Redha M. Radaydeh

Impact of delayed arbitrary transmit antenna selection on the performance of rectangular QAM with receive MRC in fading channels

Constrained switching rate imposes practical limitations on the effectiveness of selection combining diversity algorithms. This paper investigates the impact of delayed arbitrarily ordered transmit antenna selection on the average symbol error probability (SEP) performance of arbitrary rectangular quadrature amplitude modulation (QAM) with receive maximal ratio combining (MRC) diversity. New closed form expression is presented for the system average SEP considering the case of statistically independent diversity branches over which the instantaneous fading-to-noise power ratios follow Gamma distributions.

Hybrid frequency-polarization shift-keying Modulation for optical transmission

In this paper, we propose a new modulation scheme based on combining frequency and polarization modulated signals, which we will refer to as hybrid frequency-polarization shift keying (FPolSK). The FPolSK modulation is basically an extension of the conventional M-PolSK modulation over orthogonal domains. This expansion enables representing signal constellation points over multidimensional space, which ensures increasing the geometric distances between these points, and in turn, improving the system power efficiency. On the other hand, compared with M-FSK modulation, FPolSK improves the bandwidth efficiency by employing less number of orthogonal frequencies to represent information symbols. Moreover, FPolSK is extremely useful for implementing communication systems that have limitations in power and bandwidth usage. This advantage comes from the fact that FPolSK inherently enables selecting the appropriate number of orthogonal frequencies that convey with system constraints. The contribution in this paper is threefold. First, we propose a design for the transmitter and the receiver of the FPolSK technique. Second, we perform analysis for the system power and bandwidth efficiencies. Third, we derive an expression for the system power spectral density (PSD). A performance comparison between the FPolSK modulation technique and previously developed techniques is also presented in this paper. Our results reveal that the proposed modulation scheme performs better than M-PolSK, M-DPSK, and M-FSK modulation schemes in terms of both power and bandwidth efficiencies. We have also found that same bandwidth efficiency can be obtained using different FPolSK modulation formats, and the PSD of the FPolSK modulation does not contain discrete components that are considered as a waste of power. Finally, the effects of the laser phase noise and fiber dispersion on the performance of the proposed modulation are also discussed in detail.

Performance of Cellular Mobile Systems Employing SNR-Based GSC in the Presence of Rayleigh and Nakagami-

This paper studies the performance of cellular mobile systems employing a signal-to-noise ratio (SNR)-based generalized selection combining (GSC) algorithm in the presence of background white noise and multiple cochannel interfering signals. Closed-form expressions are derived for the received signal-to-interference-plus-noise ratio (SINR) distribution and outage probability, considering the case when the interfering signals experience mixed Rayleigh and Nakagami-q fading conditions, and the desired signal replicas are attenuated by flat Rayleigh fading. These expressions are obtained via the new representation of the total interference-to-noise ratio (INR) distribution for the mixed mode of fading experienced by different interferers. The derived expressions for the aforementioned statistical measures are valid for an arbitrary number of interferers and system diversity order and can be employed to investigate the impact of various system and fading parameters on the performance measures. Several case studies can be deduced from the results presented in this paper, including interference-limited systems, wherein the impact of white noise can be neglected.

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This paper studies the performance of Rake receivers with maximal ratio combining (MRC) in the presence of cochannel interference over slowly varying frequency-selective fading channels with combined spatial receive antenna diversity and temporal multipath diversity. Two models for the instantaneous powers of the residual multipath components and the resolved cochannel interfering signals, which represent the overall interfering signals, are employed. The first model considers the phase asynchronism between the desired signal replicas and interfering signals, whereas the second model assumes that the instantaneous powers of interfering signals incoherently add up. The desired signal replicas and interfering signals are assumed to experience statistically independent Rayleigh fading processes with arbitrary statistics. For the system model previously described, new closed-form expressions for the probability density function (pdf) of the combined signal-to-interference-plus-noise ratio (SINR) are derived. These expressions are then used to obtain formulas for various performance measures. The case study under consideration and the corresponding derived expressions for the statistical measures generalize many previous results and can usefully be employed to investigate the impact of various system and channel parameters on the performance of Rake receivers with MRC in the presence of cochannel interference.

Cochannel Interferers

The performance of selection combining (SC) diversity in the presence of additive white Gaussian noise as well as multiple co-channel interfering signals over fading channels is analysed. The analysis considers two SC algorithms, namely, the signal-to-noise ratio-(SNR) based SC algorithm and the signal-to-interference-plus-noise ratio (SINR)-based SC algorithm. Closed-form expressions for the distribution of the resulting SINR and the outage probability performance are derived for both SC algorithms. The derived expressions are valid for arbitrary number of interfering signals, and when the desired signal replicas experience independent Rayleigh fading with generalised statistics. In addition, they are applicable for the general case when the interfering signals are subject to arbitrary fading models, which include the cases of identical, non-identical, correlated and mixed-mode fading scenarios. Numerical results are presented to examine the impact of different fading conditions and system parameters on the outage performance for both SC algorithms under consideration.

MRC in the Presence of Asynchronous Cochannel Interference Over Frequency-Selective Rayleigh Fading Channels

The use of transmit antenna selection algorithms in multiple-antenna systems enables significant reduction in implementation cost and complexity while maintaining acceptable performance. An attractive and quite flexible selection algorithm is to allow the receiver to pick any of the transmit antennas that can satisfy a predetermined performance target. Such an algorithm is referred to as the arbitrarily ordered transmit antenna selection algorithm. However, the effectiveness of transmit antenna selection is decreased by several propagation impairments over the feedback channel from the receiver to the transmitter. Of these impairments, the feedback channel time delay may impose a significant impact on the achieved performance. This paper aims to investigate the impact of this time delay on the performance of receive maximal-ratio combining (MRC) diversity employing the arbitrarily ordered transmit antenna selection algorithm. In order to obtain quantitative measures for this impact, new expressions for various performance criteria are obtained by using the new derived formulas for the probability density function (pdf) and the moment generating function (MGF) of the combined signal-to-noise ratio (SNR). Numerical and simulation results are presented to illustrate the effect of delayed (i.e. outdated) feedback information on the system performance for various transmit antenna selection scenarios.

SNR and SINR-based selection combining algorithms in the presence of arbitrarily distributed co-channel interferers

This paper derives exact expressions for the average error performance of M-ary orthogonal signals with noncoherent equal-gain diversity combining over nonidentical generalized Rician, Nakagami-m, Nakagami-g, and implicitly Rayleigh fading channels. The assumption of generalized distributed fading envelopes implies that the received average signal-to-noise ratios (SNRs) and/or the fading parameters can have arbitrary nonidentical values. The derived expressions are precisely given in terms of either one-fold integral or rapidly convergent infinite series, which can be readily evaluated numerically. In addition, they can be usefully used to study the impact of arbitrary correlation among diversity branches on the system average error performance.

Receive maximal-ratio combining with outdated arbitrary transmit antenna selection 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.

Compact formulas for the average error performance of noncoherent m-ary orthogonal signals over generalized rician, nakagami-m, and nakagami-q fading channels with diversity reception

Exact results are presented for infinite integrals that consist of higher-order powers of the one dimensional Gaussian Q-function averaged over Rayleigh fading envelopes in multi-branch diversity reception with maximal ratio combining (MRC). Some known results for the average of the 1st and 2nd powers are shown as special cases. The results obtained in this paper are utilized to study the average symbol error probability (SEP) performance of differentially encoded quadri-phase shift-keying (DE-QPSK) in Rayleigh fading channels employing MRC, and new exact expressions are presented for different fading scenarios. The derived mathematical expressions are verified using Monte Carlo simulations.

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

This paper analyzes the average bit error rate (BER) of noncoherent M-ary frequency-shift keying (FSK) signals over multichannel nonidentically distributed Nakagami-q (Hoyt) fading employing diversity combining. The first part of the paper considers the conventional postdetection noncoherent equal-gain combiner (NC-EGC), in which a Fourier series inversion formula is employed to derive a simple and rapidly converging series-based expression for the system average BER. This expression is valid for arbitrary values of received average signal-to-noise ratios (SNRs) and fading parameters. The derived expression is then compared with some existing ones in the literature, and the results show a large reduction in computational complexity, particularly when M and/or the diversity order increases. In the second part, a new noncoherent combiner is proposed to achieve improvements over the conventional NC-EGC. It is also shown that this new combiner results in a simple closed-form expression for the system average BER that is given in terms of elementary functions; hence, it can be easily numerically evaluated with noticeable computation efficiency.