An iterative method for estimating covariance matrices of communication signals in a wireless communication system, wherein communication signals in the wireless communication system include reference symbols and data symbols; the method comprising: receiving at least one communication signal transmitted over a radio channel, the received communication signal comprising at least one designated communication signal intended for a receiver node and one or more interfering communication signals; the method comprising: a) computing a reference symbol covariance matrix estimate R RS ̃ k l based on reference symbols in the received communication signal; b) inputting said reference symbol covariance matrix estimate R RS ̃ k l to a detector or a decoder so as to obtain a demodulated or decoded communication signal in a first iteration step, and thereafter inputting a covariance matrix estimate output from e) to the detector or the decoder in subsequent iteration steps to obtain an updated demodulated or decoded communication signal for each iteration; c) inputting the demodulated or decoded communication signal to a symbol generator so as to obtain a regenerated communication signal; d) computing an updated data covariance matrix estimate R data ̃ k l for each iteration based on data symbols of said regenerated communication signal; e) combining said reference symbol covariance matrix estimate R RS ̃ k l and said updated data covariance matrix estimate R data ̃ k l so as to obtain a covariance matrix estimate output based on said combined covariance matrix estimate; and f) forwarding said covariance matrix estimate output to the detector or decoder in b) so as to obtain the updated demodulated or decoded communication signal for each iteration. receiving at least one communication signal transmitted over a radio channel, the received communication signal comprising at least one designated communication signal intended for a receiver node and one or more interfering communication signals; the method comprising: a) computing a reference symbol covariance matrix estimate R RS ̃ k l based on reference symbols in the received communication signal; b) inputting said reference symbol covariance matrix estimate R RS ̃ k l to a detector or a decoder so as to obtain a demodulated or decoded communication signal in a first iteration step, and thereafter inputting a covariance matrix estimate output from e) to the detector or the decoder in subsequent iteration steps to obtain an updated demodulated or decoded communication signal for each iteration; c) inputting the demodulated or decoded communication signal to a symbol generator so as to obtain a regenerated communication signal; d) computing an updated data covariance matrix estimate R data ̃ k l for each iteration based on data symbols of said regenerated communication signal; e) combining said reference symbol covariance matrix estimate R RS ̃ k l and said updated data covariance matrix estimate R data ̃ k l so as to obtain a covariance matrix estimate output based on said combined covariance matrix estimate; and f) forwarding said covariance matrix estimate output to the detector or decoder in b) so as to obtain the updated demodulated or decoded communication signal for each iteration. a) computing a reference symbol covariance matrix estimate R RS ̃ k l based on reference symbols in the received communication signal; b) inputting said reference symbol covariance matrix estimate R RS ̃ k l to a detector or a decoder so as to obtain a demodulated or decoded communication signal in a first iteration step, and thereafter inputting a covariance matrix estimate output from e) to the detector or the decoder in subsequent iteration steps to obtain an updated demodulated or decoded communication signal for each iteration; c) inputting the demodulated or decoded communication signal to a symbol generator so as to obtain a regenerated communication signal; d) computing an updated data covariance matrix estimate R data ̃ k l for each iteration based on data symbols of said regenerated communication signal; e) combining said reference symbol covariance matrix estimate R RS ̃ k l and said updated data covariance matrix estimate R data ̃ k l so as to obtain a covariance matrix estimate output based on said combined covariance matrix estimate; and f) forwarding said covariance matrix estimate output to the detector or decoder in b) so as to obtain the updated demodulated or decoded communication signal for each iteration.