A method in a receiving communication node (21,22) for performing channel estimation on a signal received over a radio channel from a transmitting communication node (21,22), which receiving and transmitting communication nodes (21,22) are comprised in a radio communications network, the method comprising - receiving the signal from the transmitting communication node (21,22), - filtering the received signal by applying matched filter to the received signal in a matched filter process resulting in an estimated channel, wherein the method is characterized in comprising: - transforming (301,703) the estimated channel from a frequency domain to a discrete cosine transform domain in a discrete cosine transformation process, - truncating (302,704) the transformed estimated channel in the discrete cosine transform domain by applying a sloped window truncation function having a sloped part, which sloped part has a negative slope and is of an adaptive length, onto the transformed estimated channel, wherein the adaptive length of the sloped part in the discrete cosine transform domain is calculated (303,705) based on channel state information, and - transforming (304,706) the truncated transformed estimated channel from the discrete cosine transform domain to the frequency domain in an inverse discrete cosine transformation process resulting in a channel estimate of the channel estimation. - receiving the signal from the transmitting communication node (21,22), - filtering the received signal by applying matched filter to the received signal in a matched filter process resulting in an estimated channel, wherein the method is characterized in comprising: - transforming (301,703) the estimated channel from a frequency domain to a discrete cosine transform domain in a discrete cosine transformation process, - truncating (302,704) the transformed estimated channel in the discrete cosine transform domain by applying a sloped window truncation function having a sloped part, which sloped part has a negative slope and is of an adaptive length, onto the transformed estimated channel, wherein the adaptive length of the sloped part in the discrete cosine transform domain is calculated (303,705) based on channel state information, and - transforming (304,706) the truncated transformed estimated channel from the discrete cosine transform domain to the frequency domain in an inverse discrete cosine transformation process resulting in a channel estimate of the channel estimation. - transforming (301,703) the estimated channel from a frequency domain to a discrete cosine transform domain in a discrete cosine transformation process, - truncating (302,704) the transformed estimated channel in the discrete cosine transform domain by applying a sloped window truncation function having a sloped part, which sloped part has a negative slope and is of an adaptive length, onto the transformed estimated channel, wherein the adaptive length of the sloped part in the discrete cosine transform domain is calculated (303,705) based on channel state information, and - transforming (304,706) the truncated transformed estimated channel from the discrete cosine transform domain to the frequency domain in an inverse discrete cosine transformation process resulting in a channel estimate of the channel estimation.