Multi-carrier Code Division Multiple Access Technology Research

In this paper, after introduction of the code division multiple access (CDMA) and orthogonal multicarrier (MC) technique, the system model of MC-CDMA is analyzed and the bit error rate (BER) performance in downlink and uplink channel is shown in AWGN channel by computer simulation. Then, we discuss the model of a 256 sub-carriers MC-CDMA system and analyze BER performance in a frequency-selective Rayleigh fading channel.The paper proposes a feedback pre-equalization (F-PE) method based on channel estimation in a frequency-selective Rayleigh fading channel. Through analyzing decision variable of receiver, the F-PE method can increase autocorrelation of desire user's spreading sequence, and improve the BER performance. The conclusion is identified by computer simulation.The paper studies a noncoherent demodulation based on differential encoding in MC-CDMA system and makes computer simulation of BER performance compared with that of coherent demodulation based on perfect channel estimation.