Timing synchronization for OFDMA femtocells in the presence of co-channel interference

The Femtocell is an attractive solution to improve the indoor coverage of cellular systems. By applying spectrum reuse, femtocells can improve the efficiency of spectrum usage. However, since femtocells are deployed by end-users, insufficient coordination between base stations leads to the reuse of the same frequency resources and results in CCI (co-channel interference), which seriously complicates the synchronization problem, particularly in OFDM based systems, such as WiMAX and LTE. In this paper, we investigate the timing synchronization problem in the presence of CCI of an OFDMA macro/femto uplink scenario. We consider the cross-correlation based timing synchronization and propose a pre-filter to mitigate the CCI effect. The simulation results show that this method effectively eliminates the effect of CCI on the cross-correlation based timing synchronization and provides a performance close to that of no CCI case.