Dual-Loop Resilient Scheduling with Predictive Path Reconfiguration for Deterministic Industrial Wireless Networks

To meet the deterministic and low-latency communication demands of Industry 4.0, this paper formulates resilient scheduling in interference-prone 6TiSCH industrial wireless networks as an explicit mixed-integer linear program (MILP) and proposes Dual-Loop Intelligent Resilient Scheduling (DL-IRS), a Software-Defined Networking (SDN) architecture. An inner loop performs minimum-perturbation, local channel-offset remapping to absorb transient narrowband interference; an outer loop performs make-before-break activation of a shadow schedule, triggered by trend-based early warning when local recovery is insufficient; shadow resources are reserved in advance and the schedule update is installed before an explicit activation slot. Both loops draw on a Conflict-Aware Spatial-Spectral Allocation (CASA) heuristic, whose underlying decision problem is proven NP-complete via a reduction from graph coloring. Cooja/Contiki-NG simulations demonstrate that under an SNR = 0 dB narrowband-interference condition, DL-IRS sustains a packet delivery ratio (PDR) of 96.8%, representing a 35.3 percentage point improvement over standard 6TiSCH scheduling. The detection-to-activation chain of the outer loop is reported explicitly (38.0 ms in a relay-failure experiment) rather than assumed to be zero. This chain was measured for the compute-on-trigger branch only; the Phase A proactive reservation mechanism is specified as part of the architecture but is not evaluated experimentally in this paper.