An EM-based iterative receiver with unknown interferers

In code division multiple access (CDMA.) systems, the iterative receiver can provide an excellent performance when the spreading codes and channel codes of all users are known. In practice, however. there are users whose information of spreading codes and channel codes is not available. In this case, a blind multiuser detector for unknown interferers can be applied within the iterative receiver. In the paper, we attempt to estimate the covariance of interferers within the iterative receiver based on the expectation and maximization (EM) algorithm. Through iterations, a better estimate of the covariance of interferers is available and it results in a better performance.