I. Introduction
Age-of-Information (AoI) is a critical networking performance metric for periodic services that require timely transmissions. Kaul et al. [3] measures the AoI as the time that elapsed since the last received update was generated. In this paper, we study AoI-minimization problems of supporting a periodic transmission task under a single-unicast networking scenario. Specifically, the task requires a sender to send a batch of data (packets) periodically to a receiver over a multi-hop network, possibly using multiple paths. We use a stylized deterministic model to model the network. Our objective is to minimize peak/average AoI subject to both a minimum and a maximum throughput requirement, by jointly optimizing throughput and multi-path routing strategy. We assume the amount of data in the batch is fixed, hence the throughput (the ratio of the volume of the data batch over the task activation period) only varies with the task activation period.