Multicarrier DS-CDMA performance with different assignment strategies of quasi-orthogonal codes

Alternative code assignment policies for the forward link of a multicarrier DS-CDMA system employing the recently proposed quasi-orthogonal sequences are put forth. It is demonstrated how different allocation strategies of quasi-orthogonal codes alter the interference level suffered by active units; it is also shown how to shape the rate of interference growth as a function of the number of active users within the reference cell, by implementing some specific code allocation patterns. The performance, in terms of average bit error probability, achieved by various schemes is assessed in a frequency selective fading environment, and the advantages of different solutions highlighted.