In smart environments, Unmanned Aerial Vehicles (UAVs) can be used as mobile base stations to deliver services to monitoring areas. However , smart devices are located outside of the UAV coverage area. Therefore, the combination of UAV and relay hops can be used to increase the coverage area to devices outside of the UAV coverage. Signal strength plays a vital role in identifying the coverage area of UAVs. This paper examines the Received Signal Strength (RSS) of the cooperation UAV and relay for improving wireless coverage and establishing large-scale communication in smart environments in Beyond the fifth Generation (B5G). The findings show that UAV cooperation can increase wireless coverage through relay hops from Device to Device (D2D). Received signal strength has significantly. enhanced the cooperation of UAV and relay to extend the smart environment coverage area. Finally, multihop D2D helps increase UAV spectrum efficiency and RSS in different environment coverage scenarios.