Development of Integrated image broadcast and unicast systems for heterogeneous network environment

由于近年来图像编码技术的飞速发展和个人计算机性能的提高，具有接收和发送图像能力的终端数量急剧增加。相反，宽带网络并不是对每个用户都可用，而且网络环境非常异构，从仅9600 bps的PDC型蜂窝电话到千兆比特网络。本研究的目的是解决在这种环境下的各种问题，以有效地传输图像。研究结果如下：提出了一种基于内容服务器自适应分配和内容自适应复制的流量均衡方法。我们还研究了新的图像流量速率控制。对于分层图像编码，我们提出了非常有效的无损和有损分层图像编码技术，并对每一类的比特分配参数进行了微调。然后将其应用于透明介质缩放，提出了一种灵活、简便的带宽分配方案。从异构网络环境下网络控制方法发展的角度出发，将WDM网络作为高速网络，提出了一种高效而简单的路径分配算法。验证了该算法在实时交通工程中的可行性。虽然这超出了我们最初的研究计划的范围，但由于ad-hoc网络是分层传输的，我们也研究了它们的路由构造方法。作为异构网络的低速部分，现在已经成为现实。研究期已经结束，但我们仍在努力整合这些具体的研究课题，并仍在开发一个原型商业系统。

Owing to the rapid advance of recent image coding technique and the performance of personal computers, the number of terminals with the ability of receiving and sending images are growing dramatically. On the contrary, broadband network is not available for every user and the network environment is very heterogeneous ranging from mere 9600 bps PDC type cellular phone to Giga bit network. The aim of this research was to tackle with various problems under such environment to efficiently transmit images.The outcomes of the research are as follows. We proposed an -innovative method for traffic balancing by the adaptive allocation of contents servers and adaptive replication of contents. We also studied the new rate control for image traffic. As for the layered image coding, we proposed very efficient hierarchical image coding techniques both for loss-less and lossy cases and fine-tuned the parameters for bit assignment for each class. Then we applied them to transparent media scaling and proposed a scheme for flexible and easy bandwidth assignment.From the viewpoint of development of network control method under heterogeneous network environment, we also focused WDM network as very high speed network and proposed an efficient yet simple path assignment algorithms. Then we showed the feasibility of real time traffic engineering with this algorithm. Although it is beyond the scope of our original research proposal, we also studied the routing constructing method of ad-hoc networks assuming the hierarchical transmission since they are. becoming realistic now as the very low speed part of die heterogeneous networks.The research term is now over, however we are still trying to integrate these specific research topics and still developing a prototype commercial system.