Abstract
The Direct Sequence Code Division Multiple Access (DS-CDMA) communication systems can offer higher system capacity than other present radio communication systems in existence, if the orthogonal spreading sequences are used for every user within the same cell. In practice, this situation does not always hold. The spreading sequences may not be orthogonal and then multiple access interference (MAI) exists. Even the orthogonal spreading sequences are used, the property of orthogonal will also be destroyed by transmission through frequency selective fading channel. In this situation, the interference of MAI and intersymbol interference (ISI) will be produced. These interferences cause a severe performance degrade for DS-CDMA communication systems. For this reason, we propose a blind partial parallel interference cancellation (B-PPIC) which combines with blind estimation method and PIC\ technique. The proposed B-PPIC aims to improve the systems performance by estimating channel parameters and fading power for each user in blind sense, and then using these information to regenerate estimates of the interfering signals to achieve efficient interference cancellation. Finally, we subtract those reconstructed interference signals from the received signal and recover the transmitted data bits with more accuracy.