Exploiting Data Significance in Remote Estimation of Discrete-State Markov Sources

Abstract: We consider the semantics-aware remote estimation of a discrete-state Markov source with normal (low-priority) and alarm (high-priority) states. Erroneously announcing a normal state at the destination when the source is actually in an alarm state (i.e., missed alarm error) incurs a significantly higher cost than falsely announcing an alarm state when the source is in a normal state (i.e., false alarm error). Moreover, successive reception of an estimation error may cause significant lasting impact, e.g., maintenance cost and misoperations. Motivated by this, we assign different costs to different estimation errors and introduce two new age metrics, namely the Age of Missed Alarm (AoMA) and the Age of False Alarm (AoFA), to account for the lasting impact incurred by different estimation errors. Notably, the two age processes evolve dependently and can distinguish between different types of estimation errors and different synced states. The aim is to achieve an optimal trade-off between the cost of estimation error, lasting impact, and communication utilization. The problem is formulated as an average-cost, countably infinite state-space Markov decision process (MDP). We show that the optimal policy exhibits a switching-type structure, making it amenable to policy storage and algorithm design. Notably, when the source is symmetric and states are equally important, the optimal policy has identical thresholds, i.e., threshold-type. Theoretical and numerical results underscore that our approach extends the current understanding of the Age of Incorrect Information (AoII) and the cost of actuation error (CAE), showing that they are specific instances within our broader framework.