基于云安全模型的簇状树形无线传感器网络路由协议

由于传统的簇状树形无线传感器网络路由协议簇首能耗方差较大,导致存活节点数量和节点剩余能量较少,降低了无线传感器网络的使用寿命,为此设计一种基于云安全模型的簇状树形无线传感器网络路由协议。通过计算簇状树形无线传感器网络在接收与发送数据时的传输能耗,利用云安全模型获取云安全态势各种要素之间的不确定关系,预测节点的综合信任值,以预测结果为基础,采用蚁群算法获取分区节点的最优路径,完成簇状树形无线传感器网络路由协议。实验结果表明,本文设计的路由协议簇首能耗方差较小,存活节点数和节点剩余能量更多,接收数据包量比其他2种协议分别高出了48.1%和22.6%。由此可见,本文设计的路由协议延长了簇状树形无线传感器网络的使用寿命。     

一种抗干扰半静态分簇路由算法

针对无线传感器网络( WSNs)分簇路由算法中的能量洞、热点和抗干扰问题,设计一种抗干扰半静态分簇( AlSSC)路由算法,给无线传感器网络提供能量多、距离短、链路质量好的路径来传输数据.该算法利用节点定位获取节点地理位置,综合考虑传感器节点剩余能量和干扰信噪比,通过节点距离度量、节点聚簇、簇间融合、簇头选举和簇头轮换五个步骤进行无线传感器网络节点的分簇.仿真结果表明:这种路由算法可以提高无线传感器网络通信链路质量,均衡网络能量消耗.     

基于Zigbee技术的无线传感器网络协议的设计

本文提出了使用zigbee技术构建簇树形拓扑结构的无线传感器网络.首先,概述了无线传感器网络的特点;其次,重点阐述了此类拓扑结构的无线传感器网络协议设计思想;最后,在实际的硬件环境下验证所设计的协议.     

无线传感器网络中能量有效的加权分簇算法

针对无线传感器网络中节点受到能量和带宽等资源的严格制约的问题,通过分簇可以使网络中节点能量负载均衡,从而延长网络的生存周期.本文从能量和节点度的角度出发,分析了无线传感器网络中现有的一些分簇算法,提出了一种新的适合于无线传感器网络的能量有效的加权分簇算法,通过仿真和分析,得出该分簇算法是一种有效的分簇算法.     

基于能量约束的无线传感器网络可靠性研究

针对传感器网络系统(WSN)对任务完成所需能量有约束的特点,首先建立了WSN系统的网络模型和任务模型,引入了能量权函数,建立了基于任务的无线传感器网络系统可靠性模型,最后针对无线传感器网络的典型层次簇拓扑结构,给出了建模实例。该方法为WSN系统的任务级划分与拓扑结构的选择和优化提供依据和参考。     

WSN中一种能量均衡的分簇路由协议的设计

无线传感器网络中,LEACH协议是典型的分簇路由协议.文章针对LEACH协议的缺点,结合PEGASIS协议的优点,从簇首选择、簇的形成、簇间路由等方面对LEACH协议进行了改进,设计了一种能量均衡的分簇路由协议EBLP,并进行了仿真分析.仿真结果表明,EBLP协议节约了能量,平衡了能量消耗,延长了无线传感器网络的生存时间.     

TLTS:大规模无线传感器网络下基于簇的两级TDMA调度协议

媒质接入控制子层是节点能量消耗的主要所在,因此无线传感器网络设计的基于TDMA的MAC协议具有固有的节能特性,但是其可扩展性较差.基于簇的TDMA协议则可有效提高系统的可扩展性,但同时带来了簇间传输干扰问题.针对此问题提出了一种基于簇的两级TDMA调度协议--TLTS协议.通过两级TDMA调度,避免了簇间传输干扰,提高了能量有效利用率.实验结果显示,当节点密度较高时,TLTS协议更适合用于大规模部署的无线传感器网络中.     

树形无线传感器网络的建模与性能上界分析

探究无线传感器网络的性能上限,对于理解网络在最不理想情形下的行为非常重要,而且能够提供合适的设计参考.基于此,提出了一种对树形无线传感器网络建模,并对网络性能确定性上界进行分析的方法.该方法通过树形拓扑的深度、最大子路由节点数和最大子终端节点数来确定模型,并借助网络演算的相关知识,推导出了由拓扑结构和传输特性决定的节点缓存上界、节点带宽需求及端到端数据流延迟上界的递推公式,并且还示范了如何将推导出的公式应用到IEEE 802.15.4/Zig Bee树形无线传感器网络中.     

基于WSN的长大隧道环境监测系统设计与实现

针对长大隧道对环境信息监测的特殊需求,充分利用无线传感器网络自组网布设灵活方便的特性,实现了一种基于无线传感器网络的环境信息监测系统.基于簇的能量高效路由算法构建无线传感器网络,以STM32W108无线微控制器为核心设计了低功耗网络节点,在STM32F107VX网络控制器最小系统基础上设计了网络汇聚节点.基于分层的设计思想,设计了B/S (Browser/Server)模式访问的监控中心软件.经过现场测试,系统运行稳定、可靠,以较低的成本达到设计要求.     

WSN免疫模型设计及其分簇算法

针对无线传感器网络容易出现能量衰竭和分簇繁琐问题,设计一种基于人工免疫计算理论的无线传感器网络模型,采用网格理论来划分初始簇,并对网络节点及节点簇等进行相关定义。最后提出一种免疫型无线传感器网络分簇算法——aiCWSN。通过实验,该模型和算法能够减少网络能量过快衰竭和提高网络的收敛性。     

基于SNMP协议的网络拓朴发现算法分析

当前,互联网安全管理模块中采用了大量基于SNMP协议的工具,研究该协议网络拓扑发现的步骤和方法,对于保障互联网信息传输的安全性有重要意义。文章通过对SNMP协议、网络拓扑发现技术和算法的研究,设计了一个网络拓扑发现系统,该系统能够对网络结构进行准确、高效的自动发现,从而简化网管部署,提高效率。文章还对网络层拓扑发现、链路层拓扑发现以及相关算法进行了分析。     

无线传感器网络拓扑控制研究

随着无线传感器网络的广泛应用,传感器节点的部署环境也更加复杂,网络性能受到很大影响,通过优化拓扑结构,最大化利用节点有限资源成为拓扑控制研究的重要内容,网络拓扑控制在延长网络生命周期、节约节点资源、降低网络干扰等方面发挥着重要的作用,它能够提高路由协议和MAC协议的效率,为数据融合、时间同步和目标定位等很多方面提供基础。设计实现一种高效的拓扑控制机制已成为无线传感器网络的研究重点,该文中主要是针对现有的部分拓扑控制算法进行了分析和比较。     

Moving routing protocols to the user space in MANET middleware

Mobile Ad Hoc Network (MANET) middleware must be aware of the underlying multi-hop topology to self-adapt and to improve its communication efficiency. For this reason, many approaches rely on specific cross-layer communications to interact with the network protocols in the kernel space. But these solutions break the strict layering of the network stack and hinder the portability of middleware and applications.The main argument of this paper is to move the routing protocols to the user space to simplify the development, testing, deployment and portability of middleware and applications. If routing is just another software component in the user space, cross-layering can be elegantly solved using advanced software engineering techniques like component frameworks and explicit APIs. As a consequence, a slight performance cost must be paid to achieve portability and easy deployment. But we will demonstrate that the performance obtained by a user-space routing protocol is satisfactory for a wide range of applications.We have implemented the unicast MANET OLSR protocol in Java (jOLSR) and, on top of it, we have created a novel overlay multicast protocol (OMOLSR). We have then integrated both routing protocols (jOLSR, OMOLSR) as software components in a well-known group communication toolkit (JGroups). Modifying the JGroups toolkit, we have devised a topology-aware group communication middleware for MANETs (MChannel). In our MChannel middleware, group membership is obtained directly from OMOLSR multicast trees and failure detection is obtained from jOLSR active probing. We have validated our approach in several real testbeds to demonstrate the feasibility and efficiency of our middleware.     

TCP Offload系统的设计与实现

网络带宽的迅速发展使主机协议处理开销成为系统整体性能的瓶颈。为了提高网络应用的性能、降低主机系统的资源占用，该文采用网卡子系统分担主机的网络包收发和TCP协议处理，设计实现了一个TCP offload系统，分析了一般TCP offload系统在性能和实施的困难，给出系统设计的基本原则，介绍了系统在通信接口、资源管理、事件管理和用户接口等方面的实现。系统测试结果表明，网卡能处理高速的网络应用，在一些情况下甚至达到线速。     

IS-IS路由性能监测系统的设计与实现

设计分布式中间系统-中间系统（IS—IS）路由性能监测系统,采用被动监测的方案,分析IS—IS路由协议交互过程中的数据包,利用路由变更和路由拓扑整合算法真实动态地呈现网络拓扑及路由变化,在实验网中进行测试以验证该系统的功能和性能,其监测结果可为网络的运行和维护提供重要依据。     

P2P流媒体系统中基于网络坐标的拓扑优化研究

近年来,基于P2P的大规模流媒体直播系统得到了广泛应用,但是应用层覆盖网与底层物理网络存在失配问题。针对该问题,提出了一种基于Vivaldi网络坐标算法的流媒体系统拓扑优化机制——NCSTO(Network Coordinate System in P2P StreamingTopology Optimization),通过采用双重采样和样本过滤器,能够有效地针对覆盖网进行拓扑优化,减少网络失配,提高系统运行效率,降低带宽浪费。     

Random Walk Routing in WSNs with Regular Topologies

Topology is one of the most important characteristics for any type of networks because it represents the network's inherent properties and has great impact on the performance of the network. For wireless sensor networks (WSN), a well-deployed regular topology can help save more energy than what a random topology can do. WSNs with regular topologies can prolong network lifetime as studied in many previous work. However, little work has been done in developing effective routing algorithms for WSNs with regular topologies, except routing along a shortest path with the knowledge of global location information of sensor nodes. In this paper, a new routing protocol based on random walk is proposed. It does not require global location information. It also achieves load balancing property inherently for WSNs which is difficult to achieve by other routing protocols. In the scenarios where the message required to be sent to the base station is in comparatively small size with the inquiry message among neighboring nodes, it is proved that the random walk routing protocol can guarantee high probability of successful transmission from the source to the base station with the same amount of energy consumption as the shortest path routing. Since in many applications of WSNs, sensor nodes often send only beep-like small messages to the base station to report their status, our proposed random walk routing is thus a viable scheme and can work very efficiently especially in these application scenarios. The random walk routing provides load balancing in the WSN as mentioned, however, the nodes near to the base station are inevitably under heavier burden than those far away from the base station. Therefore, a density-aware deployment scheme is further proposed to guarantee that the heavy-load nodes do not affect the network lifetime even if their energy is exhausted. The main idea is deploying sensors with different densities according to their distance to the base station. It will be shown in this paper that incorporating the random walk routing protocol with the density-aware deployment scheme can effectively prolong the network lifetime.     

Fractal: A mobile code-based framework for dynamic application protocol adaptation

The rapid growth of heterogeneous devices and diverse networks in our daily life, makes it is very difficult, if not impossible, to build a one-size-fits-all application or protocol, which can run well in such a dynamic environment. Adaptation has been considered as a general approach to address the mismatch problem between clients and servers; however, we envision that the missing part, which is also a big challenge, is how to inject and deploy adaptation functionality into the environment. In this paper we propose a novel application level protocol adaptation framework, Fractal, which uses the mobile code technology for protocol adaptation and leverages existing content distribution networks (CDN) for protocol adaptors (mobile codes) deployment. To the best of our knowledge, Fractal is the first application level protocol adaptation framework that considers the real deployment problem using mobile code and CDN. To evaluate the proposed framework, we have implemented two case studies: an adaptive message encryption protocol and an adaptive communication optimization protocol. In the adaptive message encryption protocol, Fractal always chooses a proper encryption algorithm according to different application requirements and device characteristics. And the adaptive communication optimization protocol is capable of dynamically selecting the best one from four communication protocols, including Direct sending, Gzip, Bitmap, and Vary-sized blocking, for different hardware and network configurations. In comparison with other adaptation approaches, evaluation results show the proposed adaptive approach performs very well on both the client side and server side. For some clients, the total communication overhead reduces 41% compared with no protocol adaptation mechanism, and 14% compared with the static protocol adaptation approach.     

Multicast and customized deployment of large-scale operating systems

With the recent paradigm shift of cloud computing, deployment of operating systems (OSs) onto a large-scale computer network is becoming necessary. Note that there are usually numerous nodes with various functions in a cloud computing system. Thus, it is usually required to deploy different operating systems onto different nodes. In such a customized setting, conventional techniques of using unicast deployment to distribute a massive cloud OS onto thousands of nodes is time consuming and bandwidth-intensive. In this work, we thus propose a multicast deployment approach so as to significantly improve deployment efficiency. Furthermore, our multicast deployment approach can leverage existing configurations of the unicast counterpart. Specifically, the advantageous features of the proposed approach include the support of a reliable multicast protocol, a heterogeneous infrastructure, and cloud hypervisor environments. To evaluate the feasibility of the proposed approach in practical applications, CentOS and Ubuntu are used when implementing our deployment approach on several tens of nodes. Empirical studies show that both the required time for the entire distribution process, i.e., from starting delivery until the OS is ready, and the network bandwidth consumption are significantly reduced as compared with conventional unicast approaches. Consequently, less effort is required on monitoring and maintenance for system administrators.