A multi-carrier CDMA system using a concatenated orthogonal/PN spreading scheme

Direct sequence code division multiple access (DS-CDMA) is currently of great interest for mobile communications applications. It provides reasonable privacy and security, and good immunity to interference and fading. We propose a new communication scheme combining both multi-carrier (MC) modulation and DS-CDMA with a concatenated orthogonal/pseudo-noise (PN) spreading scheme. This scheme incorporates the advantages of both DS-CDMA with a concatenated scheme, and an MC modulation technique to combat the effect of a multipath fading channel. The system performance is investigated for a single correlator and a maximal ratio combiner. The performance analysis is carried out under a multiuser and multipath Rayleigh/Rician fading environment. It is shown that the proposed system outperforms the MC-CDMA system with a conventional PN sequence.