BER Performance Simulation of Generalized MC DS-CDMA System with Time-Limited Blackman Chip Waveform

Multiple access interference encountered in multicarrier direct sequence-code division multiple access (MC DS-CDMA) is the most important difficulty that depends mainly on the correlation properties of the spreading sequences as well as the shape of the chip waveforms employed. In this paper, bit error rate (BER) performance of the generalized MC DS-CDMA system that employs time-limited Blackman chip waveform is presented for Nakagami-m fading channels. Simulation results show that the use of Blackman chip waveform can improve the BER performance of the generalized MC DS-CDMA system, as compared to the performances achieved by using timelimited chip waveforms in the literature

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

Çok girişli çok çıkışlı sistemlerde anten seçimi ve anten seçiminde kullanılan algoritmaların karşılaştırılması

Çoklu anten sistemleri, kablosuz haberleşme sistemlerinin güvenilirlik ve kapasitesini arttıran bir yaklaşımdır. Bunun yanında çoklu anten sistemleri ebat, güç ve donanım bakımından iyileştirilmesi gereken sistemlerdir. Çok Girişli Çok Çıkışlı (ÇGÇÇ) sistemlerde anten seçimi, düşük maliyetli ve düşük karmaşıklığa sahip bir sistem tasarlamak için gereklidir. Bu çalışmada, anten seçiminin ÇGÇÇ sistemlerdeki önemi ele alınmıştır ve literatürde yaygın olarak kullanılan algoritmaların avantajları ve dezavantajları incelenmiştir

Optimum antenna configuration in MIMO systems: A differential evolution based approach

In this paper, we address the problem of determining the optimum antenna configuration for a multi-input multi-output(MIMO) system at any given signal-to-noise ratio (SNR). We used two-level differential evolution (DE) algorithm thatfinds both an appropriate expression among a set of candidate expressions within the list of the optimization softwareused, and the parameter values (coefficients) belonging to the selected expression. The results of the proposed expressionare compared with the results of high SNR approximation, asymptotic approach and optimum antenna number ratios. It isshown that the numerical outcomes produced by the new expression exhibit very good agreement with the optimum antennanumber ratios, and this agreement is almost independent of the specific value of SN

Application of multilayer perceptron networks to laser diode nonlinearity determination for radio-overfibre mobile communications

This paper presents a new approach based on multilayer perceptron networks to determine the 3(rd)-order intermodulation distortion levels in microwave-intensity-modulated GaAIAs laser diodes. The Levenberg-Marquardt algorithm is used to train the network. The results obtained from the network are in excellent agreement with the experimental results reported elsewhere. (C) 2004 Wiley Periodicals, Inc.This paper presents a new approach based on multilayer perceptron networks to determine the 3rd-order intermodulation distortion levels in microwave-intensity-modulated GaAIAs laser diodes. The Levenberg–Marquardt algorithm is used to train the network. The resultsobtained from the network are in excellent agreement with the experimental results reported elsewhere

New results on the performance of multitone DS-CDMA systems in Nakagami-m fading channels

In this letter, new results on the BER performance of multitone DS-CDMA systems for transmissions over Nakagami-m fading channels with exponentially decaying multipath intensity profile are presented. The results show that, in viewpoint of the BER performance, there is a critical relation between the number of resolvable paths and the effect of the rate of average power decay

Differential evolution based prediction of rain attenuation over a LOS terrestrial link situated in the southern United Kingdom

[1] The principal objective of a rain attenuation prediction method is to achieve acceptable estimates of the attenuation incurred on the signal due to rain. In this paper, a differential evolution (DE) based model for predicting rain attenuation in a terrestrial point-to-point line of sight (LOS) link at 97 GHz is proposed using previously available experimental data obtained in the southern United Kingdom. Rainfall rate and percentage of time are used as input data in the proposed prediction model. Excellent agreement between the experimental data and the model output indicates that the presented DE based method may efficiently be used for accurate prediction of the rain attenuation levels.The principal objective of a rain attenuation prediction method is to achieve acceptable estimates of the attenuation incurred on the signal due to rain. In this paper, a differential evolution (DE) based model for predicting rain attenuation in a terrestrialpoint-to-point line of sight (LOS) link at 97 GHz is proposed using previously availableexperimental data obtained in the southern United Kingdom. Rainfall rate and percentage of time are used as input data in the proposed prediction model. Excellent agreement between the experimental data and the model output indicates that the presented DE based method may efficiently be used for accurate prediction of the rain attenuation levels