Abstract:

This paper presents two low-complexity iterative multiuser algorithms:parallel soft cancellation probabilistic data association (P-SC-PDA) and successive soft cancellation probabilistic data association (S-SC-PDA) for asynchronous CDMA systems.The computational complexity of the proposed algorithms is just o(K³) where K is the number of active users.Simulation results show that performance of the S-SC-PDA algorithm is significantly better than P-SC-PDA.With information delivered by the decoder, if the user signals to be detected is arranged such that signals of users with high detection reliabilities are detected first, and those with low detection reliabilities are detected later, even better performance can be obtained with S-SC-PDA.

Key words: iterative multiuser detection algorithm, probabilistic data association (PDA), low-density parity check codes (LDPC)