Kahalo I. Improving the energy efficiency and the quality of service in the integrated LTE/Wi-Fi networks.

The thesis is devoted to solving the scientific and technical task of improving the energy efficiency and the quality of service in the integrated LTE/Wi-Fi networks by developing the method of adaptive unlicensed spectrum access, the method of radio resource planning and network structure design, as well as improving the algorithm of the link level queueing in the Wi-Fi network in order to tolerate short-term link failures during the transmission of the real-time video streams. In particular, the method of adaptive radio resources planning and integrated LTE/Wi-Fi network structure design based on the Voronoi diagram is proposed first time. The proposed method takes into account the spatial localization of the users that allows improving the service quality and the energy efficiency of the network up to 40%, by avoiding interference. The method of adaptive unlicensed spectrum access for the scenario of the Wi-Fi/LTE-U coexistence has been further improved to increase the radio resource utilization and the data rate in the LTE network by preventing the inter-system interference. The algorithm of link level queuing in the Wi-Fi network is developed to tolerate the short-term link failures during the transmission of multiple real-time video streams. The developed algorithm allows improving the quality of real-time video streaming over the integrated LTE/Wi-Fi network by 5-45% according to the MSE metric. The efficiency of the all aforementioned solutions has been evaluated using the developed simulation model. According to the simulation results, it was proven that the combination of the proposed method for frequency reuse among LTE cells, adaptive network structure design and the unlicensed spectrum utilization allowed to increase data rates for subscribers of integrated LTE/Wi-Fi network by 25% while mitigating the inter-system interference between Wi-Fi and LTE.