The impact of shadowing and the severity of fading on the first and second order statistics of the capacity of OSTBC MIMO Nakagami-lognormal channels

This article presents a thorough statistical analysis of the capacity of orthogonal space-time block coded (OSTBC) multiple-input multiple-output (MIMO) Nakagami- lognormal (NLN) channels. The NLN channel model allows to study the joint effects of fast fading and shadowing on the statistical properties of the channel capacity. We have derived exact analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the capacity of MIMO NLN channels. It is observed that an increase in the MIMO dimension or a decrease in the severity of fading results in an increase in the mean channel capacity, while the variance of the channel capacity decreases. On the other hand, an increase in the shadowing standard deviation increases the spread of the channel capacity, however the shadowing effect has no influence on the mean channel capacity. We have also presented approximation results for the statistical properties of the channel capacity, obtained using the Gauss-Hermite integration method. It is observed that approximation results not only reduce the complexity, but also have a very good fitting with the exact results. The presented results are very useful and general because they provide the flexibility to study the impact of shadowing on the channel capacity under different fading conditions. Moreover, the effects of severity of fading on the channel capacity can also be studied. The correctness of theoretical results is confirmed by simulations

The impact of shadowing and the severity of fading on the first and second order statistics of the capacity of OSTBC MIMO Nakagami-lognormal channels

Published version of an article in Wireless Personal Communications (2011), 1-16. Also available from the publisher at http://dx.doi.org/10.1007/s11277-011-0275-xThis article presents a thorough statistical analysis of the capacity of orthogonal space-time block coded (OSTBC) multiple-input multiple-output (MIMO) Nakagami- lognormal (NLN) channels. The NLN channel model allows to study the joint effects of fast fading and shadowing on the statistical properties of the channel capacity. We have derived exact analytical expressions for the probability density function (PDF), cumulative distribution function (CDF), level-crossing rate (LCR), and average duration of fades (ADF) of the capacity of MIMO NLN channels. It is observed that an increase in the MIMO dimension or a decrease in the severity of fading results in an increase in the mean channel capacity, while the variance of the channel capacity decreases. On the other hand, an increase in the shadowing standard deviation increases the spread of the channel capacity, however the shadowing effect has no influence on the mean channel capacity. We have also presented approximation results for the statistical properties of the channel capacity, obtained using the Gauss-Hermite integration method. It is observed that approximation results not only reduce the complexity, but also have a very good fitting with the exact results. The presented results are very useful and general because they provide the flexibility to study the impact of shadowing on the channel capacity under different fading conditions. Moreover, the effects of severity of fading on the channel capacity can also be studied. The correctness of theoretical results is confirmed by simulations

Extended Generalized-K (EGK): A New Simple and General Model for Composite Fading Channels

In this paper, we introduce a generalized composite fading distribution (termed extended generalized-K (EGK)) to model the envelope and the power of the received signal in millimeter wave (60 GHz or above) and free-space optical channels. We obtain the first and the second-order statistics of the received signal envelope characterized by the EGK composite fading distribution. In particular, expressions for probability density function, cumulative distribution function, level crossing rate and average fade duration, and fractional moments are derived. In addition performance measures such as amount of fading, average bit error probability, outage probability, average capacity, and outage capacity are offered in closed-form. Selected numerical and computer simulation examples validate the accuracy of the presented mathematical analysis.Comment: Composite fading distribution, generalized-K distribution, probability density function, cumulative distribution function, fractional moments, level crossing rate, amount of fade duration, moments, amount of fading, average bit error probability, average capacit

Statistical analysis of the capacity of mobile radio channels

Doktorgradsavhandling i informasjons- og kommunikasjonsteknologi, Universitetet i Agder, Grimstad, 201

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

Level crossing rate of SC receiver over gamma shadowed Weibull multipath fading channel

U ovom radu je razmotren bežični telekomunikacijski sustav sa SC prijemnikom koji radi u prisustvu Weibull-ovog fedinga i Gamma sjenke. Utjecaj Weibull-ovog fedinga na primljeni signal se ogleda u promjeni anvelope signala, a utjecaj Gamma sjenke u promjeni snage izlaznog signala. SC prijemnik se koristi za smanjenje utjecaja fedinga i sjenke na karakteristike sustava. Izraz za srednji broj osnih presjeka izlaznog signala iz SC prijemnika je izveden u zatvorenom obliku. Dobiveni rezultati se mogu koristiti za izračunavanje prosječnog trajanja otkaza bežičnog sustava. Numerički rezultati su predstavljeni grafički, kako bi se prikazao utjecaj parametara fedinga i sjenke na karakteristike sustava.The wireless telecommunication system consisting of selection combining (SC) receiver which works in Gamma shadowed Weibull multiple-faded channel is discussed in this work. The received signal suffers Weibull small scale fading which leads in variation of the signal envelope and Gamma large scale fading which results in variation of the SC receiver output signal envelope power. SC receiver is utilized to abate the impact of Gamma large scale fading effects and Weibull small scale fading effects on system characteristics. The formula for average level crossing rate (LCR) of signal envelope at SC combiner output is performed in the closed shape. The result we get can be applied to calculate the average fade duration (AFD) of such wireless systems. The obtained solutions are plotted in a few graphs to point out the impact of Weibull fading envelope severity parameter and Gamma shadowing severity parameter on system features

On the MIMO Capacity for Distributed System under Composite Rayleigh/Rician Fading and Shadowing

Wireless channels are commonly affected by short-term fading and long-term fading (shadowing). The shadowing effects must be taken into account also when mobility is present in the wireless scenario. Using a composite fading model, the total channel capacity can be studied for a scenario with short-term Rayleigh fading along with shadowing. This work provides quantitative results for these kinds of scenarios with Rayleigh fading and shadowing, considering also multiple-input and multiple-output systems, which have not been previously reported. In addition, the channel capacity has been studied in depth in its relation with the shadowing level, signal to noise ratio, and the number of elements in the multiple-input and multiple-output system. Moreover, the channel performance with shadowing has been compared to the one without it. Furthermore, Rician model with shadowing is studied and its results are reported. In addition, correlated and experimental results are provided. It is identified that the distributed MIMO systems can benefit from shadowing in Rician channels. This advantage has not been reported previously. This type of fading is proposed for massive MIMO by others and our results open the door to emulate massive MIMO on a reverberation chamber.This work has been supported by “Gobierno de Extremadura” with project number IB13113, PYR-2014 GENIL project (PYR-2014-CEB09-0010/MICINN), and CEIbioTIC project (mP_TIC_11)

Composite and Cascaded Generalized-K Fading Channel Modeling and Their Diversity and Performance Analysis

The introduction of new schemes that are based on the communication among nodes has motivated the use of composite fading models due to the fact that the nodes experience different multipath fading and shadowing statistics, which subsequently determines the required statistics for the performance analysis of different transceivers. The end-to-end signal-to-noise-ratio (SNR) statistics plays an essential role in the determination of the performance of cascaded digital communication systems. In this thesis, a closed-form expression for the probability density function (PDF) of the end-end SNR for independent but not necessarily identically distributed (i.n.i.d.) cascaded generalized-K (GK) composite fading channels is derived. The developed PDF expression in terms of the Meijer-G function allows the derivation of subsequent performance metrics, applicable to different modulation schemes, including outage probability, bit error rate for coherent as well as non-coherent systems, and average channel capacity that provides insights into the performance of a digital communication system operating in N cascaded GK composite fading environment. Another line of research that was motivated by the introduction of composite fading channels is the error performance. Error performance is one of the main performance measures and derivation of its closed-form expression has proved to be quite involved for certain systems. Hence, in this thesis, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing i.n.i.d. GK fading is derived in terms of the extended generalized bivariate Meijer G-function

Theoretical and experimental contributions for modeling wireless channels

Trabalho de Conclusão de Curso (graduação)—Universidade de Brasília, Faculdade de Tecnologia, Departamento de Engenharia Elétrica, 2017.Este trabalho de conclusão de curso visa agregar contribuições teóricas e experimentais para a modelagem de redes sem fio à partir de quatro projetos realizados durante um estágio supervisionado entre a Universidade de Brasília e a escola francesa de engenharia ENSEIRB-MATMECA durante o ano de 2017. Todos os projetos desse trabalho giram em torno do tema "desafios atuais nas comunicações sem fio" e tem como objetivo a apresentação de tais desafios através de uma breve introdução teórica seguida da realização de simulações, análises estatísticas ou medições em campo. O primeiro projeto propõem um estudo teórico e a validação experimental da distribuição de desvanecimento α-μ/Γ generalizada, usada nesse trabalho para caracterizar ambientes realistas que experimentam desvanecimento composto. Ainda no escopo de análises estatísticas, o segundo projeto propõe uma caracterização da qualidade do sinal celular à partir de dados de potência medidos usando um aplicativo Android de analise de qualidade de redes móveis. As análises estatísticas realizadas poderão auxiliar operadoras de telefonia móvel à parametrizar suas redes e contribuir para o melhoramento da cobertura celular no pais. Em seguida, o terceiro projeto desenvolvido nesse trabalho de conclusão de curso propõe estudos práticos e teóricos de interferência entre os sistema LTE 700MHz e TV digital em Brasília na região da Asa Norte, um tema recente de grande importância dada a desconexão da TV analógica no Brasil até 2018. Por fim, o quarto projeto, realizado em parceria com a Agência Nacional de Telecomunicações (ANATEL) propõe contribuições para o desenvolvimento de um simulador de rede IMT para uso em estudos de compartilhamento e compatibilidade proposto para ajudar na identificação de novas faixas de frequência para o IMT-2020. Os projetos propostos nesse trabalho focam na caracterização e modelagem de canais sem fio à partir do levantamento de estatísticas de primeira ordem, na análise de qualidade das redes celulares no país com base nas informações sobre a cobertura celular experimentada pelos usuários de telefonia móvel e na análise da interferência entre sistemas à partir de estudos entre o LTE e a TV digital e da busca de novas possíveis frequências para o 5G. A realização do estágio supervisionado e desse trabalho de conclusão de curso é um requerimento oficial para a obtenção do título de "Engenheiro diplomado do Instituto politécnico de Bordeaux, especialidade Engenharia eletrônica" pela ENSEIRB-MATMECA e para a obtenção do titulo de "Engenheiro de redes de comunicação" pela Universidade de Brasília.This final course assignment aims to add theoretical and experimental contributions to the modeling of wireless networks from four different projects carried out over an supervised internship held between the University of Brasília and the french school of engineering ENSEIRB-MATMECA during the year of 2017. All projects revolve around the central theme "current challenges in wireless communications" and aims to present such challenges through a brief theoretical introduction followed by simulations, statistical analyzes or field measurements. The first project proposes a theoretical study and the experimental investigation of the α-μ/Γ generalized fading distribution, used in this work to characterize realistic environments that experience composite fading. A second project, also based on statistical analysis, proposes a characterization of the mobile phone signal quality from power data measured using an Android application of mobile network quality analysis. Statistical analyzes can help mobile operators to parameterize their network and contribute to the improvement of cellular coverage in the country. Next, the third project developed in the internship proposes practical and theoretical studies of interference between the LTE 700MHz system and digital TV in Brasília in the region of Asa Norte, a recent topic of great importance given the analogue TV disconnection in Brazil until 2018. Finally, the fourth project, carried out in partnership with the National Telecommunications Agency (ANATEL), proposes contributions for the development of an IMT network simulator for use in sharing and compatibility studies to help in the identification of new frequency bands for the IMT-2020. The projects proposed in this work focus on the characterization and modeling of wireless channels from first order statistics, on the analysis of the quality of cellular networks in the country based on the information collected from the App about the network coverage experienced by final users and on the analysis of interference between systems based on studies between LTE and digital TV and on the search for new possible frequencies for 5G. The realization of the supervised internship was an official requirement to obtain the title of "Licensed Engineer of the Polytechnic Institute of Bordeaux, specialized in Electronic Engineering" by ENSEIRB-MATMECA and to obtain the title of "Network Communications Engineer" by the University of Brasília