Akademik Veri Yönetim Sistemi
PHYSICAL COMMUNICATION, cilt.23, ss.76-83, 2017 (SCI-Expanded)
In this paper, approximate outage probability (OP) and average symbol error rate (SER) of cooperative directsequence codedivision multiple access (DS-CDMA) systems with amplifyandforward (AF) relaying are evaluated over asymmetric fading channels. Practically, the channels between source (S), relay (R) and destination (D) nodes in a DS-CDMA system can be subject to different fading due to the nature of wireless medium. Motivated by this reality, the SD path is assumed to be Nakagami-m distributed which is a general fading model for different types of channel conditions while SR and RD paths are considered to experience Rician fading in order to include line of sight conditions. First, closed form solutions are obtained for both the cumulative distribution function and the probability density function of SRD paths. Then, a closedform total moment generating function (MGF) of the considered system is derived. The lower bound of the OP is calculated with the help of the inverse Laplace transform of the derived MGF expression while average SER is analyzed by evaluating the integral over the derived MGF. Finally, an asymptotic MGF expression is proposed for high signal-to-noise ratio (SNR) analysis df AF DS-CDMA systems. The simulation results are provided to verify the correctness of the analytical derivations. It is shown that the approximate OP and average SER results are in well agreement with the simulations and the asymptotic results are tight from medium to high SNR regime. (C) 2017 Elsevier BM. All rights reserved.