AI summaryⓘ
The authors study how a transmitter can best send updates to two receivers that also share information with each other (gossip) to keep their data fresh. They consider the trade-off between sending direct updates, which costs more, and relying on gossip, which can be slower or outdated. Using a mathematical model called a Markov Decision Process, they find the best strategy that balances freshness (age of information) and transmission cost. Their strategy suggests the transmitter should send updates only when the receivers' information is too old or too similar, otherwise it should wait and let gossiping do the work. This work helps understand the balance between communication cost and information freshness in gossip networks.
Age of Information (AoI)GossipingMarkov Decision Process (MDP)Relative Value Iteration (RVI)Transmission CostScheduling PolicyInformation FreshnessDecentralized CommunicationThreshold PolicyTime-slotted System
Authors
Irtiza Hasan, Ahmed Arafa
Abstract
We study the optimal transmission and scheduling policy for a transmitter (source) communicating with two gossiping receivers aiming at tracking the source's status over time using the age of information (AoI) metric. Gossiping enables local information exchange in a decentralized manner without relying solely on the transmitter's direct communication, which we assume incurs a transmission cost. On the other hand, gossiping may be communicating stale information, necessitating the transmitter's intervention. With communication links having specific success probabilities, we formulate an average-cost Markov Decision Process (MDP) to jointly minimize the sum AoI and transmission cost for such a system in a time-slotted setting. We employ the Relative Value Iteration (RVI) algorithm to evaluate the optimal policy for the transmitter and then prove several structural properties showing that it has an age-difference threshold structure with minimum age activation in the case where gossiping is relatively more reliable. Specifically, direct transmission is optimal only if the minimum AoI of the receivers is large enough and their age difference is below a certain threshold. Otherwise, the transmitter idles to effectively take advantage of gossiping and reduce direct transmission costs. Numerical evaluations demonstrate the significance of our optimal policy compared to multiple baselines. Our result is a first step towards characterizing optimal freshness and transmission cost trade-offs in gossiping networks.