Patent ID: 8374139

Claim:
A method for downlink synchronization in a cellular orthogonal frequency division multiple access (OFDMA) system, the method comprising: allocating a primary advanced preamble (PA Preamble) in a second frame in an OFDM superframe having four frames including a first, the second, a third and a fourth frame along time domain, wherein the PA Preamble is allocated in a first OFDM symbol along time domain in the second frame; allocating one or more secondary advanced preambles (SA Preambles) within the superframe, wherein the one or more SA Preambles are allocated in a corresponding first OFDM symbol along time domain in the first, the third, or the fourth frames; and transmitting the OFDM superframe by a base station, wherein the OFDM superframe further comprises a superframe header (SFH) that is located in the first frame of the OFDM superframe along time domain, and wherein the PA Preamble is allocated after the SFH such that the mobile station takes less than a superframe length to decode the SFH after decoding the PA Preamble and the SA Preambles for complete cell-ID information.