Studies on Broadcast-base Cyberspace for Realizing a Large-scale Virtual Space

在大规模网络虚拟环境中，由于客户端数量的增加，会导致服务器负载过大。为了减少服务器的负载，我们提出了一种基于广播的网络空间。首先，我们假设一个由虚拟空间组成的大量模型数据作为数据项广播的环境。在该系统中，服务器将虚拟空间划分为多个子空间，并通过宽带信道向客户端重复广播子空间的空间数据。考虑服务器和客户端之间的广播带宽和用户在虚拟空间中的移动速度，研究了两种广播节目调度策略，以减少用户虚拟形象迁移到相邻子空间的平均等待时间。此外，我们还提出了在客户端预取的方法。其次，假设物体的位置和属性的实时信息作为数据项进行广播，并提出了一种提高广播效率的调度策略。我们的调度策略考虑了对象的受欢迎程度、对象与观察对象的虚拟角色之间的距离以及广播周期。通过仿真实验验证了所提方法的性能。

In large-scale networked virtual environments, excessive load on the server occurs due to an increase of clients. In order to reduce the server load, we proposed a broadcast-based cyberspace.First, we assumed an environment where a large volume of model data composed of virtual space is broadcasted as data items. In the proposed system, a server divides virtual space into multiple subspaces and repeatedly broadcasts spatial data of the subspaces to clients using a broadband channel. We investigate two scheduling strategies of the broadcast program in order to reduce the average waiting time for the avatar of a user to migrate to an adjacent subspace considering the broadcast bandwidth between a server and clients and movement speed of the user in virtual space. Moreover, we also proposed prefetching methods at clients.Next, we assumed an environment where the real-time information on positions and properties of objects is broadcasted as data items and propose a scheduling strategy for improving broadcast efficiency. Our scheduling strategy considers the object popularity, distance between objects and avatars which observes the object, and the broadcast period. We confirmed the results of simulation experiments regarding the performance of our proposed method.