是利用Java2安全机制实现移动代理权限的特化；二是采用资源代理模式实现移动代理基于角色的权限特化，对敏感资源进行双重保护。该方案既采取粗粒度的角色解决方案，又结合采取了低粒度的基于Java安全的解决方案，能有效地实现移动代理存取权限的特化。     

一种基于安全移动代理的路由算法设计

移动代理通过遍历网络收集信息,由于网络的开放性,代理及其内部数据的安全受到巨大威胁。提出了一种基于安全移动代理的路由算法的设计思想,使用概率值来构造路由表,通过移动代理在网络节点间地迁移,来发现网络状态,更新节点路由表。同时在网络节点处建立信任表,定期生成TestDataAgent（测试代理）在虚拟空间中运行,并对其属性和关键数据进行检测以保证网络节点的可靠性,实现代理在网络中的安全。还用Grasshopper移动代理开发平台构造了一个简单网络模型,对此算法进行了验证。     

一种基于异步执行机制的新型移动代理方案

移动代理是一种新兴的网络技术，它提供了一个新的计算方式，在网络分布式环境中有着极为重要的作用。随着移动软件混合性的增加，也伴随着对安全的威胁。保护移动代理的代码及数据免受窜扰已成为移动代理能正常运行的关键。传统的密码机制不能直接应用到移动代理环境，考虑到移动代理的动态性和智能性等特点，提出了一种基于异步执行机制的新型移动代理方案，以增强移动代理和其执行环境的安全可靠性、最后对其做了安全分析和性能分析。     

一种基于层次移动IPv6网络的动态HA机制

在移动IPv6中,当MN(移动节点)位于外地网络时,发向MN的数据报文需要首先路由至HA(家乡代理),然后再转发至MN的当前位置.为了解决上述方式路由效率较低的问题,提出了一种在层次移动IPv6环境中的动态HA机制,并且给出了基于这种机制的全IP无线网络结构.在本方案中,通过利用MIPv6的本身特性,并结合一种安全的动态DNs(域名服务)更新机制,实现MN家乡地址和HA的动态配置,有利于简化网络管理,提高路由效率以及实现HA负载均衡等.另外,通过AAA(认证、授权和计费)上下文预转移机制,可以有效减小域间切换时延.     

面向高动态高空平台网络的路由协议研究

提出了一种面向高动态高空平台网络的路由协议,该协议通过按需查找方式确定高动态用户所属的高空平台,根据最短延时路由表在高空平台之间转发数据,并通过用户切换策略保证数据传输的连续性。仿真结果表明,该协议能够适应用户高速移动和频繁切换的高动态环境,具有可靠性高、延时小、路由开销小、抗毁性强等特点,为高动态高空平台网络的数据转发提供了一种可行的解决方法。     

SDN中基于分布式决策的控制器负载均衡机制

针对SDN多控制器负载均衡过程中,控制器选取僵化和交换机迁移冲突问题,提出了一种基于分布式决策的控制器负载均衡机制,分为三个阶段进行实施：首先通过周期性收集网络信息,结合控制器负载状况构建分布式迁移决策域;然后在域中依据选取概率确定迁移交换机,综合权衡数据收集、交换机迁移和状态同步三种代价选择目标控制器;最后建立迁移时钟模型,完成交换机迁移和控制器角色转换.仿真结果表明,与现有的负载均衡机制相比,降低了网络的通信开销,流建立时间平均缩短0.14s,控制器资源利用率提高了21.7%.     

一种基于改进蚁群算法的选播路由算法

为了在网络负载较大的情况下实现多目标多路径的选播路由,该文根据蚂蚁寻径与选播路由的相似性,提出了一种基于改进蚁群算法的选播路由算法。在运用数据包传输的历史信息来模拟路径信息素的基础上,增加了目标地址泛洪负载信息来模拟食物气味散发的过程,使得各个节点可以获得服务器和链路的最新信息。节点根据路径上的信息素、食物的气味以及链路的可见度等综合生成概率表,作为后继蚂蚁路径选择的依据。运用NS-2对该算法进行仿真,测试结果表明它可以减少传输时延,降低服务器负载的波动幅度,实现链路的负载均衡,增加网络的容量,提高选播服务的可扩展性。     

Improving the multiple access method of home networks over the electrical wiring

Data communications on domestic low-voltage powerlines benefit from an ubiquitous and already existent infrastructure. Nevertheless, high-speed communications on this environment faces obstacles such as attenuation and noise. The HomePlug standard defines Media Access Control (MAC)- and physical (PHY)-layer protocols for home electrical wiring networks. Its MAC protocol has introduced the deferral counter (DC) mechanism, which adapts the contention of the nodes for the medium according to the network load. This article proposes the Contention window Pro-active Increase (CPI) mechanism to enhance the performance of HomePlug. The CPI mechanism is based on DC and improves the HomePlug efficiency by faster increasing the contention window size. As a consequence, there are fewer collisions and the aggregated throughput increases. Under high network load, our simulation results show a tradeoff concerning throughput and jitter. CPI improves HomePlug throughput by up to 3% with no jitter increase and by up to 15% at the cost of additional jitter.     

Optimal joint utility based load balancing algorithm for heterogeneous wireless networks

The rapid development of mobile broadband services with continuously increasing traffic volumes has resulted in a number of challenges, including ubiquitous network coverage, high bandwidth, and reliable services for reasonable price, etc. To address these challenges, evolved packet system (EPS) is proposed as the evolution of the packet core network. While resource management and load balancing issues in EPS are discussed in 3GPP standardization, relatively few research works consider mechanism design for load information monitoring and evaluation. Furthermore, even though some load balancing algorithms have been proposed for integrated networks, the load balancing scheme design which achieves the optimization of joint system performance has not been extensively studied. In this paper, an inter-access system anchor based load balancing mechanism is introduced which performs load monitoring and evaluation for access gateways and networks, and an optimal load balancing algorithm is proposed for heterogeneous integrated networks. To characterize the performance of integrated networks, the concept of utility function is introduced and the comprehensive performance of integrated networks which support both single type service and multimedia service is modeled mathematically. Applying vertical handoff as an efficient mechanism for achieving load balancing, the optimal number of handoff users is obtained through solving the optimization problem. Numerical results demonstrate that load balancing between access networks can be achieved, and the optimal number of handoff users corresponding to the maximal joint network utility can be obtained.     

基于节点控制的空间信息网拓扑重构算法

空间信息网是一种融合陆海空天信息系统的新型自组织网络,成为研究热点.针对网络特点和应用需求,提出一种预防和恢复相结合的拓扑重构策略,通过检测拓扑关键点触发预防性重构,通过拓扑故障触发恢复性重构,重构时在一定范围内选择冗余节点,该节点在虚拟力的导向下自主地移动剑待维护区域,并以修复区域的局部拓扑通信代价最小为目标,进行拓...     

Dense cluster gateway based routing protocol for multi-hop mobile ad hoc networks

In a multi-hop mobile ad hoc network dynamic clusterization of nodes can be quite effective for better management of routing problems. In a cluster based protocol inter cluster data transfer takes place through the cluster gateways. Therefore, it is important to maintain information about the gateways as a part of the routing tables in order that the inter cluster routing proceeds smoothly even as the nodes move about. In this paper we propose a randomized approach for inter cluster routing over dense cluster gateways (DCG). A group of large number of gateway edges between two adjacent clusters offering inter cluster connectivity between the two is referred to as a DCG. The minimum number of gateway edges that define a DCG is dependent on the characteristics of particular ad hoc network. A DCG is expected to offer robust inter cluster connectivity as it typically has a large number of gateway edges. Our protocol is an improvement over the cluster based routing using k-tree core backbone proposed in [Information Processing Letters 88 (2003) 187–194]. It distributes the routing load on the cluster gateways without adding the extra overhead of maintaining information about dense cluster gateways. We also propose a heuristic which reduces the load on the cluster-heads. The heuristic elects some nodes to act as sub-cluster-heads which share a part of the workload of the respective cluster-heads. The protocol has been implemented on ns-2 simulator. An analysis of the result of the experiments has been presented.     

On the scalability of network management information for inter-domain light-path assessment

We investigate the necessary amount of network management information for light-path assessment to dynamically set up end-to-end light-paths across administrative domains in optical networks. Our focus is on the scalability of partial management information. We pose light-path assessment as a decision problem, and define the performance as the Bayes probability of an erroneous decision. We then characterize the scalability of management information as its growth rate with respect to the total resources of the network to achieve a desired performance. Scalability is achieved if the management information needed is only a negligible fraction of the total network resources. Specifically, we consider in this work one type of partial information that grows only logarithmically with the number of wavelengths supported per link. We derive an upper bound for the Bayes error in terms of the blocking probability when a new call is presented at the entrance of the network. We evaluate the upper bound using both independent and dependent models of wavelength usage for intra- and inter-domain calls. Our study shows that there exists a "threshold effect": The Bayes error decreases to zero exponentially with respect to the load when the load is either below or above a threshold value; and is nonnegligible when the load is in a small duration around the threshold. This suggests that the partial information considered can indeed provide the desired performance, and a small percentage of erroneous decisions can be traded off to achieve a large saving in the amount of management information.     

Sleep mode operation for IEEE 802.16e UGS based WiMAX

To solve the problem of energy efficiency drop in wireless metropolitan area network communication due to frequently sleep-awake transitions, the energy-saving mechanism of the sleep mode operation was researched in WMAN. In this paper we propose a dynamic algorithm to tune the ratio of the sleep windows and receive windows according to the real time load. Then, a Markov chain model was set up to analyze the energy efficiency and mean access delay. NS2 simulation results show that the proposed algorithm can achieve marked gain in energy efficiency compared to the traditional energy saving mechanism.     

Throughput enhancement with a modified 802.11 MAC protocol with multi-user detection support

A modification to the traditional CSMA-based media access control protocol, named 802.11-MUD, is proposed in this paper which differs from the IEEE 802.11 in its support of simultaneous transmissions/receptions with multi-user detection (MUD). A joint information and renewal theoretic analysis framework is introduced to study the performance of 802.11-MUD. While the information theoretic part is useful for modeling the increase in sum capacity attributed to MUD, the renewal theoretic part is good for modeling the impact of MUD on alleviating the collision probability and increasing the network throughput. In addition, this analytical framework helps us finetune the 802.11-MUD system (called 802.11-MUD^* after the optimal tuning) and achieve significantly enhanced network throughput especially in busy networks.