Asymptotic Capacity Analysis Under Different Adaptive Transmission for TAS/MRC MIMO Scheme Subject to Weibull Fading Channels Toufik Chaayra a , Faissal El Bouanani b,∗ , Hussain Ben-azza a a ENSAM, Moulay Ismail University, Meknes, Morocco b ENSIAS, Mohammed V University, Rabat, Morocco Abstract This paper investigates a unified average channel capacity (ACC) analysis under different adaptive transmis- sion of multiple-input multiple-output (MIMO) system, combining single transmit antenna selection (TAS) and maximal-ratio combining (MRC) receiver operating under independent flat Weibull multipath fading channels (WFCs). Based on a tight approximate probability density function expression of the signal-to- noise ratio (SNR) at the considered receiver output, we derive new accurate closed-form expressions of ACC for TAS/MRC system employing several rate adaptation techniques, namely optimal rate adaptation, op- timal simultaneous power and rate adaptation, channel inversion with fixed rate (CIFR), truncated CIFR (TCIFR), and continuous power TCIFR (CTCIFR). Further, asymptotic expressions, in both high and low- SNR regimes, are investigated. The results show high accuracy for significant values of L t × L r TAS/MRC system. Indeed, the smaller L t × L r , the better the PDF’s accuracy, therefore, the better are the capacities. Numerical outcomes have been assessed by utilizing Mathematica and Matlab Software and corroborated via Monte-Carlo simulations. Keywords: Rate adaptation policies, cumulative distribution function, diversity, Fox’s H-function, maximal-ratio combining, Meijer’s G-function, probability density function, symbol error rate, transmit antenna selection, Weibull fading 1. Introduction Multiple-input multiple-output (MIMO) regimes have been produced in order to alleviate the perfor- mance degradation of multipath fading in wireless frameworks and to fulfill the high information rate re- quests for future wireless communication through expanded spectral efficiency [1]. The performance of wireless transmission can be essentially enhanced by combining all the signals received by the individual antennas utilizing different combining methods, namely equal gain combining (EGC), selective combining (SC), and maximal-ratio combining (MRC), known to outperform all diversity techniques [1]-[2]. The energy/spectral efficiency is becoming a key factor in the design of wireless communication systems. This has stimulated the enormous efforts that have been made so far within the communication theory communities to understand better the performance behavior of wireless communications in low/high power regimes and to develop new methods aiming to adapt/optimize the transmission rate in order to achieve a high capacity system. Although the signal strength in large-scale communications is typically very low, one can take advantage of extremely important bandwidth to achieve high capacity [3]-[4]. As the lifetime of nodes’ batteries in wireless sensor networks (WSNs) are limited, the signal is most often transmitted with a very low power to save as much as possible the batteries’ energy consumption [5]-[6]. Also transmitting with high power * Corresponding author Email addresses: t.chaayra@edu.umi.ac.ma (Toufik Chaayra), f.elbouanani@um5s.net.ma (Faissal El Bouanani), hbenazza@yahoo.com (Hussain Ben-azza) Preprint submitted to Physical Communication June 25, 2019