George P. Efthymoglou

Another look at the performance of MRC schemes in Nakagami-m fading channels with arbitrary parameters

In this letter, we take a close look at the performance of maximal ratio combining (MRC) schemes operating in a flat-Nakagami-m fading environment with arbitrary fading parameters. We derive an expression for the probability density function (pdf) of the output signal-to-noise ratio (SNR) by expressing the moment generating function of the output SNR in the form of multiple Barnes-type contour integrals. By evaluating the inverse transform and converting the multiple contour integrals into infinite series, we are able to derive an expression for the pdf of the output SNR when the Nakagami fading parameters along the diversity branches take on real and arbitrary values. Consequently, the average bit-error rate can now be expressed in terms of Lauricellas multivariate hypergeometric function, which can be easily evaluated numerically. Special cases of the main results reduce to known results in the literature. The results, which apply to independent as well as correlated diversity branches, will be useful for predicting the system performances when the Nakagami fading parameters are real and arbitrary.

Performance of DS-CDMA receivers with MRC in nakagami-m fading channels with arbitrary fading parameters

The receivers that combine spatial antenna diversity with temporal multipath diversity are known as two-dimensional (2-D) RAKE receivers. In this paper, we consider the outage probability and the bit error rate performance of a coherent binary phase shift keying 2-D RAKE receiver in the context of an asynchronous direct sequence (DS)-code division multiple access (CDMA) system operating in a Nakagami-m fading channel with real and arbitrary fading parameters. The closed-form expressions derived for the two wireless performance measures are easily evaluated numerically and enable the link designer to examine the effects of system parameters, such as the number of receive antennas, RAKE fingers per antenna, and asynchronous CDMA users in the cell, as well as channel conditions, such as the amount of fading in the combined paths and the multipath intensity profile of the channel on the link performance. In addition, the diversity loss due to correlated fading among the spatially separated RAKE fingers is quantified.

Performance of Multihop Relay Systems with Co-Channel Interference in Rayleigh Fading Channels

In this letter we investigate the effect of co-channel interference on the performance of multihop transmission systems that employ amplify-and-forward relays and operate in a Rayleigh fading environment. We assume that an arbitrary number of interferers with arbitrary powers are present at each relay node and derive useful bounds for important performance measures, such as the outage probability and the average symbol error probability of various digital modulation schemes.

Error rates of M-ary signals with. Multichannel reception in Nakagami-m fading channels

In this letter, we present closed. form expressions for the exact average symbol-error rate (SER) of M-ary modulations with multichannel reception over Nakagami-m fading channels. The derived expressions extend already available results for the nondiversity case, to maximal-ratio combining-(MRC) and postdetection equal-gain combining (EGC) diversity systems. The average SERs are given in terms of Lauricellas multivariate hypergeometric function FD (n) . This function exhibits a finite integral representation that can be used for fast and accurate numerical computation of the derived expressions

Outage Analysis of Multihop Relay Systems in Interference-Limited Nakagami-

In this paper, we study the outage probability of multihop transmission systems with amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols operating over a Nakagami-m fading environment in the presence of cochannel interference. We consider the case of interference-limited relays with ideal AF relay gains based on the inverse of the fading amplitude of the desired signal in the previous link. For an arbitrary but fixed number of Nakagami-distributed interferers per hop, we derive a closed-form expression for the outage probability of an N-hop AF relaying system in terms of the multivariate Lauricella function FB(N) that can be evaluated with commonly available computer software. Moreover, the outage performance of an N-hop DF relaying system is also derived in closed form, and the two performances are compared. Simulation results are also provided to demonstrate the accuracy of the analytical expressions.

m

The performance of M-ary modulation schemes operating in a generalised gamma fading environment in the presence of additive white Gaussian noise is studied. The multipath fading channel is modelled by the three-parameter generalised gamma distribution, which includes the Rayleigh, Nakagami and Weibull distributions as special cases and the log-normal distribution as a limiting case. The Suzuki distribution can also be adequately approximated by the generalised gamma distribution. The performances of the selection combining (SC), equal gain combining (EGC) and maximal ratio combining (MRC) diversity schemes are considered. Specifically, the exact average symbol error rates (ASER) for coherent multilevel modulation schemes with SC and MRC are derived using the moment generating function-based approach, while the ASER of EGC is obtained by employing the characteristic function-based approach. The analytical results are validated by computer simulation.

Fading Channels

In this paper, we analyze the performance of multi-hop transmission systems that employ amplify-and-forward relays over a Rayleigh fading environment in the presence of a Poisson field of interferers. The interference model considers the effect of spatial distribution of co-channel interferers in the vicinity of the relays and the destination node. Using a tight upper bound on the end-to-end signal-to-interference ratio, a closed-form expression for the system outage probability is derived. Moreover, a lower bound for the average symbol error rate of general modulations, the exact average bit error rate (BER) of binary modulations and the average channel capacity are presented in the form of single-fold integrals that can be reliably evaluated numerically, whereas closed-form results are obtained for a special case of the dual-hop relaying system. Finally, asymptotic expressions for the system outage probability and the end-to-end BER are derived which provide useful insights regarding the factors affecting the performance of the considered system. The novel expressions can be used to show the impact of interference model parameters such as the transmit power, path loss exponent, and spatial density of interferers on the performance of multi-hop wireless systems. Simulation results are further provided to demonstrate the accuracy of the analytical expressions.

Performance of diversity receivers in generalised gamma fading channels

This letter derives the envelope and phase distributions for correlated non-zero mean and non-identical Gaussian quadratures. The resulting envelope distribution generalizes many of the commonly used envelope distributions such as Rayleigh, Rice, and Hoyt distributions. Special cases of the phase distribution also agree with results already available in the literature.

Performance Analysis of Multi-Hop Amplify-and-Forward Relaying Systems in Rayleigh Fading Channels with a Poisson Interference Field

In this letter, we present a moment generating function (MGF) based performance analysis of generalized selection combining (GSC) receivers operating over independent and identically distributed (i.i.d.) K fading channels. Analytical expressions for the marginal MGF of the signal-to-noise ratio of a single diversity branch for integer plus one-half values of the fading parameter are obtained and used to efficiently evaluate the average error probability of GSC receivers.

On the envelope and phase distributions for correlated gaussian quadratures

In the present study, the performance of digital communication systems operating over a composite fading channel modelled by the generalised-K distribution is analysed and evaluated. Novel closed-form expressions for the outage performance, the average bit error probabilities of several modulation schemes and the channel capacity under four different adaptive transmission schemes are derived. The analytical expressions are used to investigate the impact of different fading parameters of this composite fading channel model on the average bit error rate performance for a variety of digital modulation schemes and the spectral efficiency of different adaptive transmission policies.