Scalable Routing and Multicast in Mobile Ad Hoc Wireless Networks

在这项研究中，研究人员考虑了由多跳无线网络互连的大量移动站。这种无线基础设施的应用范围从自组织网络(如协作、分布式计算)到灾难恢复(如火灾、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大、移动性强，并且无需固定(有线或无线)基础设施的支持即可运行。最后一个特征使该系统有别于现有的蜂窝系统，这实际上使它的设计更具挑战性。在这种环境下，研究人员建议开发能够很好地扩展到大量节点并且能够处理移动性的路由和组播策略。大数量和流动性的结合使这个问题变得非常困难。事实上，如果节点是固定的，则可以通过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--这是一个巨大的挑战。当有固定的基础设施支持固定的“家乡代理”概念时，移动IP解决方案工作得很好。当所有节点移动时，家乡代理策略就不那么明显了。除了大数据量和移动性，我们还解决了支持多媒体通信的需求，对交互业务的低延迟要求和对实时流(语音/视频)的服务质量支持。在无线路由领域，已经提出并实现了几种方案(例如，分层路由、按需路由等)。研究人员将讨论现有方案的优缺点，并将引入两个新的方案--分层、移动路由和Fisheye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(如源树、基于核心的树等)，并展示了它们在高移动性网络中的性能低下。然后，我们引入了一个新的概念--转发组多播，其中树被一个由转发节点组成的网格所取代--后者在移动性方面比树更容易维护。研究人员提出将按需路由策略扩展到这种结构，以处理大规模的数据。

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.