Temporal Correlation Modeling And Performance Analysis Of The UAV Networks

As the aerial base station,unmanned aerial vehicles(UAVs)can be deployed as an effective supplement to the existing ground cellular network,so as to implement coverage/capacity enhancement and meet the high dynamic service requirements of blind and hot spots.In the UAV network,the deployment of UAVs will be affected by the range of the target area and the user’s dynamic traffic demands in the area.Moreover,due to the conversion of line-of-sight(LOS)and non-line-of-sight(NLOS)links and the change of obstructions,three-dimensional air-to-ground(A2G)channel fluctuates in time.In addition,the high dynamics of UAVs lead to changes in the spatial distribution of UAV,which makes the rate fluctuations more severe.Utilizing tool of stochastic geometry,this paper models temporal correlation to measure the degree of fluctuation of the network state between different time slots,and time statistical performance indicators are quantified to more accurately characterize network performance at the user.The main contributions of this article are summarized as follows:(1)A finite UAV network with non-uniform PPP based on the twodimensional Random WayPoint model is proposed,and it is derived that the exact expressions of interference correlation coefficient and joint coverage probability in two slots at the typical user,which are used to analyze the time-varying nature of the interference topology and the temporal dependence of network coverage performance between different time slots.Theoretical results show that the non-uniform UAV distribution makes temporal correlation location-dependent.(2)Aiming a correlation of the occlusion effect on the air-to-ground link in the UAV network,the shadow fading model of the threedimensional space channel is proposed in order to measure the correlation of the occlusion effect.To be specific,the correlation coefficient of shadow fading is calculated to quantify the correlation of the occlusion effect.On this basis,an analysis framework of the temporal correlation of the UAV network with occlusion effect is proposed.Theoretical results show the influence of the correlation of shadow fading on the temporal correlation of channel and network topology in the UAV network.(3)The LOS and NLOS probabilistic transmission models are used to model the time-varying A2G channel,and considering the constraints of the target area on the UAV deployment,the UAV networks are modeled as Matern cluster processes.On the basis,signal and interference correlation coefficients are derived to quantify the fluctuations of the link and topology respectively.Furthermore,because of invalidation of instantaneous performance metrics,the long-term average performance indicators are modeled to accurately quantify network coverage and capacity performance.Theoretical and simulation results reflect the effect of UAV deployment parameters on large-scale performance indicators,and can be used to guide the actual deployment of UAVs.