Uplink acquisition of synchronization parameters in MC-CDMA systems

Abstract

Most of the current synchronization schemes used for the forward/downlink MC-CDMA (multi-carrier code division multiple access) systems are not suitable for the reverse/uplink case. The technique proposed gives a new way to estimate the time-frequency synchronization parameters in an uplink MC-CDMA system, with the consideration that all the users reach the base station in an asynchronous mode. The proposed scheme combines the CDMA insertion mode for different spreading codes for all the users, and the SS-MC-MA (spread spectrum multi-carrier multiple access) mode as an insertion technique for the offset correction sequences. The insertion of pilots and offset correction sequences for each user are located at different carriers and obey to the non-overlapping principle with the rest of the user's position.