| 摘要 |
PROBLEM TO BE SOLVED: To provide an orthogonal frequency division multiple access (OFDMA) system and method for controlling frequency offsets in which frequency offsets of access users are controlled in uplink communication. SOLUTION: The OFDMA system solves a problem that the system performance is deteriorated in uplink communications because subcarrier stations have different carrier frequency offsets. Each subcarrier station compensates for, similarly to downlink communications, a frequency offset thereof in response to a frequency offset control signal provided by a base station and then transmits an uplink frame to the base station. The base station compensates for an average frequency offset using the uplink frame, which has a small frequency offset shift because each subcarrier station (SS) compensates for the frequency offset thereof previously, and this the frequency offset of each SS can be correctly compensated in the uplink communication to prevent inter-carrier interference. COPYRIGHT: (C)2006,JPO&NCIPI
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