Analysis of Ethernet Powerlink Wireless Extensions Based on the IEEE 802.11 WLAN

The industrial communication scenario is experiencing the introduction of wireless networks at all levels of factory automation systems. The benefits deriving from such an innovation are manifold, even if wireless systems cannot be thought as a complete replacement of wired networks. Rather, they will be even more used in the near future to realize hybrid (wired/wireless) configurations. In particular, it is envisaged that wireless networks may be employed to implement extensions of (possibly already installed) wired systems. In this paper we consider wireless extensions of Ethernet Powerlink, a very popular Real-Time Ethernet network, implemented by means of the IEEE 802.11 WLAN. Specifically, we focus on a widespread network configuration and address two types of extensions based on, respectively, bridge and gateway devices. In the second part of the paper we provide an analysis of the hybrid networks aimed at evaluating the most relevant performance indexes. Since the reliability of wireless networks may represent a critical aspect, the analysis is carried out taking into account the presence of interference as well as fading in the wireless segment. The results we show, obtained from a theoretical analysis and validated by numerical simulations, allow to get some useful insights on the overall performance of the hybrid networks.