Scheduling to Minimize Age of Synchronization in Wireless Broadcast Networks with Random Updates

TL;DR

This paper introduces a scheduling approach to minimize Age of Synchronization (AoS) in wireless broadcast networks, addressing data freshness for random updates, and proposes an index-based heuristic that performs close to optimal solutions.

Contribution

It formulates AoS minimization as a Markov decision process and develops a computationally efficient index-based heuristic policy based on restless multi-arm bandits.

Findings

The index policy achieves performance close to the optimal MDP solution.

AoS minimization differs significantly from AoI minimization in scheduling effectiveness.

The proposed policy effectively reduces AoS in simulated wireless broadcast scenarios.

Abstract

In this work, a wireless broadcast network with a base station (BS) sending random time-sensitive information updates to multiple users with interference constraints is considered. The Age of Synchronization (AoS), namely the amount of time elapsed since the information stored at the network user becomes desynchronized, is adopted to measure data freshness from the perspective of network users. Compared with the more widely used metric---the Age of Information (AoI), AoS accounts for the freshness of the randomly changing content. The AoS minimization scheduling problem is formulated into a discrete time Markov decision process and the optimal solution is approximated through structural finite state policy iteration. An index based heuristic scheduling policy based on restless multi-arm bandit (RMAB) is provided to further reduce computational complexity. Simulation results show that the proposed index policy can achieve compatible performance with the MDP and close to the AoS lower bound. Moreover, theoretic analysis and simulations reveal the differences between AoS and AoI. AoI minimization scheduling policy cannot guarantee a good AoS performance.