Maksymyuk T. Increasing the energy and the spectral efficiency of fifth generation heterogeneous mobile networks

The thesis is devoted to solving an actual scientific task of developing models and algorithms for throughput increasing in heterogeneous mobile networks with conditions of limited spectral resources and developing models to design the multi-tier structure of heterogeneous network during network planning stage to support throughput requirements while ensuring the minimal level of interference. Current stage and of development trends of mobile networks towards fifth generation standards has been studied in details. Main limiting factors for heterogeneous mobile networks deployment have been determined such as interference, handover complexity, necessity of centralized radioresources management, backhaul complexity and absence of existing models for structure-functional synthesis of multi-tier cellular infrastructure. Existing technical solutions for 5G heterogeneous networks have been classified such as network densification, spectral aggregation, coordinated multi-point, D2D, utilization of millimeter waves, multi-antenna systems, software defined radio access networks, etc. The model of heterogeneous network convergence, which takes into account the interference between co-channel D2D domains to support necessary signal-to-interference plus noise ratio and to increase the spectral efficiency of heterogeneous network. Using the multi-hop routes for D2D domains based on the proposed model of air interfaces convergence allows to decrease number of requests to base station that additionally increase the spectral efficiency by 4% due to less signaling data. Based on the proposed model the method of content replication was developed that allows to increase the throughput utilization efficiency by 7%. The task of interference avoidance between D2D domains has been solved by introducing the developed coordinated multi-point method with joint transmission between cells and D2D domains. Based on this method an algorithm was developed and simulations have been conducted, that allows to increase the spectral efficiency by 83% and 29% for cells and D2D domains respectively. The task of multi-tier heterogeneous network design has been solved by introducing fractal geometry model of cellular infrastructure. Developed model allows resource planning by calculations of scale-invariant geometric pattern. Based on the proposed model, the method of centralized dynamic reconfiguration of multi-tier cellular infrastructure that allows to improve process of spectral resources management and increase the spectral and energy efficiency of heterogeneous network.