Temat: MC-CDMA - Prolib Integro

Skocz do pozycji: 1.

Tytuł:: Improving Performance of MC-CDMA Systems Using UTTCM Channel Coding
Autorzy:: Bendjillali, Ridha Ilyas
Bendelhoum, Mohammed Sofiane
Abderraouf, Elarbi
Lahcene, Mohamed
Tematy:: channel coding
MC-CDMA
MSE
UTTCM
ZF; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/58906723.pdf Link otwiera się w nowym oknie
Opis:: 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
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Channel Identification Using Chaos for an Uplink/Downlink Multicarrier Code Division Multiple Access System
Autorzy:: Frikel, M.
Safi, S.
Targui, B.
M'Saad, M.
Tematy:: channel identification
chaos code
equalization
MC-CDMA system; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/308067.pdf Link otwiera się w nowym oknie
Opis:: A scheme of chaotic spreading sequence for multicarrier code division multiple access system (MC-CDMA) iproposed to estimate the transmission channel. This systespreads spectrum and identifies the channel, simultaneously. The proposed scheme uses a chaotic sequence generated by a logistic map as a training signal and estimate channel parameters according to dynamics of the chaotic sequence. Encoding data by chaotic sequences is first built and then the orthogonal codes are used to spread the encrypted data for multiusers scheme. At the reception, first the channel parameters are identified using a training chaotic sequence in order to equalize the received data, and then the encrypted information is decoded for the desired user. The studies reveal that the proposed system (chaos plus orthogonal codes) significantly outperforms the Walsh-Hadamard code spreading in MC-CDMA system. The performance of the system is considered in the multiuser case by means of simulation. The simulation result shows that the proposed chaotic code spreading approach for channel identification achieves significant improvement in the channel identification, comparing to using others training sequence or the least square method.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 3.

Tytuł:: An Improved Downlink MC-CDMA System for Effcient Image Transmission
Autorzy:: Bendelhoum, M. S.
Djebbari, A.
Boukli-Hacene, I.
Taleb-Ahmed, A.
Tematy:: data compression
MC-CDMA
MSSIM
performance evaluation
PSNR
SNR
SPIHT; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/308187.pdf Link otwiera się w nowym oknie
Opis:: 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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 4.

Tytuł:: Performance Evaluation of MC-CDMA Systems with Single User Detection Technique using Kernel and Linear Adaptive Method
Autorzy:: Fateh, Rachid
Darif, Anouar
Safi, Said
Tematy:: BRAN channels
equalization
kernel method
MC-CDMA
reproducing kernel Hilbert space; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/2058482.pdf Link otwiera się w nowym oknie
Opis:: 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.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 5.

Tytuł:: Adaptive Algorithms Versus Higher Order Cumulants for Identification and Equalization of MC-CDMA
Autorzy:: Zidane, M.
Safi, S.
Sabri, M.
Boumezzough, A.
Frikel, M.
Tematy:: blind identification and equalization
higher order cumulants
RLS
LMS
MC-CDMA systems; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/307974.pdf Link otwiera się w nowym oknie
Opis:: In this paper, a comparative study between a blind algorithm, based on higher order cumulants, and adaptive algorithms, i.e. Recursive Least Squares (RLS) and Least Mean Squares (LMS) for MultiCarrier Code Division Multiple Access (MC-CDMA) systems equalization is presented. Two practical frequency-selective fading channels, called Broadband Radio Access Network (BRAN A, BRAN B) normalized for MC-CDMA systems are considered. In the part of MC-CDMA equalization, the Zero Forcing (ZF) and the Minimum Mean Square Error (MMSE) equalizer techniques were used. The simulation results in noisy environment and for different signal to noise ratio (SNR) demonstrate that the blind algorithm gives approximately the same results obtained by adaptive algorithms. However, the proposed algorithm presents the advantage to estimate the impulse response of these channels blindly except that the input excitation is non-Gaussian, with the low calculation cost, compared with the adaptive algorithms exploiting the information of input and output for the impulse response channel estimation.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 6.

Tytuł:: Using Least Mean p-Power Algorithm to Correct Channel Distortion in MC-CDMA Systems
Autorzy:: Zidane, M.
Safi, S.
Sabri, M.
Frikel, M.
Tematy:: adaptive equalization
adaptive identification
BER
BRAN C
LMP
MC-CDMA system
ZF; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/308275.pdf Link otwiera się w nowym oknie
Opis:: This work focuses on adaptive Broadband Radio Access Network (BRAN) channel identiﬁcation and on downlink Multi-Carrier Code Division Multiple Access (MCCDMA) equalization. We use the normalized BRAN C channel model for 4G mobile communications, distinguishing between indoor and outdoor scenarios. On the one hand, BRAN C channel parameters are identiﬁed using the Least Mean p-Power (LMP) algorithm. On the other, we consider these coeﬃcients in the context of adaptive equalization. We provide an overview and a mathematic formulation of MC-CDMA systems. According to these fundamental concepts, the equalizer technique is investigated analytically to compensate for channel distortion in terms of the bit error rate (BER). The numerical simulation results, for various signal-to-noise ratios and diﬀerent p threshold, show that the presented algorithm is able to simulate the BRAN C channel measured with different accuracy levels. Furthermore, as far as the adaptive equalization problem is concerned, the results obtained using the zero-forcing equalizer demonstrate that the algorithm is adequate for some particular cases of threshold p.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 7.

Tytuł:: Higher Order Cumulants for Identification and Equalization of Multicarrier Spreading Spectrum Systems
Autorzy:: Safi, S.
Frikel, M.
Zeroual, A.
M'Saad, M.
Tematy:: blind identification and equalization
communication channels
higher order cumulants
MC-CDMA systems; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/309082.pdf Link otwiera się w nowym oknie
Opis:: This paper describes two blind algorithms for multicarrier code division multiple access (MC-CDMA) system equalization. In order to identify, blindly, the impulse response of two practical selective frequency fading channels called broadband radio access network (BRAN A and BRAN E) normalized for MC-CDMA systems, we have used higher order cumulants (HOC) to build our algorithms. For that, we have focussed on the experimental channels to develop our blind algorithms able to simulate the measured data with high accuracy. The simulation results in noisy environment and for different signal to noise ratio (SNR) demonstrate that the proposed algorithms are able to estimate the impulse response of these channels blindly (i.e., without any information about the input), except that the input excitation is i.i.d. (identically and independent distributed) and non-Gaussian. In the part of MC-CDMA, we use the zero forcing and the minimum mean square error equalizers to perform our algorithms. The simulation results demonstrate the effectiveness of the proposed algorithms.
Dostawca treści:: Biblioteka Nauki

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na półce

Skocz do pozycji: 8.

Tytuł:: Compensation of Fading Channels Using Partial Combining Equalizer in MC-CDMA Systems
Autorzy:: Zidane, M.
Safi, S.
Sabri, M.
Tematy:: bit error rate
blind channel identiﬁcation
higher order cumulants
MC-CDMA systems
partial combining equalizer; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/307612.pdf Link otwiera się w nowym oknie
Opis:: In this paper the performance of a partial combining equalizer for Multi-Carrier Code Division Multiple Access (MC-CDMA) systems is analytically and numerically evaluated. In the part of channel identification, authors propose a blind algorithm based on Higher Order Cumulants (HOC) for identifying the parameters representing the indoor scenario of Broadband Radio Access Networks (BRAN A) channel model normalized for MC-CDMA systems. Theoretical analysis and numerical simulation results, in noisy environment and for different Signal to Noise Ratio (SNR), are presented to illustrate the performance of the proposed algorithm in the one hand, and the other hand the impact of partial combining equalizer on the performance of MC-CDMA systems.
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 9.

Tytuł:: Suitable Spreading Sequences for Asynchronous MC-CDMA Systems
Autorzy:: Addad, M.
Djebbari, A.
Tematy:: BER
crest factor
multiple access interference
MC-CDMA
peak-to-average power ratio
zero correlation zone; Pokaż więcej
Wydawca:: Instytut Łączności - Państwowy Instytut Badawczy
Powiązania:: https://bibliotekanauki.pl/articles/307793.pdf Link otwiera się w nowym oknie
Opis:: 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.
Dostawca treści:: Biblioteka Nauki

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