Peak Age of Information in Multi-Path Networks

In multi-path networks, there is the possibility of out-of-order packet receptions at the destination, i.e., a packet generated sooner than another one can be received later, which is the main challenge in analyzing the age-related metrics in multi-path networks. Most of the previous works on multi-path networks have only focused on studying the average age of information (AoI). However, analyzing the average peak AoI (PAoI), another age-related metric, can be even more challenging since we need to know when a local peak occurs in the AoI function. In this work, for a general multi-path network, we find the relation of the average PAol based on some characteristics of the ages of the incoming links at the destination. As a case study, we derive the average PAoI in a network of two parallel preemptive queues. In the symmetric case, where sampling and transmission rates are identical for both queues, we find that based on the amounts of sampling and transmission rates, the average PAoI is between 38.33 to 50 percent smaller compared to the scenario with only one queue.