Dynamic Network Control to Prevent System Failures in Multi-hop Wireless Networks

在多跳无线网络中，由于节点的位置经常发生变化，一些节点由于节点的移动性而离开网络，网络并不保证是连通的，网络的拓扑结构也会随着时间的推移而变化。由于这种拓扑结构的变化，网络的性能有时会降低。此外，如果网络由普通终端组成，恶意节点可能会进入网络并故意攻击网络。因此，网络可能无法正常运行。由于目前的网络系统必须提供足够的可靠性和宽带环境，我们必须克服这些导致系统故障的问题。在这样的背景下，本课题的目的就是研究网络控制方法，以克服这些问题，提高多跳无线网络的可靠性。研究结果如下：研究了计算机病毒引起的终端故障对无线多跳网络性能的影响，并提出了一些防止病毒在网络中传播的方法。提出了利用中继站进行拓扑控制以提高可靠性的方法，并对提出的方法进行了评估。提出了一种负载均衡的计费奖励方法，并对提出的方法进行了评估。此外，我们还开发和评估了一些优化方法和协议，以提高可靠性。

In multi-hop wireless networks, the network is not guaranteed to be connected, and the topology of the network changes with time because positions of nodes often change and some nodes leave the network because of mobility of nodes. Due to such change of the topology, performance of the network is sometimes degraded. Furthermore, if the network consists of general terminals, malicious nodes may enter the network and attack the network intentionally. As a result, the network may fail to function properly. Because recent network systems have to provide sufficient reliability as well as broadband environments, we have to overcome such problems which cause system failures. With these things as background, the purpose of this project is to develop network control methods to overcome such problems and improve reliability of multi-hop wireless networks. The following are the results: We showed that effects of failure of terminals due to computer viruses on performance of wireless multi-hop networks, and proposed some methods to prevent spread of viruses in the network. Also, we proposed topology control methods with relaying stations to improve reliability, and evaluated the proposed methods. Also, we proposed charging rewarding methods for load balancing and evaluated the proposed methods. Furthermore, we developed and evaluated some optimization methods and protocols to improve reliability.