Improving simulation of wireless networked control systems based on WirelessHART

The scalability and flexibility of wireless networks are the basis of the growing success of Wireless Networked Control Systems (WNCSs). Both the HART Communication Foundation and the ISA association have recently proposed their own standard for a wireless fieldbus (WirelessHART ratified in 2007, and ISA100.11a ratified in 2009, respectively). However, WNCSs performances are hard to verify in the real world, since test beds are expensive and difficult to implement. The answer to this question is the adoption of co-simulation, which is the joint and simultaneous simulation of both physical and communication network dynamics. This paper proposes the use of a framework based on the interaction of TrueTime, together with a cross layer wireless networks simulator based on OMNET++. The proposed approach allows overcoming limits in the simulation of network aspects implemented in the TrueTime package, introducing a scalable level of details in the simulated scenario. Great attention has been paid in the OMNET++ models to accurately modelling peculiar aspects of the network and of the devices, for instance overcoming usual assumptions often made on physical and MAC layers. The support to the simulation of coexistence management between wireless networks in the same area has been improved. As an application example, a scenario involving a system controlled by a WirelessHART network has been considered; the analysis of some aspects concerning the control performance and coexistence immunity of WirelessHART with respect to the traditional IEEE802.15.4, has been carried out.