In the case of densely distributed unmanned aerial vehicle (UAV), an inter-node interference degrades the received signal to interference noise ratio (SINR). In this paper, we focused on the interference effects of densely distributed nodes so that variation of transmission efficiency can be numerically analyzed. Simulation results show that the received SINR highly depends on the antenna directivity so that the required bandwidth can be reduced with sharp beam pattern. Increasing the transmit power, however, improves the transmission efficiency very slightly due to the interference limited region of highly distributed UAV. When the ground station (GS) is located in the random position, the larger bandwidth is required to guarantee the QoS.