A unifying discrete-time model for direct sequence and multicarrier variable rate broadband CDMA

Multicarrier CDMA and direct sequence CDMA have been suggested for both narrowband and broadband multiple access systems. A series of concepts have further been proposed for variable rate broadband transmission within a CDMA system. These principally different techniques exhibit certain common characteristics that can be exploited. We propose a generalised unifying discrete-time model for describing both MC-CDMA, DS-CDMA and hybrid DSMC-CDMA narrowband and variable rate broadband schemes. The model leads to a system description which is similar to the matrix algebraic formulation of a traditional DS-CDMA system.