Assessment of LBT Systems using Petri Net modelling

Wireless communication is well established in industrial automation (IA). The rising number of different wireless technologies is the result of various IA application requirements. While WLAN and Bluetooth based systems fulfill the requirements of factory automation, WirelessHART and the upcoming ISA SP100a are more suitable for usage in process automation. However, the mentioned systems with different media access mechanisms share the same 2.4 GHz ISM band. Obviously, the growing integration of wireless automation components leads to an extended use of this limited frequency band. Thus, coexistence of wireless solutions is an important issue. This paper presents a model approach to assess communication behavior of Listen-before-Talk systems during interferences by networks with other media access mechanisms. The assessment parameters consider the requirements and conditions of IA applications. The model approach is based on high level Petri Nets. The investigations are focused on systems defined in the upcoming EN 300328 specification and not on existing wireless solutions.