A forward link intracell orthogonalization technique using multicarrier pre-decorrelation for CDMA wireless local communication system

A new intracell orthogonalization technique for a code division multiple access (CDMA) wireless local communication system is posed. On the forward link of the system, it is necessary to achieve high bit rate transmission and to reduce the complexity of the receiving terminal. To meet these two requirements, cyclically shifted spreading sequences are utilized. However, it is necessary to orthogonalize the multiple signals since these sequences are cross-correlated. One way of achieving orthogonalization is pre-decorrelation. However, the orthogonality does not clearly appear in a multipath fading channel because of the interchip interference caused by multipath. Therefore in this paper, pre-decorrelation is combined with multicarrier modulation. The results obtained through computer simulation show that the proposed technique can achieve orthogonality in a multipath fading channel. Also the proposed technique makes efficient forward link power control possible, and reduces intercell interference.