Multi-carrier DS-CDMA systems with recursive quaternary quasi-orthogonal sequences

In this paper, a novel construction for a set of quaternary quasi-orthogonal sequences (QQOSs) is established by using recursive matrix Kronecker product, which are called recursive QQOSs and have low correlation with binary Walsh-Hadamard (WH) sequences. Then different allocation policies of WH and recursive QQOSs in forward link of multicarrier DS-CDMA systems are investigated. Compared to the existing quaternary QOSs drawn from the exhaustive search of Family A sequences, our proposed construction is recursive and simple way to generate QQOSs. Meanwhile, the analysis and simulation results show that the bit error rate performance of multicarrier DS-CDMA can be improved by careful allocation of the spreading code sequences to different users.