Age of Information of a Dual Queue Status Update System: A Stochastic Hybrid Systems Method

Using redundant devices to update the status can improve the robustness against transmission failure, thus improving timeliness of information. However, out of order update arrivals resulting from multiple devices impose a significant challenge to the analysis of timeliness of information in such systems. This letter studies the average age of information (AoI) of a dual queue status update system under zero-wait policy. We leverage tools from stochastic hybrid systems to derive closed-form expression for the average AoI of the dual queue system and extend the result to the three-queue system. The results show that the average AoI of the dual queue system can be reduced by 37.5% compared to that using only a single queue.