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Using Least Mean p-Power Algorithm to Correct Channel Distortion in MC-CDMA Systems

Zidane M., Safi S., Sabri M., Frikel M.

Journal of Telecommunications and Information Technology

2018

nr 3

23--30

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.

Channel Identification Using Chaos for an Uplink/Downlink Multicarrier Code Division Multiple Access System

Frikel M., Safi S., Targui B., M'Saad M.

Journal of Telecommunications and Information Technology

2010

nr 1

48-54

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.