Research On Coverage Maximization Technology Of UAV Communication Platform In Emergency Scenario

Emergency communication scenarios have the characteristics of strong burst,which may lead to communication congestion or damage to ground basic communication facilities,and it is difficult to restore normal communication services in a short time.Unmanned aerial vehicles(UAVs)can be equipped with micro communication equipment as a low altitude communication platform.With its advantages of high flexibility,it can cover the emergency area at the first time.Due to the limited energy,scarce bandwidth resources and random user movement,the coverage of the UAV to emergency areas is seriously restricted.Larger emergency communication coverage and faster deployment speed can quickly ensure more users' normal communication and meet the needs of efficient rescue operations.Therefore,it is important to study the maximum coverage of the UAV communication platform in the emergency area.This thesis investigates the impact of UAV location deployment and power-bandwidth resource allocation on communication coverage.This thesis takes coverage of indoor users as a breakthrough,and establishes a communication model suitable for UAV to provide services for indoor users.Based on this model,the location deployment and resource allocation of UAVs covering indoor users are studied,taking account of user fairness and network stability.In view of the non normalized hybrid model caused by user's profit mobility,the maximum coverage of UAV to hybrid indoor outdoor users is further studied.The main contents and innovations of this thesis are as follows:(1)To solve the problem that the service performance of indoor and outdoor users is highly differentiated,a rapid energy-saving deployment strategy of UAV for indoor users is proposed.A signal transmission loss model that can be applied to outdoor-indoor communication is designed by considering the outdoor-indoor transmission path,outdoor transmission loss,through the wall loss and indoor transmission loss.Whenthe user's location information is unknown,a function relationship between the optimal location of the UAV and the length,width and height of the building is obtained by fitting a large amount of data.When the user's location information is known,the path loss is calculated accurately,and a fast deployment algorithm for Unmanned Aerial Vehicles Based on block coordinate descent is proposed.When multiple UAVs collaborate to cover multiple buildings,the control unit of the multi-UAV network is determined to enhance the active and robust of the multi-UAV network itself,while guaranteeing full coverage of indoor users.The simulation results show that the proposed convergence algorithm can quickly deploy the UAV and ensure that the UAV can complete the full coverage of indoor users with the minimum transmission power.(2)To solve the problem of poor stability of long-distance relay coverage network,a strategy of UAV deployment and resource allocation based on outage probability was proposed.The network stability is quantified as the outage probability,and the outage probability of the links between outdoor base stations and indoor users is studied.By optimizing the outdoor-indoor path loss model,a closed expression for the outage probability is derived in this thesis.Further,an UAV location-power-bandwidth allocation scheme based on fairness and a block coordinate descent algorithm are presented to decompose and iteratively optimize the original problem.The simulation results show that the proposed scheme can quickly optimize the deployment location,power allocation and bandwidth allocation to ensure that the UAV can cover indoor users with the minimum outage probability,and the difference of outage probability between different links is kept within 1%.(3)To solve the problem of transmission model mixing and low resource utilization caused by indoor users' profit oriented movement,a fast coverage scheme for Indoor-Outdoor-Iterative(IOI)optimization based on deployment location and resource allocation is proposed.The IOI scheme avoids building mixed transport models that cannot be normalized.A low computational complexity outdoor user distribution estimation method is presented based on user density and UAV height,and a three-dimensional(3D)location,power and bandwidth allocation scheme is further presented.Based on the relationship between the remaining resources and the resources needed by outdoor users,the corresponding algorithm is proposed in three cases to discuss the feasibility of the scheme.The simulation results show that the proposed algorithm can converge quickly,achieve the maximum coverage of the UAV for outdoor-in users,and ensure that the communication rate difference between users is less than 0.5%.