A base station for reducing radio wave interference in a wireless communication systems including a plurality of base stations (201-a, 201-b) with different cell sizes, wherein the base station comprises: an interface configured to receive cell size information of its own base station (201-a) and cell size information of neighbor base stations (201-b) from a higher layer entity ; an inter-base station interface configured to receive interference information between a cell of its own base station (201-a) and each of the neighbor cells and load information from each of the neighbor base stations (201-b); a handover parameter control block configured to change handover judgment criteria for each cell of the neighbor base stations (201-b) in order to decide whether or not to handover a terminal within the cell of its own base station (201-a) to the cell of a neighbor base station (201-b) according to cell size information of its own base station (201-a) and cell size information of the neighbor base station (201-b); a handover judgment unit configured to decide whether or not to handover the terminal to the cell of a neighbor base station (201-b) by generating a handover cost function from interference information and load information exchanged with each of the neighbor base stations (201-b), and from a received signal quality measured by and reported from the terminal for the cell of each of the neighbor base stations (201-b), by comparing the generated handover cost function with the handover judgement criteria value, and if the handover cost function value exceeds the handover judgment criteria value, by deciding to initiate a handover of the terminal to the cell of the neighbor base station (210-b); and wherein when the cell size of its own base station (201-a) is larger than the cell size of the neighbor base station (201-b), the handover parameter control block is configured to make the handover easier to perform by lowering the corresponding handover judgment criteria value. an interface configured to receive cell size information of its own base station (201-a) and cell size information of neighbor base stations (201-b) from a higher layer entity ; an inter-base station interface configured to receive interference information between a cell of its own base station (201-a) and each of the neighbor cells and load information from each of the neighbor base stations (201-b); a handover parameter control block configured to change handover judgment criteria for each cell of the neighbor base stations (201-b) in order to decide whether or not to handover a terminal within the cell of its own base station (201-a) to the cell of a neighbor base station (201-b) according to cell size information of its own base station (201-a) and cell size information of the neighbor base station (201-b); a handover judgment unit configured to decide whether or not to handover the terminal to the cell of a neighbor base station (201-b) by generating a handover cost function from interference information and load information exchanged with each of the neighbor base stations (201-b), and from a received signal quality measured by and reported from the terminal for the cell of each of the neighbor base stations (201-b), by comparing the generated handover cost function with the handover judgement criteria value, and if the handover cost function value exceeds the handover judgment criteria value, by deciding to initiate a handover of the terminal to the cell of the neighbor base station (210-b); and wherein when the cell size of its own base station (201-a) is larger than the cell size of the neighbor base station (201-b), the handover parameter control block is configured to make the handover easier to perform by lowering the corresponding handover judgment criteria value. <EOS>