A traffic scheduler for real-time wireless communication in adaptable industrial automation systems

Hybrid wired/wireless network architectures combine the flexibility and inexpensiveness of WLANs with the real-time performance of wired real-time networks. This paper describes both a scheduling framework and a scheduling algorithm to handle real-time communication over the wireless section of a hybrid wired/ wireless industrial network, which uses a scheduled protocol that extends the IEEE 802.11n standard. The proposed scheduling framework is able to schedule real-time flows traversing one or multiple Access Points, providing both intra-and inter-cell scheduling. Moreover, the scheduling framework offers support for three different kinds of real-time flows, i. e., periodic, aperiodic, and sporadic. A simulative analysis is also provided to assess the computation times as a function of the number of flows and the number of schedulable flows in different scenarios.