Investigation On Interference Cancellation In Forward Access Channel For 3G Communication System

Conventional CDMA communication system has serious mutiple access interference (MAI), so the spectral efficiency and user capacity of channel is not maximum. In this paper, we tried to reform the structure and decision algorithm of CDMA communication system.First of all, the advantage of canceling MAI of CDMA communication system was given. The basic elements of this paper, such as the description of CDMA communication system, the problem of CDMA system, and the studying status of canceling MAI of CDMA communication system were given. In the next part, the techniques of canceling MAI were described with optimization theory and we found it is necessary to cancel the MAI.Throuth the study of the Gaussian Approximation, we got the Bit Error Rate (BER) of the DS-CDMA system with the MAI.The mian part of the thesis is the study of the MAI cancellation in forward access channel. An anti-multiple-access-interference receiver in forward access channel was proposed. We discussed the capability of this new receiver separately in the noise channel, m the jamming environment and in the fading channel, The result shows that this new receiver has not only the advantage of the linear single detection receiver but the advantage of the multiuser detection. The anti-multiple-access-interference receiver proposed in the thesis adapt to forward access channel communication.Besides this, The MAI cancellation technic in the LAS-CDMA was studied, and the advantage and the disadvantage were dicussed of the MAI cancellation in the LAS-CDMA communication system.Finally, the summarization was given and the prospect of the Canceling MAI technique was discussed.