In energy harvesting Internet of Things (IoT) systems, the age of information (AoI) should be maintained at a low level to guarantee the accuracy and reliability of derived decisions.In this paper, we design an information freshness-guaranteed and energy-efficient data generation control system (IFE-DGCS) where an IoT gateway with a directional antenna determines the polling frequency for each sector by selecting a polling sector at periodic decision epochs.When polling data, the IoT gateway transfers the RF energy to IoT devices in the polling sector by means CS-1708 of simultaneous wireless information and power transfer (SWIPT).To minimize the energy outage probability while maintaining the AoI below a certain level, a constrained Markov decision process (CMDP) is formulated and the optimal stochastic policy on the polling sector is obtained by a linear programming (LP).
To resolve the curse of the dimensionality problem in CMDP, a greedy IFE-DGCS is developed and its performance is extensively studied.Evaluation results demonstrate that IFE-DGCS with the optimal policy achieves a comparable energy outage probability to the conventional energy-oriented scheme while T-Shirts guaranteeing a sufficiently low AoI.