http://repositorio.ufc.br/handle/riufc/479 2026-04-06T16:51:48Z http://repositorio.ufc.br/handle/riufc/70647 Título: Dynamic e-ICIC using moving average crossover Autor(es): Melo, Yuri Victor Lima de; Sousa Junior, Vicente Angelo de; Maciel, Tarcísio Ferreira Abstract: Heterogeneous Networks (HetNets) are considered a technology option capable of improving system capacity and spatial spectrum reuse. However, high spectrum reuse causes high inter-cell interference among macro and small cells. Almost Blank Subframe (ABS) is a method of the Enhanced Inter-Cell Interference Coordination (e-ICIC) framework proposed for LTE systems as a means to mitigate interference among macro and small cells. ABS mutes some of macro cell transmissions in selected subframes to reduce interference to small cells, orthogonalizing macro and small cell transmissions in time-domain. In this work, we use Moving Average Crossover (MAC) based on trading know-how to propose a new dynamic ABS e-ICIC algorithm. Using system-level simulations, we attest that the proposed algorithm outperforms traditional e-ICIC by 6.4% in terms of capacity. Tipo: Artigo de Periódico 2019-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/70646 Título: Resource allocation for energy efficiency and QoS provisioning Autor(es): Mauricio, Weskley Vinicius Fernandes; Lima, Francisco Rafael Marques; Abrão, Taufik; Maciel, Tarcísio Ferreira; Sousa, Diego Aguiar Abstract: In this paper, we formulate and solve two Energy Efficiency (EE) problems, namely the Power Minimization Problem (PMP) and the Maximization of Energy Efficiency Problem (MEEP), for a wireless system using power and frequency resource allocation considering Quality of Service (QoS) requirements and multiple services. Despite those problems are nonlinear, they can be converted into Integer Linear Problems (ILPs). Therefore, the optimal solution for both PMP and MEEP can be obtained by well-known methods. Additionally, we propose two fast suboptimal algorithms as to avoid the high computational complexity of obtaining optimal solution for MEEP. Our results show that the MEEP has a better trade-off between transmitted data rate and power saving than the PMP solution. Moreover, the suboptimal algorithms present good performance compared to the optimal solution for moderated loads but with a much lower computational complexity, thus achieving a remarkable trade-off between performance and computational complexity. Tipo: Artigo de Periódico 2019-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/70645 Título: SDMA grouping based on unsupervised learning for multi-user MIMO systems Autor(es): Costa Neto, Francisco Hugo; Maciel, Tarcísio Ferreira Abstract: In this study, we investigate a spatial division multiple access (SDMA) grouping scheme to maximize the total data rate of a multi-user multiple input multiple output (MU-MIMO) system. Initially, we partition the set of mobile stations (MSs) into subsets according to their spatial compatibility. We explore different clustering algorithms, comparing them in terms of computational complexity and capability to partition MSs properly. Since we consider a scenario with a massive arrange of antenna elements and that operates on the mmWave scenario, we employ a hybrid beamforming scheme and analyze its behavior in terms of the total data rate. The analog and digital precoders exploit the channel information obtained from clustering and scheduling, respectively. The simulation results indicate that a proper partition of MSs into clusters can take advantage of the spatial compatibility effectively and reduce the multi-user (MU) interference. The hierarchical clustering (HC) enhances the total data rate 25% compared with the baseline approach, while the density-based spatial clustering of applications with noise (DBSCAN) increases the total data rate 20%. Tipo: Artigo de Periódico 2020-01-01T00:00:00Z http://repositorio.ufc.br/handle/riufc/70643 Título: A semi-distributed approach for uplink max-min energy efficiency optimization with minimum user satisfaction and adjacency constraints Autor(es): Braga Júnior, Iran Mesquita; Lima, Francisco Rafael Marques; Maciel, Tarcísio Ferreira; Monteiro, Victor Farias Abstract: Maximizing energy efficiency is one of the pillars of modern networks. In this context, we consider in this letter a nonlinear max-min energy efficiency problem in the uplink of wireless networks. Due to the problem nonlinearity we resort to epigraph form so as to obtain an integer linear problem and to propose a centralized optimal solution for it using a branch-and-bound algorithm. Also because distributed solutions are useful to deal with high computational processing and scalability problems, we propose a low-complexity semi-distributed solution for the problem using a specific signaling scheme. Simulations show that the proposed semi-distributed solution performs closely to the centralized optimal scheme and outperforms state-of-the-art algorithms in terms of energy efficiency and outage rate. Tipo: Artigo de Periódico 2021-01-01T00:00:00Z