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Ítem A flexible mid-term frequency domain scheduler for resource allocation in Hetnets based on the SINR requested by users(Institute of Electrical and Electronics Engineers Inc., 2014-11-05) Navarro Cadavid, AndrésThis article solves the resource allocation problem for the downlink of a multi-cell, multiservice Wireless Mobile Communications System (WMCS) with heterogeneous architecture deployed into an urban environment using Orthogonal Frequency Division Multiple Access (OFDMA) in its physical level. The optimization model aims to equitably satisfy services to users by making an efficient use of the available resources using the Signal to Interference-plus-Noise Ratio (SINR). It is a Mixed Integer Nonlinear Programming (MINLP) model whose solution is complex to obtain directly. The proposed solution algorithm decouples the solution space of the problem and uses an iterative and distributed approach to implement a frequency-domain scheduler in the medium term that uses a global vision of the system to allocate resources trying to obtain the SINR required for all users (the proposed goal). Since it is not always possible to achieve the proposed goal, we take advantage of the elasticity of some of the services offered and incorporating the slack variable ΔPref to solve it. The approach allows selecting the frequency allocation strategy, the exploration focus of the search space and the system administrator's vision.Ítem Calibración Basada en Medidas para Modelos de Trazado de Rayos en 3D para Ambientes Exteriores Urbanos andinos(Universidad Icesi, 2012-04-01) Guevara Ibarra, Dinael; Navarro Cadavid, Andrés; Africano, María VictoriaDue to the complexity of a real situation, estimation of path loss using the ray-tracing method usually assumes one or three large classes of homogeneous materials to represent the building walls, building roofs and street floors in order to have a viable model of the 3D environment. However, in a real case, an outdoor environment consists of many buildings and streets made of heterogeneous materials. Additionally, the characterizations of these classes of materials are usually taken from research of other authors with specific materials on site and often not done for the frequency band of operation. We analyze the behavior of the statistical variation of standard deviation, correlation coefficient and the average error between the values of estimated and measured path loss data when considering various values of permittivity of these three classes. Finally, we adjust the values of permittivity, obtaining a reasonable improvement of ray tracing to estimate the path-lossÍtem A flexible mid-term frequency domain scheduler for resource allocation in HetNets based on the SINR requested by users(Elsevier, 2015-03-01) Pachón de la Cruz, AlvaroThis article treats the resource allocation problem for the downlink of a multi-cell, multiservice Wireless Mobile Communications System (WMCS) with heterogeneous architecture deployed into an urban environment using Long Term Evolution (LTE) and Orthogonal Frequency Division Multiple Access (OFDMA) in its physical level. The optimization model aims to satisfy services to users by making an efficient use of the available resources, and a fair frequency block allocation, using the Signal to Interference-plus-Noise Ratio (SINR). It is a Mixed Integer Nonlinear Programming (MINLP) model whose solution is complex to obtain directly. The proposed solution algorithm decouples the solution space of the problem and uses an iterative and semi-distributed approach to implement a frequency-domain scheduler in the medium term that uses a global vision of the system to allocate resources trying to obtain the SINR required for all users (the proposed goal). Since it is not always possible to achieve it, we take advantage of the elasticity of some of the services offered and incorporate a slack variable to solve it. The approach allows selecting the frequency allocation strategy, the exploration focus of the search space and the system administrator's vision. The results obtained show that the implementation that uses a coordinated frequency allocation obtains better results in the amount of users with full satisfaction and in the use of power when compared to implementations using other frequency allocation strategies. In scenarios with heterogeneous architecture, the combined effect of picocells and coordinated frequency allocation improves the value for the defined performance metrics.Ítem Global Resource Scheduler in a Mobile Communications System Featuring Heterogeneous Architecture(IEEE Latin America Transactions, 2015-11-01) Navarro Cadavid, AndrésEste artículo aborda el problema de la asignación dinámica de recursos en el enlace de bajada de un sistema de comunicaciones móviles (SCM) que utiliza multiplexión por división ortogonal de frecuencia (OFDMA, por “Orthogonal Frequency Divisiom Multiple Access”). Según Metha et al. [1], se trata de un problema complejo, constituido por tres tareas interrelacionadas: la selección y la asignación de los bloques de frecuencias a los usuarios, la asignación de los bits transportados en cada bloque y la asignación de potencia a cada bloque.