Improvements of performance and capacity in DS-CDMA with carrier interference over flat and frequency selective fading channels

CDMA with multi-carrier modulations (MC-CDMA) employs frequency diversity combining techniques with which performance improvement is obtained. This paper considers a new chip shaping technique called carrier interferometry (CI). As gained in MC-CDMA, the technique exploits the frequency combining in such a way that the modulated signal does not interfere with the other carriers. It also provides a great deal of flexibility in accommodating simultaneous users by means of a relaxed orthogonality condition. The CI technique is applied to DS-CDMA and the performance is evaluated for various channel conditions (e.g. flat, frequency selective fading with/without loading). The results show that the DS-CDMA with CI shaping outperforms the conventional DS-CDMA.