The invention relates to a radio base station system for mobile communications, a node in a cellular mobile communications network, as well as a splitter device for use in a radio base system. The radio base station system comprises a first antenna and at least a first, a second and a third radio base station, the first radio base station being connected to the first antenna. The radio base station system comprises a first splitter device, which is connected to the first, the second and the third radio base station.