An adaptive scheme for simultaneous coding and spreading in direct-sequence CDMA systems

Especially in mobile communications, spread spectrum systems have been discussed extensively because of their anti-fading capability. To increase the spectrum efficiency and to support variable data rates, combined coding and spreading (CCS) schemes are applied. We investigate CCS schemes in which every user is assigned a set of M sequences. By selecting one of these sequences, log₂(M) bit are transmitted per code-sequence period. The performance of these systems is analyzed and requirements on the used user-sets to achieve low interference are derived. Finally, the construction of these sequence sets and the resulting system performance is described