Design Four Transmit Antennas STBC-MC-DS-CDMA System Based On DWPT In Flat Fading Channel

摘要

This paper provides the detail about the two main applications of multicarrier direct sequence code division multiple access (MC-DS-CDMA) which are fixed MC-DS-CDMA and Mobile MC-DS-CDMA. Fixed MC-DS-CDMA delivers point to multipoint broadband wireless access to our homes and offices. Mobile MC-DS-CDMA gives full mobility of cellular networks at high broadband speeds. The design of space time block coding STBC-MC-DS-CDMA systems based on Discrete Fast Fourier transform (FFT) or Discrete Wavelets packet transform DWPT, evaluation tests, and simulations results of these proposed systems were done. The Bit Error Rate (BERs) and the operating range of these systems are obtained using frequency domain baseband simulations. All systems that simulated in this work, are compared with each other STBC types designed using FFT and DWPT using 1,2,3 and 4 antennas in transmitter. The simulation results of these systems are examined in AWGN and flat fading channel for different Doppler frequencies (fd ) and subcarrier size and compared with each other. The proposed structures for the STBC-MC-DS-CDMA system based on (DWPT) 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. These MC-DS-CDMA systems were modeled using MATLAB V7.10 to allow various parameters of the system to be varied and tested.