Multi-rate multi-carrier CDMA with multiuser detection for wireless multimedia communications

We study two multi-rate access methods of multicarrier CDMA systems, based on transforming the concepts of multi-code (MC) and variable-spreading-length (VSL) to frequency domain. A general and uniform system model accommodating both access methods is constructed, providing a framework of programmability for system integration. We thereof develop multiuser detections (MUD) applicable to both access methods. Chip-based filtering in frequency domain replaces the conventional match-filter band and yield novel detection behaviors. The signal properties and detection performance in multi-rate traffic are analyzed and demonstrated with numerical simulations, which manifests the multi-rate approaches and the superiority of MC access over VSL access in uplink MC-CDMA. The compared study shows the domination of spreading length over the interference pattern in MUD performance.