UAV-Aided MIMO Communications for 5G Internet of Things
IEEE Internet of Things Journal
The unmanned aerial vehicle (UAV) is a promising enabler of the Internet of Things (IoT) vision, due to its agile maneuverability. In this paper, we explore the potential gain of UAV-aided data collection in a generalized IoT scenario. Particularly, a composite channel model including both the largescale and the small-scale channel fading is used to depict typical propagation environments. Besides, not only the peak transmit power constraint but also the budget power and the total energy
... ints are considered to characterize practical IoT devices. A multi-antenna UAV is employed, which follows a circular trajectory and visits the IoT devices in a sequential manner. For each transmission, the UAV communicates with a cluster of singleantenna IoT devices to form a virtual MIMO link. On these basis, we formulate a whole-trajectory-oriented optimization problem, where the transmission duration time and the transmit power of all devices are jointly designed for the whole flight. Different from previous studies, only the slowly-varying large-scale channel state information (CSI) is assumed available, to coincide with the fact that practically it is quite difficult to predictively acquire the random small-scale channel fading prior to the UAV flight. We propose an iterative scheme by leveraging the maxmin optimization and convex optimization tools, to overcome the nonconvexity of the problem. The presented scheme adapts well to the rigorous energy constraints as well as the large-scale CSI condition, thus, it can provide a significant performance gain over traditional schemes and converges quickly. Index Terms-Internet of Things (IoT), unmanned aerial vehicle (UAV), energy constraint, MIMO, large-scale channel state information (CSI).