Effective Communication: When to Pull Updates?
Pouya Agheli, Nikolaos Pappas, Petar Popovski, Marios Kountouris
TL;DR
This work addresses goal-oriented pull-based communication by introducing Grade of Effectiveness ($GoE$), a composite metric combining AoI freshness and update usefulness to quantify the impact of updates at the endpoint. It develops a CMDP framework where a query controller decides when to pull updates based on the evolving source state and the expected usefulness, while constraining the average communication cost. An iterative algorithm solves the dual problem to obtain a $\mu$-optimal policy $\pi_\mu^*$ and the corresponding $\mu^*$, with the optimal policy converging to a practical threshold-based rule. Simulation results show that the proposed effect-aware policy significantly outperforms effect-agnostic baselines in long-term $GoE$, albeit with higher transmission rate, and reveal convergent behavior and interpretable threshold boundaries. The approach offers a scalable, just-in-time querying mechanism for enhancing effectiveness in goal-oriented, information-pull systems.
Abstract
We study a pull-based communication system where a sensing agent updates an actuation agent using a query control policy, which is adjusted in the evolution of an observed information source and the usefulness of each update for achieving a specific goal. For that, a controller decides whether to pull an update at each slot, predicting what is probably occurring at the source and how much effective impact that update could have at the endpoint. Thus, temporal changes in the source evolution could modify the query arrivals so as to capture important updates. The amount of impact is determined by a grade of effectiveness (GoE) metric, which incorporates both freshness and usefulness attributes of the communicated updates. Applying an iterative algorithm, we derive query decisions that maximize the long-term average GoE for the communicated packets, subject to cost constraints. Our analytical and numerical results show that the proposed query policy exhibits higher effectiveness than existing periodic and probabilistic query policies for a wide range of query arrival rates.
