The present invention is related to cellular radio communication network and is a method for determining a Monitored set (MS) of cells associated with an Active set (AS) of cells by a particular ranking of the neighbouring cells associated with each of the cells in the Active set. A neighbouring cell list is created which contains for each active cell its neighbouring cells. These cells can be in a random order and can include other active cells. A scanning operation is done starting with the neighbouring cell (C12 or C31) on top of the list which belongs to the strongest active cell (C11), whereby this cell will be included in the Monitoring set if certain conditions (3,4;respectively, FIG. 4). Next, the list associated with the next strongest active cell (C12) is considered. This scanning is repeated until the maximum size of the Monitoring set has been reached.