On Simple Estimators of the alpha-mu Fading Distribution

In this letter, new estimators of the alpha-mu distribution are derived based on the skewness of the logarithmic alpha-mu distribution using the moments method. This distribution has been recently proposed to model the received field strength in nonlinear propagation mediums. Therefore, simple and computationally efficient estimators are required to infer the parameters of the received signal amplitude distribution in nonlinear wireless communication propagation channels. The performance of these new estimators is compared to that obtained with the estimators calculated with the moments method of the alpha-mu distribution by solving numerically transcendental equations. These estimators are easily evaluated with simple expressions.Reig, J.; Rubio Arjona, L. (2011). On Simple Estimators of the alpha-mu Fading Distribution. IEEE Transactions on Communications. 59(12):3254-3258. doi:10.1109/TCOMM.2011.080111.090223S32543258591

Estimation of the composite fast fading and shadowing distribution using the log-moments in wireless communications

In this work, we propose a framework to obtain estimators from a variety of distributions used in composite fast fading and shadowing modeling with applications in wireless communications: the Suzuki (Rayleigh-lognormal), Nakagami-lognormal, K (Rayleigh-gamma), generalized-K (Nakagami-gamma) and alpha-mu; (generalized gamma) distributions. These estimators are derived from the method of moments of these distributions in logarithmic units, usually known as log-moments. The goodness-of-fit of these estimators to experimental distributions has been checked from a measurement campaign carried out in an urban environment. Moreover a new method to separate fast fading and shadowing based on the Rathgeber procedure is proposed. The results conclude that the best-fitting distribution to the measurements is the Nakagami-lognormal. Also, the alpha-mu; distribution provides an acceptable matching with the advantage of its simplicity.The authors would like to thank the editor and reviewers their valuable comments which have enriched the quality of this paper. We would also express our gratitude to Dr. C. S. Withers, retired research statistician from the Applied Maths Group at Industrial Research Ltd, Lower Hutt, New Zealand, for his revision of the paper and his estimable remarks. This work has been funded in part by the Spanish Ministerio de Ciencia e Innovacion (TEC-2010-20841-C04-1).Reig, J.; Rubio Arjona, 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. https://doi.org/10.1109/TWC.2013.050713.120054S3672368112

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

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

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

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-𝑚,Weibull, Rice, and 𝛼-𝜇 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 𝛼-𝜇 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

The Folded Normal Distribution: A New Model for the Small-Scale Fading in Line-of-Sight (LOS) Condition

(c) 2019 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 works.[EN] In this paper, a novel form of the folded normal (FN) distribution has been proposed to model the small-scale fading in wireless communications. From a multiple-input multiple-output (MIMO) measurement campaign conducted in a lab environment with the line-of-sight (LOS) conditions at both the 60 and the 94 GHz bands, the authors obtain the parameters of the Rician, FN, and kappa-mu distributions. These parameters have been calculated by using the least square (LS) approximation and with techniques of statistical inference. The FN distribution provides the best fitting to the experimental results using the Kolmogorov-Smirnov (K-S) test for the inferred estimators with values of the ful llment of 100% and 69.82% at the 60 and 94 GHz bands, respectively, for a significance level of 1%.This work was supported by the Ministerio de Economia, Industria y Competitividad of the Spanish Government under the national projects TEC2017-86779-C2-2-R and TEC2016-78028-C3-2-P, through the Agencia Estatal de Investigacion (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER).Reig, J.; Rodrigo Peñarrocha, VM.; Rubio Arjona, L.; Martínez-Inglés, MT.; Molina-García-Pardo, JM. (2019). The Folded Normal Distribution: A New Model for the Small-Scale Fading in Line-of-Sight (LOS) Condition. IEEE Access. 7:77328-77339. https://doi.org/10.1109/ACCESS.2019.2921340S7732877339