A method and an apparatus. The method includes receiving a signal including a serving signal and an interference signal; applying a Gaussian approximation (GA) on the serving signal and the interference signal; determining, jointly, a maximum likelihood (ML) solution of rank, traffic to pilot ratio (TPR), and precoding matrix index on the GA-applied serving signal and the GA-applied interference signal. The apparatus includes an antenna for receiving a signal including a serving signal and an interference signal; a processor configured to apply a GA on the serving signal and the interference signal, and determine, jointly, an ML solution of rank, TPR, and precoding matrix index on the GA-applied serving signal and the GA-applied interference signal.