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Ítem Software platform for services in Colombian cities using the Living Labs approach(Ieee, 2011-12-05) Navarro Cadavid, AndrésComponent Based Software Engineering is a way to improve software modularization and to embed architectural concerns in the source code. Making explicit the architectural concerns in code helps to mitigate the problem of architectural erosion. The restructuring of legacy code with components in mind requires the use of tools to assess compliance with component programming principles. The property of communication integrity is one of the major principles for implementing software architectures. However, there is a paucity of tools for assessing the quality of code components. To cope with this issue, we define a component model in Java and a tool for identifying component types, which relies on a set of rules to statically check potential violations of the communication integrity property in Java source code. We illustrate its application with a case study and report the results of our experiments with it.Ítem SNR estimation for on body communications in MB OFDM Ultra Wide Band communications(Ieee Computer Society, 2010-04-12) Navarro Cadavid, AndrésIn this paper a new signal to noise ratio estimator algorithm based on the moments of the received signal is presented. The novel algorithm has been designed for Ultra Wide Band communications based on Multi Band Orthogonal Frequency Division Multiplexing (MB-OFDM) communication systems. In this proposal, we analyze the behavior of ultra wide band channels when the time and frequency fading have fast changes. Hence, different time coherence values were considered and all the frequency fading models are based in real measurements made in an anechoic chamber. It is remarkable that all the measurement campaigns were focused on body communications. We conclude that the proposed model can be used for SNR estimation in adaptive modulation and channel estimation and link quality control in MB OFDM systems. The performance of the proposed SNR estimation algorithm and its comparison with other SNR estimators was achieved through simulations based on real channel measurements.Ítem Método de evaluación y selección de herramientas de simulación de redes(Universidad Icesi, 2011-03-01) García Dávalos, Alexander; Vásquez Mejía, Andrés; Navarro Cadavid, Andrés; Escobar Paz, Lina MarcelaCurrently exists many software tools designed for Network Simulation (both commercial and Open source), situation that present an important decision to make for many researchers: Which tool use for network simulation? This paper proposes a method for evaluation/selection of network simulation tools, based in two key factors: ISO/IEC 9126-1 standard, which defines a quality model for software evaluation; and a cost function, based on values assigned to each one of the six items defined by ISO/IEC 9126-1. This method allows an expert based classification for each of the analyzed tools. We executed a test for NS-2 and NCTUns network simulation tools and obtained results was contrasted with technical reports and scientific articles related with network simulation tools.Ítem W-CDMA capacity analysis using GIS based planning tools and MATLAB simulation(IEEE, 2000-03-29) 1st International Conference on '3G Mobile Communication TechnologiesThe evolution of cellular systems towards third generation (3G) or IMT-2000 seems to have a tendency to use W-CDMA as the standard access method, as ETSI decisions have showed. However, there is a question about the improvements in capacity and the wellness of this access method. One of the aspects that worry developers and researchers planning the third generation is the extended use of the Internet and more and more bandwidth hungry applications. This work shows the performance of a W-CDMA system simulated in a PC using cover maps generated with DC-Cell, a GIS based planning tool developed by the Technical University of Valencia, Spain. The maps are exported to MATLAB and used in the model. The system used consists of several microcells in a downtown area. We analyse the interference from users in the same cell and in adjacent cells and the effect in the system, assuming perfect control for each cell. The traffic generated by the simulator is voice and data. This model allows us to work with coverage that is more accurate and is a good approach to analyse the multiple access interference (MAI) problem in microcellular systems with irregular coverage. Finally, we compare the results obtained, with the performance of a similar system using TDMA.Ítem Capacity analysis in CDMA systems using GIS based planning tools(EUROCOMM 2000. Information Systems for Enhanced Public Safety and Security. IEEE/AFCEA, 2010-04-14T15:43:12Z) Navarro Cadavid, AndrésWe show a simulation model for capacity analysis in mobile systems using a geographic information system (GIS) based tool, used for coverage calculations and frequency assignment, and MATLAB. The model was developed initially for “narrowband” CDMA and TDMA, but was modified for WCDMA. We show also some results for a specific case in “narrowband” CDMAÍtem Some parameters that affect CDMA capacity analysis. Results using GIS based simulation(3G Mobile Communication Technologies, 2001. Second International Conference, 2001-01-01T15:55:51Z) Cardona Marcet, Narcís; 2nd International Conference on 3G Mobile Communication TechnologyIn previous papers we describe a model for capacity analysis in CDMA systems using DC-Cell, a GIS based planning tool developed at Universidad Politecnica de Valencia, and MATLAB. We show some initial results of that model, and now, we are exploring different parameters like cell size, proximity between cells, number of cells in the system and “clustering” CDMA in order to improve the planning process for third generation systems. In this paper we show the results for variations of some of these parameters, specifically the cell size and number of cells. In CDMA systems is quite common to suppose only one carrier frequency for capacity estimation, and it is intuitive to think that for more base stations, mean more users. However the multiple access interference problem in CDMA systems could establish a limit for that supposition in a similar way that occurs in FDMA and TDMA systems.Ítem Up-Link/Down-Link capacity Unbalance analysis in UMTS using a GIS based Planning Tool and MATLAB simulation(WNCG 2003 Wireless Networking Symposium, 2003, Austin, 2003-01-01T16:44:31Z) Navarro Cadavid, AndrésCapacity analysis using simulation is not a new thing in literature. Most of the development process of UMTS standardization have used simulation tools; however, we thing that the use of GIS planning tools and matrix manipulation capacity of MATLAB can show us different scenarios and make a more realistic analysis. Some work is been doing in COST 273 in order to have more realistic scenarios for UMTS planning. Our work initially was centered in uplink analysis, but we are now working in downlink analysis, specifically in two areas: capacity in number of users for RT and NRT services, and Node B power. In this work we will show results for up-link capacity and some results for downlink capacity and BS power consumption.Ítem Análisis de capacidad en sistemas CDMA y WCDMA, usando herramientas de planificación basadas en GIS y dinámica poliédrica(Universitat Politècnica de València, 2003-10-17) Navarro Cadavid, Andrés; Cardona Marcet, NarcísEn este momento están entrando en operación los primeros sistemas UMTS en Europa, y están operando en varios países del mundo sistemas CDMA-2000 1xRTT, y aunque existen muchos trabajos publicados sobre la capacidad de estos sistemas, prácticamente todo lo existente se basa en el comportamiento de sistemas ideales que consideran celdas hexagonales o circulares y propagación basada en exponente inverso de la distancia y poco es lo que hay sobre el comportamiento real de dichos sistemas en entornos reales.
Sobre el exponente de pérdidas de propagación, es bien conocido que este afecta la capacidad de los sistemas CDMA; sin embargo hasta ahora no se ha considerado el efecto de los modelos de propagación que tienen en cuenta la difracción y otros fenómenos más cercanos a la realidad, y por lo tanto no se ha considerado el efecto del entorno urbano y el terreno sobre la capacidad real de los sistemas basados en CDMA.Ítem Simulation and analysis of compressed sensing technique as sampling and data compression and reconstruction of signals using convex programming(Institute of Electrical and Electronics Engineers Inc., 2016-12-14) Navarro Cadavid, Andrés; 21st Symposium on Signal Processing, Images and Artificial Vision, STSIVA 2016The information management has been treated primarily under the Nyquist sampling theory, but it is important to introduce new theories that replace deficiencies of what we know as the classical theory of sampling. These deficiencies create difficulties in data acquisition; this is a problem when large volumes of information are handled, in addition to the higher costs in storage and processing. This article presents the results obtained from the compressed sensing simulation technique applied to two types of signals. The aim of this paper was to simulate a communication system involving the data recovery applying the compressed sensing technique, analyzing sampling rates reduction, measuring the efficiency of the process and the behavior of the technique. The recovery of the signal is made using convex programming and using l1 norm minimization for recover the signals in the time domain. We used the L1Magic toolbox, which is a set of Matlab® functions used to solve optimization problems in this case with the l1eqpd function. As a summary of the obtained results, we checked the efficiency of the compressed sensing technique, minimum average rates for sampling the constructed signals, and the best performance of the technique to recover soft signals compared to non-differentiable signals. Additionally, the recovery results of an audio signal with the compressed sensing technique, by varying the sampling rate and checking the audibility of the signal, are presented. This allowed the testing of this technique in a real scenario, finding a good opportunity for the transmission of audio signals in a more efficient way.Ítem Statistical adjustment of empirical propagation path loss models to the COST 2100 Cali reference scenario(Antennas and Propagation Society International Symposium (APSURSI), 2012 IEEE, 2012-11-12) Navarro Cadavid, AndrésPropagation models used to plan outdoor wireless networks on urban environment, tend to include a high degree of empirical component. These are derived from the difficulties of accurately estimate the influence of obstacles, buildings and terrain in the signal path loss. Therefore, the final equation usually contains constants, and coefficients for the different terms, mainly obtained by statistical analysis of measurement sets, collected during drive tests on large areas of the city. Unfortunately, such results are only truly valid for the city or parts of the city on which the measurements were taken. They can also be considered appropriate for similar areas or cities at the most. If the areas are not similar enough however, a process of adjustment is necessary, leading to the finding of new constants and coefficients. The purpose of this paper is to discuss some of the findings during the process of statistically adjust the Okumura-Hata and Walfisch-Bertoni models to the Cali scenario, using measurements.
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