Optimal sequences to suppress the multiuser interference for CDMA systems

A joint transmitter-receiver multiuser interference canceling scheme is proposed to suppress the multiuser interference. The idea is to optimize the spreading and despreading waveforms of different users by using the instantaneous channel parameters. The maximum receive signal to interference plus noise ratio criterion is used. An iteration algorithm is given to generate the optimal spreading and despreading waveforms. The proposed scheme can be understood as an adaptive frequency hopping system. The numerical results indicate that, compared with the conventional spreading waveforms such as Gold sequences, the optimal waveforms can greatly decrease the multiaccess interference