3-D Deployment of VLC Enabled UAV Networks With Energy and User Mobility Awareness

The recent proliferation of light-emitting diodes (LEDs) in unmanned aerial vehicles (UAVs) for inspection, first response, environmental protection monitoring, surveillance and urban safety especially at night time, have paved the way for visible light communication (VLC) enabled UAVs. Since UAVs are power limited and size constrain ed devices, the utilization of visible light for communication and illumination in UAVs help in reducing energy and air-frame cost. Further, when the ground users are mobile, UAV placements require regular updates at optimized update intervals. Consequently, we propose energy and user mobility aware three-dimensional (3-D) deployment of VLC enabled UAV-base station ( $\mathrm {UB}_{\mathrm {v}}$ ) so that maximum coverage of users while ensuring fairness is achieved. The farthest user and shifting UAV based solutions have been proposed for the joint optimization of $\mathrm {UB}_{\mathrm {v}}$ placement and the update interval. The complexity of the proposed approaches is lower than the exhaustive-search based solution, thus, making the $\mathrm {UB}_{\mathrm {v}}$ network energy-efficient. The $\mathrm {UB}_{\mathrm {v}}$ coverage area to serve ground users has been enhanced with holographic light-shaping diffusers (LSD). The optimum angle of the LSD has been obtained based on LED optical transmitted power and desired $\mathrm {UB}_{\mathrm {v}}$ maximum coverage. A novel red, green and blue (RGB) LED solution based on light sensitivity to the human eye is proposed to increase the coverage area for the night scenario. Moreover, we derive the analytical expressions to determine the maximum coverage radius and $\mathrm {UB}_{\mathrm {v}}$ optimum altitude for the defined quality-of-service (QoS) metrics. Finally, the proposed $\mathrm {UB}_{\mathrm {v}}$ network is evaluated in terms of update instant, service time and effective users covered.