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1
Content available Improving Performance of MC-CDMA Systems Using UTTCM Channel Coding
Bendjillali Ridha Ilyas, Bendelhoum Mohammed Sofiane, Abderraouf Elarbi, Lahcene Mohamed
Journal of Telecommunications and Information Technology
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2024
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nr 2
58--65
EN
Over the past decade, personal communications have witnessed exponential growth, fueled by the increasing number of connected users and the diversity of transmitted data types. This expansion necessitates a boost in the transmission systems' capacity to accommodate higher user numbers and data rates, simultaneously striving to optimize cost and complexity. Consequently, future communication systems are pivoting towards multi-carrier spread spectrum techniques (MC-CDMA), capitalizing on the robustness of OFDM multi-carrier transmissions against multipath propagation and leveraging the flexibility of the code division multiple access (CDMA) technique. \\This study addresses data transmission quality-related concerns within an MC-CDMA system by implementing UTTCM error correction codes. These codes aim to enhance channel spectrum efficiency and mitigate error probability. Simulation results demonstrate that the proposed transmission scheme offers significant improvements in terms of bit error rate and signal-to-noise ratio, while maximizing the bandwidth shared among users. Additionally, the incorporation of such equalization techniques as zero forcing (ZF) and minimum mean square error (MMSE), ensures extensive compensation for the channel selectivity effect
2
Content available Performance Evaluation of MC-CDMA Systems with Single User Detection Technique using Kernel and Linear Adaptive Method
Fateh Rachid, Darif Anouar, Safi Said
Journal of Telecommunications and Information Technology
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2021
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nr 4
1--11
EN
Among all the techniques combining multi-carrier modulation and spread spectrum, the multi-carrier code division multiple access (MC-CDMA) system is by far the most widely studied. In this paper, we present the performance of the MC-CDMA system associated with key single-user detection techniques. We are interested in problems related to identification and equalization of mobile radio channels, using the kernel method in Hilbert space with a reproducing kernel, and a linear adaptive algorithm, for MC-CDMA systems. In this context, we tested the efficiency of these algorithms, considering practical frequency selective fading channels, called broadband radio access network (BRAN), standardized for MC-CDMA systems. As far as the equalization problem encountered after channel identification is concerned, we use the orthogonality restoration combination (ORC) and the minimum mean square error (MMSE) equalizer techniques to correct the distortion of the channel. Simulation results demonstrate that the kernel algorithm is efficient for practical channel.
3
Content available Suitable Spreading Sequences for Asynchronous MC-CDMA Systems
Addad M., Djebbari A.
Journal of Telecommunications and Information Technology
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2018
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nr 3
9--13
EN
In order to meet the demand of high data rate transmission with good quality maintained, the multi-carrier code division multiple access (MC-CDMA) technology is considered for the next generation wireless communication systems. However, their high crest factor (CF) is one of the major drawbacks of multi-carrier transmission systems. Thus, CF reduction is one of the most important research areas in MC-CDMA systems. In addition, asynchronous MC-CDMA suffers from the effect of multiple access interference (MAI), caused by all users active in the system. Degradation of the system’s bit error rate (BER) caused by MAI must be taken into consideration as well. The aim of this paper is to provide a comparative study on the enhancement of performance of an MC-CDMA system. The spreading sequences used in CDMA play an important role in CF and interference reduction. Hence, spreading sequences should be selected to simultaneously ensure low CF and low BER values. Therefore, the effect that correlation properties of sequences exert on CF values is investigated in this study. Furthermore, a numerical BER evaluation, as a function of the signal-to-noise ratio (SNR) and the number of users, is provided. The results obtained indicate that a trade-off between the two criteria is necessary to ensure good performance. It was concluded that zero correlation zone (ZCZ) sequences are the most suitable spreading sequences as far as the satisfaction of the above criteria is concerned.
4
Content available An Improved Downlink MC-CDMA System for Effcient Image Transmission
Bendelhoum M. S., Djebbari A., Boukli-Hacene I., Taleb-Ahmed A.
Journal of Telecommunications and Information Technology
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2017
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nr 4
5--16
EN
Image compression is an essential stage of the data archiving and transmitting process, as it reduces the number of bits and the time required to complete the transmission. In this article, a study of image transmission over the Multi-Carrier Code Division Multiple Access (MC-CDMA) downlink system is presented. The solution proposed relies on source coding combined with channel coding. The Discrete Wavelet Transform (DWT) method is used in conjunction with the SPIHT coder to compress the image, then the data generated is transmitted with the MC-CDMA technique over a noisy channel. The results show that image transmissions performed over MC-CDMA using the SPIHT model are better than the traditional approach like MC-CDMA in the AWGN channel.
5
Badanie jakości transmisji w interfejsie radiowym MC-CDMA
Marczak A.
Zeszyty Naukowe Wydziału ETI Politechniki Gdańskiej. Technologie Informacyjne
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2010
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T. 19
269-274
PL
Technika MC-CDMA (ang. Multi-Carrier Code Division Multiple Access) powstała z połączenia dwóch wcześniej stosowanych technik dostępu radiowego: CDMA (ang. Code Division Multiple Access) i OFDM (ang. Orthogonal Frequency-Division Multiplexing) i posiada zalety obu tych technologii. W referacie przedstawiona została budowa nadajnika i odbiornika dla tego interfejsu radiowego oraz wyniki badań symulacyjnych jakości transmisji w tym interfejsie radiowym przeprowadzone w kanale z addytywnym szumem gaussowskim (AWGN).
EN
MC-CDMA technique was created by combining two previously used radio access techniques: CDMA and OFDM and has the advantages of both technologies. The paper was presented to the construction of the transmitter and receiver for the radio interface and the simulation results of transmission quality in the radio interface in the AWGN radio channel.
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