Research On The Performance Of MC-CDMA System And Multi-user Detection

OFDM has been used in many broadband wireless systems, because of it's good performance of anti multi-path delay, and then has become a hot topic for research. The MC-CDMA, combined by the OFDM and the CDMA , with it's high spectrum efficiency, high data transmission rate, good performance of anti jamming and anti narrowband interference between symbols, catches the world's attention. So it must be of good theoretic value and practical value to research on key techniques of Multi-carrier CDMA.Based on the theoretic of OFDM, the paper analyzes the theoretic model of MC-CDMA system, assesses the performance in two situations of the white Gaussian noise channel model and the multi-path delay spread channel model, and proves the performance improvement finally.To deal with the multi-user interference, the paper proposes two methods. First, we put the sub-carrier grouping into the MC-CDMA, to reduce the interference between the users and keep the total number of users not to decline. Second, we can use the multi-user detection in the MC-CDMA, because each user in the system has different spectrum spread code, in this case, the system can make use of the information of all the users. The paper proposes an improved multi-user detection arithmetic, the multi-user decide feedback detection based on the MMSE, which can not only improve the performance, but also decline the complexity of the system, more conducive to realization.