Abstract: “The need for multi-UAV systems has been increasing with the extensive use of UAVs not only in the military activities but also in various civilian activities like search and rescue, agriculture, traffic management, building inspection, recreation, etc. But multi-UAV systems have their limitations when it comes to increased distance and the presence of obstacles in the path because of the range limitations of communication modules. Most of the communication modules like telemetry modules 3DR Sik2, Xbee, Wi-Fi modules have a communication range of up to a few kilometers, leading to less efficient multi - UAV systems in terms of long flight distance and obstacles in the path. In this paper, a relay communication system using Robot Operating System (ROS) is proposed whose first stage has been implemented and the second stage is undergoing. In this system, one of the UAVs acts as a relaying node between the UAV far in distance and GCS when the distance is large or if there are obstacles in”

Keywords: Relay system, ROS, multi - UAV, communication modules, GCS