—In this paper we investigate the potential advantages of using a roaming Unmanned Aerial Vehicle (UAV) as base station of a mobile radio network deployed in a city. The design of the UAV dynamic trajectory and Radio Resource Management (RRM) strategies are combined, with the goal to improve the sum throughput of the network. The comparison between joint and separate aerial-terrestrial RRM is discussed. With respect to previous papers, we identified a cost function, used to define the UAV path, improving significantly the performance.