Ad hoc网络

本文首先介绍了Ad hoc网络的特点和应用领域。然后对Ad hoc网络的体系结构进行了研究,给出了结点和网络的几种组织结构。最后对Ad hoc网络面临的特殊问题进行了深入分析,并对这些问题的影响及引发的研究方向进行了讨论。     

Ad hoc综述

Ad hoc作为一种自创造、自组织和自管理的网络,由于其组网的快速灵活性,节点的分布性等诸多的优点,在战争、救灾等特殊领域有着不可替代的作用.文中介绍了Ad hoc的概念、特点、发展历史及国内外的研究现状,并指出了其中需要研究的一些关键技术.     

无线Ad hoc网络

无线Ad hoc网络是随着无线通信技术的快速发展而出现的一种新型网络.文章详细介绍了无线Ad hoc网络的由来、主要特征、关键技术和应用等,并展望了它的发展前景.     

Ensuring strong data guarantees in highly mobile ad hoc networks via quorum systems

Ensuring the consistency and the availability of replicated data in highly mobile ad hoc networks is a challenging task because of the lack of a backbone infrastructure. Previous work provides strong data guarantees by limiting the motion and the speed of the mobile nodes during the entire system lifetime, and by relying on assumptions that are not realistic for most mobile applications. We provide a small set of mobility constraints that are sufficient to ensure strong data guarantees and that can be applied when nodes move along unknown paths and speed, and are sparsely distributed.

In the second part of the paper, we analyze the problem of conserving energy while ensuring strong data guarantees, using quorum system techniques. We devise a condition necessary for a quorum system to guarantee data consistency and data availability under our mobility model. This condition shows the unsuitability of previous quorum systems and is the basis for a novel class of quorum systems suitable for highly mobile networks, called mobile dissemination quorum (MDQ) systems. We also show a MDQ system that is provably optimal in terms of communication cost by proposing an efficient implementation of a read/write atomic shared memory.

The suitability of our mobility model and MDQ systems is validated through simulations using the random waypoint model and the restricted random waypoint on a city section. Finally, we apply our results to assist routing and coordinate the low duty cycle of mobile nodes while maintaining network connectivity.     

Handoff management with mobility estimation in hierarchical systems

We propose some algorithms for channel assignment and handover management in multitier systems. The algorithms are based on user speed estimation and aim to minimize signalling due to interlayer handoffs. They abandon the classic assumption of constant user speed during the call and adopt a realistic mobility model for users. The performance is studied in different environments and under various traffic conditions and compared with algorithms based on assumptions traditionally adopted in the literature. Results show that the proposed algorithms are successful in lowering the number of interlayer handoff requests while not adversely affecting call blocking and forced termination probabilities. This is paid in terms of a decrease in the system capacity.     

Ad hoc网络技术讲座 第2讲 Ad hoc网络中的路由选择问题

本文介绍了Adhoc网络中路由选择问题的特点,并从路由的驱动机制方面介绍了主动式路由协议和按需式路由协议,从网络的拓扑结构方面介绍了平面式路由协议和分簇式路由协议,最后给出了这几类路由协议的性能比较。     

用移动IP实现移动Ad hoc网与Internet的互联

移动IP是一种简单可扩展的全球Internet移动解决方案。本文介绍了移动IP和移动Ad hoc网络的融合技术,以实现移动Ad hoc网络与Internet的互联。     

Ad hoc技术

Ad　hoc技术是从无线移动Ad　hoc网络(WMANET)抽象出来的一个一般性概念，该项技术所标称的是自组识、多跳的一个临时分布式系统，是一种网络构架技术。它要面临多项难题。本文就是从OSI模型的角度把Ad　hoc技术分层介绍，最后给出了一种WMANET应用方案。     

利用有线路由协议实现Ad hoc与固定网络互联

Adhoc网络因为其自身独有的特点,将在越来越广泛的领域发挥越来越大的作用,如何将Adhoc网络与固定网络甚至Internet互联,成为人们关注的一个课题,本文提出了一种利用现有的有线网络路由协议接入有线网络的方案,并给出了一个实现的实例。     

Ad hoc 网络组网研究

Adhoc网络是一种特殊的网络,应用前景广阔。本文给出了Adhoc网络组网时必须注意的几个问题,并给出了一些解决思路。     

Quasi-tree mobility management for internet connectivity of mobile ad hoc networks

The location of mobile nodes must be managed to enable Internet connectivity of mobile ad hoc networks. Node mobility can be managed efficiently using a tree topology in which a mobile node registers with an Internet gateway along a tree path without using flooding. However, a node that loses connectivity to its parent has to find and connect to a new parent through a join-handshaking process. This tends to increase control overhead and impose some delay on on-going communication. Furthermore, the node may join its descendant because of the synchronization delay in updating topology change, creating a loop that significantly increases control overhead. We improve these problems by maintaining a quasi-tree topology in which a node maintains multiple parents. We also present a technique for detection and resolution of loops. The simulation results show that the quasi-tree mobility management approach far outperforms the traditional approaches and is highly robust against the significant increases in tree size and node mobility.     

混合传播方式Ad hoc无线网络的容量研究

提出一种混合传播方式Ad hoc网络容量研究的方法,通过比较各传播方式在其相应规模下的容量确定主导传播方式并得出网络总容量。并以单播和多播混合传播为例,研究在基于多跳、MIMO和层次化合作情况下的主导传播方式和网络总容量。当该混合网络中单播的结节过半时,由多播传播方式确定网络的总容量。     

Ad hoc网络体系结构研究

Ad hoc网络是一种有特殊用途的对等式网络,具有无中心、自组织、可快速展开、可移动等特点,这些特点使得它在战场、救灾等特殊场合的应用日渐受到人们的重视,本文首先分析了Ad hoc网络的特点和对协议的特殊需求,然后对网络结构和路由协议作了详细分析和讨论,并得出了网络分级化趋势和使用混合式路由协议的建议。     

Ad hoc网络安全综述

移动Adhoc网络是由一组自主的无线节点或终端相互合作而形成的网络,由于其动态拓扑、无线通信的特点,容易遭受各种安全威胁。从传输信道、移动节点、动态拓扑、安全机制、路由协议几方面,分析了移动AdHoc网络的安全弱点,然后结合其安全策略和机制,分析了FSR、SRP和AODV3种典型的路由协议的工作原理和优缺点。     

Ad hoc网络的资源管理

Ad hoc网络中的资源管理是一项极其复杂的工作。本文说明了Ad hoc网络中资源管理问题的研究背景,然后对资源管理问题进行了简单的形式化描述,重点阐述了Ad hoc网络中可以利用的三种资源管理方法。     

Ad hoc网络技术及研究现状

Ad hoc网络是一种新颖的网络类型，它既可以作为一种独立的网络运行，也可以作为具有固定设施网络的一种补充形式。文章对Ad hoc网络的特点和研究现状进行了介绍。     

移动Ad hoc网络信任模型研究

AdHoc网络信任模型的工作流程分为收集客体的行为信息,计算信任值,最后进行信任决策3个环节。分析了当前Adhoc网络中的5类信任模型,即基于社会网络理论的信任模型、基于分簇的信任模型、基于图论的信任模型、基于非合作博弈论的信任模型和基于合作博弈论的信任模型。指出上述模型各有优缺点在构建Adhoc网络信任模型时,必经考虑适应网络的动态拓扑和成员关系的变化,所构建信任模型的密钥管理、信任管理如访问控制不能依赖固定的可信第三方的设施并减少模型中的假设条件,算法具有鲁棒性。     

一种Ad hoc网络中的主动式QoS路由设计

随着移动技术的发展,QoS已经成为Adhoc网络中的研究热点。在最短路径算法的基础上,对在TDMA机制下的自组织网络主动式QoS路由进行改进,将带宽和误码率作为约束条件,把实际自组织网络中各个节点占用时隙的先后而影响传输时延作为路由判决的主要依据,较好地避开了干扰和拥塞,从而获得了较高的系统吞吐量,并进行了模拟仿真,验证了协议的有效性。