Joint User Association and UAV Location Optimization for Two-Tired Visible Light Communication Networks

Abstract

In this paper, an unmanned aerial vehicle (UAVs)-assisted visible light\ncommunication (VLC) has been considered which has two tiers: UAV-to-centroid\nand device-to-device (D2D). In the UAV-to-centroid tier, each UAV can\nsimultaneously provide communications and illumination for the centroids of the\nground users over VLC links. In the D2D tier, the centroids retransmit received\ndata from UAV over D2D links to the cluster members. For network, the\noptimization problem of joint user association and deployment location of UAVs\nis formulated to maximize the received data, satisfy illumination constraint,\nand the user cluster size. An iterative algorithm is first proposed to\ntransform the optimization problem into a series of two interdependent sub\nproblems. Following the smallest enclosing disk theorem, a random incremental\nconstruction method is designed to find the optimal UAV locations. Then,\ninspired by unsupervised learning method, a clustering algorithm to find a\nsuboptimal user association is proposed. Our simulation results show that the\nproposed scheme on average guarantees the users brightness 0.77 lux more than\ntheir threshold requirements. Moreover, the received bitrate plus number of D2D\nconnected users under our proposed method is 50.69% more than the scenario in\nwhich we have RF Link instead of VLC link and do not optimize UAV location.\n