A modified algorithm for joint frequency offset and channel estimation in OFDM systems

Previously, a joint estimation method [1] of carrier frequency offset and channel in orthogonal frequency division multiplexing (OFDM) systems was proposed based on the maximum likelihood (ML) criterion. However, the proposed processing structure may not be suitable for current OFDM regular implementations. In the paper, the processing structure is modified and simulations are conducted for the new proposed processing structure. The proposed algorithm can be divided into two major portions. The first part is to use the rotation concept to estimate the initial CFO and design the frequency domain equalizer. The second part is making use of iterative concept to find the true frequency peak for better estimate. The proposed scheme does not require initial random guess as regular iterative algorithms, in which may suffer from the problem of the convergence to the local maximum. The proposed approach can surely converge to the global maximum for achieving the solution. The computation complexity is much less than the grid-search method and easily be implemented in hardware. The MSE performance of the proposed algorithm is close to the Cramer-Rao Lower bound which is shown in the simulation result.