On the equivalence of PDA algorithm and SIC-MMSE algorithm

In this letter, by employing Gaussian distribution to approximate the probability density function (pdf) of the extrinsic information at the output of the multiuser detector as a function of the pdf of the input extrinsic messages, it is concluded that the Probabilistic Data Association (PDA) algorithm is equivalent to the Soft Interference Cancellation plus Minimum Mean Square Error algorithm (SIC-MMSE).