On the performance of single and multi-cell DS-CDMA systems using 'non-overlap constellation assignment' to the different groups of spreading codes

A method to reduce the effect of intercell and intracell interference in single and multi-cell DS-CDMA systems is considered in this paper. In this method, the users' signatures are not only separated by using different spreading codes but are also partitioned into two or more sub-groups each using an individual constellation for band-pass modulation. Devoting non-overlap parts of the constellation space to the different groups of spreading codes offers capacity enhancement of the system without increasing the processing gain of a standard DS-CDMA system. This transmission method may be combined with joint detection at the receiver to give further performance improvement. By this approach, the complexity of the joint detection techniques can be noticeably reduced.