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In this paper, a method for approximating the probability distribution of sum of independent and identical Weibull random variables is adopted to analyze the performance of equal gain combiner (EGC) receiver over non-identical Weibull fading channel (WFC). Our main result is to derive a generalized expression of the probability density function (PDF) of the signal-to-noise ratio (SNR) at the EGC output in the case of non-identical WFC. Based on this PDF, accurate approximation of significant performance criteria, such as outage probability (OP), the amount of fading (AoF), and average symbol/bit error probability (ASEP/ABEP), are derived. In addition, we derived the analytical expressions for channel capacities under various adaptation policies such as optimal rate adaptation (ORA), optimal simultaneous power and rate adaptation (OPRA), channel inversion with fixed rate (CIFR), and truncated channel inversion with fixed rate (TCIFR). The proposed mathematical analysis is complemented by several numerical results and validated using Monte Carlo simulation method.

In this study, we present a low computation com plexity expressions of many performance indicators of L-branch Maximal Ratio Combining (MRC). We adapt the previous results given for MRC receiver [1] to the case of correlated Weibull fading channels. Additionally, we derive a new formulas for probability density function (PDF) and moment generating function (MGF) of the output SNR in terms of simple polynomial and laguerre generalized function. All the findings are illustrated using MATHEMATICA Software and validated by comparison with earlier results [2].

In this paper, we investigate the analytical performance of the multiple-input multiple-output system (MIMO) with orthogonal space-time block codes (STBCs) subject to Weibull fading channels (WFC). Space-time block code technique provides an efficient pattern for wireless transmission over various fading channels using multiple transmit antennas. Two approximating methods of the sum of independent Weibull random variables are studied. For each approach, we derive accurate approximate expressions for several performance metrics of MIMO-STBC system operating under independent and nonidentical WFC. The proposed approximations are expressed in terms of 2 generalized hypergeometric functions, namely, Fox's H and Meijer's G functions. All the derived approximate expressions prove high accuracy, while compared with the simulation results established via Monte Carlo method and Kolmogorov-Smirnov test as well.Although the 2 approaches have approximately the same accuracy, the second method approximate expressions are much less complex than those of the first method. KEYWORDS channel capacity, Fox's H function, Meijer's G function, MIMO-STBC, probability density function (PDF), symbol error rate, outage probability, Weibull fading channels (WFC) | INTRODUCTIONTo overcome the problem of transmit diversity technique for the multiple-input multiple-output (MIMO) systems, several interesting coding and modulation techniques have been attacked in various ways recently. One famous modulation scheme is the orthogonal space-time block codes (STBCs). 1 A generalization of STBC has been investigated later in Tarokh et al. 2 Based on several studies, it is proven that the STBC can ensure the same diversity order as maximal-ratio combining (MRC). On the other hand, the monopath channel capacity is known to be less than the one of MIMO system. 3 The main advantage of STBCs is that the maximum probability decoding can be reached using a linear processing at the receiver. 4 Shin and Lee 5 analyzed, using the moment-generating function-based approach, the exact average symbol error rate (ASER) of MIMO-STBC system with some modulation schemes under Nakagami-m fading channels. In Pérez et al, 6 accurate approximate outage capacities of MIMO-STBC over several kinds of fading distribution such as Rayleigh, Rice, Nakagami-m, and Weibull were derived. The channel capacities under adaptive transmission policy of MIMO-STBC operating under Rayleigh fading channels were derived in closed form in Maaref and Aissa. 7 In addition to the small-scale fading, the shadowing, ie, large-scale fading, can affect the signal during its propagation, which will extremely reduce the advantages of MIMO system. In Yang, 8 the shadowing was modeled via the lognormal