The invention relates to an apparatus for selecting candidates in a K-Best algorithm of a MIMO decoder. The K-Best algorithm uses a layered structure comprising a first layer and subsequent layers. In each subsequent layer 2L candidates are selected by iteratively carrying out a selection step, wherein in the selection step the apparatus is configured to calculate and select at least two candidates having minimum distance values of a candidate group, and after each iteratively carried out selection step, the selected at least two candidates are sent to a further subsequent layer for iteratively generating a further candidate group of 2L candidates in the further subsequent layer.