A PO-CI/MC-CDMA scheme for high modulation styles

Abstract

Through analyzing the theoretical spreading principle, it has been proved in this paper that the benefit of pseudo-orthogonal carrier interferometry (PO-CI) spreading code is not supported when complex signal modulation (e.g., quadrature phase-shift keying (QPSK) and quadrature amplitude modulation (QAM)) types are employed. On this basis, a novel and feasible structure for this problem is brought forward. Within the structure mentioned, instead of complex modulation patterns, pulse amplitude modulation (PAM) combined with PO-CI spreading code is utilized. This allows us to maintain the throughput increase of a multi-carrier code division multiple access (MC-CDMA) system with minimal loss in performance and no bandwidth expansion.