Abstract: The iterative multiuser detector is made up by a soft-input soft-output (SISO) multiuser detector concatenated with a SISO channel decoder.The computational complexity of the optimal SISO algorithm grows exponentially with the number of users, so it can not be well applied to the system with large number of active users.The probabilistic data association (PDA) algorithm is a novel SISO multiuser detection algorithm, which has a good performance approximating to that of the optimal algorithm and low computational complexity of order O(K³).In this paper, we make an improvement for the PDA algorithm to further reduce the computational complexity of the PDA algorithm with just a small lo ss in performance.

Key words: multiuser access interfenrence (MAI), SISO multiuser detector, PDA algorithm