Research for quality assurance type multicast systems

在现有的质量保证型组播系统中，发送方收集每条链路的通信质量信息，构建最佳交付树。然而，采集通信质量信息的假设在大规模系统中存在可行性问题。本研究提出了一种在控制包被淹没的情况下，在增加通信质量信息的同时确定路径的新方法，并对其有效性进行了评价。此外，在质量保证型组播系统中需要有效的重传控制。特别是在像自组织网络这样的无线网络中，有效的重传控制对网络质量有很大的影响。本研究的特点是在自组织网络中通信链路断开的路径上进行重传，而不需要通过本地恢复重新搜索过去的传输路径。我们引入了支持小组的概念来进行局部康复。支持小组的形成是通常路径搜索算法的副产品。并且，该概念用于监视通信链路，检测断开，数据包重传，并在本地构建替代通信路径。支持小组的开销很小，因为它是由通常的路径搜索过程组成的。此外，由于对丢包的恢复是在本地快速完成的，因此重传机制在实时数据传输中是有效的。通过ODMRP和以往ad hoc组播协议的仿真，对这些算法进行了比较。结果表明，我们提出的方法提高了以往方法的数据包到达率。与以往的方法相比，该方法可以使重建间隔变长。该结果作为国际会议论文发表。

The sender collected all information on the communication quality of each link and the best delivery tree was constructed in an existing quality assurance type multicast system. However, assumption of collecting communication quality information had the problem in the feasibility in a large-scale system. In this research, when the control packet was flood, it proposed a new method to decide the path while spreading adding communication quality information, and the effectiveness was evaluated.Moreover, an efficient retransmission control is needed in the quality assurance type multicast system. Especially, an efficient retransmission control has a big influence in the network quality on a wireless network like an ad hoc network. The feature of this research is a method which retransmits in the path to which the communication link in an ad hoc network disconnects without searching for a past transmission path again by local recovery.We introduced the concept of support group for local recovery. The support group is formed as a by-product of a usual path search algorithm. And, the concept is for the watch of the communication link, the detection of the disconnection, the packet retransmission and to construct an alternative communication path locally. The support group is few the overhead because it is made from the process of a usual path search. Moreover, because recovery to the packet loss is done locally and quickly, the retransmission mechanism can be effective in a real-time data transfer. These algorithms were compared by ODMRP and the simulation which was the past, ad hoc multicast protocol. As a result, the method that we proposed improved the packet arrival rate of the past method. Moreover, it was shown that our method could make the reconstruction interval longer than the past method. This result was presented as an international conference thesis.