Average AoI Minimization in UAV-Assisted IoT Backscatter Communication Systems with Updated Information

Abstract

Unmanned aerial vehicle (UAV)-assisted data collection in Internet of Things (IoT) networks is an emerging and promising paradigm in the next generation communication systems. This paper considers a scenario where a UAV collects data from multiple IoT sensor equipments (SEs) one by one and finally flies to the data center for data processing. To reduce the energy consumption of the SEs, backscatter communication is adopted. The paper aims to minimize the average age of information (AoI) of all SEs by jointly optimizing the UAV’s data collection time from different SEs, the transmission power of the UAV, and the trajectory of the UAV. Since the optimization problem includes both discrete variables (the collection sequence of SEs) and continuous variables (the transmission power and collection time), the problem is difficult to solve by conventional methods. By exploiting the special structure characteristics of the problem, it can be divided into two sub-problems without loss of optimality. The first one is the data collection time minimization problem that contains only continuous variables, and its optimal solution is derived based on the KKT optimality conditions. While the second one contains only the discrete variables, and a backtracking scheme based UAV trajectory design method is proposed. Numerical results verify that the proposed method can always achieve significantly better performance in terms of the average AoI than three benchmark algorithms.