Modelo de referencia de laboratorios virtuales y aplicación a sistemas de teleeducación

El origen de esta tesis es encontrar respuestas a la siguiente pregunta: ¿De que forma se puede optimizar el uso de los equipos de laboratorio para que puedan ser utilizados por el máximo número de personas? La opción básica que se ha elegido es el control remoto de los instrumentos a través de internet. Con ello se consigue una accesibilidad total del laboratorio: a cualquier hora, en cualquier día, se pueden realizar medidas sencillamente con disponer de una conexión a internet. Partiendo de esta situación, se ha realizado un estudio de la evolución y situación actal de la instrumentación, de internet y de la teleeducación, los tres pilares en los que se apoya este trabajo. Se observa cómo la instrumentación está tendiendo a la conectividad global al comenzar a incorporar una conexión a red, y la posibilidad de transferir directamente resultados de medida o incluso el control directo del equipo a través de un navegador. Comienza una colaboración que se prevé estrecha entre internet y la instrumentación. La educación a distancia también está tomando un camino similar. El nuevo canal de comunicación que supone la red y la evolución de los ordenadores está permitiendo que se puedan conseguir entornos de trabajo para educación que incorporan desde el sencillo texto con hiperenlaces, herramienta básica del web, hasta transmisión en directo de clases, con vídeo, audio, transparencias e intercomunicación entre los usuarios. De esta forma, la distancia que separa al profesor de los estudiantes y a los estudiantes entre sí, queda minimizada por las capacidades de colaboración y diálogo existentes. A partir de aquí en la tesis se ha pasado al estudio de los instrumentos virtuales, las piezas básicas para el montaje de un laboratorio virtual. Se ha hecho una extensa investigación y clasificación de unos y otros lo cual ha permitido hacerse una idea de los elementos necesarios para la realización de un laboratorio virtual.Rodrigo Peñarrocha, VM. (2003). Modelo de referencia de laboratorios virtuales y aplicación a sistemas de teleeducación [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/7221Palanci

Performance of Dual Selection Combiners Over Correlated Nakagami-m Fading With Different Fading Parameters

This letter presents infinite series expressions for the outage probability, the probability density function (PDF), the average error probability for binary modulations, and average signal-to-noise ratio (SNR) of dual selection combiners (SC) over correlated fading with arbitrary fading parameters at each input of the combiner. The outage probability is calculated for both thermal noise and interference-limited scenarios. The results obtained for the outage probabilities specified for identical fading parameters at both branches of the combiner are contrasted with the results of other studies in the literature.Reig, J.; Rubio Arjona, L.; Rodrigo Peñarrocha, VM. (2006). Performance of Dual Selection Combiners Over Correlated Nakagami-m Fading With Different Fading Parameters. IEEE Transactions on Communications. 54(9):1527-1532. doi:10.1109/TCOMM.2006.881188S1527153254

On the Bivariate Nakagami-Lognormal Distribution and Its Correlation Properties

The bivariate Nakagami-lognormal distribution used to model the composite fast fading and shadowing has been examined exhaustively. In particular, we have derived the joint probability density function, the cross-moments, and the correlation coefficient in power terms. Also, two procedures to generate two correlated Nakagami-lognormal random variables are described. These procedures can be used to evaluate the robustness of the sample correlation coefficient distribution in both macro- and microdiversity scenarios. It is shown that the bias and the standard deviation of this sample correlation coefficient are substantially high for large shadowing standard deviations found in wireless communication measurements, even if the number of observations is considerable.This work was supported by the Spanish Ministerio de Ciencia e Innovacion TEC-2010-20841-C04-1.Reig, J.; Rubio Arjona, L.; Rodrigo Peñarrocha, VM. (2014). On the Bivariate Nakagami-Lognormal Distribution and Its Correlation Properties. International Journal of Antennas and Propagation. 2014:1-8. https://doi.org/10.1155/2014/328732S182014Rubio, L., Reig, J., & Cardona, N. (2007). Evaluation of Nakagami fading behaviour based on measurements in urban scenarios. AEU - International Journal of Electronics and Communications, 61(2), 135-138. doi:10.1016/j.aeue.2006.03.004Suzuki, H. (1977). A Statistical Model for Urban Radio Propogation. IEEE Transactions on Communications, 25(7), 673-680. doi:10.1109/tcom.1977.1093888Abu-Dayya, A. A., & Beaulieu, N. C. (1994). Micro- and macrodiversity NCFSK (DPSK) on shadowed Nakagami-fading channels. IEEE Transactions on Communications, 42(9), 2693-2702. doi:10.1109/26.317410Tjhung, T. T., & Chai, C. C. (1999). Fade statistics in Nakagami-lognormal channels. IEEE Transactions on Communications, 47(12), 1769-1772. doi:10.1109/26.809692Shankar, P. M. (2004). Error Rates in Generalized Shadowed Fading Channels. Wireless Personal Communications, 28(3), 233-238. doi:10.1023/b:wire.0000032253.68423.86Atapattu, S., Tellambura, C., & Jiang, H. (2011). A Mixture Gamma Distribution to Model the SNR of Wireless Channels. IEEE Transactions on Wireless Communications, 10(12), 4193-4203. doi:10.1109/twc.2011.111210.102115Reig, J., & Rubio, L. (2013). Estimation of the Composite Fast Fading and Shadowing Distribution Using the Log-Moments in Wireless Communications. IEEE Transactions on Wireless Communications, 12(8), 3672-3681. doi:10.1109/twc.2013.050713.120054Mukherjee, S., & Avidor, D. (2003). Effect of microdiversity and correlated macrodiversity on outages in a cellular system. IEEE Transactions on Wireless Communications, 2(1), 50-58. doi:10.1109/twc.2002.806363Zhang, R., Wei, J., Michelson, D. G., & Leung, V. C. M. (2012). Outage Probability of MRC Diversity over Correlated Shadowed Fading Channels. IEEE Wireless Communications Letters, 1(5), 516-519. doi:10.1109/wcl.2012.072012.120452Rui, Z., Jibo, W., & Leung, V. C. M. (2013). Outage probability of composite microscopic and macroscopic diversity over correlated shadowed fading channels. China Communications, 10(11), 129-142. doi:10.1109/cc.2013.6674217Abdel-Hafez, M., & Safak, M. (1999). Performance analysis of digital cellular radio systems in Nakagami fading and correlated shadowing environment. IEEE Transactions on Vehicular Technology, 48(5), 1381-1391. doi:10.1109/25.790511Shankar, P. M. (2009). Macrodiversity and Microdiversity in Correlated Shadowed Fading Channels. IEEE Transactions on Vehicular Technology, 58(2), 727-732. doi:10.1109/tvt.2008.926622MOSTAFA, M. D., & MAHMOUD, M. W. (1964). On the problem of estimation for the bivariate lognormal distribution. Biometrika, 51(3-4), 522-527. doi:10.1093/biomet/51.3-4.522Reig, J., Rubio, L., & Cardona, N. (2002). Bivariate Nakagami-m distribution with arbitrary fading parameters. Electronics Letters, 38(25), 1715. doi:10.1049/el:20021124Tan, C. C., & Beaulieu, N. C. (1997). Infinite series representations of the bivariate Rayleigh and Nakagami-m distributions. IEEE Transactions on Communications, 45(10), 1159-1161. doi:10.1109/26.634675Lien, D., & Balakrishnan, N. (2006). Moments and properties of multiplicatively constrained bivariate lognormal distribution with applications to futures hedging. Journal of Statistical Planning and Inference, 136(4), 1349-1359. doi:10.1016/j.jspi.2004.10.004Sørensen, T. B. (1999). Slow fading cross-correlation against azimuth separation of base stations. Electronics Letters, 35(2), 127. doi:10.1049/el:19990085Reig, J., Martinez-Amoraga, M. A., & Rubio, L. (2007). Generation of bivariate Nakagami-m fading envelopes with arbitrary not necessary identical fading parameters. Wireless Communications and Mobile Computing, 7(4), 531-537. doi:10.1002/wcm.386Lai, C. D., Rayner, J. C. W., & Hutchinson, T. P. (1999). Robustness of the sample correlation - the bivariate lognormal case. Journal of Applied Mathematics and Decision Sciences, 3(1), 7-19. doi:10.1155/s117391269900001

Path loss characterization for vehicular communications at 700 MHz and 5.9 GHz under LOS and NLOS conditions

In this letter, we present a path loss characterization of the vehicular-to-vehicular (V2V) propagation channel. We have assumed a path loss model suitable for vehicular ad hoc networks (VANETs) simulators. We have investigated the value of the model parameters, categorizing in line-of-sight (LOS) and non-LOS (NLOS) paths. The model parameters have been derived from extensive narrowband channel measurements at 700 MHz and 5.9 GHz. The measurements have been collected in typical expected V2V communications scenarios, i.e., urban, suburban, rural, and highway, for different road traffic densities, speeds, and driven conditions. The results reported here can be used to simulate and design the future vehicular networks.Fernández González, HA.; Rubio Arjona, L.; Rodrigo Peñarrocha, VM.; Reig, J. (2014). Path loss characterization for vehicular communications at 700 MHz and 5.9 GHz under LOS and NLOS conditions. IEEE Antennas and Wireless Propagation Letters. 13:931-934. doi:10.1109/LAWP.2014.2322261S9319341

Circularly polarized slotted waveguide array with improved axial ratio performance

This communication demonstrates experimentally the improvement in axial ratio performance when a slot is combined with a set of three parasitic dipoles instead of one. The analysis is performed in the context of slotted-waveguide arrays and SATCOM applications in Ka band, where a bandwidth specification as wide as 7.5% can be demanded.This work was supported in part by the Spanish MINECO under project BES-2014-067917 and in part by the European Space Agency under contract 400010860913NLUS - project LOCOMO.Ferrando Rocher, M.; Herranz Herruzo, JI.; Valero-Nogueira, A.; Rodrigo Peñarrocha, VM. (2016). Circularly polarized slotted waveguide array with improved axial ratio performance. IEEE Transactions on Antennas and Propagation. 64(9):4144-4148. https://doi.org/10.1109/TAP.2016.2586492S4144414864

Low-loss Circularly Polarized Periodic Leaky-Wave Antenna

(c) 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other worksThis letter presents a periodic leaky-wave array antenna with circular polarization at millimeter-wave frequencies. The antenna is designed on the low-loss planar Goubau transmission line to maximize the radiation efficiency of the antenna. The unit cell of the array is formed by four dipoles located on both faces of the Goubau line s substrate. A prototype has been fabricated and measured. Experimental results show an impedance bandwidth above 15% for S11 < - 10 and a 3-dB axial-ratio bandwidth of 7.6%. The radiation efficiency and maximum gain of the prototype are above 90% and 15.6 dBi, respectively, from 38 to 41 GHz. The maximum gain and the minimum axial ratio present the characteristic steering behavior of leaky-wave antennas.This work was supported by the Spanish Ministry of Education and Science (Ministerio de Educacion y Ciencia) under Projects TEC2010-20841-C04-01, TEC2013-47360-C3-3-P, and CSD2008-00068.Sánchez-Escuderos, D.; Ferrando Bataller, M.; Herranz Herruzo, JI.; Rodrigo Peñarrocha, VM. (2016). Low-loss Circularly Polarized Periodic Leaky-Wave Antenna. IEEE Antennas and Wireless Propagation Letters. 15:614-617. https://doi.org/10.1109/LAWP.2015.2463672S6146171

Experimental Rician K-factor characterization in a laboratory environment at the 25 to 40 GHz frequency band

[EN] In this work, an analysis of the Rician K-factor in a laboratory environment from 25 to 40 GHz has been carried out. The variation of the estimated K-factor has been assessed in frequency from a channel measurements campaign in both line-of-sight (LOS) and non-LOS (NLOS) conditions. Mean values of the K-factor ranging from 0.48 to 3.43 dB for LOS conditions, and from -5.54 to -0.56 dB for NLOS conditions, have been derived. The results reported here enable us to get insight into the propagation channel characteristics and can be of interest to evaluate the performance of fifth-generation (5G) networks in laboratory environments.This work has been funded in part by the Spanish Ministerio de Economia, Industria y Competitividad under the project TEC2017-86779-C2-2-R, and by COLCIENCIAS in Colombia.Bernardo-Clemente, B.; Fernández, H.; Rodrigo Peñarrocha, VM.; Reig, J.; Rubio Arjona, L. (2020). Experimental Rician K-factor characterization in a laboratory environment at the 25 to 40 GHz frequency band. IEEE. 1121-1122. https://doi.org/10.1109/IEEECONF35879.2020.9329738S1121112

Analysis of Small-Scale Fading Distributions in Vehicle-to-Vehicle Communications

[EN] This work analyzes the characteristics of the small-scale fading distribution in vehicle-to-vehicle (V2V) channels. The analysis is based on a narrowband channelmeasurements campaign at 5.9GHz designed specifically for that purpose.Themeasurements were carried out in highway and urban environments around the city of Valencia, Spain.Theexperimental distribution of the small-scale fading is compared to several analytical distributions traditionally used to model the fast fading in wireless communications, such as Rayleigh, Nakagami-&#119898;,Weibull, Rice, and &#120572;-&#120583; distributions. The parameters of the distributions are derived through statistical inference techniques and their goodness-of-fit is evaluated using the Kolmogorov-Smirnov (K-S) test. Our results show that the &#120572;-&#120583; distribution exhibits a better fit compared to the other distributions, making its use interesting to model the small-scale fading in V2V channels.This work has been funded in part by the Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia del Ministerio de Economia y Competitividad, Spain, TEC2013-47360-C3-3-P, and the Departamento Administrativo de Ciencia, Tecnologia e Innovacion COLCIENCIAS en Colombia.Rodrigo Peñarrocha, VM.; Reig, J.; Rubio Arjona, L.; Fernández González, HA.; Loredo, S. (2016). Analysis of Small-Scale Fading Distributions in Vehicle-to-Vehicle Communications. Mobile Information Systems. 2016:1-7. https://doi.org/10.1155/2016/9584815S17201

Small-Scale Fading Analysis of the Vehicular-to-Vehicular Channel inside Tunnels

[EN] We present a small-scale fading analysis of the vehicular-to-vehicular (V2V) propagation channel at 5.9 GHz when both the transmitter (Tx) and the receiver (Rx) vehicles are inside a tunnel and are driving in the same direction. This analysis is based on channel measurements carried out at different tunnels under real road traffic conditions. The Rice distribution has been adopted to fit the empirical cumulative distribution function (CDF). A comparison of the K factor values inside and outside the tunnels shows differences in the small-scale fading behavior, with the K values derived from the measurements being lower inside the tunnels. Since there are so far few published results for these confined environments, the results obtained can be useful for the deployment of V2V communication systems inside tunnels.The authors want to thank J. A. Campuzano, D. Balaguer, and L. Morag on for their support during the measurement campaign, as well as B. Bernardo-Clemente and A. VilaJimenez for their support and assistance in the laboratory activities. This work has been funded in part by Programa Estatal de Fomento de la Investigacion Cientifica y Tecnica de Excelencia delMinisterio de Economia y Competitividad, Spain, TEC2013-47360-C3-3-P, and Departamento Administrativo de Ciencia, Tecnologia e Innovacion COLCIENCIAS en Colombia.Loredo, S.; Del Castillo, A.; Fernandez, H.; Rodrigo Peñarrocha, VM.; Reig, J.; Rubio Arjona, L. (2017). Small-Scale Fading Analysis of the Vehicular-to-Vehicular Channel inside Tunnels. Wireless Communications and Mobile Computing (Online). 2017:1-6. https://doi.org/10.1155/2017/1987437S16201

Small-scale distributions in an indoor environment at 94GHz

[EN] In this paper, an extensive multiple-input multiple-output measurement campaign in a lab environment has been conducted at the 94GHz band. Using a vector network analyzer, updown converters, and omnidirectional antennas displaced in virtual arrays, we have obtained an estimation of the distribution parameters for the most usual distributions employed in the small-scale fading modeling, i.e., Rayleigh, Rice, Nakagami-m and -, by using statistical inference techniques. Moreover, in this scenario the best fit distribution to the experimental data is the Weibull distribution, using the Kolmogorov-Smirnov test. However, the - distribution provides the best fitting to the experimental results in terms of the lower tails of the distributions.This work was supported by the Ministerio de Economia y Competitividad MINECO, Spain (TEC2016-78028-C3-2-P) and by the European FEDER funds. Further information regarding the data obtained and included in this paper can be attained by contacting the author, Jose M. Molina ([email protected]).Reig, J.; Martinez-Ingles, M.; Molina-Garcia-Pardo, J.; Rubio Arjona, L.; Rodrigo Peñarrocha, VM. (2017). Small-scale distributions in an indoor environment at 94GHz. Radio Science. 52(7):852-861. https://doi.org/10.1002/2017RS006335S852861527Cudak, M., Ghosh, A., Kovarik, T., Ratasuk, R., Thomas, T. A., Vook, F. W., & Moorut, P. (2013). Moving Towards Mmwave-Based Beyond-4G (B-4G) Technology. 2013 IEEE 77th Vehicular Technology Conference (VTC Spring). doi:10.1109/vtcspring.2013.6692638Everitt, B. S., & Skrondal, A. (2010). The Cambridge Dictionary of Statistics. doi:10.1017/cbo9780511779633Helminger, J., Detlefsen, J., & Groll, H. (s. f.). Propagation properties of an indoor-channel at 94 GHz. ICMMT’98. 1998 International Conference on Microwave and Millimeter Wave Technology. Proceedings (Cat. No.98EX106). doi:10.1109/icmmt.1998.768215Moon-Soon Choi, Grosskopf, G., & Rohde, D. (s. f.). Statistical Characteristics of 60 GHz Wideband Indoor Propagation Channel. 2005 IEEE 16th International Symposium on Personal, Indoor and Mobile Radio Communications. doi:10.1109/pimrc.2005.1651506Kajiwara, A. (s. f.). Indoor propagation measurements at 94 GHz. Proceedings of 6th International Symposium on Personal, Indoor and Mobile Radio Communications. doi:10.1109/pimrc.1995.477099Maccartney, G. R., Rappaport, T. S., Sun, S., & Deng, S. (2015). Indoor Office Wideband Millimeter-Wave Propagation Measurements and Channel Models at 28 and 73 GHz for Ultra-Dense 5G Wireless Networks. IEEE Access, 3, 2388-2424. doi:10.1109/access.2015.2486778Marcum J. I. 1950 Table of Q functionsMartinez-Ingles, M.-T., Gaillot, D. P., Pascual-Garcia, J., Molina-Garcia-Pardo, J.-M., Rodríguez, J.-V., Rubio, L., & Juan-Llácer, L. (2016). Channel sounding and indoor radio channel characteristics in the W-band. EURASIP Journal on Wireless Communications and Networking, 2016(1). doi:10.1186/s13638-016-0530-7Rangan, S., Rappaport, T. S., & Erkip, E. (2014). Millimeter-Wave Cellular Wireless Networks: Potentials and Challenges. Proceedings of the IEEE, 102(3), 366-385. doi:10.1109/jproc.2014.2299397Reig, J., Martínez-Inglés, M.-T., Rubio, L., Rodrigo-Peñarrocha, V.-M., & Molina-García-Pardo, J.-M. (2014). Fading Evaluation in the 60 GHz Band in Line-of-Sight Conditions. International Journal of Antennas and Propagation, 2014, 1-12. doi:10.1155/2014/984102Thomas, H. J., Cole, R. S., & Siqueira, G. L. (1994). An experimental study of the propagation of 55 GHz millimeter waves in an urban mobile radio environment. IEEE Transactions on Vehicular Technology, 43(1), 140-146. doi:10.1109/25.282274Thomas, T. A., Vook, F. W., & Sun, S. (2015). Investigation into the effects of polarization in the indoor mmWave environment. 2015 IEEE International Conference on Communications (ICC). doi:10.1109/icc.2015.724851