Near-optimal multiuser detection in synchronous CDMA using probabilistic data association

A Probabilistic Data Association (PDA) method is proposed in this letter fo r multiuser detection over synchronous code-division multiple-access (CDMA) communication channels. PDA models the undecided user signals as binary ra ndom variables. By approximating the inter-user interference (IUI) as Gauss ian noise with an appropriately elevated covariance matrix, the probability associated with each user signal is iteratively updated. Computer simulati ons show that the system usually converges within three to four iterations, and the resulting probability of error is very close to that of the optima l maximum-likelihood (ML) detector. Further modifications are also presente d to significantly reduce the computational cost.