Examinando por Autor "Pachón de la Cruz, Alvaro"

Mostrando 1 - 7 de 7

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, Andrés
This 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.
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, Alvaro
This 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.
Aplicación de la metáfora de la colonia de hormigas en la administración de direcciones en redes móviles ad hoc
(Universidad Icesi, 2009-08-18T21:00:06Z) Veiga, Manuel Fernández; Pachón de la Cruz, Alvaro
Address management is a critical process in a network, because any node wishing to make part of the network must first obtain an address. Address management in MANETs poses particular challenges, due to their operation conditions, their dynamic topology and the unique events that take place inside them. This article presents an approach for solving the address management problem in this environment, using the self-organization and emergency principles governing the behavior of social insect colonies, particularly ant colonies. The article presents results that evaluate the proposal’s validity and efficiency through several scenarios. Three fundamental aspects were evaluated: Model functionality, efficiency and impact on user applications. The obtained results show the proposed model is able to identify, manage and solve all the events related to address management in a MANET, in an efficient manner.
Evolución de los sistemas móviles celulares GSM
(Universidad Icesi, 2006-07-28) Pachón de la Cruz, Alvaro
This paper presents the cellular systems architecture evolution. It identifies the structural components included in every stage of this evolution, describing their main functions and the aditions and/or modifications that they make over the cellular system network architecture.
La evolución en la arquitectura de las redes
(Universidad Icesi, 2006-07-28) Pachón de la Cruz, Alvaro
Los desarrollos tecnológicos y las siempre cambiantes realidades de la organización se han convertido en agentes que han obligado a los diseñadores a repensar la estructura de la red. El incremento en el número de usuarios y en el número de aplicaciones que utilizan la red incrementó el tráfico a volúmenes nunca antes sospechados, se hizo entonces necesario concebir su estructura como una estructura jerárquica y modular, con diferentes requerimientos de capacidad y desempeño en cada nivel, y obligó a entender su diseño como un proceso. En este artículo nos proponemos presentar la evolución que ha tenido la arquitectura de una red para responder a los frecuentes cambios a los que se ven expuestas las organizaciones en las que existen.
Mid-Term frequency domain scheduler for resource allocation in wireless mobile communications systems.
(Elsevier Science, 2017-01-01) Garcia-Palomares, Ubaldo M.; Pachón de la Cruz, Alvaro
This article approaches the dynamic resource allocation problem for the downlink of a wireless mobile communication system (WMCS). The article defines the architecture and functions of the global resource scheduler, as well as the quality index for scheduling, the signal to interference-plus-noise ratio (SINR). The proposed approach divides the scheduling task into two components: a distributed one, with local, short-term scope; and a centralized one, with global, medium-term scope. The optimization model considers a set of slack variables for guaranteeing feasibility. This allows the service provider to fully satisfy the users' service demands. The model type is mixed, non-linear, which demands large computational power for an exact solution. So an approximate strategy is used, in order to decouple the search space.
Modelos de comportamiento de las redes vehiculares en sus escenarios más representativos, utilizando simulación en la herramienta NCTUns
(Universidad Icesi, 2010-11-25T21:51:49Z) Nieto, Carlos Felipe; Pachón de la Cruz, Alvaro; Velasco Vivas, María Lucía
Vehicular networks allow drivers and passengers in moving vehicles to communicate from vehicle to vehicle, or from vehicle to a existing infrastructure, without the need for additional hardware. The main goals for these networks are to improve road safety and transportation efficiency. This article briefly describes the state-of-the-art and new achievements in the vehicular network field, and shows the analysis of the behavior of such networks through the use of simulation models deployed in the NCTUns simulation tool, considering the layout of typical cities in Colombia.