Ferkan Yilmaz

A New Formula for the BER of Binary Modulations with Dual-Branch Selection over Generalized-K

Error performance is one of the main performance measures and the derivation of its closed-form expression has proved to be quite involved for certain communication systems operating over composite fading channels. In this letter, a unified closed-form expression, applicable to different binary modulation schemes, for the bit error rate of dual-branch selection diversity based systems undergoing independent but not necessarily identically distributed generalized-K fading is derived in terms of the extended generalized bivariate Meijer G-function.

Impact of Pointing Errors on the Performance of Mixed RF/FSO Dual-Hop Transmission Systems

In this work, the performance analysis of a dual-hop relay transmission system composed of asymmetric radio-frequency (RF)/free-space optical (FSO) links with pointing errors is presented. More specifically, we build on the system model presented in to derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end-to-end signal-to-noise ratio in terms of the Meijers G function. We then capitalize on these results to offer new exact closed-form expressions for the higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and the ergodic capacity, all in terms of Meijers G functions. Our new analytical results were also verified via computer-based Monte-Carlo simulation results.

Product of the Powers of Generalized Nakagami-m Variates and Performance of Cascaded Fading Channels

In this paper, we analyze the fading statistics of a generic fading distribution, termed the N-product Generalized Nakagami-m (GNM) distribution (N*GNM distribution), constructed as the product of the power of N statistically independent and non-identically distributed GNM random variables, for the purpose of modeling the cascaded fading channels. In particular, using the Foxs H function, we derive the probability density function, the cumulative distribution function, the moment generating function and the moments of such channels in closed-form. These derived results are a convenient tool to statistically model the cascaded GNM fading channels and to analyze the performance of digital communication systems over these kinds of channels. As such, generic closed-form expressions for the amount of fading, the outage probability, the capacity, the outage capacity and the average bit error probabilities of digital communications systems over cascaded GNM fading channels are presented. Numerical and simulation results, performed to verify the correctness of the proposed formulation, are in perfect agreement.

A Unified MGF-Based Capacity Analysis of Diversity Combiners over Generalized Fading Channels

Unified exact ergodic capacity results for L-branch coherent diversity combiners including equal-gain combining (EGC) and maximal-ratio combining (MRC) are not known. This paper develops a novel generic framework for the capacity analysis of L-branch EGC/MRC over generalized fading channels. The framework is used to derive new results for the gamma-shadowed generalized Nakagami-m fading model which can be a suitable model for the fading environments encountered by high frequency (60 GHz and above) communications. The mathematical formalism is illustrated with some selected numerical and simulation results confirming the correctness of our newly proposed framework.

A new simple model for composite fading channels: Second order statistics and channel capacity

In this paper, we introduce the most general composite fading distribution to model the envelope and the power of the received signal in such fading channels as millimeter wave (60 GHz or above) fading channels and free-space optical channels, which we term extended generalized-K (EGK) composite fading distribution. We obtain the second-order statistics of the received signal envelope characterized by the EGK composite fading distribution. Expressions for probability density function, cumulative distribution function, level crossing rate and average fade duration, moments, amount of fading and average capacity are derived. Numerical and computer simulation examples validate the accuracy of the presented mathematical analysis.

Novel asymptotic results on the high-order statistics of the channel capacity over generalized fading channels

The exact analysis of the higher-order statistics of the channel capacity (i.e., higher-order ergodic capacity) often leads to complicated expressions involving advanced special functions. In this paper, we provide a generic framework for the computation of the higher-order statistics of the channel capacity over generalized fading channels. As such, this novel framework for the higher-order statistics results in simple, closed-form expressions which are shown to be asymptotically tight bounds in the high signal-to-noise ratio (SNR) regime of a variety of fading environment. In addition, it reveals the existence of differences (i.e., constant capacity gaps in log-domain) among different fading environments. By asymptotically tight bound we mean that the high SNR limit of the difference between the actual higher-order statistics of the channel capacity and its asymptotic bound (i.e., lower bound) tends to zero. The mathematical formalism is illustrated with some selected numerical examples that validate the correctness of our newly derived results.

On the Performance of Mixed RF/FSO Variable Gain Dual-Hop Transmission Systems with Pointing Errors

In this work, the performance analysis of a dual-hop relay transmission system composed of asymmetric radio-frequency (RF) and unified free-space optical (FSO) links subject to pointing errors is presented. These unified FSO links account for both types of detection techniques (i.e. indirect modulation/direct detection (IM/DD) as well as heterodyne detection). More specifically, we derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end- to-end signal-to-noise ratio of these systems in terms of the Meijers G function. We then capitalize on these results to offer new exact closed-form expressions for the outage probability, higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and ergodic capacity, all in terms of Meijers G functions. All our new analytical results are verified via computer-based Monte-Carlo simulations.

On the performance of hybrid RF and RF/FSO fixed gain dual-hop transmission systems

In this work, we present the performance analysis of a dual-branch transmission system composed of a direct radio frequency (RF) link and a dual-hop relay composed of asymmetric RF and free-space optical (FSO) links and compare it without having a direct RF path to see the effects of diversity on our system. The FSO link accounts for pointing errors and both types of detection techniques (i.e. indirect modulation/direct detection (IM/DD) as well as heterodyne detection). The performance is evaluated under the assumption of selection combining diversity scheme. RF links are modeled by Rayleigh fading distribution whereas the FSO link is modeled by a unified Gamma-Gamma fading distribution. Specifically, we derive new exact closed-form expressions for the cumulative distribution function, probability density function, moment generating function, and moments of the end-to-end signal-to-noise ratio of these systems in terms of the Meijers G function. We then capitalize on these results to offer new exact closed-form expressions for the outage probability, higher-order amount of fading, average error rate for binary and M-ary modulation schemes, and ergodic capacity, all in terms of Meijers G functions. All our new analytical results are also verified via computer-based Monte-Carlo simulations.

Average Bit Error Probability of Binary Coherent Signaling over Generalized Fading Channels Subject to Additive Generalized Gaussian Noise

This letter considers the average bit error probability of binary coherent signaling over flat fading channels subject to additive generalized Gaussian noise. More specifically, a generic closed form expression in terms of the Foxs H function is offered for the extended generalized-K fading case. Simplifications for some special fading distributions such as generalized-K fading and Nakagami-m fading and special additive noise distributions such as Gaussian and Laplacian noise are then presented. Finally, the mathematical formalism is illustrated by some numerical examples verified by computer based simulations for a variety of fading and additive noise parameters.

A novel framework on exact average symbol error probabilities of multihop transmission over amplify-and-forward relay fading channels

In this paper, we propose an analytical framework on the exact computation of the average symbol error probabilities (ASEP) of multihop transmission over generalized fading channels when an arbitrary number of amplify-and-forward relays is used. Our approach relies on moment generating function (MGF) framework to obtain exact single integral expressions which can be easily computed by Gauss-Chebyshev Quadrature (GCQ) rule. As such, the derived results are a convenient tool to analyze the ASEP performance of multihop transmission over amplify-and-forward relay fading channels. Numerical and simulation results, performed to verify the correctness of the proposed formulation, are in perfect agreement.