Performance of Two-Hop DS-CDMA Systems Using Amplify-and-Forward Protocol over Different Fading Channels

This study analyses the performance of directsequence code division multiple access (DS-CDMA) based on two-hop amplify-and-forward protocol over Weibull symmetric fading channels as well as Rayleigh/Rician, Rician/Rayleigh asymmetric fading phenomenas. We investigate the bit-error rate (BER) of the considered system using multiple relays by considering the effect of Weibull fading parameter and Rician K factor on the system performance. Our simulation results demonstrate the positive impacts of the value of fading parameter, Rician K factor and increasing number of relay nodes on BER performance. It is also confirmed that the Rician K factor is more effective on the system performance over Rician/Rayleigh fading channels in comparison with Rayleigh/Rician fading environment

Effective Capacity Performance of α-κ-μ Fading Channels

In this work, a closed-form expression is derived for effective capacity of α-κ-μ fading channels. Then, an asymptotic expression is also proposed for the effective capacity of the considered channel model. In addition, an investigation of truncation error analysis is carried out for the infinite series representation which is included in the derived expression. Finally, the effective capacity performance is presented by obtaining the analytical results for different values of fading parameter with simulation results

Effect of repetition coding on the BER performance of interleave-division multiple access systems

This paper investigates the bit error rate (BER) performance of interleave-division multiple access (IDMA) schemes to show the effect of repetition coding on the system performance. The considered system is tested in the presence of repetition coding by varying system parameters such as number of simultaneous users, data length, spread length, iteration number, and code rate over additive white Gaussian noise channels. In addition, the performance of the considered system is also illustrated in Rayleigh flat fading channels for a more realistic scenario. Our simulation results show that the BER performance of IDMA systems with repetition coding can achieve significant performance gains over existing uncoded IDMA schemes

Asimetrik Sönümlü Kanallarda İki Atlamalı Çöz-ve-Aktar Röleli İletimin Servis-dışı Kalma Olasılığının Analizi

Bu çalışma, iki atlamalı çöz-ve-aktar röleli iletim modelininasimetrik sönümlü kanallarda servis-dışı kalma olasılığınısunmaktadır. Ele alınan işbirlikli sistem, bir kaynak (S), birröle (R) ve bir hedeften (D) oluşmaktadır. İncelenen asimetriksenaryoya göre, kaynak-röle ve röle-hedef arasında bulunankanallar sırasıyla Rayleigh ve genelleştirilmiş Gammasönümlenmesine sahiptir. İşbirlikli sistemin servis-dışı kalmaolasılığı için analitik bir ifade türetilmiştir. Direk ve röleliiletimin servis-dışı kalma olasılığı için türetilen bu ifadekullanılarak nümerik sonuçlar verilmiştir.This work presents the outage probability of two-hop decodeand-forward (DF) relaying in asymmetric fading channels.Cooperation system considered in this work consists of asource (S), a relay (R) and a destination (D). According toasymmetric scenario assumed here, source-relay and relaydestinationlinks are subject to Rayleigh fading andgeneralized Gamma fading, respectively. An analyticalexpression is derived for the outage probability of consideredcooperation model and some numerical results of the outageprobability are presented for both direct transmission andDF relaying scheme by using the derived expression

SER Performance of Amplify-and-Forward Cooperative Diversity Over Asymmetric Fading Channels

In this paper, the performance of amplify-and-forward (AF) cooperative diversity is analyzed over asymmetric fading channels. The source-relay and the relay-destination links experience Rayleigh fading while the source-destination link is subject to generalized Gamma fading. First, the probability density function (PDF) and the moment generating function (MGF) of the source-relay-destination link and the MGF of the source-destination link are derived. Then, the symbol error rate (SER) is determined based on the MGF of the total end-to-end signal-to-noise ratio (SNR). Moreover, the SER performance of N-relay assisted AF cooperative diversity is illustrated for M-ary phase shift keying (M-PSK) and M-ary quadrature amplitude modulation (M-QAM). Based on the derived MGF expressions, the numerical results are obtained by varying the modulation types and channel parameters for different scenarios

A New Approach to Random Interleavers for Traditional IDMA Systems

In an interleave-division multiple access (IDMA) system, interleavers have a crucial role for the system performance. This paper presents a new approach to random interleavers for traditional IDMA systems. The proposed interleaver uses a random variable which is defined by Rayleigh distribution for mapping. Simulation results demonstrate that the proposed interleaver approach improves the bit-error rate (BER) performance of the IDMA systems