Contents I. Introduction
In the last decade, wireless technology is a promising candidate for industrial communication due to its flexibility for mobile terminal settings (e.g., robots, actuators, sensors, etc.). Many studies related to industrial wireless communication systems were discussed, such as positioning for industrial wireless LAN (iWLAN) [1], or coexistence of iWLAN in the context of industries 4.0 [2]. Wireless technology also offers an advantage for the factory automation (FA) systems because it can reduce physical connectivity (cable or wiring), resulting in a lower maintenance cost [3]. There are several solutions for FA wireless communication, include: Bluetooth for short- range transmission applications [4]; ZigBee that is suitable for sensor network [5]; and industrial communication standard WirelessHART [6], [7] that improves data rate and reliability of ZigBee. However, the poor compatibility with IEEE 802.11 WLAN devices such as in WirelessHART make those devices are difficult to cooperate with standard office devices such as PCs, laptops, and mobile phones in the factory environments, where the wireless LAN connection is a legacy wireless communication. To address these requirements, PROFINET has offered an industrial WLAN system using industrial point coordination function (iPCF) protocol [8]. Unfortunately, this protocol can only achieve low throughput since the protocol employs Time Division Multiple Access (TDMA) scheme and supports single user (SU) transmission. Hence, in a dense network such as an FA environment that involves many robots (terminals), this protocol’s performance cannot satisfy the real- time requirement as required in the FA system.
