一种无线传感网络代码分发协议的研究

无线传感器网络的分发协议用于更新节点程序和发送控制指令,目前普遍采用的分发协议存在传输数据量和能耗过大的问题.为此提出一种无线传感网络代码传播与维护的自调整算法,并通过设计分发协议测试系统进行算法性能测试.实验结果表明该算法能有效调节网络中数据包的传输速度,减少数据包传输量,降低能量损耗.     

基于Ad hoc的按需路由协议DSR的优化研究与实现

无线Ad hoc网络是一种不需要基础设施的自组织和自管理网络,网络中所有的节点同时具有终端和路由器的功能。因此网络可以通过节点路由发现机制转发分组,并进行路由维护。文中对DSR(动态源路由协议)的路由发现过程进行了优化,并采用OPNET仿真软件对基于DSR协议的Ad hoc网络的路由开销和时延等关键参数进行了仿真统计,分析了改进后的路由协议对网络质量的影响。     

网络入侵节点的盲取证技术研究与仿真

为了提高网络入侵的检测能力和盲取证能力,进行网络入侵节点的盲取证技术研究,提出基于分组链路转发协议融合的网络入侵节点的盲取证技术。构建入侵网络节点的分组链路转发模型,采用融合滤波控制方法进行网络入侵节点的差异性特征提取,根据提取入侵节点的差异性谱特征量进行盲源定位,采用自相关检测器进行网络入侵节点的可靠性分离,结合模糊决策方法构建入侵节点盲取证的判决统计量,采用门限阈值判断方法,结合分组链路转发协议实现路由融合,从而完成入侵节点的准确定位和盲取证。仿真结果表明,采用该方法进行网络入侵节点的盲取证,对入侵节点的定位性能较好,提高了网络入侵的检测能力,确保网络安全。     

无线Mesh网络流量自相似性研究

近年来,无线Mesh网络已成为一个倍受关注的研究领域.对无线Mesh网络流量特性的研究将有助于网络协议的研究、评估,以及网络结构的规划和建设.本文通过对无线Mesh测试网上采集的数据包进行统计分析,揭示了网络流量具有自相似的特性.同时,解释了无线Mesh网络流量自相似性是由网络中具有重尾分布特性的多个流叠加形成的,并通过仿真进一步分析了节点移动性对流量自相似性的影响.     

一种实时无源光以太网的OAM设计与实现

设计了一种新型实时以太无源光纤网络(REPON)的OAM管理机制,包括新节点发现、配置、统计、故障管理功能,在FPGA平台上实现了相应REPON协议;搭建了一个包含Vxworks网管站、中心节点和接入节点的百兆实时光纤测试网络,对OAM各项管理功能进行了测试,验证了协议的可行性。     

基于TTCN-3的CoAP一致性测试

协议一致性测试是确保协议实现与协议标准相一致的重要保障,有助于协议实现的进一步完善。CoAP (constrained application protocol)即受限应用协议是特别为受限节点和受限网络设计的通用应用层协议。CoAP目前仍处于草案阶段,对 CoAP进行了分析,并基于标准化测试语言TTCN-3设计实现了CoAP一致性测试系统,并使用该系统对CoAP实现进行了测试。     

AS5643网络RN节点自动化测试系统实现

AS5643总线作为机载网络总线,在IEEE1394B总线基础上增加了确定性传输协议。本文基于DAP公司推出的仿真卡实现了一种AS5643网络RN节点自动化测试系统,给出了测试环境搭建、网络节点硬件架构、自动化测试软件流程,为网络RN节点验收和测试提供了保证。     

自组织ZigBee网络节点通信研究

对自组织ZigBee网络的原理进行了研究,并抓住其精髓进行了剖析,给出了自组织ZigBee网络节点通信流程和软件流程。自组织ZigBee网络每个节点只和其邻近节点通信,从一个节点发出的数据包将根据相关协议的配置多跳传递到目的节点。网络中的每台设备都可直接通信,或者通过网络的转发而连接到其他设备。每个网络节点都具有选路功能,如果其中的某一条链路出现了故障,节点便可以自动转向其他可选链路进行接入,因而减轻了业务执行时发生冲突的可能性。自组织ZigBee网络的研究,对网络中的资源节俭,网络的维护与操作,升级与扩容有着指导意义。     

移动Ad Hoc网络按需路由协议的研究

移动Ad Hoc网络是一种具有高度动态拓扑结构、节点任意移动的自组织网络。路由协议能够为数据分组的传输指定路径,是移动节点相互通信的基础,对移动Ad Hoc网络的性能起着至关重要的作用。文中介绍移动Ad Hoc网络及其路由协议的基本概念和特殊性,研究几种典型按需路由协议的原理,对协议进行综合比较,简要讨论了各自的优缺点。     

AODV路由结合SWAN模型的仿真及性能分析

移动AdHoe网络是移动节点动态临时组建的自组织网络,路由协议一直是AdHoe网络研究的关键问题。使用网络模拟器NS2,设定特定的仿真环境,在不同节点密度、节点移动性和网络负载条件下,对AdHoe网络路由协议AODV的分组平均时延和成功递交率等性能进行了详细比较与分析,给出了性能曲线并阐明各协议的特性与适用环境。     

Probabilistic reliable multicast in ad hoc networks

When striving for reliability, multicast protocols are most commonly designed as deterministic solutions. Such an approach seems to make the reasoning about reliability guarantees (traditionally, binary, “all-or-nothing”-like) in the face of packet losses and/or node crashes. It is however precisely this determinism that tends to become a limiting factor when aiming at both reliability and scalability, particularly in highly dynamic networks, e.g., ad hoc networks. Gossip-based multicast protocols appear to be a viable path towards providing multicast reliability guarantees. Such protocols embrace the non-deterministic nature of ad hoc networks, providing analytically predictable probabilistic reliability guarantees at a reasonable overhead.

This paper presents the Route Driven Gossip (RDG) protocol, a gossip-based multicast protocol designed precisely to meet a more practical specification of probabilistic reliability in ad hoc networks. Our RDG protocol can be deployed on any basic on-demand routing protocol, achieving a high level of reliability without relying on any inherent multicast primitive. We illustrate our RDG protocol by layering it on top of the “bare” Dynamic Source Routing protocol, and convey our claims of reliability and scalability through both analysis and simulation.     

Relying on safe distance to achieve strong partitionable group membership in ad hoc networks

The design of ad hoc mobile applications often requires the availability of a consistent view of the application state among the participating hosts. Such views are important because they simplify both the programming and verification tasks. We argue that preventing the occurrence of unannounced disconnection is essential to constructing and maintaining a consistent view in the ad hoc mobile environment. In this light, we provide the specification for a partitionable group membership service supporting ad hoc mobile applications and propose a protocol for implementing the service. A unique property of this partitionable group membership is that messages sent between group members are guaranteed to be delivered successfully, given appropriate system assumptions. This property is preserved over time despite movement and frequent disconnections. The protocol splits and merges groups and maintains a logical connectivity graph based on a notion of safe distance. An implementation of the protocol in Java is available for testing. This work is used in an implementation of LIME, a middleware for mobility that supports transparent sharing of data in both wired and ad hoc wireless environments.     

Secure interconnection protocol for integrated Internet and ad hoc networks

Integration of ad hoc networks with the Internet provides global Internet connectivity for ad hoc hosts through the coordination of mobile IP and ad hoc protocols. In a pure ad hoc network, it is difficult to establish trust relationship between two ad hoc hosts due to lack of infrastructure or centralized administration. In this paper, an infrastructure‐supported and distributed authentication protocol is proposed to enhance trust relationships amongst ad hoc hosts. In addition, an effective secure routing protocol (SRP) is discussed to protect the multi‐hop route for Internet and ad hoc communication. In the integrated ad hoc networks with Internet accessibility, the ad hoc routing security deployed with the help of infrastructure has a fundamental impact on ad hoc hosts in term of Internet access, integrity, and authentication. Both analysis and simulation results demonstrate the effectiveness of the proposed security protocol. Copyright © 2007 John Wiley & Sons, Ltd.     

The COMMIT Protocol for Truthful and Cost-Efficient Routing in Ad Hoc Networks with Selfish Nodes

We consider the problem of establishing a route and sending packets between a source/destination pair in ad hoc networks composed of rational selfish nodes whose purpose is to maximize their own utility. In order to motivate nodes to follow the protocol specification, we use side payments that are made to the forwarding nodes. Our goal is to design a fully distributed algorithm such that (1) a node is always better off participating in the protocol execution (individual rationality), (2) a node is always better off behaving according to the protocol specification (truthfulness), (3) messages are routed along the most energy-efficient (least cost) path, and (4) the message complexity is reasonably low. We introduce the COMMIT protocol for individually rational, truthful, and energy-efficient routing in ad hoc networks. To the best of our knowledge, this is the first ad hoc routing protocol with these features. COMMIT is based on the VCG payment scheme in conjunction with a novel game-theoretic technique to achieve truthfulness for the sender node. By means of simulation, we show that the inevitable economic inefficiency is small. As an aside, our work demonstrates the advantage of using a cross-layer approach to solving problems: Leveraging the existence of an underlying topology control protocol, we are able to simplify the design and analysis of our routing protocol and reduce its message complexity. On the other hand, our investigation of the routing problem in the presence of selfish nodes disclosed a new metric under which topology control protocols can be evaluated: the cost of cooperation.     

ATP: a reliable transport protocol for ad hoc networks

Existing works have approached the problem of reliable transport in ad hoc networks by proposing mechanisms to improve TCP's performance over such networks, In this paper, we show through detailed arguments and simulations that several of the design elements in TCP are fundamentally inappropriate for the unique characteristics of ad hoc networks. Given that ad hoc networks are typically stand-alone, we approach the problem of reliable transport from the perspective that it is justifiable to develop an entirely new transport protocol that is not a variant of TCP. Toward this end, we present a new reliable transport layer protocol for ad hoc networks called ATP (ad hoc transport protocol). We show through ns2-based simulations that ATP outperforms default TCP as well as TCP-ELFN and ATCP.     

ad hoc网络中跨层设计方法的研究

ad hoc网络与传统有线和无线蜂窝网络有着显著的区别,基于传统的分层协议栈的设计方法不再适合ad hoc网络,而应采用一种新型的跨层协议栈和跨层设计方法.本文首先阐述了ad hoc网络的特点和传统的分层协议栈的弊端,介绍了跨层设计的概念.然后,详细分析了ad hoc网络中跨层设计的方法,包括策略、体系结构和信令交互方式,探讨了跨层设计的相关技术和面临的挑战.最后,总结了全文并指出了今后的工作方向.     

A transport protocol for supporting multimedia streaming in mobile ad hoc networks

Transport protocol design for supporting multimedia streaming in mobile ad hoc networks is challenging because of unique issues, including mobility-induced disconnection, reconnection, and high out-of-order delivery ratios; channel errors and network congestion. In this paper, we describe the design and implementation of a transmission control protocol (TCP)-friendly transport protocol for ad hoc networks. Our key design novelty is to perform multimetric joint identification for packet and connection behaviors based on end-to-end measurements. Our NS-2 simulations show significant performance improvement over wired TCP friendly congestion control and TCP with explicit-link-failure-notification support in ad hoc networks.     

基于Netlink的DSDV路由协议实现

无线自组网（MANET）是一种无中心的自组织网络,其在各种场景下得到了越来越多的应用。DSDV路由协议作为一种先验式路由协议,具有协议流程设计简单、延迟很低等特性,能较好地适用于移动性较弱的小规模自组织网络。文中介绍了DSDV路由协议的工作原理,提出了基于Linux系统Netlink通信机制的DSDV路由协议的软件实现架构方案,并阐述了关键模块的实现。另外,还在多台实体计算机上运行DSDV路由协议软件,并测试了多跳路由、延迟时间和通信速率。测试结果表明,文中所提方案具有可行性和有效性。     

Improved neighbor detection algorithm for AODV routing protocol

In this letter, a problem related to the behavior of WLAN 802.11 b network cards when working in the ad hoc mode is described. This behavior was noticed during experimental evaluation of an ad hoc network that was using the AODV (ad hoc On-demand Distance Vector) routing protocol. The observed problem affects the neighbor detection algorithm of the AODV routing protocol and has a deteriorating impact on performance of ad hoc networks that use this protocol. An improvement of the neighbor detection algorithm based on the differentiation of good and bad neighbors using signal to noise ratio (SNR) value is proposed, described and experimentally verified.     

Does the IEEE 802.11 MAC protocol work well in multihop wireless adhoc networks?

The IEEE 802.11 MAC protocol is the standard for wireless LANs; it is widely used in testbeds and simulations for wireless multihop ad hoc networks. However, this protocol was not designed for multihop networks. Although it can support some ad hoc network architecture, it is not intended to support the wireless mobile ad hoc network, in which multihop connectivity is one of the most prominent features. In this article we focus on the following question: can the IEEE 802.11 MAC protocol function well in multihop networks? By presenting several serious problems encountered in an IEEE 802.11-based multihop network and revealing the in-depth cause of these problems, we conclude that the current version of this wireless LAN protocol does not function well in multihop ad hoc networks. We thus doubt whether the WaveLAN-based system is workable as a mobile ad hoc testbed