AoI-Based Priority-Aware Transmission Scheduling for State Estimation in Industrial IoT Systems

In industrial Internet of Things (IoT) systems, many sensors are deployed in the field to sense the running state of equipments. Moreover, the more the sensory information collected and transmitted by sensors, the better the state estimation performance. However, the limited spectrum resources make it challenging to support the simultaneous transmission of all sensors, which will significantly reduce the estimation accuracy. Moreover, due to the heterogeneous sensing abilities of sensors, scheduling different sensors will have distinct contributions on improving the estimation performance. To address this issue, this paper proposes a priority-aware transmission scheduling scheme for state estimation. In particular, the priority is firstly given based on Age of Information (AoI), where AoI characterizes the freshness of sensory information and is related to the historical scheduling situations. Then, we investigate the relationship between the AoI of sensory information and the error of state estimation, based on which a priority-aware transmission scheduling algorithm is designed by considering the spectrum resource limitation and the sensing ability heterogeneity. To further improve the estimation accuracy, a constrained optimization problem is formulated to jointly design the transmission scheme and transmit power. Besides, a low-complexity heuristic algorithm is proposed to solve the formulated mixed integer nonlinear problem efficiently. Finally, the simulation results show the effectiveness and superiorities of the proposed transmission scheduling scheme.