Maximal Ratio Combining Diversity System Research Articles

Performance analysis of rectangular quadrature amplitude modulation with combined arbitrary transmit antenna selection and receive maximal ratio combining in Nakagami-m fading

The average symbol error probability (SEP) performance of arbitrary rectangular quadrature amplitude modulation in the context of arbitrarily ordered transmit antenna selection and receive maximal ratio combining diversity system is analysed. The channel gains are assumed to follow Nakagami-m fading distribution with in general arbitrary fading parameters. Exact expressions for the average SEP performance are derived for the general case of unequal in-phase and quadrature decision distances as well as distinct in-phase and quadrature modulation orders. The results generalise many previous case studies, and can be used to investigate the impact of various diversity-combining schemes and different modulation and channel parameters on the system average SEP performance.

Efficient bit error probability expression and very tight bound for maximal ratio combining diversity systems over Rayleigh fading channel

Bit Error Probability (BEP) provides a fundamental performance measure for wireless diversity systems. This paper presents two new exact BEP expressions for Maximal Ratio Combining (MRC) diversity systems. One BEP expression takes a closed form, while the other is derived by treating the squared-sum of Rayleigh random variables as an Erlang variable. Due to the fact that the extant bounds are loose and could not properly characterize the error performance of MRC diversity systems, this paper presents a very tight bound. The numerical analysis shows that the new derived BEP expressions coincide with the extant expressions, and that the new approximation tightly bounds the accurate BEP.

On the Maximum Number of Receiver Diversity Antennas That Can Be Usefully Deployed in a Cochannel Interference Dominated Environment

The question of how many receiver antennas to employ in a diversity system operating in cochannel interference is examined. The long-term signal-power-to-interference-power ratio, the long-term signal amplitude to the square root of the interference power ratio, the average instantaneous signal-to-interference ratio, and the average bit-error rate of a maximal ratio combining diversity system in the presence of an arbitrary number of cochannel interferers are evaluated when the desired user signal and the interfering user signals are independent, and each of them experiences correlated Ricean fading at the receiver antennas. The best number of antennas required for a fixed-size antenna array to achieve a good compromise between system performance and system cost is investigated. The results show that, in general, the performance of a fixed-size antenna array containing the maximum number of independent antennas cannot be significantly improved by adding more than one additional antenna. Some special cases where particular gains can be achieved by adding additional correlated antennas are also discussed.

Channel Capacity of Adaptive Transmission With Maximal Ratio Combining in Correlated Rayleigh Fading

We derive closed-form expressions for the single-user capacity of maximal ratio combining diversity systems taking into account the effect of correlation between the different branches. We consider a Rayleigh fading channel with two kinds of correlation: 1) equal branch signal-to-noise ratios (SNRs) and the same correlation between any pair of branches and 2) unequal branch SNRs and arbitrary correlation between branches such that the eigenvalues of the branch covariance matrix are all distinct. Three adaptive transmission schemes are analyzed: 1) optimal simultaneous power and rate adaptation; 2) optimal rate adaptation with constant transmit power; and 3) channel inversion with fixed rate.

Approximation of SNR statistics for MRC diversity systems in arbitrarily correlated Nakagami fading channels

An approximated probability density function is presented for the SNR in maximal ratio combining diversity systems with an arbitrary number of diversity branches in an arbitrarily correlated Nakagami fading environment. Comparisons between the exact and approximated distribution show good agreement over wide ranges of correlation coefficients.

Outage probability of cellular radio systems using maximal ratio combining in the presence of multiple interferers

In mobile radio systems, antenna diversity is used to combat fading and reduce the impact of cochannel interference. We derived a new expression for probability density functions of the signal-to-interference-plus-noise ratio and apply it to analyze the outage probability (OTP) for a maximal ratio combining diversity system when multiple cochannel interferers are present. Numerical results showing the impact of the number of antenna elements, the number of cochannel interferers, and signal-to-noise ratio on the OTP are presented. Simulation results validating the analytical results are also presented.