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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 Simulation of vertical handover algorithms with NCTUns(Society for Modeling and Simulation International, 2010-01-01) Navarro Cadavid, AndrésThis paper presents the simulation of Vertical Handover Algorithms (VHA) using NCTUns and tested them on scenarios with WiFi/GPRS or WiFi/WiMAX Mobile networks: The first evaluates parameters such as the network bandwidth, economic cost of the connection and the mobile node mobility and uses a cost function toevaluate candidate networks. The second one is based on application requirements such as bandwidth, latency and % packet loss rate. The third one organizes the nodes connections to balance the load on connection points, optimize battery consumption, or both. We developed several scripts in C and PERL language for inclusion in the tool like other components and use a NCTUns API to communicate with the simulation engine. In simulation scenario we use the multi-interface node for Intelligent Transportation System (ITS) networks or a node for each technology, but they behave as a single node with multiple interfaces. Simulations results are used to analyze the VHAs performance measuring handover delay, number of avoided handovers and computational cost of the algorithms.Ítem WLAN's access points java based automatic location tool(World Wireless Congress, 2007-05-23) Navarro Cadavid, AndrésIn this paper, we will show the development process and the results obtained with a Java based toll for automatic location of WLAN Access Points. We will describe the algorithm developed and the results obtained until the time we wrote the paper. Also we will discuss future work and possible evolution for the tool.Ítem Evaluation Model for Vertical Handoff Algorithms(IGI Global, 2012-02-01) Navarro Cadavid, AndrésThis chapter begins by introducing the problem of vertical handoff in heterogeneous wireless networks and illustrates the lack of a proper evaluation model to compare the different Vertical Handoff Algorithms (VHAs) that have been proposed in the literature over the last few years. In the following sections, a novel evaluation model for VHAs is introduced and described. The design of the new evaluation model is based on the multi-criteria evaluation methodology and criticality analysis, which permitted the model to be developed as a software component. The new proposed evaluation model is flexible in terms of the number of evaluation parameters and facilitates the analysis of VHAs by researchers. A specific case study considering some VHAs is presented, analyzed, and discussed in detail. The case study is used to compare the proposed evaluation model with another evaluation model (Ordinal Model) for VHAs.