Error Rate Analysis of MIMO System with OSTBC and MRC in Composite Weibull-Gamma Fading

Abstract

Abstract:A paradigm for multiple-input multiple-output (MIMO) channel modeling demands diversity technique to compensate the effects of fading and shadowing. In this paper, error performance of MIMO system is analyzed with orthogonal space time block code (OSTBC) and maximal ratio combining (MRC) techniques over Weibull-gamma (WG) fading channel. WG distribution forms a composite channel model which is used to determine the effects of multipath as well as shadowing. In this scenario, exact analytical expressions for symbol error rate (SER) are computed for MIMO systems using OSTBC and MRC. Consequently, the effects of fading severity by varying shape parameters are also shown by simulation and analytical results.Keywords: multiple-input multiple-output, orthogonal space time block code, maximal ratio combining, Weibull-gamma fading, symbol error rate. IntroductionIn the present wireless systems, the demand of proliferation of bandwidth for high data rate and reliable communication requirement is increasing. Multiple-input multiple-output (MIMO) systems have been investigated to achieve these requirements. Also, diversity techniques have been recommended for increasing the reliability of system. Orthogonal space time block codes (OSTBCs) have been employed in MIMO systems to achieve the full transmit diversity while permitting a simple maximum likelihood decoding algorithm. This algorithm is based on linear processing of received signals [1][2]. MIMO system uses receiver diversity e.g. maximal ratio combining to achieve improved error rate performance by maximizing output signal-to-noise ratio (SNR) [3].Various channel models have been addressed in literature to model small scale fading and the system performance has been evaluated for Rayleigh, Rician, Nakagami-m, Weibull fading scenario with OSTBC using different modulation techniques [4][5][6]. In [7][8][9], error rate of MIMO-MRC system has been analyzed with and without noise and interference. In [10], computationally efficient bit error rate (BER) expressions have been computed for MIMO system using OSTBC and MRC with transmit antenna selection (TAS) technique in equicorrelated Rayleigh fading environment. It has been analyzed that TAS/MRC performs better than OSTBC in terms of BER. Large scale fading effect (i.e., shadowing) has also been considered along with small scale fading for analyzing the system performance. Hence, lognormal and gamma distributions have been introduced to evaluate shadowing effects [11][12]. In [13][14][15], channel models like Rayleigh-lognormal, Nakagami-m-lognormal and Weibulllognormal channels have been investigated. Although, gamma distribution is numerically more appropriate than lognormal distribution to model shadowing effects [16], several generic/composite distributions have been proposed using gamma distribution as an alternative of lognormal distribution. For example, K [16], and Generalized-K [17] channel models have been recommended for reducing complexity and enhancing accuracy of computational analysis.In [12], a ne...