Radio Resource Management For Heterogeneous Cellular Network Under Assistance Of Unmanned Aerial Vehicle Swarm

With the rapid development of various smart devices,the types and number of these smart terminal devices in the next generation wireless communication network will increase sharply.At the same time,the access of these smart de-vices also brings more diverse types of services.These conditions are contin-ually increasing the burden on cellular networks.Especially when faced with natural disasters or sudden regional service surges,cellular networks among these areas will suffer an even greater crisis because the terrestrial wireless communication infrastructures may be destroyed or overloaded.Considering the advantages of unmanned aerial vehicle(UAV)compared to other emergen-cy communication methods,this thesis will consider deploying the UAV based aerial base station(ABS)to solve the signal coverage problem in these areas and provide access services for user terminals in these areas.However,the efficient deployment of ABS still faces many challenges.This thesis explores the radio resource management of UAV-assisted cellu-lar networks,focusing on solving the resource management problems when employing millimeter-wave(mmWave)transmission technology and wireless backhauling technology to UAV platforms.Moreover,this thesis also studies the cooperated resource scheduling method in such heterogeneous networks.The chapters are organized according to the general hierarchy of 'architecture design-technical solutions'.The research contents are introduced in the order of‘background and needs-theories and methods-experiment and verification'.The innovations and contributions of this thesis are mainly included in four aspects.1.Resource management architecture for mm Wave enabled ABS swarm networkFocusing on the problems brought by the combination of UAV platfor-m and mm Wave transmission technology,this thesis analyzes the interference environment,the energy efficiency optimization,and the bilateral mobility be-tween UAV platform and users.To solve these challenges,this thesis intro-duces a hierarchical UAV resource management architecture.In addition,a dynamic 3D interference graph method is introduces to solve the interference problem of the strong dynamics of the UAV network.Meanwhile,five typical resource management scenarios are proposed.The simulation evaluations of these five scenarios imply that using mmWave on the UAV platform is feasi-ble but also opportunistic.This thesis is to provide a reference for solving the problem of radio resource management when deploying UAV platforms in sce-narios of disaster relief,Internet of Things and cellular network enhancement.2.Backhaul link optimization method for ABS swarm assisted cellular networkFocusing on the problem that the ABS must adopt wireless backhaul and the complex motion characteristics of the UAV will seriously hamper the per-formance of the backhaul link,this thesis proposes an efficient mmWave beam alignment method.First,the flight dynamics theory is used to analyze the influ-ence of UAV on the normal offset of the phased array antenna under different flight modes.Then,we model and analyze the impact of the angular offset on beam misalignment probability.Finally,a fast beam alignment method based on cross entropy theory is proposed.Software simulation and test-bed simula-tion results show that the proposed beam alignment method can greatly reduce the impact of the UAV flight attitude on the performance of the mmWave back-haul link.3.Joint access and backhaul resource management method for ABS swarm assisted cellular networkFocusing on the problem of serious interference between the user access side and the ABS backhaul side,this thesis introduces the joint resource man-agement method for access and backhaul.First,this thesis analyzes the in-terference environment of the three proposed backhaul modes considering the different propagation characteristics of LoS and NLoS respectively.Then,the considered problem is formulated as an optimization of achievable rate.We derive the optimal solutions for the involved three modes respectively,and the closed-form optimal value for each mode is acquired.The simulation results indicate that by the way of backhauling to the tethered UAV,link performance and system throughput of entire system are improved.4.A matching based collaborative resource scheduling method for hetero-geneous networksFocusing on the resource scheduling problem in heterogeneous network environment where multiple access modes and various service demands are co-existing,this thesis proposes a matching based collaborative resource schedul-ing method.First,this thesis models the problem on the network side as a matching game problem,and the stable matching relationship between net-work resources and traffic-flows is acquired by the proposed improved delay acceptance algorithm.After that,the problem on the user side is modeled as a multi-objective optimization problem.Further,by using the obtained matching relationship,this thesis proposes an iterative algorithm to solve the optimiza-tion problem on the user side.Both simulation results of software simulation and test-bed show that the proposed resource scheduling strategy can effective-ly ensure the stability of the networks and at the meantime satisfy the needs of users.