Multiuser detection/decoding in asynchronous multitone multiple access systems

We devise the optimal defection scheme in multiuser multicarrier based systems. We focus on the critical uplink scenario where several multicarrier signals belonging to distinct users propagate through independent time-variant frequency selective fading channels, and experience independent time offsets and carrier frequency offsets. We consider an efficient discrete-time system implementation and we refer to it as multitone multiple access. When channel coding is deployed we propose to accomplish decoding through the turbo multiuser detection and decoding approach. A simplified detection method is also described.