iDSRT: Integrated Dynamic Soft Real-Time Architecture for Critical Infrastructure Data Delivery over WLAN

The real-time control data delivery system of the Critical Infrastructure (i.e. SCADA Supervisory Control and Data Acquisition system) is important because appropriate decisions cannot be made without having data delivered in a timely manner. Because these applications use multiple heterogeneous resources such as CPU, network bandwidth and storage, they call for an integrated and coordinated realtime scheduling across multiple resources to meet end-to-end deadlines. We present a design and implementation of iDSRT an integrated dynamic soft real-time system to provide fine-grained end-to-end delay guarantees over WLAN. iDSRT takes the deadline partitioning approach: end-to-end deadlines are partitioned into multiple sub-deadlines for CPU scheduling and network scheduling. It integrates three important schedulers: task scheduler, packet scheduler and node scheduler to achieve global coordination. We validate iDSRT in Linux and evaluate it in an experimental SCADA test-bed. The results are promising and show that iDSRT can successfully achieve soft real-time guarantees in SCADA system with very low packet loss rate compared to available commodity best-effort systems.