To reduce the degradation caused by the methods that estimate the carrier frequency offset(CFO)and channel state information(CSI)respectively in the traditional orthogonal frequency division multiplexing(OFDM)receiver
a combined estimation of CFO and CSI for OFDM packet transmission systems is proposed. Two estimators that estimate the CFO and CSI by iteration are used in the method. The CSI estimation is obtained by the maximum likelihood estimation(MLE)method with the CFO estimation value provided by the CFO estimate unit
and the CFO is obtained by MLE method with the CSI estimation value provided by the CSI estimate unit. With the estimation information exchanged between the CFO estimation unit and the CSI estimation unit
the accuracy of the estimation is gradually improved. Since the multidimensional searching algorithm is avoided
the complexity of the proposed method is reduced. Furthermore
the noise impact on the estimated value is considered in the iteration
and hence the performance of the algorithm is improved. The simulation results show that the proposed method can achieve the same bit error rate as the synchronization systems when symbol energy noise ratio is greater than 18 dB.
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references
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