Low Cost ATP System Design for Free Space Optics based Drone Assisted Wireless Networks

In a drone assisted wireless network, a drone is deployed over a place of interest (PoI) to relay traffic between the users at the PoI and a nearby wireless access point (WAP). To alleviate the bottleneck in the fronthaul link between the drone and the WAP, free space optics (FSO) is applied as the fronthaul communications solution. However, due to the mobility of the drone, a low cost and lightweight Acquisition, Tracking, and Pointing (ATP) system is required to ensure the low pointing loss for the FSO based fronthaul link. Although many high-accurate ATP systems have been designed for the FSO system to achieve, for example, ground-to-satellite communications, these ATP systems have high weight and cost, and so may not be suitable to be applied in the drone assisted wireless network, which may not require such high pointing accuracy. In this paper, we design and implement a novel low cost and lightweight gimbal-based ATP system to mitigate the pointing loss for the FSO based fronthaul link in a drone assisted wireless network. We experimentally evaluate the performance of the ATP system and observe that the designed ATP system can have a low pointing loss of the FSO based fronthaul system, especially when the drone is at a low speed with a proper beam divergence angle.