Performance analysis of coherent DS-CDMA systems in a Nakagamifading channel with arbitrary parameters

A new expression for the bit error rate (BER) of an asynchronous direct-sequence code-division multiple-access (DS-CDMA) system with coherent BPSK demodulation in a multipath Nakagami (1960) fading channel is derived. The analysis assumes an arbitrary number of independent, but nonidentical resolvable paths combined by the RAKE receiver. The results obtained show that in such systems, the effect of nonidentical fading on system performance cannot be ignored     

Dual MRC diversity reception of TCM-MPSK signals over Nakagamifading channels

Space diversity reception and forward error correction coding are powerful techniques for combating the multipath fading encountered in mobile radio communications. In this Letter, the authors analyse the performance of a dual maximal ratio combining (MRC) diversity system using trellis coded modulation-multiple phase shift keying (TCM-MPSK) on slow, nonselective correlated Nakagami fading channels. An alternative exact derivation is introduced for the pairwise error probability, used in calculating average bit error rate analytical upper bounds     

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 Lauricella's 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.     

BER analysis of arbitrary QAM for MRC diversity with imperfect channel estimation in generalized ricean fading channels

Imperfect channel estimation (ICE) can severely degrade the bit error rate (BER) of digital modulations with maximum ratio combining (MRC) diversity reception. The resulting performance analysis problem in its most general setting has not been addressed before. In this paper, the effect of ICE on the BER of an arbitrary square/rectangular Gray-coded quadratic amplitude modulation (QAM) in generalized Ricean fading channels when MRC reception is employed is analyzed. A general expression for the bit error probability of an arbitrary square/rectangular QAM scheme is first derived. This general formula requires a number of conditional probabilities, which is derived in closed form for independent and nonidentically distributed (i.n.d.) Rayleigh-fading channels with MRC and ICE. An efficient numerical method is also presented to compute the conditional probabilities for i.n.d. and correlated Ricean fading. In addition, extensive Monte Carlo simulations that agree excellently with the analytical results are presented.     

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.     

The performance of binary transmission in slow Nakagami-fadingchannels with MRC diversity

This letter presents equations which describe an average weighted spectrum of errors and average block-error probabilities for noncoherent frequency-shift keying (NCFSK) used in D-branch maximal ratio combining (MRC) diversity in independent very slow nonselective Nakagami-fading channels. The average is formed over the instantaneous receiver signal-to-noise ratio (SNR) after combining. The analysis is limited to additive Gaussian noise     

On the channel capacity in Rician and Hoyt fading environments with MRC diversity

Expressions for the capacity of Rician and Hoyt (Nakagami-q) fading channels with maximal ratio combining diversity are available in the literature in the form of an infinite series. We derive lower and upper bounds on the errors resulting from truncating the infinite series in those capacity expressions. We also present numerical examples for illustration purposes.     

MRC分集接收的MQAM在Nakagami信道上的性能分析

Nakagami信道是一种适应性较强的信道模型，MQAM(M-ary quadrature amplitude modulation)是一种频谱利用率较高的调制方式。在存在多径影响的无线通信环境中，最大比合并(maximum ratio combining)方式的分集接收是克服衰落的有效方法。本文利用适用范围更广的Nakagami信道模型，在多径衰落的情况下对最大比合并分集接收的MQAM系统误符号率性能作了分析。仿真结果对分析实际信道下具体系统的性能具有一定的参考价值。     

Exact performance analysis of M-ary QAM with MRC diversity in Rician fading channels

The exact expression of symbol error rate (SER) is derived for coherent square M-ary quadrature amplitude modulation (M-QAM) using Lth order maximal-ratio combining (MRC) diversity in Rician fading channels with an arbitrary fading parameter. The accuracy of the SER estimates evaluated by this expression is verified through comparison with the results evaluated by numerical integration.     

Effect of channel estimation errors on MRC diversity in Rician fading channels

We study the effect of imperfect channel estimation (ICE) on the performance of M-ary phase shift keying (M-PSK) with maximum ratio combining (MRC) in generalized Rician fading channels. First, we derive the error probability formulas for M-PSK with MRC and ICE in arbitrary Rician fading channels. Furthermore, we derive the effective receiver output signal-to-noise ratio (SNR) statistics and the outage probability, and analytically quantify the average SNR loss of M-PSK caused by ICE, assuming independent diversity branches. Finally, we point out a major approximation in a popular approach used in the literature to evaluate the adverse effect of ICE.     

Selection diversity for wireless communications in Nakagami-fadingwith arbitrary parameters

By means of analytical and numerical methods, the probability of error and the outage probability of a selection diversity RAKE receiver system employing direct sequence/code division multiple access (DS/CDMA) is derived. A noise-limited propagation environment is modeled as a Nakagami (1960)-fading channel with arbitrary fading parameters and unequal mean power at the receiver. New analytical expressions are derived for the average probability of error and outage probability. Binary detection schemes are considered including binary phase-shift keying (PSK) and frequency-shift keying (FSK). Both coherent and noncoherent detection is considered as well as identical and arbitrary fading. It is shown that the effect of arbitrary fading on system performance is significant and may not be ignored     

Performances of EGC and MRC diversity for UWB PAPM systems in IEEE channel models

Accurate approximations to the bit error rates of equal gain combining and maximal ratio combining diversity are obtained for pulse-amplitude-and-position-modulation operating in IEEE ultra-wide bandwidth (UWB) channel models. Numerical results are presented to show the accuracy of the approximations for the IEEE CM1 and CM3 UWB channel models. Results for pulse amplitude modulation and pulse position modulation are obtained as special cases of the more general results. Precise estimates of the loss of equal gain combining relative to maximal ratio combining are obtained for both lineof- sight CM1 and non-line-of-sight CM3 channels. Noteworthy, while the performance loss of equal gain combining with respect to maximal ratio combining is less than 0.4 dB for the non-lineof- sight channel, it can be as much as 2 dB for the line-of-sight channel.     

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 arbitrarilyordered 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.     

Efficient transmit diversity scheme for synchronisation channel in OFDM cellular systems

Transmit diversity is a well-known technique that improves receiving performance by mitigating the amplitude variation of received signal. A number of diversity techniques have been investigated for data and control channels in OFDM cellular systems [1]. However, the diversity schemes for the synchronisation channel have not yet been fully investigated. Because of the inherent characteristics of a synchronisation channel, FSTD and TSTD can be considered as diversity schemes [2]. For data and control channels, it is important to increase the average detection probability for reliable system operation. For the synchronisation channel, however, the searching time is more important than the average detection probability. It implies that the transmission scheme increasing the average detection probability after multiple detection trials can be more beneficial even if it degrades the average detection performance at a first detection trial.     

Approximate SER of H-S/MRC in Nakagami fading with arbitrary branch power correlation

An accurate approximation to the average symbol-error rate of hybrid selection/maximal-ratio combining (H-S/MRC) in correlated Nakagami-m fading with positive integer values of m is obtained by using a Green's matrix approximation. This approach is valid for different M-ary linear modulation schemes. We illustrate our methodology using M-ary phase-shift keying as an example.     

Estimation of Nakagami-m fading channel parameters with application to optimized transmitter diversity systems

An optimum power loading algorithm for transmitter diversity systems over correlated and unbalanced Nakagami (1960) paths and its performance evaluation under perfect channel estimate conditions are derived. In addition, various online estimators of the required Nakagami channel parameters for optimized power loading and the comparison of their mean square error via Monte Carlo simulations are presented. Some of these estimators are used to obtain the performance of optimized transmitter diversity systems under imperfect channel estimation (ICE). These numerical results show that the diversity gain of these optimized systems compared with equipower systems increases as the severity of fading decreases and as the degree of branch imbalance increases even under ICE. On the other hand, in weakly correlated and (or) unbalanced branches, optimized transmitter diversity systems offer negligible gain or even losses compared with unoptimized systems because of the ICE.     

一种用于信道分集性能研究的新方法

对于无线通信系统来说,信道分集是实现可靠通信、提高通信性能的有效方法.目前,分集复用折衷性能是衡量不同信道分集技术性能的常用方法,该法仅适应于高信噪比情况.本文基于信道分集因子统计特性从一个新的角度对信道分集进行了研究,针对传统信道分集技术提出了一种新的信道分集性能研究方法,理论分析及仿真结果表明方法是有效的.     

Outage and BER of MRC diversity in bandlimited micro-cellular systems with CCI

Maximal ratio combining for bandlimited BPSK in micro-cellular systems with cochannel interference is considered. A Nakagami/Rayleigh fading model is assumed. Spectrum raised-cosine and Beaulieu-Tan-Damen pulse shapes are employed. Exact closed-form expressions for outage probability with equal and different interferer powers are derived. An average bit error rate approximation is derived using a Gaussian assumption for the cochannel interference. Monte-Carlo simulation is used to validate the Gaussian assumption. The results are valid for arbitrary diversity order and desired user fading parameter. Slow flat fading, asynchronous timing and independent fading gains are assumed.     

On the performance of energy detection-based CR with SC diversity over IG channel

Cognitive radio (CR) is a viable 5G technology to address the scarcity of the spectrum. Energy detection-based sensing is known to be the simplest method as far as hardware complexity is concerned. In this paper, the performance of spectrum sensing-based energy detection technique in CR networks over inverse Gaussian channel for selection combining diversity technique is analysed. More specifically, accurate analytical expressions for the average detection probability under different detection scenarios such as single channel (no diversity) and with diversity reception are derived and evaluated. Further, the detection threshold parameter is optimised by minimising the probability of error over several diversity branches. The results clearly show the significant improvement in the probability of detection when optimised threshold parameter is applied. The impact of shadowing parameters on the performance of energy detector is studied in terms of complimentary receiver operating characteristic curve. To verify the correctness of our analysis, the derived analytical expressions are corroborated via exact result and Monte Carlo simulations.     

Expression for evaluating performance of BPSK with MRC in Nakagami fading

A strikingly simple and fast to compute expression is derived for the performance of binary phase shift keying (BPSK) with maximal ratio combining (MRC) diversity in a Nakagami (1960) fading channel. The expression is valid for all Nakagami-m parameters. Furthermore, no concession is made as far as the accuracy of the results is concerned.