Construction Method of Hierarchical Ad hoc Network Intended for Densely Distributed Sensors

为了构建面向密集和广泛分布的传感器的无线自组织网络，本研究项目研究了一种在这些传感器节点之间有效传输数据的方法。在2005-2006两年的研究期间，主要研究了以下两个课题。用于多跳数据传输的中继节点(地标节点)选择方法在传感器密度高的分布环境中，可能会有无线传播范围内的多个传感器在消息泛洪和数据分组转发中增加冗余流量。为了实现有效的洪泛和数据转发，本研究项目提出了一种选择地标节点作为控制报文和数据包路由转发节点的方法。通过与IETF中针对高密度自组网而标准化的OLSR(优化链路状态路由)的比较，给出了该算法的性能评估。该项目使用软件仿真技术，评估了选择的中继节点数量和用于路由信息交换的泛洪消息数量。结果表明，与OLSR2相比，本文提出的方法可以有效地降低这两个参数。本研究项目还提出了一种适用于高密度自组网的改进的AODV(Ad hoc On-Demand Distance Vector)路由协议。它具有这样的特征，即它不引入任何额外的消息开销，它仅使所需的节点中继路由请求消息，并且它应对网络配置变化。本研究项目使用网络模拟器进行了性能评估。结果表明，与原AODV协议相比，该协议可以减少控制消息的总数，并且减少了由于控制消息开销而导致的数据分组丢失。

In order to construct wireless ad hoc networks intended for densely and widely distributed sensors, this research project studies a method of transferring data effectively among those sensor nodes. During two year research period from 2005 to 2006, the following two research topics are studied.1. Selection method of relaying nodes (landmark nodes) for multi-hop data transferIn the environment of high density distribution of sensors, it is possible that many sensors within the radio propagation range increase redundant traffic in the message flooding and data packet relaying. For the purpose of effective flooding and data relaying, this research project proposed a procedure to select landmark nodes which work as relaying nodes for routing control messages and data packets. This research project also showed the performance evaluation of the proposed procedure with the comparison to OLSR (Optimized Link State Routing), which is being standardized in IETF for high density ad hoc networks. This project used a software simulation technique and evaluated the number of selected relaying nodes and the number of flooded messages for routing information exchange. The results showed that the proposed procedure could reduce both of them compared with OLSR.2. Ad hoc routing suitable for high density ad hoc networksThis research project also proposed a modified version of AODV (Ad hoc On-demand Distance Vector) routing protocol adapted to high density ad hoc networks. It has features such that it does not introduce any additional message overhead, that it makes only the required nodes relay route request messages and that it copes with network configuration change. This research project showed the performance evaluation using a network simulator. The results indicate that the proposed protocol can reduce the total number of control messages and that data packet loss due to the control message overhead is reduced compared with the original AODV.