Several practical wireless scenarios exist where the transmitted signal might undergo severe channel fading. This work presents the Extreme Two-Wave (ETW) fading model, encompassing simultaneously the Two-Ray and the k-µ Extreme fading models, which have been shown to provide a tight fit to empirical measurements in harsh propagation conditions. The ETW model is a limiting case of the recently introduced Multicluster Two-Ray (MTW) fading model and can be used to model wireless communications links in some of the new use cases defined in 5G and beyond wireless networks in environments experiencing severe fading. The chief probability functions are obtained for the proposed ETW model, as well as the outage probability. In addition, the ETW model is extended to incorporate shadowing effects.

We introduce and characterize the Multi-cluster Two-Wave (MTW) fading model, which generalizesboththe Durgin’s Two-Wave with Diffuse Power (TWDP) and the$\kappa $-$\mu $models under a common umbrella. The MTW model consists of an arbitrary number of clusters of waves each of which may include one or two dominant (specular) components. The chief probability functions of the MTW fading model are obtained, including the probability density function, the cumulative distribution function and the generalized moment-generating function. The proposed model is empirically validated using channel measurements in the sub-THz band and a number of applications are exemplified, including the outage probability in noise-limited and interference-limited scenarios and the energy detection probability. A composite Inverse Gamma (IG)/MTW model is also investigated, thus extending the proposed propagation model to include shadowing.

The Beckmann fading is a general multipath fading model which includes Rice, Hoyt and Rayleigh fading as particular cases. However, the generality of the Beckmann fading also implies a significant increased mathematical complexity. Thus, relatively few analytical results have been reported for this otherwise useful fading model. The performance of energy detection for multi-branch receivers operating under Beckmann fading is here studied, and the inherent analytical complexity is here circumvented by the derivation of a closed-form expression for the generalized moment generating function (MGF) of the received signal-to-noise ratio (SNR), which is a new and useful result, as it is key for evaluating the receiver operating characteristics. The impact of fading severity on the probability of missed detection is shown to be less critical as the SNR decreases. Monte Carlo simulations have been carried out in order to validate the obtained theoretical expressions.

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.

This paper presents the performance analysis of a wireless system with multiple transmit and receive antennas under Hoyt fading. Receive antennas are assumed to perform Maximal Ratio Combining (MRC), whereas the antenna at the transmit end that maximizes the instantaneous output signal-to-noise ratio (SNR) is selected for transmission. When the number of receive antennas is arbitrary, an exact compact expression is derived for the outage probability. For two receive antennas, closed-form expressions are presented for the ergodic capacity and the average error rates of different modulations, which are given as a finite sum of well known functions. An asymptotic error rate analysis is also performed when the number of receive antennas is arbitrary. It is shown that severe fading conditions do not always degrade wireless systems performance. Actually, our results show that severe fading can be beneficial in terms of channel capacity if the transmit array is large enough due to the antenna selection performed at the transmitter. Monte Carlo simulations have been carried out to validate the derived expressions, showing an excellent agreement with the analytical results.

This work presents exact closed-form expressions for the channel capacity of wireless communication systems with multiple receive antennas under correlated Rayleigh fading, where spatial diversity is exploited with the maximal ratio combining (MRC) technique. Instantaneous channel state information is assumed to be known at both the transmit and receive ends, allowing different adaptation strategies to optimize the performance. Unlike previous related works, correlation among the receive antennas is assumed to be arbitrary and no particular requirement about the eigenvalues of the correlation matrix is considered. Additionally, the average received power per antenna is assumed to be also arbitrary.

Closed-form expressions for the average symbol error rate (ASER) of general rectangular quadrature amplitude modulation (QAM) in Rayleigh fading are derived in this work for MIMO MRC systems. The number of antennas are assumed to be arbitrary at both the transmit and receive ends. An expression is derived in terms of a finite summation where all the terms are explicitly given and can be easily calculated. Additionally, a compact result is also provided in terms of coefficients which must be numerically computed. Monte Carlo simulations have also been carried out, showing an excellent agreement with the theoretical results.

This work explores the average bit error rate (BER) of uncoded MIMO systems in Rayleigh fading channels with co-channel interference (CCI) and background noise. We consider that maximal ratio transmission (MRT) is used at the transmit end. At the receiver we consider two different schemes: maximal ratio combining (MRC) and interference cancellation (IC) via null steering of the receive array radiation pattern. We provide analytical expressions of the BER for different modulation techniques and provide a comparison between the two proposed receiver schemes.

This work explores the performance of MIMO (multiple-input/multiple-output) systems in Rayleigh fading channels with co-channel interference (CCI) and thermal noise. We provide analytical expressions for the outage probability of maximal ratio transmission combined with one of two different receive antenna array schemes, maximal ratio combining (MRC) and interference cancellation (IC) via null steering of the array pattern. We derive the statistics of the signal to interference-plus- noise ratio (SINR) for each technique in a closed-form and obtain an integral expression to calculate the average bit error rate (BER) or symbol error rate (SER). Our results show the conditions under which IC yields significantly better performance than MRC and vice versa. We also determine the impact on performance of the number of antennas in the transmit array.

We propose a new approach to outage probability analysis of predetection maximal ratio combining (MRC) diversity reception in Nakagami-$m$fading channels. We generalize prior work in that we consider L independent cochannel interferers with arbitrary powers and fading parameters as well as the effects of additive white Gaussian noise (AWGN). Our approach results in a general expression for outage probability under very broad assumptions. Moreover, our approach leads to a closed-form expression for outage probability in most cases of interest. We also provide numerical results that demonstrate the performance improvement obtained through MRC diversity combining in the presence of cochannel interferers.

We determine exact closed-form expressions for the outage probability of multiple-input/multiple-output systems in Rayleigh fading with maximal ratio diversity combining and co-channel interference. Our analysis generalizes prior work in that we place no restrictions on the number or power of the interferers, or on the number of antennas at the transmitter and receiver. We also present an alternative mathematical approach to performance analysis that leads to an undemanding expression for the SINR moment generating function, which can then be used to evaluate average probability of error and the moments of the SINR. Our numerical results indicate that, for a fixed total interference power, system performance degrades when there are dominant interferers. In addition, for a fixed total number of transmit and receive antennas, outage probability and average bit error rate decrease when the transmitter and receiver have the same number of antennas.

Close form analytical expressions are derived for the outage probability of predetection maximal ratio combiner (MRC) diversity reception with M branches in both Rayleigh and Nakagami-m fading channels. This formulation is obtained in the presence of the white Gaussian noise and Q interferers, without restrictions about the power, number or distribution parameters of interferers. Closed-form expressions are derived and results are easily computable.