We introduce the fluctuating two-ray (FTR) fading model, a new statistical channel model that consists of two fluctuating specular components with random phases plus a diffuse component. The FTR model arises as the natural generalization of the two-wave with diffuse power (TWDP) fading model; this generalization allows its two specular components to exhibit a random amplitude fluctuation. Unlike the TWDP model, all the chief probability functions of the FTR fading model (PDF, CDF, and MGF) are expressed in closed-form, having a functional form similar to other state-of-the-art fading models. We also provide approximate closed-form expressions for the PDF and CDF in terms of a finite number of elementary functions, which allow for a simple evaluation of these statistics to an arbitrary level of precision. We show that the FTR fading model provides a much better fit than Rician fading for recent small-scale fading measurements in 28 GHz outdoor mm-wave channels. Finally, the performance of wireless communication systems over FTR fading is evaluated in terms of the bit error rate and the outage capacity, and the interplay between the FTR fading model parameters and the system performance is discussed. Monte Carlo simulations have been carried out in order to validate the obtained theoretical expressions.

We present exact expressions for the average bit error rate (BER) and symbol error rate (SER) of different modulation techniques of a wireless system with multiple transmit and receive antennas. The receive antennas are assumed to use maximal ratio combining (MRC) or post-detection equal gain combining (EGC), whereas the transmit antenna that maximizes the output signal-to-noise ratio (SNR) is selected. Exact expressions of the moment generating function (MGF) of the output SNR and all its derivatives are also derived. We consider a Nakagami-m fading channel where the long-term SNR and fading parameters from the different transmit antennas are arbitrary and may be different from each other. For a given transmit antenna, the fading at the receive antennas is assumed to be independent and identically distributed (i.i.d). For the case when the Nakagami fading parameter m has an integer value in every channel, results are given in closed-form as a finite sum of simple terms. When fading parameters take any real value, our results are given in terms of the multivariate Lauricella hypergeometric function F_A ⁽ⁿ⁾. Numerical results for the error rates of different modulation techniques are presented.. Our results are validated by Monte Carlo simulation.

We show that the popular and general κ-μ shadowed fading model with integer fading parameters μ and m can be represented as a mixture of squared Nakagami-m̑ (or Gamma) distributions. Thus, its PDF and CDF can be expressed in a closed form in terms of a finite number of elementary functions (powers and exponentials). The main implications arising from such connection are then discussed, which can be summarized as follows. First, the performance evaluation of communication systems operating in κ-μ shadowed fading becomes as simple as if a Nakagami-m̑ fading channel was assumed. Second, the κ-μ shadowed distribution can be used to approximate the κ-μ distribution using a closed-form representation in terms of elementary functions, by choosing a sufficiently large value of m. Finally, restricting the parameters μ and m to take integer values has limited the impact in practice when fitting the κ-μ shadowed fading model to field measurements. As an application example, the average channel capacity of communication systems operating under κ-μ shadowed fading is obtained in closed-form.

We explore tradeoffs between different reception strategies of multiple receive antennas in fading channels with co-channel interference (CCI). Our tradeoff analysis is based on outage probability. We assume the signal from the desired user at the receive antenna array to be affected by Rice, Nakagami or Rayleigh fading, while CCI signals are assumed to experience Rayleigh fading. We provide closed-form analytical expressions for the outage probability of different diversity schemes, such as maximal ratio combining (MRC) and optimum combining (OC), and also for interference cancellation (IC) based on antenna beamsteering, which steers nulls in the array radiation pattern in the direction of the strongest interferers. Our analysis provides a unified framework for studying outage probability of different multiple-antenna reception strategies, and our closed- form expressions are easily computed, facilitating a performance comparison under a range of operating conditions. Our numerical results show that IC yields significantly better performance than MRC if the system is interference-limited and the number of dominant interferers is lower than the number of receive antennas, or when the output SINR is low. In addition, when the background noise can be neglected, we provide numerical results for MRC and OC when the signals from the desired user at the different receive antennas are arbitrarily distributed.

The Beckmann distribution is a general multipath fading model for the received radio signal in the presence of a large number of scatterers, which can thence be modeled as a complex Gaussian random variable where both the in-phase and quadrature components have arbitrary mean and variance. However, the complicated nature of this distribution has prevented its widespread use and relatively few analytical results have been reported for this otherwise useful fading model. In this paper, we derive a closed-form expression for the generalized moment-generating function (MGF) of the signal-to-noise ratio (SNR) of Beckmann fading, which permits to circumvent the inherent analytical complexity of this model. This is a new and useful result, as it is a key for evaluating several important performance metrics of different wireless communication systems and also permits to readily compute the moments of the output SNR. Thus, we obtain simple exact expressions for the energy detection performance in Beckmann fading channels, both in terms of the receiver operating characteristic (ROC) curve and of the area under ROC curve. We also analyze the outage probability in interference limited systems affected by Beckmann fading, as well as the outage probability of secrecy capacity in wiretap Beckmann fading channels. Monte Carlo simulations have been performed to validate the derived expressions.

We present a novel relationship between the distribution of circular and non-circular complex Gaussian random variables. Specifically, we show that the distribution of the squared norm of a non-circular complex Gaussian random variable, usually referred to as the squared Hoyt distribution, can be constructed from a conditional exponential distribution. From this fundamental connection we introduce a new approach, the Hoyt transform method, that allows to analyze the performance of a wireless link under Hoyt (Nakagami-q) fading in a very simple way. We illustrate that many performance metrics for Hoyt fading can be calculated by leveraging well-known results for Rayleigh fading and only performing a finite-range integral. We use this technique to obtain novel results for some information and communication-theoretic metrics in Hoyt fading channels.