Hybrid Ethernet/IEEE802.11 Networks for Real-Time Communications

The industrial communications field is experiencing the introduction of two major innovations, represented by the adoption of Ethernet and of wireless technologies, at the lowest level of factory automation systems, commonly referred to as field level. Since at such a level many installations are, at present, based on (traditional) fieldbuses, it is very likely that, in the near future, we will be faced with hybrid configurations comprising all types of the above networks. In this paper we investigate the behavior of such hybrid networks, focusing on configurations comprising both Ethernet and IEEE~802.11 segments. Specifically, we first propose a communication profile, for the stations of the network, which makes use of both the UDP and IP protocols. Then, we describe how the typical data transfer functions of the field level could be implemented within such a communication profile. We conclude the paper presenting some performance figures obtained from numerical simulations. The results reveals the ability of the hybrid network configurations we considered to fulfill the tight timing constraints typical of field-level industrial communications.