Authors : Nader Abdullah Khadam, Laith Ali Abdul-Rahaim, Arash Ahmadi, Seyed Vahab Makki and Golamreza Karimi
Abstract: In this study, the performance of MultiCarrier Direct Sequence Code Division Multiple Access (MC-DS-CDMA) in fixed MC-DS-CDMA and mobile MC-DS-CDMA applications have been improved by using the compensations of space time block coding and Discrete Fast Fourier Transform (FFT) or Discrete Wavelets Transform DWT. These MC-DS-CDMA systems had been simulated using MATLAB 2015a. Through simulation of the proposed system, various parameters can be changed and tested. The Bit Error Rate (BERs) of these systems are obtained over wide range of signal to noise ratio. All simulation results had been compared with each other using different subcarrier size of FFT or DWT with STBC for 1, 2, 3 and 4 antennas in transmitter and under different ITU multipath fading channels and different Doppler frequencies (fd). The proposed structures of STBC-MC-DS-CDMA system based on DWT batter than based on (FFT) in varies Doppler frequencies and subcarrier size. Also, proposed system with STBC based on 4 transmitters better than other systems based on 1 or 2 or 3 transmitters in all Doppler frequencies and subcarrier size in all simulation results. Finally, digital hardware designed for transmitter and receiver of STBC-MC-DS-CDMA algorithm to prove the efficiency of the system techniques using FPGA type to check and optimized the chip area of implementation of proposed system.
Nader Abdullah Khadam, Laith Ali Abdul-Rahaim, Arash Ahmadi, Seyed Vahab Makki and Golamreza Karimi, 2019. MC-DS-CDMA System Based on DWT and STBC in Multipath Fading ITU Channels Model. Journal of Engineering and Applied Sciences, 14: 10740-10757.