Effective Content Distribution Technique for Wireless Internet

在无线互联网中，移动用户利用无线媒体的灵活可访问性，可以接收到各种各样的内容。在本研究中，我们研究了几种适用于无线互联网的有效且健壮的内容分发技术。无线组播通信中的拥塞控制技术典型的无线组播通信方法会导致整个系统的性能下降。这是因为无线信道质量的频繁变化带来了代表节点的频繁变化。提出了一种新的拥塞控制方法，利用网络支撑技术解决了这一具有代表性的波动问题。无线传输协议的发展我们表明，不同协议层的重传控制不匹配以及不同无线网络切换时的带宽变化较大是无线TCP的重要技术问题。对于前一个问题，我们提出了跨层方法，对于后一个问题，我们提出了ACK划分技术。面向应用层组播的覆盖网络健壮性控制提出了一种新的考虑健壮性的覆盖网络构建方法。在我们提出的方案中，移动主机试图位于覆盖组播树的较低层，这使得即使在移动用户的情况下也可以形成健壮的网络结构。无线自组织网络的内容分发技术我们用这笔资金准备的笔记型PC开发了一个实验系统。利用该实验系统，研究了自组织网络中的内容分发问题，并对组播拥塞控制协议进行了评估。

In wireless Internet, mobile users will receive various contents with making use of flexible accessibility of wireless medium. In this research, several effective and robust content distribution techniques shown below which are suitable for wireless Internet have been studied.1. Congestion control technique for wireless multicast communicationsRepresentative approach of wireless multicast communications will cause performance degradation of total system. This is because frequent change of wireless channel quality brings frequent change of the representative node. We propose a new congestion control method which resolves this representative fluctuation problem by making use of network support technology.2. Development of wireless transport protocolWe show that mismatch of retransmission controls in different protocol layers and large bandwidth change in different wireless network handover are significant technical problem for wireless TCP. We propose cross layer approach for the former problem and ACK dividing technique for the latter problem.3. Robust overlay network control for application level multicastWe propose a new overlay network construction method which takes into account robustness. In our proposed scheme, mobile hosts are tried to be located in the lower layer of overlay multicast tree, which leads to a robust network structure even with mobile users.4. Content distribution technique for wireless ad-hoc networksWe develop an experimental system with note PC's which were prepared by this grant. With this experimental system, content delivery in ad-hoc network is investigated and multicast congestion control protocol is evaluated.