Performance Analysis of Space-Air-Ground Integrated Network (SAGIN): UAV Altitude and Position Angle

With the explosive growth of mobile data traffic, the Space-Air-Ground integrated network (SAGIN) has attracted the attention of academia and industry. As the communication infrastructure in the air network of the SAGIN system, Unmanned Aerial Vehicles (UAVs) are considered the air relay nodes to access ground and space networks. Due to the mobility of satellites in the space network, the formed variable position angle between the UAV and the satellite and the fixed UAV altitude can reduce the air-to-space transmission capability. Moreover, a UAV’s battery is usually very limited, which may cause SAGIN transmission energy interruptions when the battery runs out. To address these issues in the SAGIN environment, we propose an integrated UAV channel fading and UAV energy consumption model to analyze the transmission performance. Based on the network performance analysis results, we derive the optimal UAV altitude expression. The numerical results verify the accuracy of the derived expressions and evaluate the impact of some key parameters on the optimal UAV altitude in the SAGIN uplink.