Optimization of frequency resources and transmit power for 4G and 5G networks with qos constraints

• Ano de defesa: 2019
• Autor(a) principal: Braga Júnior, Iran Mesquita
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Área do conhecimento CNPq: CNPQ::ENGENHARIAS
• Link de acesso: http://repositorio.ufc.br/handle/riufc/79404

The current cellular systems are capable of providing several data services besides traditional voice call service, becoming extremely popular worldwide. Consequently, the data traffic in these networks have increased considerably in the last years and tends to increase even more in the next years. Currently, there is a huge expectation for the 5th Generation (5G) networks implementation since these systems should promises to achieve high data rates and provide connections to a huge number of devices. However, 4th Generation (4G) networks play and will still play an important role in mobile systems, until 5G networks is fully diffused. Thus, at least in the coming years, there will be a need to develop methods that aim to improve the existing 4G networks, as well as to deal with the new requirements of the 5G networks. In order to achieve high data rates, 4G networks have applied many improvements in radio access network. For LTE - Advanced (LTE-A) systems, one of these improvements was the adoption of Orthogonal Frequency Division Multiple Access (OFDMA) and Single Carrier - Frequency Division Multiple Access (SC-FDMA) as multiple access schemes for uplink and downlink transmissions of mobile networks. On the other hand, 5G networks should deal with a set of new use cases that require new approaches, such as Full-Duplex (FD), massive Multiple Input Multiple Output (MIMO) and millimeter Wave (mmWave). FD arises as a promising technology since it has the potential to double the system capacity without need for additional spectrum. Moreover, Radio Resource Allocation (RRA) is a crucial functionality in mobile networks since RRA algorithms are responsible for managing the system resources, such as power and frequency spectrum which in general are scarce. In addition, RRA algorithms can be used to improve the spectral and energy efficiency of mobile networks, as well as to satisfy Quality of Service (QoS) requirements. Therefore, we study in this thesis the use of RRA in mobile networks in order to assure an efficient use of the system resources and to guarantee a given QoS. Specifically, we split this work in two parts. In the first, we model RRA as an optimization problem that consist of maximizing the energy efficiency subject to minimum satisfaction per service in uplink Long Term Evolution (LTE) system using SC-FDMA. In the second part, we focus on new approaches for 5G networks, modeling RRA as an optimization problem that consist of maximizing the total data rate subject to QoS constraints in FD networks. As main contributions we have the characterization of the optimal solutions, low complexity heuristic solutions, performance evaluations by means of computational simulations and, finally, the complexity analysis of the involved algorithms.