Modeling And Analysis Of UAV-assisted D2D Emergency Communication Network

With the emergence and development of 5G emerging communication technologies,the integration of different communication means to form a new emergency communication system has become one of the current research hotspots.In many existing cellular communication technologies,unmanned aerial vehicle(UAV)can temporarily act as air base station when ground base stations are damaged,providing emergency communication services for users in disaster-stricken areas.Device-to-device(D2D)technology allows users to directly communicate with each other without relying on the ground infrastructure,which can improve the coverage of cellular networks.Therefore,the combination of UAV and D2 D communication technology can be used as one of the feasible technologies for emergency communication network.However,due to the limited spectrum resources and the lack of control base stations in emergency scenarios,the joint deployment of UAV and D2 D communications often shares spectrum for information transmission,resulting in more complex interference distribution in the network.In order to evaluate the specific impact of interference on the performance of UAV-assisted D2 D emergency communication network,this thesis conducts network modeling and performance analysis related research on the network scenario of D2 D communication multiplexing UAV uplink and downlink resources,which provides theoretical support for key network parameter configuration and technology selection.The specific work contents are as follows:(1)When D2 D communication and UAV downlink share the spectrum,a UAV-assisted D2 D communication network model based on directional antenna was proposed,in which the location distribution of UAV,D2 D users and downlink users were all established as Poisson point process models,which characterized the independence and randomness of the network nodes.based on stochastic geometry theory,derived the analytical expressions of the successful transmission probabilities for D2 D users and downlink users,and the Monte Carlo method is used for simulation verification.The result shows that compared with omnidirectional antennas,UAVs equipped with directional antennas can effectively improve network performance.At the same time,there exists the optimal height and density of UAV to maximize the system sum-rate.(2)When D2 D communication and UAV uplink share the spectrum,an interference suppression strategy based on the guard zone mechanism was proposed,and the interference in the network was reduced by setting up guard zones around the uplink users.A mixed model based on Poisson point process and Poisson hole process is analyzed.In order to simplify the calculation,the first-order statistical approximation method was used to dilute the Poisson hole process model to a homogeneous Poisson point process with the same density,and the successful transmission probability and user transmission rate of D2 D users and UAV uplinks in the network were deduced.The simulation results verify the accuracy of the theoretical formula,and the proposed guard zone mechanism can improve the users’ successful transmission probability,but with the increase of the protection radius,the system sum-rate are also decreasing.It is necessary to select the optimal guard area radius according to the service quality requirements of D2 D users and UAV uplink users.The theoretical analysis and performance evaluation of the emergency communication network in which the UAV and D2 D communication share the spectrum are carried out in this dissertation,and two theoretical analysis methods that can reduce network interference are proposed for different network scenarios,which can provide theoretical insights for the design and application of emergency communication networks.