Scalable Routing and Multicast in Mobile Ad Hoc Wireless Networks

在这项研究中，研究人员考虑了通过多跳无线网络相互连接的大量移动站。这种无线基础设施的应用范围从特设网络（如协作、分布式计算）到灾难恢复（火灾、洪水、地震）、执法（如人群控制）、搜索和救援以及战场。该系统的主要特点是用户数量多，移动性强，无需固定（有线或无线）基础设施的支持即可运行。最后一个特点使这个系统与现有的蜂窝系统区别开来，实际上使它的设计更具挑战性。在这种环境下，研究人员提出了一种路由和组播策略，可以很好地扩展到大量节点，并且可以处理移动性。庞大的人口和流动性使得这个问题很难解决。事实上，如果节点是固定的，那么可以用分层路由有效地处理大型网络。当节点移动时，必须动态更改分层分区——这是一个重大挑战。当有固定的基础设施支持固定的“家庭代理”概念时，移动IP解决方案可以很好地工作。当所有节点都移动时，Home Agent策略就不那么明显了。除了庞大的数量和移动性，我们还解决了支持多媒体通信的需求，对交互式流量的低延迟要求和对实时流（语音/视频）的QoS支持。在无线路由领域，已经提出并实现了几种方案（如分层路由、按需路由等）。研究人员将讨论现有方案的优缺点，并将介绍两种新方案——分层移动路由和鱼眼路由——它们克服了现有方案的一些局限性。在无线组播领域，我们回顾了有线网络中使用的传统方案（例如，源树，基于核心的树等），并展示了它们在高移动网络中的表现。然后我们引入了一个新概念，转发组多播，其中树被转发节点的网格所取代-后者在面对移动性时比树更容易维护。研究人员建议将按需路由策略扩展到这种结构以处理大规模。

In this study the researchers consider a large population of mobile stations which are interconnected by a multihop wireless net. The applications of this wireless infrastructure range from ad hoc networking (eg, collaborative, distributed computing) to disaster recovery (fire, flood, earthquake), law enforcement (eg, crowd control), search and rescue and battlefield. Key characteristics of this system are the large number of users, their mobility and the ability to operate without the support of a fixed (wired or wireless) infrastructure. The last feature sets this system apart from existing cellular systems and in fact makes its design much more challenging.In this environment, the researchers propose to develop routing and multicast strategies which scale well to a large number of nodes and which can handle mobility. The combination of large number and mobility makes the problem very hard. In fact, large networks can be effectively handled with hierarchical routing, if nodes are stationary. When nodes move, the hierarchical partitioning must be dynamically changed - a significant challenge. Mobile IP solutions work well when there is a fixed infrastructure supporting the concept of fixed "Home Agent". When all nodes move, the Home Agent strategy is less obvious. In addition to large number and mobility, we address also the need to support multimedia communications, with low latency requirements forinteractive traffic and QoS support for real time streams (voice/video).In the wireless routing area, several schemes have already been proposed and implemented (eg, hierarchical routing, on-demand routing etc). The researchers will discuss the pro's and con's of the existing schemes, and will introduce two new schemes - hierarchical, mobile routing and Fisheye routing - which overcome some of the limitations of the existing schemes. In the wireless multicast area, we review the traditional schemes used in wireline networks (eg, Source Trees, Core Based Tree, etc) and show how they perform poorly in highly mobile networks. We then introduce a new concept, Forwarding Group Multicast, in which the Tree is replaced by a mesh of Forwarding Nodes - the latter being much easier to maintain than the tree in the face of mobility. The researchers propose to extend the on-demand routing strategy to such structure to handle large scale.