Focusing on the problem that the extrinsic information transfer(EXIT)functions of the iterative processing unit in existing methods are of low accuracy
an accurate method named optimal histogram(OptHIST)is proposed. The OptHIST algorithm is implemented in the following steps. The log-likelihood ratio data are classified according to the value(+1 or-1)of the info bits
and the optimal histogram is then used to estimate the probability distribution function of the log-likelihood ratio. The optimal probability distribution function is obtained in the sense of the integrated mean squared error.Then the exact EXIT function is obtained through integrating the probability distribution function of log-likelihood ratio. Compared with the existing methods
the proposed OptHIST method is more robust than the histogram method and more applicable than the direct average method. Simulation results show that the OptHIST method can reduce the error by about 7% to 15%
compared with the histogram method
for the processing unit which adopts rigid a-post probability algorithm.
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references
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