Estimation Algorithm of Mobile OFDM CFOs Based on Step-Size

In order to maintain orthogonality among subcarriers for mobile OFDM, a CFOs step-size estimation model is established to avoid severe performance degradation caused by ICI, and algorithmic stability, step-size parameter, the error of CFOs estimate and etc are investigated. First, after an averaging window algorithm is introduced, the mathematic model of stepsize estimation algorithm is obtained through step-size parameter and time-varying CFOs. Then, based on the results of MATLAB simulation, the determination of step-size parameter, the advantages of step-size algorithm and precision are discussed. Finally, time sequence plots of added CP, interleaver and subcarrier modulation with VHDL are presented. Experimental results indicate that the maximum of CFOs errors is 0.00987 in ±3¿ variance interval, when mobile velocity is 400 km/h, according with verdicted principle that in order for the ICI effects to be negligible, the error of CFOs estimation must be accurate within 1-2% of the subcarrier spacing, and programs can correctly implement on circuit board.