A synchronization scheme for multi-carrier CDMA systems

A new time-domain synchronization scheme for multi-carrier CDMA systems is developed, which does not require the DFT or FFT of the whole OFDM block. This scheme is particularly proposed for being used with the time-domain data detection techniques which do not need the whole DFT analysis of the input signal (Seunghyeon Nahm and Wonyong Sung, 1996, 1998). Timing detection is performed using the correlation property of the guard interval in the time domain. The carrier frequency synchronization is performed in two steps: tracking to the nearest subcarrier frequency followed by correction of the remaining frequency offset, which is a multiple of the subcarrier frequency interval. The guard interval-based frequency offset detection method is employed for the first step (Daffara and Adami, 1995). A synchronization block containing null symbols on a small number of subcarriers is proposed for the second step, which enables efficient implementation of frequency offset detection using the decimation-in-frequency technique.