High-performance, high-capacity MC-CDMA via carrier interferometry

This paper proposes a novel scheme which doubles capacity in MC-CDMA systems without any cost in bandwidth and with negligible cost in performance. Specifically: (1) complex spreading codes are used instead of conventional real value spreading codes; and (2) two groups of orthogonal complex spreading codes are used simultaneously, where minimum cross-correlation exists between the two groups. Simulations performed over Rayleigh fading channels using these novel codes demonstrate that the proposed scheme enables gain of 100% in terms of MC-CDMA capacity with negligible performance losses.