CFO Compensation for Uplink OFDMA Systems With Conjugated Gradient

In this paper, the authors propose an iterative low-complexity Carrier Frequency Offset (CFO) compensation algorithm based on the Conjugate Gradient (CG) method for uplink orthogonal frequency division multiple access systems. In general, a linear Minimum Mean Square Error (MMSE) CFO compensation algorithm is simple and efficient, but it requires an inverse operation to compute the MMSE solution of the CFO-induced Inter-Carrier Interference (ICI) matrix whose size equals the number of subcarriers. Thus, the complexity becomes prohibitively high when the number of subcarriers is large.