RECEIVER DESIGN AND PERFORMANCE ANALYSIS FOR COMMUNICATION CHANNELS WITH CARRIER PHASE NOISE AND FADING

Ph.DDOCTOR OF PHILOSOPH

Approximations for Performance Analysis in Wireless Communications and Applications to Reconfigurable Intelligent Surfaces

In the last few decades, the field of wireless communications has witnessed significant technological advancements to meet the needs of today’s modern world. The rapidly emerging technologies, however, are becoming increasingly sophisticated, and the process of investigating their performance and assessing their applicability in the real world is becoming more challenging. That has aroused a relatively wide range of solutions in the literature to study the performance of the different communication systems or even draw new results that were difficult to obtain. These solutions include field measurements, computer simulations, and theoretical solutions such as alternative representations, approximations, or bounds of classic functions that commonly appear in performance analyses. Field measurements and computer simulations have significantly improved performance evaluation in communication theory. However, more advanced theoretical solutions can be further developed in order to avoid using the ex- pensive and time-consuming wireless communications measurements, replace the numerical simulations, which can sometimes be unreliable and suffer from failures in numerical evaluation, and achieve analytically simpler results with much higher accuracy levels than the existing theoretical ones. To this end, this thesis firstly focuses on developing new approximations and bounds using unified approaches and algorithms that can efficiently and accurately guide researchers through the design of their adopted wireless systems and facilitate the conducted performance analyses in the various communication systems. Two performance measures are of primary interest in this study, namely the average error probability and the ergodic capacity, due to their valuable role in conducting a better understanding of the systems’ behavior and thus enabling systems engineers to quickly detect and resolve design issues that might arise. In particular, several parametric expressions of different analytical forms are developed to approximate or bound the Gaussian Q-function, which occurs in the error probability analysis. Additionally, any generic function of the Q-function is approximated or bounded using a tractable exponential expression. Moreover, a unified logarithmic expression is proposed to approximate or bound the capacity integrals that occur in the capacity analysis. A novel systematic methodology and a modified version of the classical Remez algorithm are developed to acquire optimal coefficients for the accompanying parametric approximation or bound in the minimax sense. Furthermore, the quasi-Newton algorithm is implemented to acquire optimal coefficients in terms of the total error. The average symbol error probability and ergodic capacity are evaluated for various applications using the developed tools. Secondly, this thesis analyzes a couple of communication systems assisted with reconfigurable intelligent surfaces (RISs). RIS has been gaining significant attention lately due to its ability to control propagation environments. In particular, two communication systems are considered; one with a single RIS and correlated Rayleigh fading channels, and the other with multiple RISs and non-identical generic fading channels. Both systems are analyzed in terms of outage probability, average symbol error probability, and ergodic capacity, which are derived using the proposed tools. These performance measures reveal that better performance is achieved when assisting the communication system with RISs, increasing the number of reflecting elements equipped on the RISs, or locating the RISs nearer to either communication node. In conclusion, the developed approximations and bounds, together with the optimized coefficients, provide more efficient tools than those available in the literature, with richer capabilities reflected by the more robust closed-form performance analysis, significant increase in accuracy levels, and considerable reduction in analytical complexity which in turns can offer more understanding into the systems’ behavior and the effect of the different parameters on their performance. Therefore, they are expected to lay the groundwork for the investigation of the latest communication technologies, such as RIS technology, whose performance has been studied for some system models in this thesis using the developed tools

Log-moment estimators of the Nakagami-lognormal distribution

[EN] In this paper, estimators of the Nakagami-lognormal (NL) distribution based on the method of log-moments have been derived and thoroughly analyzed. Unlike maximum likelihood (ML) estimators, the log-moment estimators of the NL distribution are obtained using straightforward equations with a unique solution. Also, their performance has been evaluated using the sample mean, confidence regions and normalized mean square error (NMSE). The NL distribution has been extensively used to model composite small-scale fading and shadowing in wireless communication channels. This distribution is of interest in scenarios where the small-scale fading and the shadowing processes cannot be easily separated such as the vehicular environment.This work has been funded in part by the Programa de Estancias de Movilidad de Profesores e Investigadores en Centros Extranjeros de Ensenanza Superior e Investigacion of the Ministerio de Educacion, Cultura y Deporte, Spain, PR2015-00151 and by the Ministerio de Economia, Industria y Competitividad of the Spanish Government under the national project TEC2017-86779-C2-2-R, through the Agencia Estatal de Investigacion (AEI) and the Fondo Europeo de Desarrollo Regional (FEDER).Reig, J.; Brennan, C.; Rodrigo Peñarrocha, VM.; Rubio Arjona, L. (2019). Log-moment estimators of the Nakagami-lognormal distribution. EURASIP Journal on Wireless Communications and Networking. 1-10. https://doi.org/10.1186/s13638-018-1328-6S110J. M. Ho, G. L. Stüber, in Co-channel interference of microcellular systems on shadowed Nakagami fading channels. Proc. IEEE 43rd Vehicular Technology Conference, 1993 (VTC 93) (IEEESecaucus, 1993), pp. 568–571.A. A. Abu-Dayya, N. C. Beaulieu, Micro- and macrodiversity NCFSK (DPSK) on shadowed Nakagami-fading channels. IEEE Trans. Commun.42(9), 2693–2702 (1994).X. Wang, W. Wang, Z. Bu, Fade statistics for selection diversity in Nakagami-lognormal fading channels. Electron. Lett.42(18), 1046–1047 (2006).D. T. Nguyen, Q. T. Nguyen, S. C. Lam, Analysis and simulation of MRC diversity reception in correlated composite Nakagami-lognormal fading channels. REV J. Electron. Commun.4(1–2), 44–51 (2014).P. Xu, X. Zhou, D. Hu, in Performance evaluations of adaptive modulation over composite Nakagami-lognormal fading channels. 2009 15th Asia-Pacific Conference on Communications (IEEEShanghai, 2009), pp. 467–470.G. C. Alexandropoulos, A. Conti, P. T. Mathiopoulos, in Adaptive M-QAM systems with diversity in correlated Nakagami-m fading and shadowing. IEEE Global Telecommunications Conference (GLOBECOM 2010) (IEEEMiami, 2010), pp. 1–5.Ö. Bulakci, A. B. Saleh, J. Hämäläinen, S. Redana, Performance analysis of relay site planning over composite fading/shadowing channels with cochannel interference. IEEE Trans. Veh. Technol.62(4), 1692–1706 (2013).W. Cheng, Y. Huang, On the performance of adaptive SC/MRC cooperative systems over composite fading channels. Chin. J. Electron.25(3), 533–540 (2016).M. G. Kibria, G. P. Villardi, W. Liao, K. Nguyen, K. Ishizu, F. Kojima, Outage analysis of offloading in heterogeneous networks: Composite fading channels. IEEE Trans. Veh. Technol.66(10), 8990–9004 (2017).K. Cho, J. Lee, C. G. Kang, Stochastic geometry-based coverage and rate analysis under Nakagami & log-normal composite fading channel for downlink cellular networks. IEEE Commun. Lett.21(6), 1437–1440 (2017).R. Singh, M. Rawat, Closed-form distribution and analysis of a combined Nakagami-lognormal shadowing and unshadowing fading channel. J Telecommun. Inf. Technol.4:, 81–87 (2016).J. Reig, L. Rubio, Estimation of the composite fast fading and shadowing distribution using the log-moments in wireless communications. IEEE Trans. Wireless. Commun.12(8), 3672–3681 (2013).S. Atapattu, C. Tellambura, H. Jiang, A mixture gamma distribution to model the SNR of wireless channels. IEEE Trans. Wireless Commun.10(12), 4193–4203 (2011).Q. Wang, H. Lin, P. Kam, Tight bounds and invertible average error probability expressions over composite fading channels. J. Commun. Netw.18(2), 182–189 (2016).J. M. Holtzmann, On using perturbation analysis to do sensitivity analysis: derivatives versus differences. IEEE Trans. Autom. Control. 37(2), 243–247 (1992).H. Suzuki, A statistical model for urban radio propagation. IEEE Trans. Commun.25(7), 673–680 (1977).M. D. Yacoub, The α- μ distribution: a physical fading model for the Stacy distribution. IEEE Trans. Veh. Technol.56(1), 122–124 (2007).P. M. Shankar, Error rates in generalized shadowed fading channels. Wirel. Pers. Commun.28(3), 233–238 (2004).J. -M. Nicolas, Introduction aux statistiques de deuxième espèce: applications des logs-moments et des logs-cumulants à l’analyse des lois d’images radar. Traitement du Signal. 19(3), 139–167 (2002). Translation to English by S. N. Anfinsen.C. Withers, S. Nadarajah, A generalized Suzuki distribution. Wirel. Pers. Commun.62(4), 807–830 (2012).M. Abramowitz, Handbook of Mathematical Functions, with Formulas, Graphs, and Mathematical Tables, 9th edn. (Dover, New York, NY, 1972).M. K. Simon, M. S. Alouini, Digital Communication over Fading Channels, 2nd edn. (Wiley, Hoboken, NY, 2005).Z. Sun, J. Du, in Proc. 10th International Conference, ICIC 2014, ed. by D. -S. Huang, V. Bevilacqua, and P. Premaratne. Log-cumulant parameter estimator of log-normal distribution. Intelligent computing theory (SpringerNew York, NY, 2014), pp. 668–674.S. Zhang, J. M. Jin, Computation of Special Functions (Wiley, New York, 1996).G. Casella, R. L. Berger, Statistical Inference (Duxbury Thomson Learning, Pacific Grove, CA, 2002).C. Kleiber, S. Kotz, Statistical Size Distributions in Economics and Actuarial Sciences (Wiley, Hoboken, NJ, 2003).L. Devroye, Non-uniform Random Variate Generation (Springer, New York,1986).A. Abdi, M. Kaveh, Performance comparison of three different estimators for the Nakagami m parameter using Monte Carlo simulation. IEEE Commun. Lett.4(4), 119–121 (2000).L. Rubio, J. Reig, N. Cardona, Evaluation of Nakagami fading behaviour based on measurements in urban scenarios. Int. J. Electron. Commun. (AEÜ). 61(2), 135–138 (2007)

An Exponentially-Tight Approximate Factorization of the Joint PDF of Statistical Dependent Measurements in Wireless Sensor Networks

We consider the distributed detection problem of a temporally correlated random radio source signal using a wireless sensor network capable of measuring the energy of the received signals. It is well-known that optimal tests in the Neyman-Pearson setting are based on likelihood ratio tests (LRT), which, in this set-up, evaluate the quotient between the probability density functions (PDF) of the measurements when the source signal is present and absent. When the source is present, the computation of the joint PDF of the energy measurements at the nodes is a challenging problem. This is due to the statistical dependence introduced to the received signals by the radio source propagated through fading channels. We deal with this problem using the characteristic function of the (intractable) joint PDF, and proposing an approximation to it. We derive bounds for the approximation error in two wireless propagation scenarios, slow and fast fading, and show that the proposed approximation is exponentially tight with the number of nodes when the time-bandwidth product is sufficiently high. The approximation is used as a substitute of the exact joint PDF for building an approximate LRT, which performs better than other well-known detectors, as verified by Monte Carlo simulations.Comment: This is a pre-print version of an article submitted to IEEE Transactions on Wireless Communications and it is under revie

EFFICIENT SYMBOL ERROR RATE ANALYSIS OF COOPERATIVE NON-REGENERATIVE RELAY SYSTEMS OVER GENERALIZED FADING CHANNELS

ABSTRAC

Effects of Correlation of Channel Gains on the Secrecy Capacity in the Gaussian Wiretap Channel

Secrecy capacity is one of the most important characteristic of a wireless communication channel. Therefore, the study of this characteristic wherein the system has correlated channel gains and study them for different line-of-sight (LOS) propagation scenarios is of ultimate importance. The primary objective of this thesis from the mathematical side is to determine the secrecy capacity (SC) for correlated channel gains for the main and eavesdropper channels in a Gaussian Wiretap channel as a function from main parameters (μ, Σ, ρ). f(h1, h2) is the joint distribution of the two channel gains at channel use (h1, h2), fi(hi) is the main distribution of the channel gain hi. The results are based on assumption of the Gaussian distribution of channel gains (gM, gE). The main task of estimating the secrecy capacity is reduced to the problem of solving linear partial differential equations (PDE). Different aspects of the analysis of secrecy capacity considered in this research are the Estimation of SC mathematically and numerically for correlated SISO systems and a mathematical example for MIMO systems with PDE. The variations in Secrecy Capacity are studied for Rayleigh (NLOS) distribution and Rician (LOS) distribution. Suitable scenarios are identified in which secure communication is possible with correlation of channel gains. Also, the new algorithm using PDE has a higher speed and than analog algorithms constructed on the classical statistical Monte Carlo methods. Taking into account the normality of the distribution of system parameters, namely the channel gain (gM, gE), the algorithm is constructed for systems of partial differential equations which satisfies the secrecy criterion. Advisor: H. Andrew Harm

Performance analysis of diversity wireless systems

Ph.DDOCTOR OF PHILOSOPH

Co-channel interference in heterogeneous networks: Rician/Rayleigh scenario

The purpose of this study is to analyze interference for a macro cellular network h which embeds femtocells and/or relay nodes. Femtocells and relay nodes are being introduced to improve coverage and capacity of conventional cellular networks. However, their introduction comes with additional interference between the uacrocell and femtocell/relay node, and between individual femtocells/relay nodes. Hence, there is a need for analytical expressions for the performance measures such that outage probability and average capacity so that the effect of co-channe1 interference is understood thoroughly. In this thesis, analytical and numerical results are presented for outage probability and average capacity in a Rician/Rayleigh Scenario. In this scenario, the desired signal experiences Rician fading channel and the interfering signals experience Rayleigh fading channels. Closed-form and infinite series expressions are found for the outage probability and an infinite sum expression is found for the average capacity. The analysis approximates SINR by its tight upper bound SIR; therefore, the outage probability result is a tight lower bound and the average capacity result is a tight upper bound of their corresponding results without the approximation. Moreover, the thesis, as a background work, includes detailed studies of the relevant probability distributions used to model fading channels and radio link performance metrics in the absence of interference