PReSENt: A Collaboration Framework for Resource Sharing in Wireless Mesh Networks

Many protocol particulars developed for the wireless mesh networks, such as multi-path routing, channel assignment, topology control, assume that a network-wide collaboration is available to establish connections to the network outside. However, the collaboration can be easily discouraged in the presence of selfish behaviors, referred to as free-riding. In this paper, we propose a framework, PReSENt, to promote and make more secure the practices of collaboration among nodes by securing a compensation to the collaboration. When the PReSENt is enabled in wireless mesh networks, a node accumulates credits, an amount quantifying its resource provision when it provides its resource for other nodes. The nodes consuming the resource publish rewards, an amount quantifying their resource usage. The credits are used to guarantee the resource sharing for the provider from the customers in the future, whose amount is proportional to its relative contribution to the network-wide collaboration. The rewards are used to validate their corresponding credits in order to prevent false accumulations of the credits in selfish nodes. We formally define the underlying security model of the PReSENt and prove that the PReSENt is secure in the random oracle model. We then implement the PReSENt in J-Sim to illustrate its operational behaviors with respect to correct and secure resource sharing.     

无线Mesh网络协作式路由度量的研究

本文针对无线通信的广播特性和传输多样性,提出一种适用于无线Mesh网络协作通信系统的路由度量COOPM。通过COOPM选出来的路由,可以使多个节点协作给同一接收方发送数据,从而提高整体网络吞吐量,得到更高的网络容量。     

一种有效的无线Mesh网络流量整形模型

流量整形对QoS(quality of service)控制有着重要的影响.研究并分析发现,无线Mesh网络具有自相似性,其自相似性对网路的QoS性能具有较大的影响.总结并优化了最近几年发展起来的能够深刻透视计算机网络业务流控制问题的网络演算技术,分析发现统计网络演算可以用来计算性能的概率或统计边界问题,适合于无线Mesh网络.运用统计网络演算建立了无线Mesh网络自相似业务流的贪婪分形整形器的数学模型;推导了贪婪分形整形器的统计性能模型.包括整形器的输出特性、队列长度与延迟等性能;数据分析证明贪婪分形整形器对无线Mesh网络自相似业务进行整形不会增加网络端到端延迟和缓冲区容量需求.     

SE-DSR:一种安全增强的Mesh网络多径动态源路由协议

DSR协议是一种典型的按需多跳路由协议,能够很好地实现既有网络之间的无缝连接又能适应网络的动态变化。为满足无线Mesh网络需求,在分析DSR协议的基础上,本文提出了一种新的安全增强的无线Mesh网络多径DSR路由协议-SE_DSR协议,其基本思想是采用多径路由发现机制为协议提供负载均衡和路由容错能力,采用双向路径信任评估和单向证书链验证的方式为协议提供安全保障。相比传统安全协议,SE_DSR协议虽然牺牲了少量存储开销,但它在保证路由安全的同时缩短了路由发现时延,提高了数据传输速率。性能分析和仿真实验表明,该协议在提供负载均衡和容错的同时还能有效防御多种攻击,具有较高的网络吞吐量和较强的安全性能。     

无线传感器网络中一种新型的混合型数据收集协议

无线传感器网络节点数量庞大,单个节点资源极其有限,其数据收集协议设计的首要目标是有效节约能源、延长网络生命周期.分析和比较了现有几种典型的数据收集协议,立足于实际应用需求,设计出一种基于分簇结构的混合型数据收集协议(MDGP). MDGP是一种具备区分服务机制和网内数据融合的数据收集协议,适合于矿井安全监测等大规模检测应用.提出了一个能平衡负载、减少簇头节点的簇头产生算法.采用反向汇聚树结构传输处理数据流,同时对一些紧急数据的处理也进行了详细的讨论.仿真实验表明,MDGP比传统的数据收集协议能获得更长的生命期,达到了较好的预期效果.     

无线网状网跨层路由的研究

目前,无线网状网跨层路由设计方兴未艾,以往无线路由设计是基于最小跳数的,缺少对无线网状网特性的综合考虑,并不能充分发挥出无线网状网的优势。该文提出了基于"队列负载率"和"链路传输效率"的跨层路由协议算法,通过将MAC层的网络状态信息传递给网络层的路由代理,以便选择负载较小的最佳路由。通过仿真可以发现,改文提出的路由不仅显著提高了吞吐量,而且使包的投递更加可靠,提高了QoS。     

一种基于稳定性的无线mesh网络路由协议

无线网状网络(mesh)以其高速率高容量,易于部署的特点受到学术界和产业界的格外关注,其路由协议是研究重点与难点之一.本文分析了无线mesh网络路由协议的设计特点,在经典移动ad-hoc路由协议AODV的基础上提出了一种基于稳定性的无线mesh网络的路由协议并在ns2上给予仿真了实现,仿真结果表明该协议在所需性能上优于AODV,更适合无线mesh网络.     

无线Mesh网络及其路由安全研究

无线mesh网依靠无线链路多跳传输数据,减轻了对有线网络的依赖,此外,其频谱效率高、覆盖范围大、可扩展性强、可靠性强等优点,受到了人们的关注。本文简述了无线mesh网络的起源和发展,对其结构进行了研究,归纳了无线mesh网络主要特征。最后,对无线mesh网络的路由安全进行了分析。     

Securing Wireless Mesh Networks

Now found in domestic, commercial, industrial, military, and healthcare applications, wireless networks are becoming ubiquitous. Wireless mesh networks (WMNs) combine the robustness and performance of conventional infrastructure networks with the large service area and self-organizing and self-healing properties of mobile ad hoc networks. In this article, the authors consider the problem of ensuring security in WMNs, introduce the IEEE 802.11s draft standard, and discuss the open security threats faced at the network and data-link layers.     

无线传感器网络安全体系的构建

安全作为无线传感器网络设计中的重要问题已经受到越来越多的关注.由于其节点的硬件能力有限,以及拓扑结构的动态变化,使得现有的一些安全技术不能适用.结合传感器网络的特点和部分安全技术,提出了一种分层、逐步建设的安全体系来解决当前无线传感器网络安全所面临的一些威胁.     

基于IEEE 802.11的长距离无线Mesh网络

基于IEEE 802.11的长距离无线Mesh网络(LDmesh)的单跳链路长度在几十到上百公里,具有带宽高、成本低、覆盖广等优点,可广泛应用于偏远乡村或人口分布稀疏地区的无线宽带接入等.LDmesh网络是点到点的链路,链路的干扰特性和传输特性与传统无线Mesh网络有显著不同,原有的基于CSMA的MAC协议不再适用,进而影响到上层协议的设计.分析了LDmesh网络的研究进展,从链路性能、MAC协议、路由协议及网络管理等方面深入论述了LDmesh网络面临的挑战和进一步研究方向.     

基于多准则的无线网状网路由判据

通过对无线网状网几种现有路由判据的分析比较,提出了一种基于多准则的路由判据LB-WCETT,它综合考虑了链路质量、信道多样性以及信道负载等因素。仿真结果表明,该判据能使无线网状网性能得到较大的提高。     

无线Mesh网络组播路由协议

组播服务是无线Mesh网络面向实际应用的一种重要服务,网络层组播路由协议则是服务实现的核心支撑协议.无线Mesh网络独有的结构特征、性能要求以及多射频、多信道和多速率的引入使得许多传统组播路由协议无法直接进行应用,近几年来,已有不少针对特定无线Mesh网络的组播路由协议相继提出.归纳总结了协议的设计目标、原则和分类方法;阐述了各类典型协议的主要机制,并就这些协议的技术特点和性能差异进行了详细比较;最后结合无线Mesh网络的发展趋势和协议面向实际混合业务环境的实用化目标分析了多射频、多信道以及多速率对组播路由的影响,指出了基于实测环境和实际业务需求建立组播路由跨层优化模型与具体优化机制的重要性.     

一种可扩展的多接口多信道无线网状网结构

吞吐量和可扩展性问题是无线网络发展面临的巨大挑战.本文提出了一种基于多接口多信道可扩展的无线网状网结构,它采用具备较远传送能力的超级节点来降低跳数以提高网络的扩展性.多接口多信道的方法被用来增加并发传输,从而提高网络的吞吐量.仿真结果表明,较之以往的单信道多跳网络,采用本文提出的结构,仅需部署占总节点数20%左右的超级节点就能将系统的吞吐量提高至5倍.     

一种基于群组的无线传感器网络安全策略

保护无线传感器网络安全重要性日益突出,尤其是野生动物监测、环境监控以及军事应用场合。然而随着传感器处理能力和普适性不断提高,对网络资源的保护需求提出了更高要求。提出了一种无线传感器网络群组密钥管理安全策略,为传感器提供细粒度访问控制和动态部署能力,具有鲁棒性和灵活性。     

Efficient Multicast Algorithms for Multichannel Wireless Mesh Networks

The wireless mesh network is an emerging technology that provides high quality service to end users as the "last mile” of the Internet. Furthermore, multicast communication is a key technology for wireless mesh networks. Multicast provides efficient data distribution among a group of nodes. However, unlike other wireless networks, such as sensor networks and MANETs, where multicast algorithms are designed to be energy efficient and to achieve optimal route discovery among mobile nodes, wireless mesh networks need to maximize throughput. This paper proposes two multicast algorithms: the Level Channel Assignment (LCA) algorithm and the Multichannel Multicast (MCM) to improve the throughput for multichannel and multi-interface mesh networks. The algorithms build efficient multicast trees by minimizing the number of relay nodes and total hop count distances of the trees. The algorithms use dedicated channel assignment strategies to reduce the interference to improve the network capacity. We also demonstrate that using partially overlapping channels can further diminish the interference. Furthermore, additional interfaces help to increase the bandwidth, and multiple gateways can further shorten the total hop count distance. Simulations show that those algorithms greatly outperform the single-channel multicast algorithm. We also observe that MCM achieves better throughput and shorter delay while LCA can be realized in distributed manner.     

Application-aware scheduling for VoIP in Wireless Mesh Networks

Wireless Mesh Networks (WMNs) are seen as a means to provide last mile connections in Next Generation Networks (NGNs). Because of their auto-configuration capabilities and the low deployment cost WMNs are considered to be an efficient solution for the support of multiple voice, video and data services in NGNs. This paper looks at the optimal provision of resources in WMNs for Voice over IP (VoIP) traffic, which has strict performance requirements in terms of delay, jitter and packet loss. In WMNs, because of the challenges introduced by wireless multi-hop transmissions and limited resources, providing performance quality for VoIP comparable to the voice quality in the traditional circuit-switched networks is a major challenge.This paper analyses different scheduling mechanisms for TDMA-based access control in mesh networks as specified in the IEEE 802.16-2004 WiMAX standard. The performance of the VoIP applications when different scheduling mechanisms are deployed is analysed on a variety of topologies using ns-2 simulation and mathematical analysis. The paper concludes that on-demand scheduling of VoIP traffic – typically deployed in 802.11-based WMNs – is not able to provide the required VoIP quality in realistic mesh WiMAX network scenarios and is therefore not optimal from a network operator’s point of view. Instead, it is shown, that continuous scheduling is much better suited to serve VoIP traffic. The paper then proposes a new VoIP-aware resource coordination scheme and shows, through simulation, that the new scheme is scalable and provides good quality for VoIP service in a wide range of network scenarios. The results shown in the paper prove that the new scheme is resilient to increasing hop count, increasing number of simultaneous VoIP sessions and the background traffic load in the network. Compared to other resource coordination schemes the VoIP-aware scheduler significantly increases the number of supported calls.     

网状网路由技术研究

无线网状网络Wireless mesh networks以其高速率高容量,易于部署的特点受到学术界和产业界的广泛关注,路由协议是研究的重点与难点之一。该文结合近年来国外的研究成果,着重从路由协议方面介绍无线网络的研究现状。对LEACH、SPIN和Directed diffusion等多种路由协议进行详细分析,最后对这些协议的特点进行归纳和比较,并展望了未来这一研究方向的发展趋势。     

基于Cluster的无线Mesh网络位置管理方法

提出一种基于Cluster的位置管理方法,充分考虑到Mesh结构的特点,利用Cluster内部各小区路径的相似性,采用似组播方式分发信令,提高了Mesh网络中位置管理的效率.数值分析显示,此方法显著地降低了位置管理的信令开销.