Carrier frequency offset estimation & compensation in AMC OFDM

Sensitivity to Carrier Frequency Offset (CFO) is a well known issue in Orthogonal Frequency Division Multiplexing (OFDM). The recent wireless standards, which propose OFDM as modulation technique, prefer to use it with Adaptive Modulation and Coding (AMC). Inter carrier interference (ICI) created by CFO disturbs the selection of modulation order and channel coding rate in AMC. Effect of CFO on OFDM with AMC is studied in this work. The survey of Fractional CFO (FCFO) estimation techniques is presented in this paper. The optimal but complex to implement method for CFO estimation-the ML estimation is applied to OFDM with AMC. Efforts are made to reduce its complexity while actual implementation. Performance comparison of original and reduced complexity methods are presented based on accuracy and complexity.