I. Introduction
The installation cost for the wire harness testing system of the FCE is high. The existing system adopts a real-time Ethernet/IP network to communicate with sensors and the server. The customers of the FCE desire to replace the existing sensors with wireless sensors to reduce installation costs. The engineers of the FCE attempted to employ commercial wireless sensor network solutions such as IEEE 802.15.4, but the prototypes cannot overcome the time constraint since the density of the sensors is too high to upload mass data to the server. There have been many attempts for solving this problem [1] but with complex network topology. The sensor network considered in this study contains only one cluster. Although the network topology is simple, the amount of data that all sensors in a cluster need to upload to the cluster head in a unit of time exceeds the maximum bit rate of the 802.15.4 communication module.