Date Added: Dec 2009
In Orthogonal Frequency-Division Multiplexing Access (OFDMA), each user employs a different set of orthogonal subcarriers to simultaneously transmit data. The use of orthogonal subcarrier sets for different users eliminates Multiple Access Interference (MAI) under perfect conditions. OFDMA, therefore, has been or is being considered for various wireless systems. Frequency synchronization is critically important for the OFDMA uplink. With imperfect synchronization, InterCarrier Interference (ICI) is generated due to the loss of subcarrier orthogonality, contributing both cochannel and interchannel interference.