Performance of complex wavelet packet based multicarrier CDMA system with precoding technique

In this paper, based on the analysis of the principle of multi-carrier code division multiple access (MC-CDMA) and the use of the optimized complex wavelet packet, a novel complex wavelet packet based MC-CDMA (CAT-MC-CDMA) system is proposed. It can overcome the decrease of spectrum efficiency and energy of DFT based conventional MC-CDNM (DFT-MC-CDMA) due to inserting cyclic prefix (CP). Meanwhile, making use of the reciprocity between forward link and reverse link channels under the Division Duplex (TDD) schemes, we adopt the precoding technique to simplify the receiver architecture and suppress the multi-access interference (MAI) effectively. The system performance is investigated in multi-path Rayleigh fading channel. Theoretical analysis and simulation results show the system has superior BER (bit error rate) performance over the conventional MC-CDMA, the system with precoding technique also outperforms other detection combining techniques, such as EGC (equal gain combining), MRC (maximum ratio combining), ORC (orthogonality restoring combining), MMSEC (minimum mean square error combining).