A time synchronization scheme for quasi-synchronous up-link of MC-CDMA systems

We propose a new method for time synchronization or time delay estimation in quasi-synchronous up link of multi-carrier code division multiple access (MC-CDMA) systems. The method is cyclic prefix based and estimates the average time delay of multipath multiuser signals. Position of cyclic prefix correlation peaks is estimated using a low complexity algorithm, which exploits the fact that these peaks exist in periodic fashion with a period equal the MC-CDMA frame length. This approach allows the fast Fourier transform (FFT) window placement at a fixed distance from the estimated time delay avoiding any intersymbol interference (ISI) users.