Ad Hoc与Internet互连的动态网关方案

移动Ad Hoe网络(MANET)是一种自治的、不需要固定基础设施的网络.将MANET与Internet连接可以扩展MANET的应用,实现资源共享,扩大网络的覆盖范围.文中提出一种具有三个层次的MANET与Internet互连的动态网关方案,把动态网关作为连接MANET和Internet的界面.最后文中通过仿真试验,动态网关方案使混合网络的性能得到了提高.     

移动自组网与Internet互连的动态网关策略

移动自组网(MANET)是自治的无基础设施的网络,它通过IP路由支持多跳无线通信。它与Internet 相比存在着许多差异,不仅有网络拓扑结构的不同,还存在通信方式的不同。因此,MANET与Internet组合成混杂网络(hybrid network)是一个具有挑战性的课题。移动自组网(MANET)的结点要进行Internet连接,就必须寻找Internet网关。如何寻找和维持与Internet网关的连接是这个问题的关键,再者,就是如何切换到一个更合适的相邻网关。在这篇文章中,首次提出动态网关的概念,动态网关作为MANET和Internet之间的接口起桥梁作用。通过模型分析,证明动态网关体系结构适合于自组网与Internet互联。仿真结果显示,利用动态网关的网络性能优于单一固定网关的体系结构的网络性能。     

基于网关信息素更新的MANET接入Internet开销控制方法

 寻找可用网关是MANET接入Internet过程中产生开销最大的一个环节。为了有效控制接入过程中的路由开销,根据蚂蚁寻径与移动节点寻找网关的相似性,提出了一种基于网关信息素更新的接入网络开销控制算法。该算法模仿蚁群算法中信息素更新方式,运用路由应答报文中携带的信息对网关信息素进行更新。节点在寻路时根据路径上的信息素浓度、链路带宽和时延等参数计算转发概率并进行转发。通过运用NS2.29对该算法进行仿真,结果表明该算法虽然平均端到端时延略有增加,但是有效地减少了归一化路由开销,并提高了分组投递率,验证了算法的有效性。     

基于仿真的有线/MANET混合网络TCP性能研究

MANET网络是未来民用和军事通信应用的理想选择,它和Internet的通信是必不可少的。该文分析研究了有线/MANET混合环境中的一些关键问题,比如,网关的隐藏终端和暴露终端、移动节点速度、流的数目等对TCP性能的影响,为有线/MANET混合网络在未来民用和军事领域的应用提供有益的参考。     

一种基于中心代理的移动Ad—Hoc网络接入方法

本文针对已有接入方法所存在的缺点,提出一种以移动节点间相互竞争出现的中心节点作为移动代理,利用移动IP协议实现MANET接入Internet的新方法,并对中心代理节点的选取、MANET整体移动接入等问题进行了探讨。该方法具有开销小、接入灵活、不需对移动IP做大的改动等优点。     

移动自组网与Internet互联技术研究

随着Ad hoc网络技术的不断发展成熟,移动自组织网（MANET）与Internet的互联已经成为扩展无线应用的关键。文章详细分析MANET与Internet互联中的地址分配、路由发现、网关发现、协议转换几项关键技术,讨论现有MANET与Internet互联的方案,最后指出互联技术研究中的要点及未来研究的方向。     

具有自我恢复功能的密钥管理方法在MANET网络中应用研究

 针对MANET网络动态拓扑和节点处理能力弱等特征,提出了适合MANET网络环境并利用密钥的上下文来恢复网络密钥的密钥管理方法,有效地降低了系统通信量;给出了一个安全有效的密钥分配模型,该模型在占用内存和减少运算复杂性方面都具有非常明显的优势;分析结果表明该方案在安全性方面具有明显优势,分析验证了该算法在MANET网络中使用的有效性和可行性.     

移动自组网接入Internet的自适应技术研究

在移动自组网接入Internet的过程中,为适应节点高速移动导致网络拓扑频繁更新的特性,在混合式路由发现中引入自适应机制,从网关通告跳数的合理范围、广播风暴的避免、各节点和网关负载的动态变化等方面进行自适应性优化。以AODV路由协议为基础,改进网关发现算法的自适应机制,在NS2平台进行仿真,实现移动自组网与有线网络的互联,且其接入性能有一定程度优化。     

基于Web的无线传感器网络可视化管理系统的设计与实现

无线传感器网络广泛部署于工业、农业、医疗及多种场景。面向网络应用的信息管理需求,设计并实现了一种基于Web的无线传感器网络可视化管理系统。传感器节点采集用户感兴趣的对象信息,通过多跳方式汇聚至网关,网关利用以太网或GPRS／CDMA等多种Internet接入方式将信息传送给网络服务器。用户利用终端设备,可跨平台访问此管理系统,执行对IPv6无线传感器网络状态信息和传感信息的动态实时检测,并可对节点设备进行远程控制与管理。     

基于MCU的嵌入式Internet技术与网关实现

嵌入式技术和Internet技术的发展，使得嵌入式设备也能够接入Internet网。为此，文中介绍了嵌入式Internet技术的基本原理和实现方案，讨论了MCU应用系统接入Internet网的通信协议。针对嵌入式Internet技术将在实际应用中的技术难点，提出了一种嵌入式网关的设计方案，利用该方案可嵌入式系统通过以太网接入Internet网络中。     

Asymptotic Capacity of Infrastructure Wireless Mesh Networks

An infrastructure wireless mesh network (WMN) is a hierarchical network consisting of mesh clients, mesh routers and gateways. Mesh routers constitute a wireless mesh backbone, to which mesh clients are connected as a star topology, and gateways are chosen among mesh routers providing Internet access. In this paper, the throughput capacity of infrastructure WMNs is studied. For such a network with Nc randomly distributed mesh clients, Nr regularly placed mesh routers and Ng gateways, assuming that each mesh router can transmit at W bits/s, the per-client throughput capacity has been derived as a function of Nc , Nr , Ng and W . The result illustrates that, in order to achieve high capacity performance, the number of mesh routers and the number of gateways must be properly chosen. It also reveals that an infrastructure WMN can achieve the same asymptotic throughput capacity as that of a hybrid ad hoc network by choosing only a small number of mesh routers as gateways. This property makes WMNs a very promising solution for future wireless networking.     

Hopfield Neural Network Approach to Clustering in Mobile Radio Networks

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Towards efficient dynamic surface gateway deployment for underwater network

In underwater acoustic sensor network, deploying multiple surface-level radio capable gateways is an efficient way to alleviate the burdens of high propagation delay and high error probability during transmission. However, the locations of gateways need to be carefully selected to maximize the benefit in a cost-effective way. In this paper, we present our formulation of the surface gateway deployment problem as an integer linear programming (ILP) and we solve the problem with heuristic approaches to provide a realtime solution for large scale deployment problems. By applying the proposed heuristic algorithms to a variety of deployment scenarios, we show that they are nearly optimal for practical cases, which opens the door for dynamic deployment. Therefore, we extend our solution to a dynamic case and propose a modified framework that integrates Aqua-sim, a NS2-based underwater wireless sensor network simulator. Our simulation result shows the benefits of dynamic gateway redeployment over static deployment.     

Throughput Gateways-Congestion Trade-Off in Designing Multi-Radio Wireless Networks

In Wireless Mesh Networks (WMNs), traffic is mainly routed by WMN Backbone (WMNB) between the mesh clients and the Internet and goes through mesh gateways. Since almost all traffic has to pass through one of the MGs, the network may be unexpectedly congested at one or more of them, even if every mesh router provides enough throughput capacity. In this paper, we address the problem of congestion of gateways while designing WMNs. We propose a simultaneous optimization of three competing objectives, namely network deployment cost, interference between network channels and congestion of gateways while guaranteeing full coverage for mesh clients. We tailor a nature inspired meta-heuristic algorithm to solve the model whereby, several trade-off solutions are provided to the network planner to choose from. A comparative experimental study with different key parameter settings is conducted to evaluate the performance of the model.     

An efficient traffic control system using dynamic thresholding techniques in wireless mesh networks

Wireless mesh networks (WMNs) depend on a resilient and high‐performance infrastructure to provide users pervasive Internet access. In WMNs, all Internet traffic will be forwarded to the Internet gateways. Hence, these gateways are generally bottleneck nodes. This work proposes a traffic control technique to reduce the bottleneck problem and increase the utilization of network resources. Our approach provides a traffic control strategy that exploits dynamic techniques to adjust the threshold according to the traffic load of each gateway. The base threshold is defined in order to effectively control the traffic. When the current load exceeds the threshold of a gateway, the traffic redirection strategy is implemented by switching border nodes. The service regions can be adjusted for each gateway based on the traffic load. Furthermore, the proposed dynamic thresholding approaches can distribute the workloads of gateways and maintain the thresholds of any two gateways within a level range, making an in‐band balance of load. Thus, our proposed scheme can handle the unnecessary traffic redirection and reduce the traffic control overhead for various distributions of traffic. Experimental results demonstrate that our scheme outperforms other schemes in terms of packet delivery ratio and efficiency, especially in bursty traffic environments. Copyright © 2010 John Wiley & Sons, Ltd.     

Convergence of residential gateway technology

A new OSI-based model is described that can be used for the classification of residential gateways. It is applied to analyze current gateway solutions and draw evolutionary paths for the medium to long term. From this it is concluded that particularly set-top boxes and broadband modems, as opposed to game consoles and PCs, have a strong potential to evolve toward gateways that deliver network services to the home on all OSI layers, although they probably will not converge. In our model, we have not found any compelling reasons for the residential gateway industry to support concurrent multiple broadband access network connections on a single residential gateway in the near future.     

Multi-gateway association in wireless mesh networks

Most traditional models of wireless mesh networks involve a mobile device connecting to the backbone through one of the available gateways in a wireless mesh network. In this paper, we present an alternate model, in which mobile devices are allowed to connect through more than one of the available gateways. We call the model multi-gateway association (MGA). We present arguments for why such a model can result in better capacity, fairness, diversity and security when compared to the default single-association model. We also identify the primary challenges that need to be addressed when using multiple-gateway associations, and propose solutions to handle these challenges. Using simulations, we show that throughput benefits ranging from 10% to 125% can be obtained by the proposed model as compared to a default single association model with just two gateways and more importantly, benefits linear in the number of gateways are obtainable. Through simulations and analysis, we establish why only intelligent multi-gateway association and neither single or simple multi-gateway association strategies can yield significant benefits.     

Design of scalable and efficient multi-radio wireless networks

A proper design of Wireless Mesh Networks (WMNs) is a fundamental task that should be addressed carefully to allow the deployment of scalable and efficient networks. Specifically, choosing strategic locations to optimally place gateways prior to network deployment can alleviate a number of performance/scalability related problems. In this paper, we first, propose a novel clustering based gateway placement algorithm (CBGPA) to effectively select the locations of gateways. Existing solutions for optimal gateway placement using clustering approaches are tree-based and therefore are inherently less reliable since a tree topology uses a smaller number of links. Independently from the tree structure, CBGPA strategically places the gateways to serve as many routers as possible that are within a bounded number of hops. Next, we devise a new multi-objective optimization approach that models WMN topologies from scratch. The three objectives of deployment cost, network throughput and average congestion of gateways are simultaneously optimized using a nature inspired meta-heuristic algorithm coupled with CBGPA. This provides the network operator with a set of bounded-delay trade-off solutions. Comparative simulation studies with different key parameter settings are conducted to show the effectiveness of CBGPA and to evaluate the performance of the proposed model.     

An architecture for residential Internet telephony service

A new architecture that can be used for offering an Internet telephony service to residential customers is introduced. The architecture addresses scalability and availability requirements of mass-market deployment of carrier-grade services and supports interconnection with SS7 for Internet telephony calls to the public switched telephone network. The architecture is based on the concept of a gateway decomposition that separates the media transformation function of today's H.323 gateways from the gateway control function of the gateways and centralizes the intelligence in a call agent. The media gateway control protocol is introduced as the protocol between the call agent that assumes the gateway control function and the gateway that provides just the media transformation function. Interworking between the architecture and the public switched telephone network, the session initiation protocol, and H.323 are also discussed