A hierarchical downlink (DL) synchronization channel (SCH) is provided for wireless OFDM/OFDMA systems. The SCH includes a Primary SCH (P-SCH) for carrying PA-Preambles used for coarse timing and frequency synchronization, and a Secondary SCH (S-SCH) for carrying SA-Preambles used for cell ID detection. The total time length occupied by P-SCH and S-SCH is equal to one OFDM symbol time length of a data channel, and S-SCH is located in front of P-SCH in each DL frame. A perfect multi-period time-domain structure is created and maintained in P-SCH to increase preciseness of frame boundary estimation. With overlapping deployment of macrocells and femtocells, a predefined SCH configuration scheme is provided to separate frequency subbands used for macrocells and femtocells such that interferences in S-SCH can be mitigated. In addition, a self-organized SCH configuration scheme is provided to allow more flexibility for femtocells to avoid or introduce interference in S-SCH.