Data Aggregation and Scheduling to Optimize Information Freshness In Multi-Hop IoT Networks

The rapid proliferation of Internet of Things (IoT) devices with sensing, monitoring, and control capabilities has fueled the emergence of diverse real-time IoT applications. These applications often require the efficient transmission of collected sensitive data to centralized or distributed processing units, such as cloud servers, edge nodes, or fog computing platforms—to enable timely responses. Ensuring the freshness of information while maintaining sustainable data transmission under energy constraints remains a critical challenge. To address this issue, we quantify information freshness using Age of Aggregated Information (AoAI) and investigate its minimization within energy-harvesting multi-hop IoT networks. Specifically, we develop data transmission schedules that jointly consider energy harvesting and packet aggregation. This problem is formulated as a Mixed-Integer Linear Programming (MILP) model, integrating data scheduling, packet aggregation, link interference, and energy resource management across multiple nodes. To tackle the computational complexity of this NP-hard problem, we propose an Energy-Aware Column Generation Algorithm (CGA). The original problem is decomposed into a Restricted Master Problem (RMP) and a Pricing Problem (PP). The RMP models data aggregation at Base Station (BS), while the PP incorporates an Energy-Aware Scheduling Algorithm (EASA) to generate feasible scheduling solutions. Simulation results demonstrate that the proposed CGA consistently outperforms EASA, the Genetic Algorithm (GA), and the Juventas Algorithm, achieving an average deviation of only 1.84% from the global optimal solution.