Optimal link scheduling for delay-constrained periodic traffic over unreliable wireless links

This paper investigates the problem of scheduling delay-constrained traffic in a single-hop wireless industrial network in which different source devices have different data rates. We aim to maximize the packet delivery reliability while meeting the deadline for each packet. The transmission scheduling problem is decomposed into two sub-problems: subperiod-based slot allocation and slot-based transmission scheduling. The former sub-problem is formulated as a nonlinear integer programming problem, and we present a solution with polynomial-time complexity by converting it to a linear integer programming problem. For the latter sub-problem, we demonstrate that the existence of a feasible optimal schedule depends on the order of the elements in the slot allocation vector produced by solving the former subproblem. An algorithm is designed to compute a feasible slot allocation that sustains a realizable schedule. Simulation results demonstrate that our scheme ensures each device has almost the same packet delivery rate in different report periods, which is important for maintaining the stability of control systems.