A receiving method and a receiver of a telecommunication system are provided. The receiver comprises one or more antennas, a radio frequency unit connected to the antennas for receiving signals transmitted by one or more transmitters using a multitude of channels, and an estimator. The estimator is configured to select one or more channel pairs, each channel of each channel pair being a given distance from each other, determine symbol estimates for the signals of the channels of the channel pairs, remove the effect of data modulation from the signals of the channels of the channel pairs, obtain noise estimates by subtracting the signals of the channels of the channel pairs from each other, and determine a noise covariance matrix for the desired channel on the basis of the obtained noise estimates.