**1.2. Effect of sampling period on NCS**

Network scheduling deals with to elect a sampling rate, aiming to reduce the number of data transmitted over the network . The effectiveness of the control system depends on such a sampling rate [8–10]. A region is acceptable in networked control performance terms if it is contained within two sampling rate boundaries, which can be statistically determined.

The use of a common-bus network architecture and a particular network protocol introduces different forms of time delay uncertainties between, sensors, actuators and controllers [8]. Hence, it is quite important to explore different network protocols and network scheduling strategies, before to implement the RTDS, in order to obtain a desired control performance.

For networked control, the minimum transmission frequency (*fm*) is necessary to guarantee good system performance without decreasing the network performance. As the transmission frequency increases the system performance improves; however, the load on the network also increases until a maximum transmission frequency (*fh*) is reached, then the system performance decreases because the network performance is overloaded.

This phenomenon represents non-linear situations with respect to sudden changes in state of the network, failure situations, or saturation in the channel or traffic, among others. However; it is possible to propose a linear model in the context of proper use of the network, thereby deferring the modeling of nonlinearity in these systems until future work.

The main objective of this work is to explore several issues on communication network scheduling of a RTDS, besides to implement a particular network scheduling strategy to evaluate its effectiveness using numerical simulations. This is presented using a simulated case study, based upon a 2-DOF helicopter simulation benchmark [13]. This simulation provides an approximation to system response, in which, for demonstration purposes, the main results are obtained for a typical fault scenario. Thus, for this simulation, a scheduling strategies is implemented using TrueTime [1, 2] performing dynamic scheduling. Several researches have focused on control over network, shared-network control systems have special interest.
