Server selection for equalizing of performance in distributed cooperative system

In recent years, in distributed cooperative systems such as distributed file systems and online games, equalization of performance between collaborative nodes is one of important issues as well as explicit performance such as bandwidth, delay and packet loss rate. Selection of the server which can offer equal performance to collaborative nodes is necessary to offer equalized performance. Therefore, to achieve this problem, we propose a server selection method that select the server by calculating the circumcenter of collaborative nodes according to the distance between nodes obtained by performance measures. However, depending on the location of nodes, there is a problem that using circumcenter is not always sufficient to find the most appropriate server. In this paper, we also propose a method to improve the accuracy of server selection by solving the problem of using circumcenter by downhill simplex method. We show probability of selection of the most suitable server can be improved around 55 % compared to the the method using circumcenter.